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1 Thifensulfuron-methyl - Volume 3, Annex B.8 : Environmental fate and behaviour July 2014

Thifensulfuron-methyl

Annex B (Volume 3)

B.8 Environmental fate and behaviour


Version history

When What

17-07-2014 Initial Renewal Assessment Report

February 2015 Updated following assessment of

additional information requested by

EFSA in support of renewal

March 2015 Updated following PRAPeR expert

consultation at meeting 126


B.8 ENVIRONMENTAL FATE AND BEHAVIOUR

For this renewal of the approval of the active substance Thifensulfuron-methyl

supplementary data have been submitted by two Applicants (DuPont and a Task Force

comprised of Cheminova A/S and Rotam Agrochemical Europe, henceforth referred to

as the Task Force). The Applicants made completely separate submissions. However

for the purposes of presenting the new information in this updated RAR section, all

acceptable data have been combined and evaluated below in the appropriate

assessment report sections. For the purposes of performing the environmental

exposure assessment, data sets have been combined and the assessment presented here

therefore represents all substance input parameters irrespective of data ownership.

Both Applicants provided new route of degradation studies with parent

Thifensulfuron-methyl in soil. In addition both Applicants submitted extensive

packages of new soil rate of degradation studies and soil adsorption studies for up to

10 metabolites. The new soil degradation and sorption data submitted have been

summarised in Table B.8.1 below. In some cases the UK RMS considered that the

submission of new data was unnecessary, as acceptable data were already available in

the original DAR. Where the UK RMS considered that new data were unnecessary,

the studies have not been evaluated in detail. However they have been checked to

ensure they do not include any data that may be considered adverse (for example

identifying new or existing metabolites at increased levels compared with the original

data). In some cases, existing information from the original DAR has been superseded

by new data that complies with modern data requirements. Where new or existing

study summaries have not been relied on, they have been greyed out. A summary box

outlining the source of the study, the level of UK RMS evaluation and a brief note on

how the data has been used has been included at the beginning for every study.

Table B.8.1 Summary of new data submitted by DuPont and the Task Force

Substance

Study type

Route/rate of

degradation in

aerobic soil

Adsorption in soil

Thifensulfuron-

methyl

DuPont

Task Force

DuPont

Task Force

IN-L9223 DuPont

Task Force

DuPont

Task Force

IN-L9225 - Task Force

IN-L9226 Task Force Task Force

IN-A5546 DuPont

Task Force

DuPont

Task Force

IN-V7160 DuPont DuPont

IN-A4098* DuPont x 3

Task Force

DuPont x 6

Task Force

IN-W8268 Task Force Task Force

IN-RDF00 DuPont DuPont

IN-JZ789 Task Force Task Force

IN-B5528 Task Force Task Force

*As a result of the EFSA peer review an additional rate of degradation study on the IN-A4098

metabolite was identified as being relied upon in the AIR assessment of metsulfuron methyl and

an additional adsorption study was identified as being relied upon in the AIR assessment of

triasulfuron. These additional data have been included in the relevant sections of the RAR

below.


In addition to the data summarised in Table B.8.1 above both Applicants separately

submitted new soil, aqueous photolysis and aqueous hydrolysis studies with

Thifensulfuron-methyl. DuPont additionally submitted new field dissipation studies at

4 EU locations as well as a ready biodegradability study with the active substance.

The Task Force additionally submitted a new anaerobic soil degradation study and

water sediment study with the active substance. All new data are included in this

updated RAR.

Text of the original study summaries from the Draft Assessment Report (DAR) has

been copied into this RAR. Summary boxes have been inserted throughout to

highlight where new data have been evaluated. Original study evaluations have not

been revisited in detail, other than to consider whether the original studies would still

be considered acceptable and to consider whether metabolites previously identified in

those studies are triggered for inclusion in the exposure assessment according to

current guidance.

Existing studies have not generally been revisited but the degradation/dissipation data

have been re-evaluated according to FOCUS kinetics guidance. Where necessary

obsolete Tables and conclusions in relation to DT50s established at the first Annex I

inclusion (approval) have been removed from the evaluation of the original studies

presented in this RAR.

Updated Guidance used in this document is as follows: .......................

FOCUS (2006) “Guidance Document on Estimating Persistence and Degradation

Kinetics from Environmental Fate Studies on Pesticides in EU Registration”

Report of the FOCUS Work Group on Degradation Kinetics, EC Document

Reference Sanco/10058/2005 version 2.0, June 2006

FOCUS (2001). FOCUS Surface Water scenarios in the EU Evaluation process

under 91/414/EEC. Report of the FOCUS working group on Surface water

Scenarios, EC Document Reference Sanco/4802/2001 rev 2 final (May 03).

FOCUS (2007).”Landscape and Mitigation Factors in Aquatic risk assessment.

Volume 1. Extended Summary and Recommendations. Report of the FOCUS

working group on Landscape and Mitigation Factors in Ecological risk assessment,

EC Document Reference Sanco/10422/2005 v2.0.

FOCUS (2011). Generic guidance for Tier 1 FOCUS groundwater scenarios.

Version 2.0, January 2011

FOCUS (2011). Generic guidance for Tier 1 FOCUS surface water scenarios.

Version 1.0, January 2011.

A summary of a literature review conducted by DuPont is included in Appendix 2.

Changes made to the RAR in February 2015 to address key issues highlighted in the

Evaluation Table are highlighted in yellow.

Background information

Thifensulfuron-methyl is a member of the sulfonylurea herbicide group. The intended

use for Thifensulfuron-methyl is on winter and spring cereals, corn/maize and soybean


applied 1 to 2 times per season at doses between 3.75 to 51 g Thifensulfuron-

methyl/ha. The environmental degradation of Thifensulfuron-methyl produces up to

11 metabolites requiring further consideration in either soil, groundwater surface water

or sediment. A summary table of metabolite codes used throughout this section is

shown in Table B.8.2 and a summary of peak occurrence levels of each metabolite is

shown in Table B.8.3. Table B.8.3 also indicates which environmental compartments

metabolites have been included in for the purposes of the environmental exposure

assessment.

The proposed product from DuPont (‘Thifensulfuron-methyl 50SG’) contains

Thifensulfuron-methyl as the only active substance at a concentration of 50 g a.s./kg.

For the Task Force the proposed products from Cheminova A/S and Rotam contain

680 to 682 g/kg Thifensulfuron-methyl and 68 to 70 g/kg Metsulfuron-methyl. The

proposed GAPs are summarised in Table B.8.4.

For the purposes of this Annex I Renewal assessment, only metabolites formed from

Thifensulfuron-methyl have been considered. However for the Task Force products, it

is possible that the Metsulfuron-methyl component would also be a source of common

metabolites (such as IN-A4098, triazine amine). The relative rates of formation of

such common metabolites were considered outside the scope of this assessment. The

UK RMS proposes that the potential environmental exposure of common metabolites

such as IN-A4098 should be addressed at product authorisation level.

Table B.8.2 Summary of the metabolites of Thifensulfuron-methyl in soil, water and sediment

Chemical name/

Trivial name

Code Structure Environmental

compartment

Thifensulfuron-methyl;

TSM;

TIM;

Methyl 3-(4-methoxy-6-

methyl-1,3,5-triazin-2-

ylcarbmoylsufamoyl)

thiophene-2-carboxylate

(IUPAC)

DPX-M6316

S

S

HN

HN

N N

N OCH3

CH3

OO O

OCH3

O

Soil, water and

sediment

Thifensulfuron acid;

TIM acid;

TH-A

IN-L9225

S

S

HN

HN

N N

N OCH3

CH3

OO O

OH

O

Soil, water and

sediment


Chemical name/

Trivial name


compartment

O-Desmethyl

thifensulfuron-methyl;

O-Desmethyl TIM;

Hydroxy-TM;

DM-TH

IN-L9226

S

S

HN

HN

N N

N OH

CH3

OO O

OCH3

O

Soil, water and

sediment

O-Desmethyl

thifensulfuron acid;

O-Desmethyl TIM acid

IN-JZ789

S

S

HN

HN

N N

N OH

CH3

OO O

OH

O

Soil, water and

sediment

2-Ester-3-triuret;

Thiophene acetyl

formylurea

IN-RDF00

S

S

HN

HN

HN

HN

OO O

OCH3

O

O O O

water

2-Acid-3-triuret Unknown

S

S

HN

HN

HN

HN

OO O

OH

O

O O O

Soil, water and

sediment

Thiophene urea Unknown

S

S

HN NH2

OO O

OCH3

O

Water (minor)

2-Ester-3-sulfonamide;

Thifensulfonamid

IN-A5546

S

O

CH3

O

S

NH2

O

O

Soil, water and

sediment


Chemical name/

Trivial name


compartment

2-Acid-3-sulfonamide IN-L9223

S

S

NH2

O O

OH

O

Soil, water and

sediment

Thiophene sulfonimide;

TP-SI

IN-W8268

S

S

NH

O

O

O

soil

Triazine amine;

2-Amino-4-methoxy-6-

methyl-1,3,5-triazine

MM-TA

IN-A4098 H2N

N N

N OCH3

CH3

Soil and water

O-Desmethyl triazine

amine;

4-Amino-6-methyl-

1,3,5-triazin-2-ol

IN-B5528 H2N

N N

N OH

CH3

Soil (minor)

Water (major)

Methyl triazine diol IN-F5475 HO

N N

N OH

CH3

Water (minor)

Triazine urea;

TA-U

IN-V7160

H2NHN

N N

N OCH3

CH3

O

Soil, water and

sediment


Chemical name/

Trivial name


compartment

Thiophenyl triazinyl

amine*

S

O

CH3

O

N

NN

CH3

O

CH3

HN

Water

Methyl-2-(4-methoxy-6-

methyl-1, 3, 5-triazin-2-

yl-amino)-3-thiophene-

carboxylate*

IN-D8858 6*

S

CO2CH

3

N

N

N

CH3

NH

O CH3

Water

*Some uncertainty exists over the structure of a proposed photoproduct identified in the DuPont and Task Force data

sets. The Task Force proposed the structure was thiophenyl triazinyl amine, whilst DuPont proposed the structure

was actually IN-D8856 (arising from photoisomerisation of the thiophene ring). This is further discussed in Section

B.8. but on the basis of the UK RMS evaluation, the evidence supporting the IN-D8856 structure seems more

plausible. A data requirement for further information on this metabolite has been proposed.


Table B.8.3: Major metabolites of Thifensulfuron-methyl

Metabolite Compartment

Maximum applied

radioactivity (%)

Environmental exposure

assessment compartments

IN-A4098

Soil 18.0

PECsoil, PECgw, PECsw Water 19

Sediment 7 a

IN-A5546 Soil 27.7

PECsoil, PECgw, PECsw pH 4 Sterile Buffer 93.1

IN-JZ789 Soil 10


IN-L9223

Soil 19


Sediment 8 a

IN-L9225

Soil 94


Sediment 6 a

IN-L9226 Soil 18.5

PECsoil, PECgw, PECsw Water 13.3

b

IN-RDF00 pH 4 Sterile Buffer 33.6 PECsw

IN-V7160 Soil 9.6


IN-W8268 Soil 29.6 PECsoil, PECgw, PECsw

2-acid-3-triuret Soil 17 PECsoil, PECgw, PECsw

Thiophenyl triazinyl

amine

Water (aqueous

photolysis) 14.3 PECsw

IN-D8858 6 Water (aqueous

photolysis) 15.3 PECsw

a Not a major metabolite in sediment

b Hydrolysis study; max 2% in water-sediment study

Table B.8.4: Summary of the proposed uses of Thifensulfuron-methyl from DuPont and the Task

Force

Crop

Max

number of

applications

Growth stage

Rate of active substance


(g/ha)

DuPont

Winter

cereals

1 BBCH 12-39

(winter and spring

application)

6–37.5

Spring

cereals

1 BBCH 12-39 6–30

Maize 2 BBCH 12-18 5.6–11.25 (total)

Soybean 2 BBCH 10-14 3.75–7.5 (total)

Task Force

Winter

cereals

1 BBCH 13-39

(spring

application only)

51

Spring

cereals

1 BBCH 13-39 41


B.8.1 Route and rate of degradation in soil (IIA 7.1.1, IIIA 9.1.1)

The fate and behaviour studies were conducted using one or both radiolabelled

forms of Thifensulfuron-methyl ([thiophene-2-14

C]-Thifensulfuron-methyl and

[triazine-2-14

C]-Thifensulfuron-methyl). The 14

C-radiolabels were placed in the

most stable ring positions of Thifensulfuron-methyl as indicated in Figure B.8.1.

S

SNH

NH

N

NNO O

O

CH3

OCH

3

O

O CH3

*

+

Figure B.8.1: Positions of radiolabels in Thifensulfuron-methyl * Denotes [thiophene-2-

14C]Thifensulfuron-methyl

+ Denotes [triazine-2-14

C]Thifensulfuron-methyl

B.8.1.1 Aerobic and anaerobic studies (II 7.1.1, IIIA 9.1.1)

B.8.1.1.1 Soil microbial studies

Report: Rapisarda, C. (1984); Aerobic soil metabolism of DPX-M6316

[thiophene-2-14

C]

DuPont Report No.: AMR 236-84

Guidelines: U.S. EPA 162-1

Test material: [14

C]-Thifensulfuron-methyl technical

Lot/Batch #: [thiophene-2-14

C]-Thifensulfuron-methyl: Lot # 1788-151

Purity: Radiochemical purity 99%

Previous

evaluation:

In DAR for original approval (1996).

In the submission received from DuPont it was proposed that this study

does not meet current guidelines as it was not conducted to GLP. In the

DuPont submission this study has been superseded by the study of

Cleland (2011; DuPont-29365). However in the environmental

exposure assessment DuPont proposed retaining information on the

maximum soil formation levels of metabolites IN-A5546 and IN-

W8268 from this original study, as they represented the highest and

most conservative values from all studies. IN-A5546 was actually

detected at higher amounts in the soil photolysis study but this study did

represent peak levels of IN-W8268 (29.6% AR in the Keyport soil).

This study also represented peak levels of the IN-L9226 metabolite

(18.5% in Keyport soil). In the Task Force submission this original

study has been superseded by the study of Simmonds (2012a). The UK

RMS accepted the new route study from the Task Force


In the opinion of the UK RMS the fact that the study was not conducted

to GLP does not automatically mean that the study cannot be considered

to meet current guidelines, because the study was initiated before GLP

was mandatory for environmental safety studies (i.e. 1993). However

the UK RMS has briefly reviewed this original route of degradation

study to determine whether it does meet current guidelines, irrespective

of the GLP status. A number of critical deficiencies were noted. The

study was only conducted with a single radiolabel position (thiophene-14

C) and therefore the fate of the triazine ring after cleavage was not

determined in this study. Soil biomass was not determined over the 52

week study duration. Analysis was via a single method (TLC) with no

confirmatory method. The analytical method was unable to separate the

IN-L9225 and IN-L9223 metabolites and results were therefore reported

as the sum of these metabolites. Due to the inadequate separation of

metabolites and the absence of labelling of the triazine ring, the study is

considered to provide only limited information on the route of

degradation. Due to these deficiencies the UK RMS accepted that this

original study would not meet current guidelines and accepted that

results should be superseded by the modern route of degradation studies

submitted. For completeness the original text of the study summary

from the 1996 DAR has been included below. Since this information is

not now relied on, it has been greyed out. However for the purposes of

conducting a conservative environmental exposure assessment, the

information on peak levels of the IN-W8268 and IN-L9226 metabolites

have been retained

The study (AMR 236-84) was started in 09/1983 and reported by C. Rapisarda

(1984). No GLP statement was included in the report. The US EPA, Pesticide

Assessment Guidelines: Environmental Fate 162-1 was used. The study was

conform to SETAC guideline except for minor deviations (Soil biomass was not

determined but 14

C-glucose was highly mineralised in soils, incubation temperature

was 25°C) and was found acceptable.

Protocol -[thiophene-2-14

C]Thifensulfuron-methyl (radiochemical purity 98%) was

applied to two sterile and non sterile soils at 0.05 mg/kg (80 g a.s./ha), 25°C and 70

% of the field moisture capacity for 52 weeks (in aerobic conditions in darkness).

Soluble and bound residues were extracted (water-organic solvents and NaOH) and

analysed by TLC (and MS for Thifensulfuron acid in Gardena soil). CO2 was

trapped (Na OH) and soil residues was combusted. The characteristics of the test

soils are given in table 7.1.1. No statistical analysis were performed.


Table 7.1.1 - Soil characteristics

Keyport Silt

Loam

Newark, DE

Flanagan

Silt Loam

Rochelle, IL

Gardena Silt

Loam

Rodgers,

ND

Sand (USDA, 2000-50 µm) % 12 2 43

Silt (USDA, 50-2 µm), % 83 81 51

Clay (< 2 µm) % 5 17 6

Organic matter, % 7.5 4.3 5.0

Nitrogen, % 0.3 0.26 0.29

pH 5.2 5.4 8.1

Cation exchange capacity

(mEq/100 g)

15.5 21.2 27.7

Results - Radioactivity was fully recovered. In non sterile soils, Thifensulfuron-

methyl was rapidly degraded (DT50=2-6 days, DT90=30 days). Up to 40-50% of

radioactivity was recovered as 14

CO2. Unextractable residues was 30-37 % of

applied after about 100 days and 20-30 % after 52 weeks (mostly unidentified

alkaline hydrolysable). The metabolic pathway proceeded via formation of the free

carboxylic acid analogue of Thifensulfuron-methyl (Thifensulfuron acid) followed

by hydrolysis to 2-acid-3-sulfonamide and cyclization to thiophene sulfonimide.

Other pathways involved O-demethylation, to form O-demethyl Thifensulfuron-

methyl, and hydrolysis of the sulfonylurea bridge to form 2-ester-3-sulfonamide

(figure. 7.1.1). O-demethyl Thifensulfuron-methyl, Thifensulfuron acid + 2-acid-3-

sulfonamide and thiophene sulfonimide rapidly peaked (max.15%, 18% and 28%)

before decreasing to low levels (remained > 10 % in Flanagan soil only, table

7.1.2). In sterile soils, [thiophene-2-14

C] Thifensulfuron-methyl was degraded at

much slower rates (DT50=24-32 days). No new radiolabelled metabolites were

detected and no 14

CO2 was recovered. Metabolites accumulated and bound residues

were < 10 %.

In conclusion, the DT50 and DT90 of Thifensulfuron-methyl in soil were between

2-6 days and 30 days respectively. Thifensulfuron-methyl and metabolites were

mainly degraded by soil micro-organisms. The thiophene moiety was highly

mineralised (up to 50% over a 52 week period) and degradation products did not

accumulate in non sterile conditions.


Table 7.1.2 - Aerobic degradation of [thiophene-2-14C]-Thifensulfuron-methyl.

Composition of radioactivity in Flanagan soil extracts

Percent of the recovered radioactivity at

weeks 14C-Compounds 0 2 4 6 8 20 52

Non-Sterile Soils

Thifensulfuron-methyl 93.5 15.1 11.2 8.1 7.6 2.6 1.5

Thifensulfuron acid (IN-L9225)+ 2-acid-3-

sulfonamide (IN-L9223) 1.3 23.7 22.9 16.2 18.2 18.1 16.5

2-ester-3-sulfonamide (IN-A5546) 1.4 10.5 5.3 2.9 2.3 0.8 1.8

O-demethyl-Thifensulfuron-methyl (IN-

L9226) 2.1 12.8 13.5 10.5 15.5 5.8 5.1

Thiophene sulfonimide (IN-W8268) 1.3 26.7 28.6 24.7 21.1 11.4 11.2

Polar Material 0.2 3.8 4.2 3.8 1.9 7.8 4.4

Total Extracted 99.8 92.6 85.7 66.2 66.7 46.5 40.5

Sterile Soils

Thifensulfuron-methyl -- 72.8 51.1 40.9 47.7 11.6 9.3


sulfonamide (IN-L9223) -- 3.2 3.6 4.5 8.1 12.9 15.4

2-ester-3-sulfonamide (IN-A5546) -- 10.6 21.1 25.5 12.7 22.6 19.2

O-demethyl- Thifensulfuron-methyl (IN-

L9226)

-- 8.8 15.2 15.1 15.3 21.1 24.6

Thiophene sulfonimide (IN-W8268) -- 3.7 6.5 6.8 11.0 14.1 14.9

Polar Material -- 0.5 1.6 3.6 0.5 4.8 5.8

Total Extracted -- 99.6 99.2 96.4 95.3 87.2 89.2

Table 7.1.3 - Aerobic degradation of [thiophene-2-14C]-Thifensulfuron-methyl.

Composition of radioactivity in Keyport soil extracts

Percent of the recovered radioactivity at

weeks 14C-Compounds 0 2 4 6 8 20

Non-Sterile Soils

Thifensulfuron-methyl 97.1 7.9 2.4 1.6 2.5 1.6


sulfonamide (IN-L9223) 0.3 16.1 10.6 6.1 8.5 6.6

2-ester-3-sulfonamide (IN-A5546) 1.2 1.9 5.8 2.6 4.0 0.5

O-demethyl-Thifensulfuron-methyl (IN-

L9226) 0.8 2.8 3.6 3.9 4.2 2.8

Thiophene sulfonimide (IN-W8268) 0.3 16.6 17.4 7.0 8.3 4.1

Polar Material 0.2 1.0 1.9 3.4 1.6 2.7

Total Extracted 99.9 46.3 41.7 23.1 29.1 18.3

Sterile Soils

Thifensulfuron-methyl -- 66.0 41.4 35.3 25.5 1.6


sulfonamide (IN-L9223) -- 2.4 2.1 2.2 2.5 6.6

2-ester-3-sulfonamide (IN-A5546) -- 18.7 31.1 35.5 43.1 0.5


O-demethyl- Thifensulfuron-methyl (IN-

L9226)

-- 5.0 14.5 15.5 15.7 2.8

Thiophene sulfonimide (IN-W8268) -- 4.1 7.9 8.5 10.5 4.1

Polar Material -- 2.9 2.1 0.8 0.4 2.7

Total Extracted -- 99.1 99.1 97.8 97.7 93.9

Rapisarda, C. (1984)

Report: Cleland, H. (2011); Aerobic soil metabolism of [14

C]-DPX-M6316 (Thifensulfuron-

methyl) in two soils

DuPont Report No.: DuPont-29365

Guidelines: U.S. EPA 162-1 , SETAC Europe (1995) Deviations: None

Testing Facility: Charles River Laboratories, Tranent, Scotland, UK

Testing Facility Report No.: 809280

GLP: Yes

Certifying Authority: Department of Health (U.K.)

Previous

evaluation: None: Submitted by DuPont for the purpose of renewal under

Regulation 1141/2010.

The following study was submitted by DuPont to supersede the original

route of degradation in soil study from the DAR that was no longer

considered acceptable (see Rapisarda, 1984 above). However during the

UK RMS evaluation of this new study, a significant number of major

methodological issues were identified. These issues are briefly

summarised below. Due to these deficiencies the UK RMS concluded

that the new study from Cleland (2011) was also not acceptable and

could not be used in the regulatory assessment. For completeness the

original study summary from DuPont is provided below. Since this

information is not now relied upon, it has been greyed out. It should be

noted that the assessment of the route of degradation in soil in the RAR

is based on the acceptable study submitted by the Task Force (see

Simmonds, 2012a further below).

Summary of UK RMS evaluation of Cleland (2011)

Overall the UK RMS had serious concerns with regards the quality of

data presented, based on the analytical methodology and the quality of

the accompanying chromatography. For simplicity the UK RMS has

produced a bullet point list of the issues raised. Some of these issues

could potentially be addressed by the Applicant by providing further

clarification on the methods used. However the overall poor quality of

the reported analysis suggested that the study would not be acceptable

even if the more minor issues were satisfactorily addressed.

The methodology in section 3.6.2.2 of the original report states

that the soil extracts were analysed by 30 second fraction

collection and then LSC counting. It is difficult to tell if the

chromatograms presented are reconstructed from fraction


collection or analysed directly by a radio-detector. The flow

chart of the analytical methodology omits entirely how the soil

extracts were analysed.

Further clarification regarding the solvents used for extraction is

required since the Applicant has reported in the text of the study

report that the first three extractions use acetone: 0.1 M

ammonium carbonate (aq) (9:1). However, Table 3 of the study

report states the first three extractions to occur with 100ml of

acetonitrile: 0.1M ammonium carbonate (aq) (90:10). In

addition the LOD is not reported.

The chromatography of the standard mixtures by UV (HPLC

system for analysis of soil extracts; Figures 6 of the original

report) appears of poor quality. Since this aspect is important to

determining the overall acceptability of the analytical method the

UK RMS has produced a separate summary comparing the

methods used in this study with those used in the new route sudy

provided by the Task Force. This summary follows the

evaluation of the Task Force study of Simmonds, 2012a.

The chromatography in Figures 8-11 is at best of mixed quality

in the opinion of the UK RMS. This raises general doubts about

the identification (by retention time) and quantification of several

of the components.

Thifensulfuron-methyl and thifensulfuron acid are correctly

identified using retention time and MS data. In this regard there

is consistency between the studies provided by DuPont and the

Task Force. However the DuPont study at several timepoints

incorrectly assigns the peak that should be thifensulfuron acid as

o-desmethyl Thifensulfuron-methyl.

The %AR values for IN-L9225 and IN-L9226 at some

timepoints were very different depending on whether they were

labelled with thiopene or triazine. This should not be the case as

both of these metabolites contain both labelled moieties.

The RMS notes that there appears to be an inexplicable rise and

fall of several metabolites in different soils. For example

metabolites decline below the detectable level at one or more

timepoints and then are recorded at substantial levels at a later

timepoint. This is observed with IN-A4098, IN-V7160 and IN-

L9223. Some of this may be due to mis-identification of

metabolites.

IN-L9223 only contains the moiety which is labelled in the

thiophene position, and IN-V7160 and IN-A4098 both contain

the moiety which is labelled in the triazine position. However,

IN-L9223 is present in substantial amounts at every time point in

both soils treated with triazine labelled test substance. Similarly

the IN-V7160 and IN-A4098 metabolite is occasionally detected

in the thiophene labelled samples.

IN-L9223 has a retention time of approximately 13.1 min (Figure

7) but comparison of data in Tables 8-11 with the

chromatograms in Figures 8-11 suggest that the peak at 4-5 min


has been identified as IN-L9223.

The peak at 4-5 min is assigned to IN-L9223 where the triazine

labelled test substance was used. However the triazine labelled

part of the molecule is not present in IN-L9223. This also

suggests that the peak at 4-5 min has been mis-assigned.

The peak at 4-5 min is effectively unretained by the column and

therefore could be made up of one or more polar components.

The study author records unidentified polar components and

unidentified non-polar components but there is no definition of

either – the retention time at which uncharacterised polar

material become characterised components is not recorded.

IN-L9225 is consistently identified as the broad peak around 30

min. In the Sandy Loam soil (thiophene label) this peak is

present in the 45 day sample but in Table 10 it is recorded as not

detected. It is not clear if MS data was used to label the peak as

not detected. The data are unclear as IN-L9225 reappears at 59

days at 20% AR, roughly the same as at 30 days.

Where the triazine labelled test substance was used, a broad peak

at 10-15 min is labelled as IN-V7160. No retention time is given

for a standard of IN-V7160 in this HPLC system. A peak at the

same retention time (see Figures 10 and 11; very broad from 9 to

15 min) is labelled as IN-A4098 in the 120 day samples (Tables

9 and 11) and from 59 days in the two tables. It is not clear if

there is any evidence other than these chromatograms for this

change in identification. As the report states that MS data was

not used, it is not clear if it was based on the second HPLC

system. In Table 9 IN-A4098 is recorded as trace, 16%, nd, nd,

trace, 24%, nd, 25%. This pattern suggests there is a problem

with its identification.

It is difficult to see how the data for the 120 day sample in Table

11 could come from the data in the chromatogram (Sandy loam;

triazine label; Figure 11). For example IN-L9226, IN-V7160,

and IN-A4098 seem to have been identified and quantified from

what is a broad zone of radioactivity between 9 and 28 min. This

same comment applies to various other sampling timepoints.

Detection of IN-L9226 fluctuates in Tables 10 and 11. As the

pathway suggests that it is only formed from the parent this

seems inconsistent and suggests a problem with identification.

The same could be said of IN-V7160 in Table 9 (it is only

directly formed from IN-L9225).

Evidence is presented for the identification of DPX-M6316 and

IN-L9225 by mass spectroscopy. It is based on the unlabelled

material present in the application solution; it is not clear if

reference substances were ‘admixed’ into these samples before

analysis (presumably not).

The report states that IN-L9223, IN-A4098, IN-V7160, and IN-

L9226 were identified by comparison of retention time using the

LC-MS method. This probably means that this HPLC method

was used with radiolabel detection (of extracts) and UV detection


of the standards. This confirmatory co-elution method is still

reverse phase chromatography using an ODS column; it is not

very different from the original HPLC method and brings into

question whether it is different enough for confirmation. No

chromatograms are presented for this confirmatory analysis.

Bearing in mind the poor quality of the original chromatography

there would have to be doubts about this as a confirmatory

method of identification.

As stated above, due to these methodological issues, the UK RMS

considered the study to be unacceptable. The Applicant study summary

is provided below, highlighted in grey to indicate that it is not currently

accepted.

Executive summary:

The biotransformation of [14

C]-Thifensulfuron-methyl was studied in two agricultural soil in

the laboratory for up to 120 days. [14

C]-Thifensulfuron-methyl was applied at the rate of

0.6 g a.s./g oven dry soil. Samples were incubated under aerobic conditions in darkness at

20 2C, with a soil moisture of ca. 50% of maximum water holding capacity (0 bar

moisture).

Material balance, calculated as the percent of applied radioactivity (% AR), was maintained

90% throughout the study. Initial (Day 0) solvent-extractable residues ranged from 94.4 to

97.9% AR and decreased to 4.0-30.8% AR at 120 days. Non-extractable residues increase to

57.1–61.5% AR, while evolution of 14

CO2 reached maximum values of 16.1–43.9% AR, at

120 days.

HPLC analysis of the soil extracts demonstrated that [14

C]-Thifensulfuron-methyl rapidly

declined in each soil type. [14

C]-Thifensulfuron-methyl decreased from quantitative levels at

Day 0 (immediately after application) to values of 0% AR in Tama soil treated with

[thiophene-2-14

C]-Thifensulfuron-methyl, 1.01% AR in Nambsheim soil treated with

[thiophene-2-14

C]-Thifensulfuron-methyl, 0% AR in Tama soil treated with [triazine-2-14

C]-

Thifensulfuron-methyl and 0.73% AR in Nambsheim soil treated with [thiophene-2-14

C]-

Thifensulfuron-methyl at Day 120. Biotransformation data is presented in Table B.8.6 to

Table B.8.9.

In the silty clay loam soil treated with [thiophene-2-14

C]-Thifensulfuron-methyl, the amount

of test item decreased to a value of 0% AR at Day 120. The largest metabolite was identified

as IN-L9225 and accounted for a maximum of 47.71% AR at Day 7, before decreasing to

1.07% AR at Day 45. The metabolite identified as IN-L9226 accounted for a maximum of

39.45% AR at Day 3, before decreasing to 0.29% AR at Day 60.

In the sandy loam soil treated with [thiophene-2-14

C]-Thifensulfuron-methyl, the amount of

test item decreased to a value of 1.01% AR at Day 120. The largest metabolite was identified

as IN-L9225 and accounted for a maximum of 73.18% AR at Day 3, before decreasing to

0.78% AR at Day 120. The metabolite identified as IN-L9226 accounted for a maximum of



In the silty clay loam soil treated with [triazine-2-14

C]-Thifensulfuron-methyl, the amount of

test item decreased to a value of 0% AR at Day 120. The largest metabolite was identified as

IN-L9225 and accounted for a maximum of 40.65% AR at Day 7, before decreasing to

0.77% AR at Day 120. The metabolite identified as IN-A4098 accounted for a maximum of


In the sandy loam soil treated with [triazine-2-14

C]-Thifensulfuron-methyl, the amount of test

item decreased to a value of 0.73% AR at Day 120. The largest metabolite was identified as

IN-L9225 and accounted for a maximum of 68.44% AR at Day 7, before decreasing to

25.97% AR at Day 30. The metabolite identified as IN-A4098 accounted for a maximum of


I. MATERIALS AND METHODS

A. MATERIALS

1. Radiolabelled test material: [14



C]-Thifensulfuron-methyl: 3631034

[triazine-2-14


Radiochemical purity: [thiophene-2-14

C]-Thifensulfuron-methyl: 97.2%

[triazine-2-14


Specific activity: [thiophene-2-14

C]-Thifensulfuron-methyl: 10.7

Ci/mg

[triazine-2-14


Ci/mg

Stability of test compound: Not determined

2. Soils

The study was conducted with two soil types of varying characteristics. The soils

were freshly collected from the top 20 cm of agricultural land and stored refrigerated

prior to use. A summary of the physical and chemical properties of the soils is

provided in Table B.8.5. The percent sand, silt, and clay are quoted on the basis of

the USDA classification.


Table B.8.5 Physiochemical characteristics of test soils

Parameter Results Reference

Soil Identity Tama Nambsheim

Charles River Code S675 S676

Geographic Location Toulon/Doug Murray

Farm, Stark County,

Illinois, USA

European Research and

Development Center

(ERDC), 24 rue du Moulin,

68740, Nambsheim, France

Texture Class Silty Clay Loam Sandy Loam USDA 1995 textural

classification systema Sand (%)

Silt (%)

Clay (%)

18 72

51 19

31 9

Texture Class Light Clay Sandy Loam International Textural

Classification Systema Sand (%) 34 82

Silt (%) 35 9

Clay (%) 31 9

pH (in water) 6.7 7.7 a

pH (in 0.01 M CaCl2) 6.4 7.4 a

Organic Matter (%) 5.7 3.8

Walkley-Black

methoda

Initial Soil Biomass

(µg organic carbon/g soil) 253.67 264.48

by fumigation

methodb

Final Soil Biomass

(µg organic carbon/g soil) 185.40 153.87

by fumigation

methodb

Cation Exchange Capacity

(mEq/100g) 17.3 10.7

a

Moisture Content (%) at 0 bar 84.9 59.1 a

Moisture Content (%) 29.1 18.1 b

a Determined by Agvise Laboratories as a separate GLP study

b Determined by Charles River under this study number.

B. STUDY DESIGN

1. Experimental conditions

Portions of sieved soil (50 g oven dry soil equivalent) were adjusted to moisture a

content equivalent to ca 50% of their respective maximum water holding capacities at

0 bar applied pressure. A solution of radiolabelled test substance, dissolved in water

with 0.1% acetonitrile as co-solvent was prepared and applied to soil samples, in

separate test vessels, at a rate of 0.6 mg a.s./kg oven dry soil. Additional samples for

determination of biomass were prepared and incubated following application of an

equal amount of blank application solution. Water lost due to evaporation was

replaced and soils were incubated in the dark at 20 2C under aerobic conditions for

up to 120 days in a flow through system which allowed the trapping of evolved

carbon dioxide and volatile organic compounds. 2. Sampling

Microbial biomass was determined at zero time and Day 120. Soil samples were

taken for analysis at zero time and 3, 7, 14, 21, 30, 45, 59, 90, and 120 days after

application.


3. Description of analytical procedures

Duplicate sodium hydroxide solutions used to trap volatile components, and a single

ethanediol used to trap organic volatiles, were replenished and analysed at each

sampling intervals. Soil samples were subjected to the following extraction sequence:

The soil was transferred to a pre-weighed plastic pot with 100 mL acetone: 0.1 M

ammonium carbonate (aq) (9:1). Samples were sonicated at ca 50ºC for ca

15 minutes. Extracts and residues were separated by centrifugation (ca 4000 rpm for

ca 15 minutes). This was repeated a twice for extracts two and three. Residues were

extracted a fourth time by sonicating at ca 50ºC with 0.1 M ammonium carbonate (aq)

for ca one hour. Extracts and residues were separated by centrifugation. Residues

were extracted a fifth time by sonicating at ca 50ºC with 100 mL acetone for

ca 15 minutes. This was repeated for extract six. Volumes of individual extract

solutions were made up to fixed volumes of 130 mL with the appropriate extractant

and triplicate aliquots taken from each extract for LSC.

Extracts were stored separately, but were combined for analysis. The volume of the

combined extract was measured and triplicate aliquots were taken and submitted for

LSC to determine the radioactive content.

Soil samples aliquots were combusted and 14

C levels were measured using LSC. The

soil extracts were analysed using reverse phase HPLC with a gradient of acetonitrile

and water adjusted to pH 2.2 with trifluoroacetic acid. The eluent was passed through

an UV detector (254 nm) to detect reference standard and a radiodetector to detect

radiolabelled components. The limit of quantification for radiolabelled components,

using representative blank samples, was determined as 0.47% AR.


II. RESULTS AND DISCUSSION

A. DATA

Table B.8.6 Biotransformation of [thiophene-2-14

C]-Thifensulfuron-methyl, expressed as %

AR, in silty clay loam soil incubated at 20C

Component

Sampling times (Days)

0 3 7 14 21 30 45 59 90 120

Thifensulfuron-

methyl 86.71 1.73 0.81 nd nd nd 1.53 nd na na

IN-L9223 0.98 7.06 9.11 4.77 7.19 5.21 6.38 11.04 na na

IN-A4098 nd 0.25 nd nd 1.21 nd nd nd na na

IN-V7160 nd 0.17 nd nd nd nd nd nd na na

IN-L9226 0.42 39.45 nd nd nd nd 2.32 0.29 na na

IN-L9225 nd 21.54 47.71 17.55 13.12 5.71 1.07 nd na na

Unidentified Polar

Components 1.43 0.17 nd nd 1.33 nd 1.06 nd na na

Unidentified Non-

Polar Components 4.86 3.21 nd nd 5.84 3.15 2.37 nd na na

Total Extractable

Radioactivity 94.39 73.58 57.63 22.32 27.98 14.06 14.73 11.33 5.06 3.99

14CO2 ns 3.92 9.00 17.87 24.76 29.25 33.81 37.89 41.44 43.90

Non-extractable

Residue <LOQ

a 21.63 31.29 60.59 46.48 59.76 54.69 49.06 49.43 52.91

Material Balance 94.39 99.13 97.92 100.78 99.22 103.07 103.23 98.28 95.93 100.80

nd = Not Detected ns = Not Sampled a <LOQ = Below Limit of Quantification


Table B.8.7 Biotransformation of [triazine-2-14


AR, in silty clay loam soil incubated at 20C

Component


0 3 7 14 21 30 45 59 90 120

Thifensulfuron-

methyl 93.29 2.28 1.39 0.36 nd 0.22 0.26 0.20 0.19 nd

IN-L9223 1.84 7.94 10.81 6.51 12.08 9.19 12.80 3.24 4.45 7.16

IN-A4098 0.08 16.94 nd nd 0.13 23.74 nd 25.47 30.07 20.88

IN-V7160 nd nd 13.63 17.62 19.74 1.11 29.80 5.52 nd nd

IN-L9226 nd 5.68 0.14 0.64 nd nd nd nd nd 0.75

IN-L9225 nd 21.89 40.65 11.44 10.32 2.58 1.69 0.93 0.26 0.77

Unidentified polar

components 0.66 21.73 3.47 7.38 10.39 5.15 5.47 10.78 5.10 6.90

Unidentified

non-polar

components

2.01 3.64 nd 0.36 1.78 0.69 nd nd nd 0.70

Total extractable

radioactivity 97.88 80.11 70.08 44.34 54.45 42.46 50.03 46.14 40.08 37.15

14CO2 ns <LOQ

a 1.31 3.16 2.99 7.09 10.21 11.29 16.10 15.88

Non-extractable

residue 0.44 19.21 28.78 51.77 44.04 57.55 44.18 46.30 47.00 44.32



Table B.8.8 Biotransformation of [thiophene-2-14

C]-Thifensulfuron-methyl, expressed as

% AR, in sandy loam soil incubated at 20C

Component


0 3 7 14 21 30 45 59 90 120

Thifensulfuron-methyl 85.56 0.27 nd nd nd nd nd 0.67 nd 1.01

IN-L9223 0.63 2.86 27.66 25.20 3.04 4.44 6.46 4.48 10.30 8.23

IN-A4098 nd 2.46 nd nd nd nd nd nd nd nd

IN-W8268 nd nd nd nd nd 0.67 nd nd nd nd

IN-V7160 0.47 0.35 0.39 nd nd nd nd nd nd nd

IN-L9226 3.58 0.31 9.24 nd nd 6.51 20.87 nd 7.31 0.73

IN-L9225 nd 73.18 20.72 23.85 46.07 23.30 nd 21.44 nd 0.78

Unidentified polar

components 2.18 3.14 8.13 4.03 nd nd 4.62 2.94 0.61 0.37

Unidentified non-polar

components 4.71 0.72 4.13 1.06 1.16 5.24 3.83 0.67 nd nd

Total extractable

radioactivity 97.13 83.50 70.28 54.14 50.26 40.15 35.80 31.60 18.95 11.12

14CO2 ns 1.49 3.68 7.16 9.37 11.43 16.60 19.27 23.50 27.23

Non-extractable residue <LOQa 13.49 24.24 36.52 39.27 48.11 46.72 48.16 54.32 61.46




Table B.8.9 Biotransformation of [triazine-2-14


AR, in sandy loam soil incubated at 20C

B. MASS BALANCE

In the silty clay loam soil (Tama) treated with [thiophene-2-14

C]Thifensulfuron-methyl,

material balance was quantitative (mean = 99.3% AR) for all samples. Solvent

extractable radioactivity in the soil decreased from 94.4% AR at Day 0 to 4.0% AR after

120 days. Bound residues increased to a maximum of 59.8% AR at Day 30.

Radiolabelled volatile organics were below the limit of quantification throughout the

study. 14

CO2 accounted for a maximum of 43.9% AR at Day 120.

In the sandy loam soil (Nambsheim) treated with [thiophene-2-14

C]Thifensulfuron-

methyl, material balance was quantitative (mean = 98.5% AR) for all samples. Solvent




study. 14


In the silty clay loam soil (Tama) treated with [triazine-2-14





Component


0 3 7 14 21 30 45 59 90 120

Thifensulfuron-

methyl 91.79 0.20 nd nd nd nd nd nd nd 0.73

IN-L9223 2.79 2.91 4.00 5.35 4.79 5.66 9.93 6.51 4.28 4.44

IN-A4098 0.36 nd 0.06 nd nd 0.21 nd 16.35 16.82 5.16

IN-V7160 nd 4.34 4.99 8.02 11.69 11.67 15.19 0.94 nd 1.56

IN-L9226 2.27 39.88 nd nd nd nd 21.56 nd 0.18 4.92

IN-L9225 nd 36.71 68.44 49.41 43.16 25.97 nd 17.56 10.42 5.82

Unidentified

polar

components

0.71 0.15 2.45 2.64 4.42 4.29 3.35 4.50 4.68 6.58

Unidentified

non-polar

components

nd 0.65 nd nd nd 1.15 2.50 3.16 1.89 1.55

Total

extractable

radioactivity

97.91 85.13 79.94 65.42 64.38 48.95 52.53 49.02 38.27 30.77

14CO2 ns 0.47 0.77 1.42 2.35 3.65 5.64 8.39 12.47 16.52

Non-extractable

residue <LOQ

a 14.89 18.48 32.08 35.08 50.17 44.92 50.19 56.79 57.01

Material

Balance 97.91 100.49 99.19 98.92 101.81 102.77 103.09 107.60 107.53 104.30

nd = Not Detected

ns = Not Sampled a <LOQ = Below Limit of Quantification



study. 14


In the sandy loam soil (Nambsheim) treated with [triazine-2-14






study. 14


C. BOUND AND EXTRACTABLE RESIDUES

The percentage of radioactivity in the extractable fraction decrease steadily from Day 0

through Day 120 for both soils, while the bound residues generally increased. In the silty

clay loam soil (Tama), bound residues increased to a maximum of 57.6-59.8% AR at Day

30. In the sandy loam soil (Nambsheim), bound residues increased to a maximum of

57.1-61.5% AR at Day 120.

D. VOLATILISATION

Volatile radioactivity identified as 14

CO2 accounted for maximum values of 16.5–43.9%

AR. Radiolabelled volatile organics were below the limit of quantification throughout

the study.

E. TRANSFORMATION OF PARENT COMPOUND

Biotransformation data is presented in Table B.8.6 to Table B.8.9 .

In the silty clay loam soil treated with [thiophene-2-14

C]Thifensulfuron-methyl, the

amount of test item following application decreased to a value of 0% AR at Day 120.

The largest metabolite was identified as IN-L9225 and accounted for a maximum of

47.7% AR at Day 7, before decreasing to 1.1% AR at Day 45. The metabolite identified

as IN-L9226 accounted for a maximum of 39.4% AR at Day 3, before decreasing to

0.3% AR at Day 60.

In the sandy loam soil treated with [thiophene-2-14

C]Thifensulfuron-methyl, the amount

of test item following application decreased to a value of 1.0% AR at Day 120. The

largest metabolite was identified as IN-L9225 and accounted for a maximum of

73.2% AR at Day 3, before decreasing to 0.8% AR at Day 120. The metabolite identified

as IN-L9226 accounted for a maximum of 20.9% AR at Day 45, before decreasing to

0.7% AR at Day 120.

In the silty clay loam soil treated with [triazine-2-14

C]Thifensulfuron-methyl, the amount

of test item following application decreased to a value of 0% AR at Day 120. The largest

metabolite was identified as IN-L9225 and accounted for a maximum of 40.6% AR at

Day 7, before decreasing to 0.8% AR at Day 120. The metabolite identified as IN-A4098

accounted for a maximum of 30.1% AR at Day 90, before decreasing to 20.9% AR at

Day 120.

In the sandy loam soil treated with [triazine-2-14

C]Thifensulfuron-methyl, the amount of

test item following application decreased to a value of 0.7% AR at Day 120. The largest


metabolite was identified as IN-L9225 and accounted for a maximum of 68.4% AR at

Day 7, before decreasing to 26.0% AR at Day 30. The metabolite identified as IN-A4098

accounted for a maximum of 16.8% AR at Day 90, before decreasing to 5.2% AR at

Day 120.

III. CONCLUSION

The fate of [14

C]-Thifensulfuron-methyl in two fresh soils obtained from natural sources was

studied. [14

C]-Thifensulfuron-methyl degraded into several degradation products. The major

metabolites were identified as IN-L9225 (maximum 73% AR), IN-L9226 (40%) and

IN-A4098 (30%). There was an increase in the non-extractable residues indicating that [14

C]-

products were incorporated into the soil, which was accompanied by a maximum CO2

evolution of ca 44% AR.

(Cleland, H., 2011)

Report: M. Simmonds (2012a) [14

C]-Thifensulfuron-Methyl: Route and Rate of

Degradation in Four Soils at 20ºC. Battelle UK Ltd [Cheminova A/S], Unpublished report

No.: WB/10/004 [CHA Doc. No. 283 TIM]

Guidelines: OECD Guideline for the Testing of Chemicals No. 307, 2002

Deviations from OECD 307/2002 guidelines and any omissions of 307 mandated data are

detailed.

GLP: GLP compliance certification (Battelle UK Ltd), 2010

Certifying authority: Department of Health (U.K)

Previous

evaluation:

None: Submitted by the Task Force for the purpose of renewal under


The following study was fully evaluated by the UK RMS and considered

acceptable. Minor deviations from the guidelines are detailed in the

study summary below, based on the study summary from the Task

Force. A separate kinetic assessment is provided in Section B.8.1.4.

This study represents the only acceptable data that was available on the

route of degradation in aerobic soils. It has been used to derive

formation fractions and degradation rates for the major soil metabolites.

In a degradation study, the route and rate of degradation of 14

C-Thifensulfuron-methyl was

studied in four UK soils (sandy loam Longwoods, loam Farditch, sandy clay loam

Lockington and loam Kenslow). The study was carried out under aerobic conditions in a

closed system in darkness at 20 ± 2°C. Soil properties are detailed inTable B.8.11. Soil

microbial activity was measured at the initial and end points of the study.

The soils (100 g dry weight, 2mm sieved) were incubated at a moisture content between the

water holding capacity at 0.33 bar (pF 2.5) and 0.1 bar (pF 2). Thiophene-[2-14

C] (Specific

radioactivity 5.17 MBq/g, purity 98.8%) and Triazine-[2-14

C] (Specific radioactivity 5.18

MBq/g, purity 99.4%) labelled Thifensulfuron-methyl was applied to the soil surface at an

application rate of 100 μg/100g soil, equivalent to a field application rate of 1 mg/kg dry soil

weight. This is equivalent to 0.25 kg/ha (an exaggerated application rate to aid the analytical


requirements of the study) when assuming an equal distribution in the upper 2.5 cm soil layer,

and a soil bulk density of 1.0 g/cm3. Samples were incubated for up to 120 days and aerobic

conditions were maintained by the constant passage of moist carbon dioxide free air.

Following application, the soil flasks were connected to a series of trapping solutions to

collect any volatile products evolved (the first trapping flask contained ethylene glycol

followed by two flasks containing 2M potassium hydroxide) and at intervals of 0, 1, 3, 7, 14,

30, 60, 90 and 120 days after application duplicate flasks were removed from the incubation

system for analysis. The soil samples then underwent two successive extraction procedures,

namely with methanol/water/formic acid (80:20:1 v/v/v) by shaking at ambient temperature

(four separate extractions employed), followed by a further shake at ambient temperature

using acetonitrile/water (1:1 v/v). The remaining soil was extracted by repeating the process

to give a total of three successive extractions. The extracted soil samples were air-dried,

ground to a fine powder and the residual radioactivity quantified by combustion analysis. At

each sampling interval the radioactivity in the trap solutions associated with each sample was

quantified by liquid scintillation counting (LSC).

All extracts from each soil sample were combined and analysed by reverse phase high

performance liquid chromatography (HPLC). Liquid Chromatography-Mass Spectrometry-

Mass Spectrometry (LC-MS/MS) of treatment dilutions and representative soil extracts

produced structural confirmation of the test item and metabolites present.

Individual recoveries were all within the required range of 90 to 110% AR, namely 93.8% -

104.2% AR for the thiophene-labelled soils and 94.4% - 103.2% AR for the triazine-labelled

soils.

The distribution of radioactivity was slightly different between soil types, most noticeably for

the Longwoods sandy loam, where the level of extractable radioactivity remained higher

throughout the study. The remaining soils demonstrated a much more significant decline in

extractable radioactivity over the duration of the study.

In total, five metabolites (IN-L9225, IN-JZ789, 2-Acid-3-triuret, IN-L9223, IN-A4098)

reached trigger criteria concentrations (>10% single time point, >5% on two consecutive time

points or >5% at the end of the study). Many of these metabolites exceeded all three trigger

criteria (Table B.8.10).

Table B.8.10 Summary of metabolites versus key trigger values

Metabolite >10% at any single time

point

>5% at two or more

time points

>5% at end of study

IN-L9225 X X X

IN-JZ789 X X

2-Acid-3-triuret X X X

IN-L9223 X X X

IN-A4098 X X X

2. Soil


Table B.8.11 Soil Physicochemical Properties

Soil name pH

(H2O)

OM

%

(OC

%)

Sand1

%

Silt1

%

Clay1

%

CEC

meq/

100g

Biomass

µg C/g soil2

(Initial/final)2

Classifi

cation

MWHC

%

Bulk

density

(gm/cc)

Longwoods 7.5 2.95

(1.71) 72 13 15 14.0 674.8/574.3

Sandy

loam 43.6

1.31

Farditch 6.5 6.41

(3.27) 36 47 17 14.6 867.6/932.5 Loam 90.4

0.95

Lockington 5.5 5.86

(3.40) 51 20 29 22.1

1534.4/1461.

9

Sandy

Clay

loam

80.2 1.05

Kenslow 5.5 7.00

(4.06) 48 39 13 11.9

1195.4/1089.

1 Loam 83.5

0.98

1 USDA Textural class;

2 initial biomass performed at Chemex Environmental International

2biomass was above the minimum required by OECD 307 and therefore acceptable

CEC = Cation exchange capacity, OM = Organic matter, MWHC = Maximum water holding capacity

A detailed account of the soil histories were provided by the applicant and were found to be

acceptable for the purposes of the study.

Table B.8.12 Mean Distribution of Radioactivity as Percent of Applied, Longwoods Sandy

loam, Thiophene-label

DAT

MeOH/Water/Formic

acid

Soil Extract

Acetonitrile/Water

Soil Extract

Unextracted

from soil

Total

Volatiles*

Mass

Balance

0 99.12 NA 0.75 NA 99.87

1 92.74 4.28 2.35 0.14 99.50

3 89.25 5.48 3.32 0.36 98.41

7 89.60 6.20 6.74 0.58 103.11

14 89.42 4.92 7.44 0.82 102.59

29 84.91 5.04 5.87 2.02 97.83

61 80.40 5.63 14.45 3.37 103.84

90 72.97 6.21 17.63 5.48 102.28

120 64.46 9.83 21.63 6.76 102.66

* Present in KOH traps and confirmed as 14

CO2


Table B.8.13 Mean Distribution of Radioactivity as Percent of Applied, Farditch loam,

Thiophene-label

DAT

MeOH/Water/Formic

acid

Soil Extract

Acetonitrile/Water

Soil Extract

Unextracted

from soil

Total

Volatiles*

Mass

Balance

0 97.61 NA 2.37 NA 99.98

1 87.32 7.03 4.50 0.14 98.98

3 82.66 8.60 7.25 0.44 98.94

7 78.58 8.50 11.66 0.94 99.68

14 67.99 9.35 20.55 1.40 100.14

29 55.16 8.81 29.24 4.98 98.17

61 38.60 12.65 37.39 9.43 98.06

90 23.92 12.25 49.12 13.51 98.79

120 16.93 12.46 51.00 15.71 96.09


CO2

Table B.8.14 Mean Distribution of Radioactivity as Percent of Applied, Lockington Sandy

Clay Loam, Thiophene-label

DAT

MeOH/Water/Formic

acid

Soil Extract

Acetonitrile/Water

Soil Extract

Unextracted

from soil

Total

Volatiles*

Mass

Balance

0 97.43 NA 2.19 NA 99.72

1 88.18 6.52 3.97 0.15 98.82

3 83.02 9.26 6.34 0.40 99.02

7 82.16 7.49 9.06 0.81 99.51

14 70.42 10.47 18.74 1.71 101.33

29 52.01 10.02 31.02 6.08 99.11

61 28.32 15.01 43.86 13.69 100.88

90 21.00 12.52 43.03 20.30 96.83

120 18.08 12.69 44.65 19.88 95.29


CO2


TableB.8.15 Mean Distribution of Radioactivity as Percent of Applied, Kenslow Loam,

Thiophene-label

DAT

MeOH/Water/Formic

acid

Soil Extract

Acetonitrile/Water

Soil Extract

Unextracted

from soil

Total

Volatiles*

Mass

Balance

0 97.39 NA 2.26 NA 99.65

1 85.10 7.30 5.95 0.24 98.58

3 73.67 12.43 11.67 0.90 98.67

7 71.06 10.30 16.59 1.56 99.50

14 60.17 8.09 30.81 3.15 102.22

29 39.37 10.61 39.80 9.92 99.69

61 19.69 9.44 52.73 15.50 97.35

90 19.11 8.04 48.80 22.57 98.51

120 16.45 10.09 48.11 24.48 99.12


CO2

Table B.8.16 Mean Distribution of Radioactivity as Percent of Applied, Longwoods Sandy

Loam, Triazine-label

DAT

MeOH/Water/Formic

acid

Soil Extract

Acetonitrile/Water

Soil Extract

Unextracted

from soil

Total

Volatiles*

Mass

Balance

0 101.07 NA 0.59 NA 101.66

1 98.41 NA 2.01 0.01 100.42

3 93.44 4.01 3.35 0.03 100.83

7 89.01 5.91 6.87 0.07 101.85

14 85.95 5.26 7.30 0.16 98.67

29 78.54 9.75 9.46 0.44 98.18

61 77.86 8.82 14.16 0.73 101.56

90 68.29 10.22 20.69 1.44 100.64

120 62.53 16.50 20.82 1.41 101.25


CO2


Table B.8.17 Mean Distribution of Radioactivity as Percent of Applied, Farditch Loam,

Triazine-label

DAT

MeOH/Water/Formic

acid

Soil Extract

Acetonitrile/Water

Soil Extract

Unextracted

from soil

Total

Volatiles*

Mass

Balance

0 99.52 NA 1.58 NA 101.10

1 96.15 1.65 3.47 0.01 101.28

3 92.01 4.86 4.31 0.04 101.22

7 84.89 6.87 8.02 0.11 99.89

14 78.75 7.78 10.11 0.46 97.09

29 58.13 14.26 21.15 2.65 96.18

61 39.56 14.34 35.88 8.41 98.18

90 26.42 12.54 48.83 13.70 101.48

120 19.89 13.17 48.33 17.17 98.55


CO2

Table B.8.18 Mean Distribution of Radioactivity as Percent of Applied, Lockington Sandy

Clay Loam, Triazine-label

DAT

MeOH/Water/Formic

acid

Soil Extract

Acetonitrile/Water

Soil Extract

Unextracted

from soil

Total

Volatiles*

Mass

Balance

0 99.75 NA 1.80 NA 101.55

1 93.99 4.31 2.26 0.01 100.57

3 88.79 6.80 5.29 0.04 100.91

7 79.70 8.43 11.78 0.43 100.33

14 69.28 10.84 15.07 1.27 96.45

29 43.88 18.09 28.42 4.61 94.99

61 25.77 16.44 47.08 8.23 97.52

90 19.46 14.09 50.12 14.00 97.66

120 22.68 15.57 48.04 12.99 99.27


CO2


Table B.8.19 Mean Distribution of Radioactivity as Percent of Applied, Kenslow Loam,

Triazine-label

DAT

MeOH/Water/Formic

acid

Soil Extract

Acetonitrile/Water

Soil Extract

Unextracted

from soil

Total

Volatiles*

Mass

Balance

0 99.81 NA 1.95 NA 101.76

1 92.38 5.23 2.95 0.02 100.58

3 86.77 6.90 7.62 0.15 101.43

7 72.75 10.49 17.15 0.67 101.05

14 58.81 8.41 26.56 2.90 96.67

29 37.84 14.52 37.43 7.71 97.49

61 23.52 10.77 47.26 15.56 97.11

90 20.69 9.21 49.06 18.33 97.27

120 18.45 9.68 49.90 21.97 100.00


CO2

B. Extractable radioactivity of parent compound and associated metabolites DATA

Table B.8.20 Composition of Extractable Radioactivity by HPLC as percent of applied,

Longwoods Sandy Loam, Thiophene-label

DAT % AR

Th

ifen

sulf

uro

n

-met

hy

l

IN-L

92

23

IN-J

Z7

89

2-A

cid

-3-

triu

ret

IN-L

92

25

To

tal

un

kn

ow

ns*

0 99.12 99.12 0.00 0.00 0.00 0.00 0.00

1 97.02 40.35 0.11 0.14 0.08 56.12 0.18

3 94.73 8.18 0.24 0.30 0.08 85.76 0.13

7 95.80 1.60 0.44 0.35 0.41 92.30 0.70

14 94.34 0.01 0.15 0.20 0.08 93.52 0.37

29 89.94 0.00 0.15 0.29 0.17 88.97 0.36

61 86.02 0.00 7.90 6.24 16.95 43.74 11.18

90 79.18 0.00 7.76 9.24 14.26 42.14 5.77

120 74.28 0.00 12.20 5.77 11.38 38.32 2.93

* All <5% each)

The UK RMS noted that there were some relatively significant increases in levels of

metabolites IN-L9223, IN-JZ789 and 2-acid-3-triuret occurring between the 29 and 61 d

sampling points. The formation of these metabolites followed the significant degradation of


the primary IN-L9225 metabolite that also occurred between days 29 and 61. This pattern of

residues did make reliable kinetic fitting of the data problematic due to the delay in formation

of secondary metabolites (see Section B.8.3). This pattern was seen in other soils in this

study (e.g. Kenslow, thiophene label, Table B.8.23 and Longwood triazine label, Table

B.8.24).


Farditch Loam, Thiophene-label

DAT % AR

Th

ifen

sulf

uro

n

-met

hy

l

IN-L

92

23

IN-J

Z7

89

2-A

cid

-3-

triu

ret

IN-L

92

25

To

tal

un

kn

ow

ns*

0 97.61 95.08 0.00 0.00 0.00 2.53 0.00

1 94.35 35.08 0.93 0.41 0.73 56.34 0.41

3 91.26 4.87 2.43 0.21 1.45 80.88 1.19

7 87.08 1.19 3.32 1.65 2.89 77.31 0.67

14 77.34 0.06 2.10 3.92 1.61 68.10 1.55

29 63.96 0.00 14.52 6.08 11.59 26.42 5.35

61 51.24 0.60 14.76 4.22 10.07 14.80 6.52

90 36.16 0.37 10.43 3.40 7.23 10.55 3.91

120 29.38 0.00 12.28 7.15 3.76 4.56 1.50

* All <5% each)


Lockington Sandy Clay Loam, Thiophene-label

DAT % AR

Th

ifen

sulf

uro

n

-met

hy

l

IN-L

92

23

IN-J

Z7

89

2-A

cid

-3-

triu

ret

IN-L

92

25

To

tal

un

kn

ow

ns*

0 97.53 94.35 0.00 0.00 0.00 3.17 0.00

1 94.70 42.62 0.95 0.34 0.76 49.06 0.45

3 92.28 12.81 2.47 1.09 1.46 73.65 0.48

7 89.64 3.70 2.68 1.84 2.45 77.70 1.17

14 80.89 2.80 3.12 1.49 1.56 69.11 2.80

29 62.02 0.62 18.71 4.47 7.89 25.01 5.30

61 43.33 0.35 17.22 2.81 9.36 6.16 6.35

90 33.51 0.09 12.87 1.48 7.83 4.25 7.00

120 30.77 0.19 17.27 4.27 2.03 2.76 4.24


* All <5% each)


Kenslow Loam, Thiophene-label

DAT % AR

Th

ifen

sulf

uro

n

-met

hy

l

IN-L

92

23

IN-J

Z7

89

2-A

cid

-3-

triu

ret

IN-L

92

25

To

tal

un

kn

ow

ns*

0 97.39 93.42 0.00 0.00 0.00 3.96 0.00

1 92.39 28.38 1.57 0.50 0.99 60.15 0.47

3 86.10 4.23 3.39 1.96 1.67 73.45 1.30

7 81.35 2.11 4.13 3.11 2.42 68.37 1.15

14 68.26 0.62 4.75 3.45 0.42 58.30 0.73

29 49.98 0.26 19.31 2.14 7.05 14.38 6.83

61 29.13 0.09 15.64 3.34 4.45 2.74 2.87

90 27.15 0.09 14.68 2.85 4.14 2.78 2.60

120 26.54 0.00 16.87 6.45 1.77 0.39 1.06

* All <5% each)


Longwoods Sandy Loam, Triazine-label

DAT % AR

Th

ifen

sulf

uro

n

-met

hy

l

IN-A

40

98

IN-J

Z7

89

2-A

cid

-3-

triu

ret

IN-L

92

25

To

tal

un

kn

ow

ns*

0 101.08 101.08 0.00 0.00 0.00 0.00 0.00

1 98.41 56.62 1.63 0.00 0.00 40.15 0.00

3 97.45 14.61 4.49 0.24 0.11 77.76 0.13

7 94.91 2.25 1.91 0.25 0.21 89.76 0.16

14 91.21 0.00 2.34 0.19 0.16 88.09 0.39

29 88.29 0.00 2.47 0.66 0.37 84.10 0.69

61 86.68 0.00 9.50 9.73 9.96 48.48 5.69

90 78.51 0.00 7.38 8.31 9.61 42.81 3.43

120 79.02 0.00 9.46 5.42 8.63 45.57 7.63

* All <5% each)



Farditch Loam, Triazine-label

DAT % AR

Th

ifen

sulf

uro

n

-met

hy

l

IN-B

55

28

IN-A

40

98

IN-J

Z7

89

2-A

cid

-3-

triu

ret

IN-L

92

25

To

tal

un

kn

ow

ns*

0 99.52 98.58 0.00 0.94 0.00 0.00 0.00 0.00

1 97.80 68.66 0.07 3.145 0.02 0.13 25.65 0.12

3 96.87 25.12 2.46 6.81 1.59 0.88 59.61 0.40

7 91.76 2.52 0.71 3.51 0.73 1.42 82.21 0.66

14 86.53 0.00 1.42 4.37 0.83 1.43 77.91 0.57

29 72.39 0.00 1.70 7.95 2.44 2.84 53.06 4.39

61 53.89 0.00 3.12 12.87 2.56 7.72 10.82 16.81

90 38.96 0.00 1.14 10.57 6.66 6.41 6.37 7.82

120 33.06 0.00 1.50 9.38 4.89 2.88 6.07 8.34

* All <5% each)


Lockington Sandy Clay Loam, Triazine-label

DAT % AR

Th

ifen

sulf

uro

n

-met

hy

l

IN-B

55

28

IN-A

40

98

IN-J

Z7

89

2-A

cid

-3-

triu

ret

IN-L

92

25

To

tal

un

kn

ow

ns*

0 99.75 98.55 0.00 1.20 0.00 0.00 0.00 0.00

1 98.30 65.49 0.26 4.06 0.12 0.97 27.85 0.21

3 95.59 18.46 2.19 8.48 2.14 1.97 61.72 0.51

7 88.13 3.77 0.82 5.40 0.43 1.79 75.47 0.44

14 80.12 0.12 1.64 6.76 1.25 1.77 66.83 1.74

29 61.97 0.10 2.32 10.74 2.05 1.77 40.03 4.93

61 42.21 0.15 1.69 17.35 0.50 3.13 5.35 14.04

90 33.54 0.08 1.36 10.97 0.00 2.83 3.25 15.04

120 38.25 0.33 2.09 13.99 0.00 2.81 3.95 14.78

* All <5% each)



Kenslow Loam, Triazine-label

DAT % AR

Th

ifen

sulf

uro

n

-met

hy

l

IN-B

55

28

IN-A

40

98

IN-J

Z7

89

2-A

cid

-3-

triu

ret

IN-L

92

25

To

tal

un

kn

ow

ns*

0 99.81 99.05 0.00 0.00 0.00 0.00 0.00 0.00

1 97.61 55.44 1.12 4.88 0.25 0.54 34.94 0.44

3 93.67 17.34 1.91 8.62 2.39 2.77 60.15 0.49

7 83.24 2.19 3.00 9.08 0.56 2.41 65.23 0.78

14 67.21 0.00 3.03 11.65 1.34 0.53 49.13 1.53

29 52.36 0.00 4.98 17.97 0.71 1.64 25.53 1.54

61 34.29 0.00 1.84 17.67 0.63 3.57 1.70 8.87

90 29.89 0.00 0.00 16.52 3.79 2.81 1.12 5.65

120 28.13 0.00 0.00 15.31 5.00 2.00 0.84 4.98

* All <5% each)

Bound residue fractionation was carried out on the 90 day sampling point. The unextracted

radioactivity was found to be fairly evenly distributed between all three fractions for both

radiolabels (see Table B.8.28 and 29).

Table B.8.28 Bound Residue Fractionation – Thiophene label

Soil Type

Sampling

Interval

(days)

Incubation Unit % NER

% of unextracted

Fulvic acid Humic

acid

Humin

Farditch 90 9319 17.34 53.75 14.67 31.58

Lockington 90 9345 57.54 36.15 32.66 31.19

Kenslow 90 9371 44.06 27.96 41.46 30.58

Longwoods 90 9389 48.11 41.96 35.62 22.43

Table B.8.29 Bound Residue Fractionation – Triazine label

Soil Type

Sampling

Interval

(days)

Incubation Unit % NER

% of unextracted

Fulvic acid Humic

acid

Humin

Farditch 90 9438 49.43 35.53 42.37 22.09

Lockington 90 9458 40.05 33.98 33.99 32.04

Kenslow 90 9477 49.21 37.95 34.97 27.09


Conclusions:

[14

C]-Thifensulfuron-methyl was rapidly degraded in aerobic soil incubated at 20ºC, to form

IN-L9225 and other secondary metabolites (2-Acid-3-triuret, IN-JZ789, IN-L9223 (thiophene

label only) together with IN-A4098 and IN-B5528 (triazine label only)), soil bound residues

and, by mineralisation, carbon dioxide.

The following metabolites accounted for ≥10% of applied radioactivity at any single time

point, >5% at two consecutive time points or >5% at the end of the study. The proposed

degradation scheme is shown in Figure B.8.2.

IN-L9225 (Thifensulfuron acid, max. 94%)

IN-JZ789 (O-Desmethyl thifensulfuron acid, max. 10%)

2-Acid-3-triuret (IN No. unknown, max. 17%)

IN-L9223 (2-Acid-3-sulfonamide, max. 19%).

IN-A4098 (Triazine amine, max. 18%)

(Simmonds, 2012a)


Figure B.8.2 Proposed degradation pathway for Thifensulfuron-methyl in aerobic soil

(Simmonds, 2012)

Thifensulfuron acid = IN-L9225

O-Desmethyl thifensulfuron acid = IN-JZ789

2-Acid-3-sulfonamide = IN-L9223

Triazine amine = IN-A4098

O-desmethyl triazine amine = IN-B5528


Comparison between Task Force (Simmonds, 2012a) and DuPont (Cleland, 2011) route

of degradation in soil studies

Due to the significant differences between metabolite identification in the two studies the UK

RMS has provided a further summary of the analysis in each report.

When comparing the information provided in both new route of degradation in soil studies,

superficially the data from both sources appears to contain a number of inconsistencies.

However when analysed in detail, the inconsistencies mostly appear to stem from the poor

quality of the data in the DuPont study and the poor interpretation of those data such as the

identification of components based on very weak evidence and mis-assignment of peaks. On

the basis of the UK RMS evaluation, the poor data stems from poor chromatography and the

low amounts of radioactivity applied to the test vessels.

Both studies identify Thifensulfuron-methyl and Thifensulfuron acid using retention time and

MS data. There is consistency between the studies although the DuPont study at several

timepoints incorrectly assigns the peak that should be thifensulfuron acid as o-desmethyl

Thifensulfuron-methyl.

The Task Force study provides strong evidence (retention time and MS data) for the

identification of 2-acid-3-triuret, 2-acid-3-sulfonamide, and triazine amine. The DuPont data

are not inconsistent with this as their study does not consider 2-acid-3-triuret at all and the

poor quality of the chromatography and lack of MS data mean that 2-acid-3-sulfonamide and

triazine amine are not properly identified.

The Task Force study provides some evidence for the presence of O-desmethyl thifensulfuron

acid (retention time and weak MS data) and weak evidence for the presence of O-desmethyl

triazine amine (weak retention time and weak MS data). Again the DuPont study is not

inconsistent with this as they do not consider O-desmethyl triazine amine and the poor quality

of the chromatography means that O-desmethyl thifensulfuron acid could be present even

though they do not identify it.

The DuPont study identifies O-desmethyl Thifensulfuron-methyl and triazine urea whereas

neither is identified in the Task Force study. The data are not inconsistent because the

evidence presented in the DuPont study is very weak – the triazine urea could in fact be

triazine amine and the chromatography is so poor that O-desmethyl Thifensulfuron-methyl

cannot really be identified.

A polar peak consistently appears in the DuPont study (both labels) but does not appear in the

Task Force study (thiophene label). This is an inconsistency between the studies. This is the

peak that was identified as 2-acid-3-sulfonamide in the DuPont study but clearly is not. It

could be a single component or a mixture of components as it is essentially unretained. It

reached at least 10% AR in all four test systems and was up to 27% AR.

The comparison for each component is summarised in the table below. In addition, the

HPLC chromatograms of the certified reference standards have been provided for both

studies from the original reports (see Figure 6 for DuPont analysis and Figure 7 for the Task

Force). Overall the UK RMS concluded that the information in the Task Force study

could be considered reliable whilst the information in the DuPont study was regarded as

unreliable.


Component Du Pont study Task Force study Comments


Identified (evidence

strong)

Retention time and

MS data


strong)

Retention time and MS

data

Consistent between studies

Thifensulfuron acid


strong)

Retention time and

MS data


strong)


data

Consistent between studies

Du Pont at various timepoints label the

peak where the acid elutes as o-

desmethyl Thifensulfuron-methyl (no

evidence)

2-acid-3-triuret Not considered in

this study.


strong)


data

Task Force initially thought this was

O-desmethyl Thifensulfuron-methyl

but provide good evidence for its i.d.

2-acid-3-sulfonamide

Incorrectly

identified

Wrong retention

time, no MS data


strong)


data

Du Pont also identify it as present in

triazine labelled samples which is not

possible

O-desmethyl



very weak)

Based on retention

time alone but poor

chromatography

means this evidence

is very weak.

Identified (but then

discounted)

(evidence based on

retention time and MS)

Task Force did further i.d. work by MS

to show it was not present

O-desmethyl

thifensulfuron acid Not identified

Identified

(evidence not strong)

Based on retention time

and MS data but MS data

weak

Could be present in the Du Pont study

but peaks so broad it is impossible to

tell.

Triazine amine


weak)

Based on retention

time but poor

chromatography and

no MS data.


strong)


data

Task Force appear to have misassigned

a minor polar peak as triazine amine at

early timepoints1.

Du Pont seem to identify the same

peak as triazine amine and triazine urea

at different times.

O-desmethyl triazine

amine

Not considered in

this study.

Identified

(evidence weak)


data

Task Force identified this metabolite

using retention time and MS. However

the component in question was very

polar (essentially unretained) and MS

data was weak.

Triazine urea


very weak)

based on retention

time

Not identified

Du Pont identify this component but no

reference standard information (no

retention time) is provided; also no MS

data.

1 Note this possible misassignment of a minor polar peak at early timepoints does not affect the acceptability of the Task

Force study in the opinion of the UK RMS. Metabolite IN-A4098 did appear to be correctly assigned at later timepoints,

where it was formed in major (>10% AR) amounts.


DuPont route of degradation in soil study (Cleland, 2011)


Task Force route of degradation in soil study (Simmonds, 2012a)


In response to Open Point 4.2 in the Evaluation Table the UK RMS has included a figure of

the proposed full degradation pathway of thifensulfuron methyl in soil under aerobic

conditions containing all metabolites that require further consideration (see Figure B.8.2a

below). The figure was provided by DuPont and was considered a plausible degradation

scheme by the UK RMS, taking into account information from all reliable information

submitted by both Applicants.

Figure B.8.2a Proposed degradation pathway for thifensulfuron-methyl in aerobic soil (taken

from Reporting Table 4(17))


B.8.1.1.2 Soil rate of degradation studies - laboratory

B.8.1.2 Anaerobic degradation

Report: Hawkins, D.R., Elsom, L.F., Kane, T.J. (1991); The anaerobic soil

metabolism of [triazine-2-14

C]DPX-M6316



Test material: Radiolabelled and nonradiolabelled Thifensulfuron-methyl

technical

Lot/Batch #: Radiolabelled: [Triazine-2-14

C]-Thifensulfuron-methyl,

radiochemical file no. 227

Nonradiolabelled: M6316-53

Purity: Radiochemical purity 98.58%

Nonradiolabeled purity: 98.3%

GLP: Yes

Previous

evaluation: In DAR for original approval (1996).


fully meets the current guidelines OECD 307 and US EPA OPPTS

835.4100. The study was noted to only be performed with labelling in

the triazine ring. DuPont were asked for further justification for why

this study should still be regarded as acceptable. DuPont proposed that

the degradation of Thifensulfuron-methyl in anaerobic soil in this study

demonstrated that the degradation in soil was essentially similar under

both aerobic and anaerobic conditions. They proposed that further

testing with the thiophene label would not be expected to add

significant additional information regarding this route of degradation.

Thifensulfuron-methyl consists of triazine and thiophene moieties

attached by a sulfonylurea bridge. The principal degradation pathway is

via hydrolysis of the thiophene carboxylic acid ester to yield IN-L9225,

followed by cleavage of the bridge to yield triazine and thiophene based

metabolites. In the anaerobic study with the triazine ring, the anaerobic

half life was short (approximately 5 d) and IN-L9225, IN-V7160 and

IN-A4098 were identified as metabolites, each of which retains the

triazine 14

C label. A similar metabolite profile was available from the

DuPont aerobic route of degradation studies (noting the deficiencies in

the studies already highlighted by the UK RMS). IN-L9225 is the

principal metabolite in both aerobic and anaerobic soils. IN-L9225 is

more rapidly degraded under aerobic conditions. Although the

formation of novel anaerobic metabolites from the thiophene ring

cannot be completely excluded, it is noted that this study was accepted

during the original Annex I considerations. The UK RMS therefore

accepts that the original study is sufficient to meet current guidelines.

This study has been used to provide information on the anaerobic route

of degradation in soil. For completeness the original text of the study

summary from the 1996 DAR has been included below. For

information, a new study provided by the Task Force provides

additional information with labelling in both ring positions (see


Simmonds, 2011a) below.

The study (AMR 1349-88) was started in 12/1989 and reported by D.R. Hawkins,

L.F. Elsom, T.J. Kane. (1990). GLP statement was included in the report. The US

EPA, Pesticide Assessment Guidelines: Environmental Fate 162-1 was used. The

study was conform to SETAC guideline except for minor deviations (incubation

temperature was 25°C, soil moisture level and pH were slightly different) and was

found acceptable.

Protocol - [triazine-2-14

C]Thifensulfuron-methyl (radiochemical purity 98.6% -

Thifensulfuron-methyl DPX-M6316, purity 98.3%) was applied to Keyport silt

loam soil (table 7.1.4) at 0.050 mg/kg (50 g a.s./ha). Incubation was made at 25°C,

75% of water content at 33 kPa, in darkness and under aerobic conditions for 3

days. Then the soil samples were flooded and incubated for a further 60 days under

anaerobic conditions (N2). Radiolabelled CO2 was trapped (NaOH). Water and soil

were analysed separately. After extraction (water-organic solvents then NaOH)

compounds were analysed by TLC and HPLC. Least square regression analysis

were used for statistical analysis.

Table B.8.30 - Soil Characteristics

Location Soil Sand

(%)

Silt

(%)

Clay

(%)

OM

(%)

pH CEC

meq/100 g Stine Farm

Newark,

Delaware,

U.S.A.

Keyport

Silt Loam

17

60

23

1.5

7.2

8.7

OM = organic matter content, CEC = Cation exchange capacity

The microbial biomass was 62.2 mg C/100 grams soil

Results - Total recovery of radioactivity ranged from 96 to 110%. [triazine-2-14C]Thifensulfuron-methyl was rapidly degraded aerobically (DT50=2 days) and

then anaerobically (DT50=5 days). Radioactive volatiles were < 1.2 % and bound

residues reached 9.5%. The major pathway of degradation was the hydrolysis of

the ester to form Thifensulfuron acid (peaked at 0.036 ppm). Hydrolysis of the

sulfonylurea functional group to form the triazine urea and triazine amine also

occurred (Table 7.1.5).

In conclusion, under aerobic conditions at 25°C, the half-life of Thifensulfuron-

methyl was approximately 2 days. Under anaerobic conditions, the half-life was

approximately 5 days. In this study, two third of initial Thifensulfuron-methyl was

aerobically degraded when anaerobic degradation started. Deesterification occurred

under anaerobic condition but other pathways are questionable.


Table 7.1.5 - Anaerobic degradation of [triazine-2-14

C]Thifensulfuron-methyl

Component (% applied radioactivity)

Days after

Applicati

on

Thifensulfuro

n-methyl

Thifensul-

furon acid

Triazine

Urea

Triazine

Amine

Unknown

(**)

Volatiles

(CO2)

0 92.8 1.9 0.9 nd nd -

3 (*) 37.2 9.1 7.7 4.1 17.8 1.2

3+7 6.8 63.1 3.3 2.3 5.7 0.7

3+15 1.5 72.9 3.4 2.5 3.8 0.4

3+30 0.5 63.2 4.1 3.3 5.6 0.5

3+45 0.5 53.9 4.4 4.4 7.9 1.0

3+60 0.5 53.4 2.6 4.1 12.3 0.8 (*) Soils were flooded 3 days after application, nd = not detected

(**) These are totals from 3 components. Maximum of any one component does not exceed 12%

(Hawkins, Elsom and Kane, 1991)

Report: R. Simmonds (2011a) [14

C]-Thifensulfuron-methyl: Anaerobic

degradation in soil. Battelle UK Ltd. [Cheminova A/S], Unpublished

report No.: WB/10/005 [CHA Doc. No. 244 TIM]

Guidelines: OECD Guideline for the Testing of Chemicals No. 307, 2002

Deviations from OECD 307/2002 guidelines and any omissions of 307 mandated data are

detailed.

GLP: GLP compliance certification (Battelle UK Ltd), 2010

Certifying authority: Department of Health (U.K)

Previous

evaluation:



The following study was briefly reviewed by the UK RMS and

considered acceptable. It should be noted that an acceptable anaerobic

degradation study was already available in the original DAR (see

Hawkins, Elsom and Kane, 1991 above). Therefore the new study is not

cirtical to the assessment. However this study has been used to provide

additional information on the anaerobic route of degradation in soil and

in particular this study provides information from both radiolabel

positions that was absent from the original study in the DAR. The

results from the new study do not have any consequences for the

regulatory assessment. For example no new major metabolites are

found that were not also found at comparable levels during the aerobic

study. This partially supports the acceptance of the original anaerobic

study which was only labelled in the triazine ring position. Although the

metabolite IN-B5528 was found at higher levels in this study compared

to the aerobic study, it was noted that this metabolite was not found in

significant levels over the first 90 d (≤ 3% AR up to day 90) and only

exceeded 5% at the final sampling time of 120 d after prolonged

anaerobic conditions (peak of 8.7% at 120 d). Since maintenance of

anaerobic conditions for such prolonged periods is not considered likely


in typical agricultural soils, this metabolite is not considered to be of

relevance for the environmental exposure assessment and has not been

considered further.

This study provides specific information on the fate of the active

substance labelled in the thiophene ring position under anaerobic

conditions which was not available in the original DAR or in the

submission from DuPont. Therefore the detailed study summary from

the Task Force is provided below.

Executive Summary:

The route and rate of degradation of [thiophene14

C]-Thifensulfuron-methyl (specific

radioactivity 5.17 MBq/g, purity 98.8%) and [triazine-2-14

C]-Thifensulfuron-methyl (specific

radioactivity 5.18 MBq/g, purity 99.4%) have been studied under aerobic/ anaerobic

conditions in a silt loam soil (100 g dry weight, 2mm sieved) at 20 ± 2ºC in the dark. [14

C]-

Thifensulfuron-methyl was applied in acetonitrile at an application rate of 100 µg per 100 g

soil, equivalent to 1 mg/kg (corresponding to a field application rate of 250 g a.i./ ha,

assuming an incorporation depth of 2.5 cm and a soil density of 1.0 g/cm3). The treated

samples were initially incubated under aerobic conditions for 1 day (experimentally

determined DT50). Following the aerobic phase, nitrogen purged deionised water was added

to the remaining samples and anaerobic conditions were established and maintained by a flow

of nitrogen through the flasks. The air drawn over the surface of the units was passed through

a series of traps (ethylene glycol, potassium hydroxide (x2)) to collect evolved radiolabelled

material. Anaerobic conditions were maintained for 121 days. The redox potential of the soil

and water was monitored to determine that anaerobic conditions had been established.

Samples were taken for analysis at 0 and 1 day during the aerobic phase and at 3, 7, 14, 31,

60, 90 and 121 days after waterlogging. The water was decanted (where appropriate) and the

soil samples were extracted with methanol: water: formic acid (80: 20: 1 v/v/v) followed by

extraction with acetonitrile: water (50: 50 v/v). Components present in the water and soil

extracts were characterised and quantified by HPLC. The unextracted radioactivity in the soil

was quantified by combustion/LSC.

The mean recovery of radioactivity from each soil system ranged from 93.2 to 102.6%

applied radioactivity (AR) for thiophene label and 93.6 to 101.7% for the triazine label. The

total extractable radioactivity declined to 79.5% and 73.8% at the end of the study for

thiophene and triazine labels, respectively. The non extractable residues increased steadily to

18.7% and 23.0% at the final sampling interval for thiophene and triazine labels, respectively.

The level of volatile radioactivity (14

CO2) generated during the study was ≤1.0% AR for both

labels.

Under initial aerobic conditions, levels of Thifensulfuron-methyl decreased rapidly to 32.4%

and 39.7% AR (thiophene and triazine labels respectively) with corresponding increases of

IN-L9225 to 58.6% and 54.3% AR (thiophene and triazine labels respectively). Once the

system was flooded and conditions turned anaerobic, the degradation of Thifensulfuron-

methyl continued but a slower rate than during the aerobic phase.

The DT50 values for Thifensulfuron-methyl in the complete data set were determined

following the recommendations of the FOCUS work group using a Hockey-stick model (HS).

The slow phase degradation rate was (k2) used to derive a DT50 value for the anaerobic phase


only. For the complete data set the results were 0.6 and 0.7 days for thiophene and triazine

labels respectively. The DT50 under anaerobic conditions were 15.4 and 4.7 days for

thiophene and triazine labels respectively based on the slow phase of the Hockey Stick

model. The UK RMS accepted these values, noting that they are not actually used in the

subsequent environmental exposure assessment (see Table B.8.38).

In total, five metabolites (IN-L9225, IN-JZ789, IN-L9223, IN-A4098, IN-B5528) reached

trigger criteria concentrations (>10% single time point, >5% on two consecutive time points

of >5% at the end of the study). Many of these metabolites exceeded two or more trigger

criteria (Table B.8.31).

Table B.8.31 Summary of anaerobic metabolites versus the trigger values

Metabolite >10% at any single time

point

>5% at two or more

time points

>5% at end of study

IN-L9225 X X X

IN-JZ789 X X

IN-L9223 X X X

IN-A4098 X X X

IN-B5528 X

Materials and Methods

Materials:

2. Soil One UK soil, Farditch (10/044), was obtained from Chelmorton, UK (see

Table B.8.32).


Soil

name

pH

(H2O)

OM

%

(OC%)

Sand1

%

Silt1

%

Clay1

%

CEC

mEq/100g

Biomass

µg C/g soil2

(Initial/ End)

Classifi

cation

MWHC

%

Bulk

mass

(gm/

cc)

Farditch 6.0 6.0

(3.48) 29 54 17 12.5 590.1/211.5

Silt

Loam 79.2

0.95

1 USDA Particle Size Distribution and Classification,

2 At start of aerobic phase



Table B.8.33 Mean Percent recovery of AR as individual components following [thiophene-14

C]-Thifensulfuron-methyl application

Incubation

time (days)

Water

Phase

Total

Extracted

Total

Volatiles

Non-extractable

Residue Mass Balance

Aerobic Incubation

0 NA 99.03 NA 3.01 102.04

1 NA 92.49 0.00 5.63 99.13

Anaerobic incubation

3 25.24 92.46 0.21 6.98 100.65

7 49.53 91.95 0.31 5.83 98.09

14 44.83 91.26 0.50 7.47 99.23

31 41.93 84.88 0.50 15.73 101.11

60 37.15 74.09 0.53 22.48 97.10

90 30.66 72.57 0.57 27.66 100.80

121 43.94 79.48 0.95 18.68 99.11

NA = Not applicable

Table B.8.34 Mean Percent recovery of AR as individual components following [triazine-14

C]-Thifensulfuron-methyl application

Incubation

time (days)

Water

Phase

Total

Extracted

Total

Volatiles

Non-extractable

Residue Mass Balance

Aerobic Incubation

0 NA 98.12 NA 2.94 101.06

1 NA 96.57 0.00 4.55 101.13

Anaerobic incubation

3 52.28 95.62 0.03 4.24 99.88

7 44.00 89.59 0.04 6.61 96.24

14 40.29 87.65 0.05 8.21 95.90

31 39.62 84.83 0.07 16.24 101.14

60 37.07 76.75 0.11 22.66 99.53

90 35.28 73.56 0.41 25.25 99.23

121 32.96 73.81 1.01 23.00 97.81

NA = Not applicable

Bound residue fractionation was performed on single sample of 90 and 121-day samples for

both radiolabels. Bound residue fractionation of these samples gave results as shown on the

following page:


Table B.8.35 Bound Residue Fractionation

Label Day

% Total applied radioactivity

Total non-

extractable

Fulvic acid Humic acid Humin

Thiophene 90 27.95 19.69 6.26 2.00

Triazine 90 26.30 16.55 5.98 3.77

Thiophene 121 18.95 11.46 4.39 3.11

Triazine 121 23.79 15.20 5.70 2.89

Table B.8.36 Mean Percent recovery of AR following [thiophene-14

C]-Thifensulfuron-

methyl application

Incubation

time

(days)

Thifensulfuron-

methyl IN-L9223 IN-JZ789 IN-L9225

Total

minor

unknowns*

Total

Aerobic Incubation

0 98.66 0.00 0.00 0.00 0.37 99.03

1 32.43 0.55 0.63 58.58 1.31 93.49

Anaerobic Incubation

3 10.09 1.11 2.38 78.79 1.09 88.88

7 8.79 9.58 8.77 60.02 4.79 91.95

14 6.91 9.78 7.52 65.09 1.94 91.26

31 2.84 13.83 6.77 59.63 1.81 84.88

60 0.07 13.99 6.03 53.36 0.64 74.09

90 0.00 13.28 6.71 52.10 0.47 72.57

121 0.00 23.56 5.78 38.83 11.30 79.47

* No individual value greater than 4.3%

Table B.8.37 Mean Percent recovery of AR following [triazine-14

C]-Thifensulfuron-methyl

application

Incu

ba

tio

n t

ime

(da

ys)

Th

ifen

sulf

uro

n-

met

hy

l

IN-B

55

28

IN-A

40

98

IN-J

Z7

89

IN-L

92

25

To

tal

min

or

un

kn

ow

ns*

To

tal

Aerobic Incubation

0 98.12 0.00 0.00 0.00 0.00 0.00 98.12

1 39.67 0.42 0.83 0.60 54.29 0.76 96.57

Anaerobic Incubation


Incu

ba

tio

n t

ime

(da

ys)

Th

ifen

sulf

uro

n-

met

hy

l

IN-B

55

28

IN-A

40

98

IN-J

Z7

89

IN-L

92

25

To

tal

min

or

un

kn

ow

ns*

To

tal

3 21.10 0.35 2.67 1.85 69.21 0.40 95.59

7 9.57 2.06 2.86 8.67 63.36 3.06 89.58

14 5.53 1.68 7.47 8.87 61.91 2.19 87.65

31 1.74 3.00 10.27 7.85 59.82 2.14 84.83

60 0.00 1.84 9.72 7.19 57.45 0.55 76.75

90 0.00 1.15 8.89 7.74 54.20 1.58 73.57

121 0.00 8.70 11.69 5.17 32.02 16.22 73.81

* No individual value greater than 4.8%

Table B.8.38 Summary of DT50 and DT90 values of [14


Phase Radiolabel DT50 (days) DT90 (days) Error level Chi

2-

test

Complete dataset

(HS)

Thiophene 0.6 4.5 1.5%

Triazine 0.7 8.8 3.9%

Anaerobic

(slow phase of HS

model)

Thiophene 15.4 - -

Triazine 4.7 - -

Conclusions:

Thifensulfuron-methyl was found to degrade rapidly in soil under aerobic conditions with a

DT50 of < 1 day. Once the system was flooded, and conditions were turned anaerobic, the

degradation continued but at a slower rate.

Five metabolites were present at > 10% AR at any single time point, > 5% at two consecutive

timepoints or >5% at the end of the study:


IN-JZ789 (O-Desmethyl thifensulfuron acid, max. 9%)

IN-L9223 (2-Acid-3-sulfonamide, max. 24%)


IN-B5528 (O-Desmethyl triazine amine, max. 9%)

(Simmonds, 2011a)

CRD notes a difference of opinion between the RMS and Co-RMS (UK and Austria,

respectively) first established during the initial commenting period:


The Co-RMS stated “It might be necessary to consider anaerobic metabolite IN-B5528 for

further risk assessment, since during the autumn and winter application there might be the

possibility for anaerobic situations e.g. through flooding. The degradation rate in the field

might be faster, so metabolite IN-B5528 might occur before 90 days during anaerobic

conditions. Submitted field studies do not show any indication, however, there were only

covering the spring applications and they were done in fields which were free from

flooding risk.”

Further risk assessment for the metabolite IN-B5528 has not been undertaken at this

stage, as the conditions raised by the Co-RMS are considered unlikely by the RMS.

B.8.1.2 Photolysis in soil

Report: Ferguson, E.M. (1986); Photodegradation of [thiophene-2-14

C]DPX-

M6316 and [triazine-2-14

C]DPX M6316 on soil


Guidelines: U.S. EPA 540/9-82-021 (1982)

Test material: 14

C-Thifensulfuron-methyl technical

Lot/Batch #: [Thiophene-2-14

C]- Thifensulfuron-methyl, [triazine2-14

C]-

Thifensulfuron-methyl, lot numbers not provided

Purity: Radiochemical purity >98% for both

GLP: No

Previous





McLaughlin (2011; DuPont-30224). In the Task Force submission this

study has been superseded by the study of Simmonds (2012).





the UK RMS has briefly reviewed this original soil photolysis study to

determine whether it does meet current guidelines, irrespective of the

GLP status. No critical deficiencies were noted. The study was

conducted with both radiolabel positions (i.e. thiophene and triazine-14

C). Analysis was via HPLC with confirmatory TLC analysis. Major

metabolites were identified as IN-A5546 (2-ester-3-sulfonamide) and

IN-A4098 (triazine amine) – the hydrolysis products formed from

cleavage of the sulfonylurea bridge. The same metabolites at similar

levels were seen in both light exposed and dark control samples,

indicating that photolysis did not lead to formation of novel metabolites.

Degradation rates were slightly longer in dark controls compared to

light exposed samples, however in all samples parent thifensulfuron was

noted to degrade more slowly than observed in the standard dark

aerobic degradation studies. It is possible that the occurrence of IN-


A5546 at these elevated levels in this study may have been an artefact

of reduced microbial degradation. Overall the UK RMS considered the

study to be adequate to meet current guidelines and concluded that the

study demonstrated that soil photolysis was not likely to be a major

route of degradation under realistic use conditions. The study was used

to provide information on the route of degradation in soil due to

photolysis. Since photolysis was considered insignificant, degradation

rates have not been updated in line with the FOCUS kinetics guidance.

This conclusion was in agreement with the conclusion in the original

DAR. The original text of the study summary from the 1996 DAR has

been included below.

The study (AMR 505-86) was started in 08/1985 and reported by E.M. Ferguson


Assessment Guidelines: Photolysis on soil 161-3 was used. The study was conform

to SETAC guideline and was found acceptable.

Protocol - [thiophene-2-14

C]Thifensulfuron-methyl and [triazine(U)-14

C]Thifensulfuron-methyl (radiochemical purity > 98%) were applied to air dried

thin soil layer (1 mm thick, non sterile soil) at 0.83 µg/cm2 (83 g a.s./ha) and

irradiated or not in natural sunlight (the spectral distribution over the wavelength

range was 290-800 nm) for 30 days at 25°C. Soils were extracted (water-organic

solvents then NaOH) and radioactive compounds were analysed by TLC and

HPLC. 14CO2 was trapped (Na OH) and soil residues determined by combustion.

Soil characteristics are given in Table B.8.39.


Table B.8.39 - Soil characteristics

Location

Soil Series

Name

Sand

(%)

Silt

(%)

Clay

(%)

OM

(%)

pH

CEC

meq/100 g

Rochelle,

Illinois, USA

Flanagan

Silt Loam

2 81 17 4.3 5.4 21.1


Results - Total recoveries of applied radioactivity were in the range 72.5-101%.

Volatile radiolabelled material (mainly CO2) accounted for 7.6% of the applied

thiophene label and < 0.01% of the applied triazine label after 30-days.

Unextractable radioactivity was < 6 %. DT50 for Thifensulfuron-methyl was 13.8-

17.6 days in irradiated samples and 20.9-25.8 days in non-irradiated samples.

Degradation pathway was similar in both conditions. Thifensulfuron-methyl was

degraded to 2-ester-3-sulfonamide (< 20 %) and triazine amine (< 32%). These

results are given in Table B.8.40. Small amounts of O-demethyl Thifensulfuron-

methyl, Thifensulfuron acid, 2-acid-3-sulfonamide, thiophene sulfonimide and

triazine urea were identified. Numerous polar peaks, each less than 10% and

totalling < 17.0%, were detected.

Table B.8.40 - Composition of the main photo degradation products

thiophene label (% applied radioactivity)

Days Irradiated Non-Irradiated

After

Application

Thifensulfuron

methyl

2-ester-3-

sulfonamide

(IN-A5546)

Thifensulfuron-

methyl

2-ester-3-

sulfonamide

(IN-A5546)

0 96.9 <0.2

2 78.9 3.9

7 54.0 10.9 57.8 15.2

14 41.4 15.7 51.2 18.8

21 31.1 19.8 43.3 24.6

30 19.9 20.4 32.5 24.4

triazine label (% applied radioactivity)

Thifensulfuron-

methyl

Triazine amine

(IN-A4098)

Thifensulfuron-

methyl

Triazine amine

(IN-A4098)

0 98.4 <0.2

2 79.6 4.4

7 59.9 12.1 63.4 16.7

14 43.9 17.5 52.1 14.6

21 35.7 23.7 48.4 17.1

30 29.4 32.3 41.5 19.4

In conclusion, Thifensulfuron-methyl was degraded in irradiated soil with a DT50

of 14 to 18 days and a DT90 from 46 to 59 days. In non-irradiated soil, the DT50

values were 21 to 26 days, and the DT90 values were 69 to 86 days. These results

indicated that photolysis will be a minor contributor to degradation on soil under


normal environmental conditions. The major degradation products of

Thifensulfuron-methyl were 2-ester-3-sulfonamide and triazine amine, the

hydrolytic cleavage products of the sulfonylurea bridge

(Ferguson, 1986)

Report: McLaughlin, S.P. (2011); Photodegradation of [14

C]DPX-M6316 on soil


Guidelines: OPPTS 835.2410 (2008), SETAC Europe (1995)

Deviations: None

Testing Facility: Smithers Viscient, Wareham, Massachusetts, USA

Testing Facility Report No.: 97.6525

GLP: Yes

Certifying Authority: Laboratories in the USA are not certified by any governmental

agency, but are subject to regular inspections by the U.S. EPA.

Previous



The following study was briefly reviewed by the UK. It should be noted

that an acceptable soil photolysis study was already available in the

original DAR (see Ferguson, 1986 above). Therefore the new study is

not critical to the assessment. However the study was used to provide

additional information on the route of degradation in soil due to

photolysis. No new metabolites are found that were not also found at

comparable levels during the new aerobic route of degradation in soil

study submitted by DuPont. However during the evaluation the UK

RMS did not consider the new route of degradation study from DuPont

to be valid. This new soil photolysis study did appear to confirm that

the IN-V7160 could be formed at levels approaching 10% in the

presence of light. The IN-A5546 metabolite was also observed at

significant levels in the light exposed samples. The pattern of

occurrence of IN-A5546 was noted to be unusual (see Table B.8.45).

Levels of the IN-L9225 metabolite between the different radiolable

samples was also noted to be variable. However no obvious deficiencies

in the study conduct or analysis could be found. Therefore the

occurrence of the IN-A5546 metabolite at a peak of 27.7% AR has been

retained and considered in the subsequent exposure assessment. The

study has been retained as providing useful information on the possible

route of degradation in the presence of light. The detailed study

summary from DuPont is provided below.

Executive summary:

The photodegradation of [14

C]Thifensulfuron-methyl was investigated after application to

thin layers of a silty clay loam soil (Tama soil, pH 6.1, 2.4% organic carbon) from the

Toulon, Illinois, USA under continuous irradiation for up to 15 days at 20 2C. Two sites

of the radiolabelled test substance, [thiophene-2-14

C]Thifensulfuron-methyl and

[triazine-2-14

C]Thifensulfuron-methyl were tested.


This study demonstrated that Thifensulfuron-methyl degraded rapdly with or without the

presence of light. The DT50 and DT90 values for Thifensulfuron-methyl in non-irradiated

samples were 5.4 and 18 days, respectively. In irradiated samples the DT50 and DT90 values

were 7.5 and 25 days, respectively.


A. MATERIALS

1. Radiolabelled test material: 14

C-Thifensulfuron-methyl



[triazine-2-14




[triazine-2-14




Ci/mg (23754 dpm/g)

[triazine-2-14


Ci/mg (75258 dpm/g)

Stability of test compound: Stable during application and extraction as shown

by recovery from Day 0 samples

2. Soil used

Characteristics of the soil used are listed in Table B.8.41.


Table B.8.41 Physicochemical characteristics of the test soil used in soil photolysis

Parameter Results

Soil name Tama Soil

SSL No. 2010-013a

Geographic location Illinois, USA

Texture class Silty clay loam

Sand (%) 11

Silt (%) 56

Clay (%) 33

pH (1:1 soil:water) 6.1

pH (1:2 soil:0.01 M CaCl2) 5.6

% Organic matter (Furnace Method) 4.1

% Organic matter (Walkley-Black Method) 4.0

% Organic carbon (Furnace Method)b 2.4

% Organic carbon (Walkley-Black Method)b 2.4

Bulk density (g/cm3) 1.08

Cation exchange capacity (meq/100g) 17.4

Water holding capacity (%)

0 Bar 69.8

0/10 Bar 47.5

1/3 Bar 34.6

15 Bar 16.7 a Tama soil was collected from Doug Murray Farm, Toulon, Illinois on 9 April 2010. Analyses were performed by Agvise

Laboratories, Northwood, North Dakota. b % Organic Carbon = % organic matter/1.7

3. Light source

Samples were exposed to artificial sunlight of a nominal intensity of 765 W/m2 from a

Xenon Arc Lamp housed in a Heraeus CPS+ unit, fitted with an infrared filter and a

UV-filter with a lower limit cutoff at 290 nm. The xenon irradiation source generates

light with a spectral distribution which resembles natural sunlight.

The intensity of the irradiation was measured using a light intensity meter

(International Light Spectroradiometer, Model RPS-900-W) and fitted with a global

sensor, which measures light intensity in the wavelength region 300 to 800 nm.

B. STUDY DESIGN


The study design for this study is summarised in Table B.8.42 Aliquots (ca. 5 g oven

dry soil equivalent) of 2 mm sieved soil were added to each test unit as a slurry and

allowed to air-dry to form thinly layered (ca. 2 mm) homogeneous soil samples. The

non-irradiated (dark) samples were placed in an environmental chamber and the

temperature was monitored regularly throughout the incubation period at a target

temperature of 20 2C. The irradiated samples were placed beneath a continuous

irradiation source, through which passed continuously circulating water from a

separate regulated water bath. Temperature was monitored regularly throughout the

irradiation period with an ASTM calibrated minimum-maximum thermometer in a

representative sample vessel at a target temperature of 20 2C.


Table B.8.42 Experimental design, soil photolysis

Parameter Description

Duration of the test 15 days

Soil condition Air dried

Soil sample weight 5 g/replicate

Test

concentrations g/g [thiophene-2-

14C] Thifensulfuron-

methyl 0.636

g/g [triazine-2-14

C] Thifensulfuron-

methyl 0.616

Control conditions Darkness

Number of

replicates

Dark 2 per sampling time (one for each radiolabel)

Irradiated 2 per sampling time (one for each radiolabel)

Test apparatus

Dark

Sealed Pyrex

vessels with screw cap

Teflon

-lined lids

Irradiated

Sealed quartz vessels with screw cap Teflon

-lined

lids

Traps for CO2 and organic volatiles One ethylene glycol and two 1 N NaOH traps

Test material

application

Identity of solvent Acetonitrile

Volume of test solution used/treatment

[thiophene-2-14

C] Thifensulfuron-methyl: 44 L

of 0.070 mg/mL primary stock solution

[triazine-2-14

C] Thifensulfuron-methyl: 28 L of

0.109 mg/mL primary stock solution

Application method Gas tight syringe

Evaporation of application solvent Yes

Indication of test material adsorbing to apparatus None

Experimental

conditions Temperature (C) 20 2

Moisture content 75% field capacity

Moisture maintenance method Adjusted at Day 0.

Duration of light/dark Continuous irradiation

2. Sampling

Sampling intervals are summarised Table B.8.43.


Table B.8.43 Sampling details for soil photolysis


Sampling intervals 0, 1, 3, 5, 7, 11, and 15 days post application

Soil sampling procedures Duplicate dark control samples were analysed immediately after the test

material was placed into the test vessels (Day 0). Duplicate irradiated and

dark samples were analysed at predetermined intervals.

Volatiles trap sampling

procedures

At each time point beginning with the Day 1 sampling, the ethylene glycol

and NaOH traps in line with the test systems were taken for analysis and

replaced with fresh trapping materials. The total volume for each of the

volatile traps was measured and duplicate aliquots were taken for LSC

analysis (ethylene glycol: 2 1 mL, NaOH: 2 2 mL).

Collection of CO2 and volatile

organics

The aerobic soil test systems were placed on volatile trapping trains

containing one ethylene glycol trap (for trapping volatile organics) and at

least two 1.0 NaOH traps in series (for trapping 14

CO2).

Sampling intervals/times Sterility checks Not applicable

Moisture content Not applicable

Redox potential/other Not applicable

Sample storage before analysis All samples were analysed on the sampling day. Subsamples were stored

frozen after the initial analysis at less than -5C.


The concentration of primary stock solutions was determined by LSC (Beckman

Model LS6500 Instrument). The actual concentrations of Thifensulfuron-methyl

(0.6 g/g nominal) were determined to be 0.636 and 0.616 g/g for the test systems

treated with [thiophene-2-14

C] and [triazine-2-14

C] Thifensulfuron-methyl,

respectively.

The soil samples were extracted twice with acetone:1 M ammonium carbonate (90:10

v/v, 2 16 mL) followed by a 0.1 M ammonium carbonate extraction. Soil extracts

were combined and concentrated before HPLC analysis. Recovery of radioactivity

during this process was between ca. 90% and 110% of that in the initial sample before

concentration. Therefore, this procedure was regarded as quantitative and no attempt

was made to adjust the extraction data for these recoveries.

TLC analyses were conducted on the soil extracts to confirm the parent

Thifensulfuron-methyl (thiophene and triazine labelled) and its metabolites using

reference standards. Each plate was qualitatively analysed with a short wave UV

lamp (Spectroline, Model XX-15NF CSA22.2N01010-0) and quantitatively analysed

with a Bioscan Analyzer (Model AR-200).

The combined concentrated soil extracts were spiked with 8 L of the reference

standard mixture and analysed for distribution of radioactivity by reverse phase

HPLC/RAM on the day of sampling and subsamples were stored frozen after the

initial analysis at -5C. The amount of radioactivity eluting from the column was

determined by collecting the eluate from the run followed by LSC analysis.

Air-dried, homogenised samples of the post-extraction solids (PES) were analysed by

combustion (Harvey Model OX-500, OX-700 Biological Oxidizer).

The LSC limit of detection (LOD) was 0.02 g/mL for [thiophene-2-14

C]

Thifensulfuron-methyl and 0.006 g/mL for [triazine-2-14

C] Thifensulfuron-methyl.

The HPLC LOD was 0.09 g/mL for [thiophene-2-14

C] Thifensulfuron-methyl and

0.03 g/mL for [triazine-2-14

C] Thifensulfuron-methyl.



A. DATA

Results of the irradiated soils as well as the dark control soils from the two radiolabels

are listed in Table B.8.45 and 46.

B. MASS BALANCE

The mean material balance for the irradiated test systems remained relatively constant

with individual values varying between 95.8 and 105.8% AR over the incubation period.

The mean material balance for the non-irradiated test systems remained relatively

constant with individual values varying between 93.6 and 105.8% AR over the

incubation period.

C. EXTRACTABLE AND BOUND RESIDUES

Most of the applied radioactivity in the irradiated samples was extractable in both labels

throughout the experiment. For the dark samples, most of the applied radioactivity was

extractable for the triazine labelled samples, however was non-extractable in the

thiophene labelled samples.

On the day of application an average 102.6% of the applied radioactivity (AR) was

extracted from the irradiated samples. Extractable residue amounted to a maximum of

101.2% AR (0.643 ppm) for [thiophene-2-14

C] Thifensulfuron-methyl and 104.2% AR

(0.641 ppm) for [triazine-2-14

C] Thifensulfuron-methyl for the irradiated soils at Day 0.

The mean extracted radioactivity decreased from 102.6% AR (0.642 ppm), on the day of

application, to 63.2% AR (0.349 ppm) after 15 days irradiation. Extractable residue

amounted to a minimum of 49.3% AR (0.314 ppm) for [thiophene-2-14

C] Thifensulfuron-

methyl and 77.1% AR (0.475 ppm) for [triazine-2-14

C] Thifensulfuron-methyl for the

irradiated soils at Day 15.

In dark control soils, the mean total extracted radioactivity decreased from 102.6% AR

(0.642 ppm), on the day of application, to 44.6% AR (0.277 ppm) after 15 days.

The mean final non-extracted residues (NER) increased from 3.2% AR (0.020 ppm) on

Day 0 to 33.5% AR (0.210 ppm) after 15 days irradiation. Non-extractable residue in

irradiated soils amounted to a maximum of 38.9% AR (0.248 ppm) for [thiophene-2-14

C]

Thifensulfuron-methyl and 28.2% AR (0.173 ppm) for [triazine-2-14

C] Thifensulfuron-

methyl. The average amount of NER in the dark control samples was 3.2% AR

(0.020 ppm) at Day 0 and increased to 53.6% AR (0.337 ppm) at Day 15.

D. VOLATILE RESIDUES

Volatile residues as CO2, or other volatiles, were insignificant for both the irradiated and

dark control soils. Throughout the experimental phase, organic volatile radioactivity was

less than the limit of quantification. Throughout the experimental phase, evolved CO2

radioactivity was a maximum of 2.4% AR (0.015 ppm) on Day 15 for [thiophene-2-14

C]

Thifensulfuron-methyl and less than the limit of detection for [triazine-2-14

C]



E. TRANSFORMATION OF THE PARENT COMPOUND

1. Irradiated soil

The mean amount of Thifensulfuron-methyl extracted from the irradiated soil

replicates accounted for 100.5% AR (0.628 ppm) on the day of application. During

the 15-day irradiation period, there was a significant decline in the mean proportion of

Thifensulfuron-methyl to 19.6% AR (0.122 ppm).

Degradates IN-V7160, IN-A5546, IN-L9225, and IN-A4098 were observed as major

(5% AR) photolysis products in the irradiated soil samples. IN-L9226 was observed

as a minor photolysis product as well as other unidentified metabolites.

2. Dark control soil

The mean amount of Thifensulfuron-methyl extracted from the dark soil replicates

accounted for 100.5% AR (0.628 ppm) on the day of application. During the 15-day

irradiation period, there was a significant decline in the mean proportion of

Thifensulfuron-methyl to 11.9% AR (0.074 ppm).

IN-L9225 was observed as a major (5% AR) degradation product in the dark soil

samples. Several minor components, including IN-V7160 and IN-A5546 were also

observed in the HPLC analysis of the dark control soil samples. In all cases, these

components remained below 5% AR and were not considered further.

In the experiment with [thiophene-2-14

C] Thifensulfuron-methyl, IN-L9225 was

present at 7.3% AR (0.046 ppm) at Day 1, increased to a maximum of 39.8% AR

(0.253 ppm) at Day 3, then decreased to 15.7% AR (0.100 ppm) at Day 15.

In the experiment with [triazine-2-14

C] Thifensulfuron-methyl, IN-L9225 was present

at 6.0% AR (0.037 ppm) at Day 1 and increased to a maximum of 44.5% AR

(0.274 ppm) at Day 15.

3. Characterisation of transformation products


Unchanged Thifensulfuron-methyl in the samples was identified using HPLC by

comparing the retention time of the radioactive peak with that of an authentic

standard. Selected samples were also analysed using TLC. The identity of the

unchanged Thifensulfuron-methyl was confirmed under both chromatographic

systems.

IN-L9225, IN-V7160, IN-A4098, and IN-A5546

The degradation products IN-L9225, IN-V7160, IN-A4098, and IN-A5546 were

identified using HPLC by comparing the retention time of the radioactive peak with

that of an authentic standard. A normal phase TLC method was used to verify the

identity of IN-L9225, IN-V7160, IN-A4098, and IN-A5546. The identity of the

radioactive component as IN-L9225, IN-V7160, IN-A4098, and IN-A5546 was

confirmed under both chromatographic systems.


4. Kinetic analysis of data

DT50 and DT90 values obtained using the single first order linear regression analysis is

summarised inTable B.8.44. The DT50 and DT90 values for Thifensulfuron-methyl in

non-irradiated samples were 5.4 days and 18 days, respectively. In irradiated samples

the DT50 and DT90 values were 7.5 days and 25 days, respectively. Thifensulfuron-

methyl was rapidly degraded during aerobic soil photolysis at 20 2C. Based on the

results of this study, soil photolysis will be a route of elimination of Thifensulfuron-

methyl from the environment.

Table B.8.44 First-order rates of degradation, DT50, and DT90, values for


Sample

First-order rate of

degradation, k

(days-1

)

DT50a

(days)

DT90

(days) r2

Irradiated -0.0918 7.5 25 0.9003

Dark control -0.1282 5.4 18 0.9054 a DT50 and DT90 values calculated as ln(2)/k and ln(10)/k, respectively.

Note: DT50 and DT90 estimates presented here are extrapolated well beyond the limit of the observed data (15 days).


Table B.8.45 Phototransformation of [thiophene-2-14

C]Thifensulfuron-methyl on

irradiated and non-irradiated soil samples

Compound

Sampling times (residues as % of applied)

Day 0 Day 1 Day 3 Day 5 Day 7 Day 11 Day 15

Thifensulfuron-

methyl (Parent)

Irradiated 97.7 77.7 61.8 52.4 45.2 43.0 13.5

Dark 97.7 81.0 28.0 41.3 29.9 22.1 7.4

Polar 2-min Irradiated ND

a ND ND 1.9 2.6 2.2 ND

Dark ND ND ND 2.6 1.8 ND ND

IN-A4098 Irradiated ND ND ND ND ND ND ND

Dark ND ND ND ND ND ND ND

IN-V7160 Irradiated ND ND ND ND ND ND ND

Dark ND ND ND ND ND ND ND

IN-A5546 Irradiated 3.4 8.2 17.5 6.4 2.8 7.8 27.7

Dark 3.4 3.5 ND ND 0.9 ND ND

IN-L9226 Irradiated ND 1.2 2.1 ND ND ND ND

Dark ND 1.2 ND ND ND ND ND

IN-L9225 Irradiated ND 2.7 1.8 10.0 13.6 5.3 1.3

Dark ND 7.3 39.8 19.8 27.0 32.0 15.7

Total unidentified Irradiated ND 2.6 3.1 3.2 3.0 5.6 6.8

Dark ND ND 2.0 4.9 6.1 10.3 1.3

Total extractable

residuesb

Irradiated 101.1 92.4 86.3 73.8 67.1 63.69 49.3

Dark 101.1 92.9 69.7 68.6 65.8 64.4 24.4

CO2 Irradiated NA

c 0.8 1.3 2.4 2.4 2.4 2.4

Dark NA NA NA NA NA NA NA

Volatile organic Irradiated NA ND ND ND ND ND ND


Non-extractable

residues

Irradiated 3.1 9.5 14.2 23.8 28.7 25.5 38.9

Dark 3.1 10.0 25.3 27.6 32.0 36.5 71.5

Total %

recoveryd,e

Irradiated 104.2 102.7 101.8 99.9 98.2 91.8 90.6

Dark 104.2 103.0 95.0 96.2 97.8 100.8 95.9 a Not Detected

b Total activity present in extracts 1 to 3.

c Not Applicable

d Value is the sum of the% AR in each component exceeding the limit of quantification.

e The total values may differ slightly from the sum of the individual values due to rounding.


Table B.8.46 Phototransformation of [triazine-2-14

C]Thifensulfuron-methyl on

irradiated and non-irradiated soil

Compound

Sampling times (residues as % of applied)

Day 0 Day 1 Day 3 Day 5 Day 7 Day 11 Day 15

Thifensulfuron-

methyl (Parent)

Irradiated 103.2 78.3 60.7 46.6 36.1 44.1 25.6

Dark 103.2 91.1 56.0 20.3 37.7 26.5 16.4

Polar 2-min Irradiated ND

a 1.1 1.2 3.1 2.8 3.6 4.0

Dark ND ND 0.6 ND ND ND ND

IN-A4098 Irradiated ND 3.0 3.9 2.1 3.5 3.8 10.3

Dark ND ND 1.0 0.6 1.3 ND ND

IN-V7160 Irradiated 1.0 1.7 2.8 5.2 4.7 8.4 9.6

Dark 1.0 ND ND ND ND ND ND

IN-L9226 Irradiated ND ND ND 1.2 ND ND 2.1

Dark ND ND 1.9 ND ND ND ND

IN-L9225 Irradiated ND 6.2 11.1 8.7 22.8 12.3 12.5

Dark ND 6.0 19.5 41.0 32.1 36.3 44.5

Total unidentified Irradiated ND 2.8 2.7 5.5 4.8 6.8 13.0

Dark ND 2.9 1.3 1.1 1.2 2.7 3.9

Total extractable

residuesb

Irradiated 104.2 92.9 82.4 72.3 74.7 79.0 77.1

Dark 104.2 100.0 80.4 63.0 72.3 65.5 64.7

CO2 Irradiated NA

c ND ND ND ND ND ND


Volatile organic Irradiated NA ND ND ND ND ND ND


Non-extractable

residues

Irradiated 3.2 10.2 19.1 19.4 24.6 20.8 28.2

Dark 3.2 9.4 21.0 28.0 26.7 37.8 35.7

Total %

recoveryd,e

Irradiated 107.4 103.1 101.5 91.7 99.3 99.8 105.3

Dark 107.4 109.3 101.4 91.0 99.0 103.2 100.4 a Not Detected

b Total activity present in extracts 1 to 3.

c Not Applicable

d Value is the sum of the% AR in each component exceeding the limit of quantification.

e The total values may differ slightly from the sum of the individual values due to rounding.

Note: On Day 15 the ‘total unidentified’ residues in the irradiated samples totalled 13% however no single peak was equal

to or above 5% of the applied radioactivity.


III CONCLUSIONS

This study demonstrated that Thifensulfuron-methyl degraded quickly under the conditions of

aerobic soil photolysis at 20 2C. No unique photoproducts were identified.

The DT50 and DT90 values for Thifensulfuron-methyl in non-irradiated samples were 5.4 and

18 days, respectively. In irradiated samples the DT50 and DT90 values were 7.5 and 25 days,

respectively.

Thifensulfuron-methyl was rapidly degraded during aerobic soil photolysis at 20 2C.

Based on the results of this study, soil photolysis will be a route of elimination of

Thifensulfuron-methyl from the environment. The major metabolites observed in the

irradiated samples were IN-A4098, IN-A5546, IN-L9225, and IN-V7160. The major

metabolite observed in the dark control sample was IN-L9225. IN-A4098, IN-A5546, and

IN-V7160 were also observed in the dark controls at 5% AR. Non-extractable residues and 14

CO2 were observed in the irradiated samples at maximum levels of 33.5% and 1.2% AR,

respectively. The proposed degradation pathway taken from the original study report is

shown in Figure B.8.3a (note in the figure there is a typographical error; IN-A5536 should

read IN-A5546).

Figure B.8.3a: Proposed degradation pathway of Thifensulfuron-methyl in soil under artificial light

(McLaughlin, 2011) [note that the metabolite labelled IN-A5536 is actually IN-A5546]

(McLaughlin, S.P., 2011)


Report: R. Simmonds, (2012) [14

C]-Thifensulfuron-methyl: Soil Photolysis.

Battelle UK Ltd. [Cheminova A/S], Unpublished report No.: WB/10/006

[CHA Doc. No. 245 TIM amdendment-1]

Guidelines: SETAC Procedures for assessing the Environmental Fate and

Ecotoxicity of Pesticides, Section 2 (March 1995) and OECD Draft

Guideline – Phototransformation of Chemicals on Soil Surfaces.

GLP: GLP compliance statement and Study Director authorisation

Previous

evaluation: None: Submitted by the Task Force for the purpose of renewal under

Regulation 1141/2010

The following study was briefly reviewed by the UK RMS and

considered acceptable. It should be noted that an acceptable soil

photolysis study was already available in the original DAR (see

Ferguson, 1986 above). Therefore the new study is not critical to the

assessment. However the study was used to provide additional

information on the route of degradation in soil due to photolysis. The

results from the new study do not have any consequences for the

regulatory assessment. For example no new metabolites are found that

were not also found at comparable levels during the aerobic study

submitted by the Task Force. In this study, the IN-V7160 metabolite

formed at lower levels than observed in the new study provided by

DuPont. Additionally the IN-A5546 metabolite was not observed at all.

The lower formation of IN-V7160 may partially have been an artefact of

the slower degradation that was observed in the irradiated samples in

this study. The slower degradation was plausibly attributed by the study

author to lower moisture in the irradiated samples. The study confirmed

the conclusions from the original DAR, that soil photolysis is not likely

to be a major route of dissipation under normal environmental

conditions. Nevertheless the formation of potential photometabolites

IN-V7160 and IN-A5546 identified from the previous photolysis studies

by DuPont have been considered for relevance in the environmental

exposure assessment. The detailed study summary from the Task Force

is provided below.

Test Materials:

[Thiophene-2-14


Specific radioactivity 5.17 MBq/g

[Triazine-2-14

C]- Thifensulfuron-methyl


Non-radiolabelled Thifensulfuron-methyl

Purity: [Thiophene-2-14

C]-Thifensulfuron-methyl 98.8%

[Triazine-2-14

C]- Thifensulfuron-methyl 99.4%

Non-radiolabelled Thifensulfuron-methyl 99.2%


CAS number: 79277-27-3

Soil

One UK soil, Farditch (10/044), was obtained from Chelmorton, UK (see Table B.8.47).


Soil

name

pH

(H2O

)

OM

%

Sand1

%

Silt1

%

Clay1

%

CEC

mEq/100g

Biomass

µg C/g

soil2

Classifi

cation

MWHC

%

Bulk

density

(g/cm3)

Farditch 6.0

6.0

(3.48

OC%

)

29 54 17 12.5 747.6 Silt

Loam 83.6

0.94

1 USDA Particle Size Distribution and Classification,

2 At start of aerobic phase

CEC = Cation exchange capacity, OM = Organic matter, MWHC = Maximum water holding

capacity at pF 0.

The phototransformation of [thiophene-2-14


[triazine-2-14

C]-Thifensulfuron-methyl was studied on silt loam soil from the UK at an

application rate of 1 mg a.i./kg soil for 28 or 35 days (equivalent to > 30 days natural summer

sunlight at 30°N). A constant temperature of 20°C (± 2°C) was achieved by circulating a

water/ethylene glycol mixture throughout the test system, monitored by a thermologger.

The test system consisted of a jacketed glass vessel with threaded cap to prevent solar

irradiation affecting the soil samples. Artificial sunlight was provided by a xenon arc lamp

(Heraeus suntest (CPS+)) with filters to cut off any radiation below 290 nm. The irradiation

intensity was adjusted so that the light received over a 24 hour period of continuous

irradiation was approximately equivalent to one natural sunlight day (30°N). This latter value

was calculated as 25.1 Watts/m2 based on a maximum light intensity of natural summer

sunlight of 67 watts/m2 and the total energy received being 37.5% of this value over a 24-

hour period.

Duplicate samples from the thiophene label for both the irradiated and dark controls were

taken at 0, 1, 3, 7, 14, 21 and 28 days. Duplicate samples from the triazine label for both the

irradiated and dark controls were taken at 0, 1.1, 4, 8, 16, 26 and 35 days.

Control samples were kept in the dark for the same period as irradiated samples. All soil

samples (ca 2 g dry weight equivalent) were dispensed into 2.8 cm diameter photolysis dishes

and the moisture content adjusted to pF2 by the addition of de-ionised water.

Each photolysis incubation unit had an inlet and an outlet to allow moist air to be pumped

across the soil surface. This was produced by bubbling air through a vessel containing de-

ionised water. Units exposed to simulated sunlight were attached to a single set of traps to

enable volatile compounds to be retained and identified. One ethylene glycol and two

potassium hydroxide traps were used to capture any volatiles degradates evolved. Two

radiolabelled forms of the test substance were used in separate incubations, [thiophene-2-14

C]-thifensulfuron and [triazine-2-14

C]-thifensulfuron.


The soil samples were extracted four times with methanol: water: formic acid (80:20:1 v/v/v)

followed by three extractions with acetonitrile: water (50:50 v/v/). The extracts were

combined and the components were quantified by high performance liquid chromatography

(HPLC) (co-chromatographed with reference standards). In addition extracts were analysed

by LC/MS to provide confirmation of structural identity of products. The samples were then

left to air-dry prior to grinding, combustion and LSC quantification.


Table B.8.48 Percentage recovery of applied radioactivity from soil treated with

[14


Days after application 0 1 3 7 14 21 28

(a) [Thiophene-2-14


Irradiated

Initial soil extract 100.3 95.8 93.5 78.7 77.4 67.2 63.2

Second soil extract 0.3 2.4 4.2 9.0 8.5 12.8 12.5

Total soil extract 100.6 98.2 97.7 87.7 85.9 80.0 75.7

Unextracted 0.8 3.0 5.3 11.2 13.4 17.1 19.6

VolatileTraps1

NA 0.1 0.2 0.7 1.6 3.0 3.8

Total 101.4 101.3 103.2 99.6 101.0 100.2 99.1

Days after application 1 3 7 14 21 28

Dark Control

Initial soil extract 90.3 83.5 67.1 61.7 53.2 47.0

Second soil extract 4.3 9.3 15.8 17.4 17.3 17.9

Total soil extract 94.6 92.8 82.8 79.0 70.4 64.8

Unextracted 4.1 9.4 15.1 21.5 26.8 31.7

VolatileTraps1

0.0 0.3 0.6 1.7 2.6 1.8

Total 98.7 102.4 98.5 102.2 99.8 98.3

Days after application 0 1.1 4 8 16 26 35

(b) [Triazine-2-14


Irradiated

Initial soil extract 101.6 98.7 89.6 84.6 78.3 66.0 63.2

Second soil extract 0.2 2.4 8.2 7.7 11.1 16.3 14.6

Total soil extract 101.8 101.2 97.9 92.3 89.4 82.3 77.8

Unextracted 0.1 2.2 5.9 8.9 12.8 19.0 22.4

Volatile Traps1

NA 0.0 0.0 0.1 0.1 0.2 0.3

Total 101.9 103.4 103.8 101.2 102.3 101.4 100.5

Days after application 1.1 4 8 16 26 35

Dark Control

Initial soil extract 94.8 81.2 76.8 60.9 51.9 48.7

Second soil extract 5.3 13.0 12.0 18.1 19.9 21.7

Total soil extract 100.2 94.2 88.8 79.0 71.9 70.4

Unextracted 3.6 9.0 13.2 21.3 28.2 27.8

Volatile Traps1

0.0 0.2 0.3 1.0 2.5 2.5

Total 103.7 103.4 102.3 101.3 102.5 100.6

NA = Not applicable 1 Radioactivity in KOH trap, likely to be

14CO2


Table B.8.49 Percentage recovery of applied radioactivity as [14


from soil

Days after application 0 1 3 7 14 21 28

(a) [Thiophene-2-14


Irradiated


IN-L9226 ND ND 2.1 2.4 2.2 3.2 4.1

IN-L9225 ND 9.1 14.3 20.4 22.6 28.3 20.6

Total minor unknowns ND ND ND 0.5 1.2 ND 1.7

Total 100.3 98.2 97.7 87.7 85.0 80.0 75.7

Days after application 1 3 7 14 21 28

Dark Control

Thifensulfuron-methyl 55.5 15.3 3.8 0.7 ND 2.0

IN-L9223 ND ND 0.1 2.0 2.6 3.2

IN-JZ789 ND 0.6 1.5 2.3 2.6 2.9

IN-L9225 39.1 76.6 77.3 71.8 64.4 54.0

Total minor unknowns ND 0.3 0.2 2.3 0.9 2.8

Total 94.6 92.8 82.9 79.0 64.4 64.8

Days after application 0 1.1 4 8 16 26 35

(b) [Triazine-2-14


Irradiated


IN-B5528 ND ND 0.3 0.6 1.5 2.1 5.0

IN-A4098 ND ND 2.3 2.9 5.2 6.2 9.7

IN-V7160 ND ND ND ND 1.2 1.6 1.1

IN-L9226 ND ND 2.1 1.6 3.3 2.1 4.9

IN-L9225 ND 10.3 16.5 22.5 17.0 24.7 16.6

Total minor unknowns ND ND ND 0.3 1.0 0.4 0.6

Total 101.6 101.2 97.9 92.3 89.4 82.3 77.8

Days after application 1.1 4 8 16 26 35

Dark Control

Thifensulfuron-methyl 60.2 9.1 3.4 0.6 0.3 ND

IN-B5528 ND ND 0.3 0.7 ND 0.4

IN-A4098 ND 1.9 2.7 2.6 6.5 5.3

IN-JZ789 ND 0.9 1.6 2.2 3.8 4.7

IN-L9225 40.0 81.7 80.9 72.9 61.1 60.1

Total minor unknowns ND 0.5 ND ND ND ND

Total 100.2 94.2 88.8 78.3 71.9 70.4


ND = Not detected

Thifensulfuron-methyl was found to degrade rapidly in soil under dark control conditions

with estimated SFO DT50 values of 1.1 and 1.3 days for the thiophene and triazine label

experiments, respectively. Under irradiated conditions Thifensulfuron-methyl also degraded

but at a slower rate than the dark control experiment, with estimated DT50 values of 25.1 days

(based on FOMC kinetics) and 19.7 days (based on DFOP kinetics) at 30°N for the thiophene

and triazine label experiments, respectively. In irradiated samples, DT90 values were greater

than the duration of the study. The slower degradation rate was thought to be due to the

lower moisture level in the irradiated samples at the soil surface where the test item was

applied.

It is concluded that the IN-L9226 (O-Desmethyl Thifensulfuron-methyl) and IN-V7160

(triazine urea) were photodegradation products since they were not formed in dark controls.

These photo-products reached maximum levels of 4.9% and 1.1% respectively at the end of

the study. Two other products observed were IN-A4098 and IN-B5528 which reached

maximum levels of 9.7% and 5.0% respectively at the end of the study.

Three metabolites were present at > 10% AR at any single time point, > 5% at two

consecutive timepoints or >5% at the end of the study in the irradiated soils:



IN-B5528 (O-Desmethyl triazine amine, max. 5%)

The proposed degradation pathway is shown in Figure B.8.3b.


S

S

HN

HN

N N

N OCH3

CH3

OO O

OCH3

O

S

S

HN

HN

N N

N OH

CH3

OO O

OCH3

O S

S

HN

HN

N N

N OCH3

CH3

OO O

OH

O

H2N

N N

N OCH3

CH3

H2N

N N

N OH

CH3

Bound Residues

O-desmethyl triazine amineIN-B5528

Triazine amineIN-A4098

O-desmethyl thifensulfuron methylIN-JZ789

Thifensulfuron acidIN-L9225


HN

N N

N OCH3

CH3

Triazine ureaIN-V7160

H2N

O

Figure B.8.3b Proposed pathway for photodegradation of Thifensulfuron-methyl in soil

(Simmonds, 2012)



the proposed photodegradation pathway of thifensulfuron methyl in soil (see Figure B.8.3

below). The previous figures (Figure B.8.3a and B.8.3b) have been removed.

N

N

NS

SNH

OO

O

NH

O

O

CH3

CH3

OMe

N

N

NS

SNH

OO

O

NH

O

O

CH3

CH3

OH

N

N

N

NH2

O

CH3

CH3

S

SNH

2

OO

O

OH

N

N

N

NH2

NH

O CH3

OMe

S

SNH

2

OO

OMe

O

N

N

NS

SNH

OO

O

NH

O

O

CH3

HOMe

N

N

N

NH2

CH3

OH

DPX-M6316

IN-L9225 [2-acid]IN-A4098

IN-L9223

IN-V7160

IN-A5546

CO2 and Bound

IN-L9226*

IN-B5528*

*Minor product in task force study only

Figure B.8.3 Proposed photodegradation pathway for thifensulfuron-methyl in soil (taken

from Reporting Table 4(22))


B.8.1.3 Aerobic degradation in soil


Report: Allen, R. (1987); DPX-M6316: Aerobic degradation in soil

DuPont Report No.: HUK 5518-269/18

Guidelines: Not provided

Test material: Thifensulfuron methyl technical

Lot/Batch #: M6316 (lot number not provided)

Purity: 95%

GLP: Yes

Previous

evaluation:


In the submission received from DuPont it was proposed that the

following study does partially meet current guidelines (OECD 307 and

US EPA OPPTS 835.4100). The UK RMS agreed that the study

provided useful and acceptable information on the rate of degradation of

parent thifensulfuron. In one of the two soils tested (Speyer 2.2), it was

noted that only 4 data points were available. However since results in

terms of DT50 were broadly consistent across all soils tested (by both

Applicants) the increased uncertainty in the value from this soil was

accepted. The study has been re-evaluated in line with the current

FOCUS kinetics guidance, and results of the new kinetic analysis are

presented in separate reports summarised in Section B.8.1.4. Results

from this study are used in selecting the overall geometric mean DT50

of Thifensulfuron-methyl for the purposes of exposure modelling.

The original text of the study summary from the 1996 DAR has been

included below. Since the original study summary did not include any

tables of the residue decline, the UK RMS has amended the summary

with the inclusion of tables taken directly from the original study report

to support a revised kinetic assessment. New information is included.

Since the kinetics assessment has been completely updated, original

DT50/90 values have been removed using strikethrough text.

An additional study (5518-269/18) was started in 01/1987 and reported by R. Allen

(1987). GLP statement was included in the report. German guidelines for the

Official Testing of Plant Protection Products Part IV, 4-1: Persistence of Plant

Protectant Products in the Soil: Degradation, Transformation and Metabolism

(December 1986) were used. The study was not conform, in several points (length

of the study = 64 days, the microbial biomass was not determined, temperature was

not 20° C, degradation rate was not determined at low (10°C) temperature) to

SETAC guideline.

Protocol - The methods were described in study AMR 236-84 (radiolabelled

Thifensulfuron-methyl) and AMR 408-85 (radiolabelled triazine amine). The

degradation rates of metabolites were estimated from metabolism study data using

linear or non linear regression. Degradation rate of technical grade Thifensulfuron-

methyl (95 % purity) was also studied (study 5518-269/18) at 0.615 mg/kg in 2


German soils (see Table B.8.50) at 22°C, 40 % max. water capacity for 64 days.

Analytical procedure was HPLC (recovery 63-114% of soil 2:2 and 57 to 101% of

soil 2:3; limit of determination 0.01 ppm). DT50 and DT90 were calculated using

linear first order and non linear kinetics.

Table B.8.50 Soil Characteristics

Origin of

Soil

Soil Series

Name

Sand

(%)

Silt

(%)

Clay

(%)

OC

(%)

pH

CEC

(meq/100g)

MWHC

(%)

Germany Speyer 2:2,

Loamy Sand

53.9 40.9 5.2 2.76 5.7 9.0 57.2

Germany Speyer 2:3,

Loamy Sand

42.4 51.3 6.3 0.95 7.0 3.8 33.1

OC = Organic carbon content, % organic matter = 1.73 x % organic carbon. CEC =

Cation exchange capacity. MWHC = Maximum water-holding capacity.

Results: Thifensulfuron-methyl was rapidly degraded in soils with half life and

non linear DT90 in the range 1.67-6 days and 3.1-29 days, respectively (table

7.1.9).

Table 7.1.9 - Degradation rate of Thifensulfuron-methyl in non-sterile soils

First order kinetic Non linear kinetic

Soil DT50 (days) DT90 (days) DT50 (days) DT90 (days)

Keyport 2 - <1 3.1

Flanagan 6 - 2.6 29

Speyer 2.2 1.67 - 1 5.2

Speyer 2.3 3.39 - 1.6 9.1

Table B.8.51 Aerobic degradation of Thifensulfuron-methyl in soil Speyer 2:2

Day Sample A

(mg/kg)

Sample B

(mg/kg)

Mean (mg/kg)

0 0.52 0.57 0.55

4 0.11 0.11 0.11

8 0.01 0.02 0.02

16 <0.01 <0.01 <0.01

32 <0.01 <0.01 <0.01

64 <0.01 <0.01 <0.01

All results quoted as dry soil equivalent and not corrected for recovery

Table B.8.52 Aerobic degradation of Thifensulfuron-methyl in soil Speyer 2:3

Day Sample A

(mg/kg)

Sample B

(mg/kg)

Mean (mg/kg)

0 0.48 0.58 0.53

4 0.17 0.20 0.19

8 0.06 0.05 0.06

16 0.02 0.05 0.02

32 <0.01 <0.01 <0.01

64 <0.01 <0.01 <0.01


All results quoted as dry soil equivalent and not corrected for recovery

In conclusion, in laboratory studies on 4 types of non-sterile soils, Thifensulfuron-

methyl was rapidly degraded with half-lives of 1.7 to 6 days, respectively, based on

first-order linear kinetics. The dissipation of Thifensulfuron-methyl followed non-

linear kinetics closer than linear kinetics and provided DT50 and DT90 values that

better represented the data. The recalculated DT50 values ranged between < 1.0 to

2.6 days and the DT90 values 3.1 to 29.0 days according to soils. Metabolites of

Thifensulfuron-methyl had lower degradation rate in the studied soils.

(Allen, 1987)

Metabolite IN-A4098 (triazine amine)

Report: Rhodes, B.C. (1987); Aerobic soil metabolism of [2-14

C] 4-methoxy-6-

methyl-1,3,5- triazin-2-amine


Guidelines: U.S. EPA 162-2 (1982)

Test material: 14

C–IN-A4098 technical metabolite

Lot/Batch #: [2-14

C]-IN-A4098, lot number not provided


GLP: No

Previous

evaluation:



following study does not meet current guidelines (OECD 307 and US

EPA OPPTS 835.4100). No further details were provided by the

Applicant as to why the study was not considered to meet current

guidelines, however the UK RMS noted that the study was not

conducted to GLP which was a criteria that this Applicant used for

rejecting earlier studies summarised above. However the UK RMS has

briefly reviewed this original IN-A4098 rate of degradation study to


GLP status. No critical deficiencies were noted. The study was

conducted with radiolabelled material and analysis was via TLC with

confirmatory HPLC analysis. Stepwise extraction involved an initial

step with methylene chloride/methanol/9N NaOH (75:25:0.5 v/v/v)

repeated four times followed by 0.1N NaOH. Extracts were pooled and

analysed by TLC. The only obvious deviations were that microbial

biomass was not determined, however 14

CO2 evolution appeared to

continue throughout the 65 week study duration, suggesting that soils

remained microbially viable. In addition total recovery of radioactivity

dropped as low as 82% at some sample times. Whilst maintenance of

acceptable mass balance is an important criteria for radiolabelled

studies, this would not have been essential for a simple rate of

degradation study, which need not have used radiolabelled material.

The study duration was noted to be long and the trapping of 14

CO2 was

via a sodium hydroxide solution in the biometer flask sidearm that was

replaced every 14 d. It is possible that low mass balance may have been


due to loss of 14

CO2 over the extended study duration. In addition, the

degradation rate from this study was consistent with values from other

studies, and there was no indication that the reduced mass balance

resulted in an artificially low DT50 for this metabolite. Overall the UK

RMS considered that the study provided useful and acceptable

information on the rate of degradation of IN-A4098. The study has

been re-evaluated in line with the current FOCUS kinetics guidance,

and results of the new kinetic analysis are presented in separate reports

summarised in Section B.8.1.4. Results from this study are used in

selecting the overall geometric mean DT50 of metabolite IN-A4098 for

the purposes of exposure modelling.

The original text of the study summary from the 1996 DAR has been

included below. Since the original study summary did not include any

tables of the residue decline, the UK RMS has amended the summary

with the inclusion of tables taken directly from the original study report

to support a revised kinetic assessment. New information is included.

Since the kinetics assessment has been completely updated, original

DT50/90 values have been removed using strikethrough text.

The study (AMR 408-85) was started in 12/1984 and reported by B. C. Rhodes



conform to SETAC guideline except for minor deviations (Soil biomass was not

determined, incubation temperature was 25°C) and was found acceptable.

Protocol - [2-14

C] 4-Methoxy-6-methyl-1,3,5-triazine-2-amine (triazine amine,

radiochemical purity 99%) was applied to Keyport soil at 0.12 mg/kg, 25° C and

70 % of the field moisture capacity for 65 weeks (in aerobic conditions in

darkness). Extraction was performed with organic solvents then NaOH. Analysis

were realised by TLC and HPLC. 14CO2 was trapped in NaOH. The characteristics

of the test soil are given in Table B.8.53.


Location Soil Sand

(%)

Silt

(%)

Clay

(%)

OM

(%)

pH CEC

meq/100 g

Newark,

Delaware

U.S.A.

Keyport

Silt

loam

11

78

11

4.7

4.3

14.1



Table B.8.54 Aerobic degradation of metabolite IN-A4098 in Keyport soil

Day IN-A4098

(% of applied 14

C)

0 93.8

4 86.4

10 80.5

17 83.1

30 85.3

61 77.0

92 59.3

122 56.8

183 41.0

244 36.3

365 30.9

435 28.1

Total extracted at day 0 = 93.8%

Results - Total recovery of radioactivity ranged from 82 to 98 %. Triazine amine

was degraded with DT50=8 months (DT90=2 years). The major decomposition

product 14CO2 and bound residues reached 38 % and 10 % respectively at the end

of the exposure period. Degradation products were dihydroxy methyl triazine

(peaked at 11% after 15 months), hydroxymethyl triazine amine, O-demethyl

triazine amine (< 2%) and unresolved polar compounds (17% after 6 months then

decreased to about 8% after 15 months). The proposed metabolic pathways for

aerobic degradation of triazine amine in soil is given in figure 7.1.2.

In conclusion, the triazine moiety of Thifensulfuron-methyl (triazine amine) was

slowly degraded in soil (DT50=8 months). 72% of the parent compound was

degraded, the main decomposition product being 14CO2 formed by complete

mineralization. Dihydroxy methyl triazine was the only extractable degradation

product recovered in significant amounts (11%).

(Rhodes, 1987)

Report: Scott, M.T. (2000); Rates of degradation of [14

C]IN-A4098, a metabolite

of metsulfuron methyl, chlorsulfuron, and Thifensulfuron-methyl, in three aerobic

soils


Guidelines: SETAC Europe (1995) Deviations: None

Testing Facility: DuPont Experimental Station, Wilmington, Delaware, USA

Testing Facility Report No.: DuPont-1802

GLP: Yes

Certifying Authority: Laboratories in the USA are not certified by any

governmental agency, but are subject to regular inspections by the U.S. EPA.

Previous

evaluation: In DAR for original approval (DAR Addendum, 2000).


following study did fully meet current guidelines (OECD 307 and US


EPA OPPTS 835.4100). The UK RMS agreed that the basic study

protocol followed acceptable guidelines. However the UK RMS also

noted that the solvent extraction method used in this study differed from

that used in other studies performed with the IN-A4098 metabolite. In

this study soils were extracted in triplicate with 1 hour ambient

extractions using acetone: 0.1N ammonium carbonate. Levels of

unextracted radioactivity were relatively high at >50% in all soils at 94

d, and in one soil unextracted radioactivity was as high as 94% AR in

one replicate at the end of the study. This contrasted with levels of

unextracted radioactivity from other studies performed with

radiolabelled metabolite. For example in the additional study submitted

by DuPont from Jungmann and Nicollier (2006) extraction was via

ambient acetonitrile followed by reflux with acetonitrile. Unextracted

residues were only between 6 to 30.5% after 90 d. Degradation rates in

the study of Scott (2000) were also noted to be at the lower end of the

range for this metabolite (i.e. 22 to 39 d compared to 100 to 250 d in

Jungmann and Nicollier (2006)). The short DT50s may have been an

artefact of the less harsh extraction methods used. In addition the

pattern of residue decline in this study appeared unusual in 2 of the 3

soils. For example, in the Mattapex soil, residues remained above

around 80% AR up to the 60 d time point, then fell to less than 10% in

the next sampling point at 94 d. The Applicant proposed that reliable

fitting could only be performed in one of the three soils in this study.

Due to the uncertainty over the extraction method and the variability in

residues in 2 of the 3 soils, the UK RMS considered the study unreliable

and has not used the results in deriving a degradation rate for the IN-

A4098 metabolite. Since reliable degradation rates are available from 4

other metabolite dosed studies this has no effect on the environmental

exposure assessment.

For completeness the original text of the study summary from the 2000

DAR Addenda has been included below. However since the study is

not used in the assessment it has been greyed out.

Note that in response to Open Point 4.4 in the Evaluation Table the UK

RMS has included the results from the Arrow soil in a revised combined

data set for this metabolite to take into account DT50 values agreed in

other peer reviewesd RARs. Although the UK RMS does not

necessarily agree with the inclusion of this specific result, in the

interests of harmonising endpoints across multiple RARs it has been

included. This additional information is included in Table B.128b in

Section B.8.1.4.

Methods : [Triazine-2-14

C] IN-A4098 (95 % purity) in acetone was applied at 1

mg/kg to 3 wet soils (0.5 ml acetone solution + 50 g equivalent dry soil at 50 % of

MWHC). Soil characteristics are given in table below. Incubation was at 20° C.

Treated samples were removed at 0, 7, 21, 31, 60 and 94 d. Soils were extracted

with acetone/0.1 N ammonium carbonate and extracts were analysed by LSC and

HPLC after concentration. Extracted soils were combusted. Volatiles were trapped.


Soil characteristics (degradation of IN-A4098)

Origin Arrow, UK Gross-Umstadt, G Mattapex, USA

Soil texture Sandy loam Silt loam I Silt loam II

Sand % 71 20 34

Silt % 21 66 53

Clay % 8 14 13

pH 5.7 7.7 6.4

OM % 4.0 2.5 4.1

CEC meq/100 g 12.3 21.9 11.7

MWHC (0 bar) 50.3 56.8 61.7

Soil biomass (mg C/100 g soil)* 40 - 85 42 - 74 71 - 98

* SIR method

Results : Recoveries were acceptable although some samples were rejected due to

unacceptable recovery. After 94 d , triazine amine was poorly mineralized (8.4 -

9.8 %) and high amounts of bound residue were formed (50.5 - 65.2 %). Extracts

consisted of triazine amine and unidentified polar degradation products. For

triazine amine, a lag phase was observed for about 1 month then significant

degradation occurred and triazine amine was only 4.4 - 16.3 % after 94 d.

Conclusions : Study on degradation of IN-A4098 (triazine amine) in 3 soils (OM

2.5 - 4.1 %, pH 5.7 - 7.7) shows a lag phase of about 1 month before significant

degradation occurs. After 94 d, triazine amine is poorly mineralized (max. 9.8 %)

and significant amounts of bound residue are formed (max. 65.2 %). Soil pH and

organic matter content do not appear to play a significant role.

Degradation of IN-A4098 (triazine amine) in soil

Soil % of applied RA (mean of 2 replicates)

DAT Extractable Bound CO2 Recovery Triazine amine

Sandy loam 0* 95.7 4.1 99.8 89.6

(Arrow) 7 91.9 3.0 0.6 95.5 87.1

21 93.7 7.4 1.8 102.9 86.8

31 84.1 9.5 2.5 96.1 66.4

60** 76 11.4 6.3 93.7 36.0

94** 18.4 65.2 8.4 91.9 4.4

Silt loam I 0* 94.3 5.4 99.8 90.0

(G-U) 7 97.2 1.6 0.2 99.1 90.7

21 93.6 4.0 0.9 98.6 86.4

31 99.1 5.6 1.6 106.4 68.4

60** 85.0 6.2 4.9 96.0 79.8

94 39.5 50.5 8.6 98.6 16.3

Silt loam II 0* 99.2 1.3 100.5 95.7

(Mattapex) 7 99.0 1.8 0.3 101.1 93.3


21 91.0 5.8 1.3 98.1 85.7

31 92.7 6.6 2.6 102.0 83.0

60 85.7 7.8 6.8 100.4 79.8

94 32.9 55.8 9.8 98.5 7.4

* 3 replicates ** one replicate (second replicate not used due to unacceptable recovery 122% or < 57.2 %)

(Scott, 2000)

Report: Jungmann, V., Nicollier, G. (2006); Rate of degradation of [triazinyl-6-14

C]-labelled CGA 150829 (metabolite of CGA 152005) in various soils under

aerobic laboratory conditions at 20 deg. C

DuPont Report No.: SYN T001214-06 (Study No.12)

Guidelines: Directive 95/36/EC (1995) Deviations: None

Testing Facility: Syngenta Crop Protection, Basel, Switzerland

Testing Facility Report No.: T001214-06

GLP: Yes

Certifying Authority: Not given

Previous



IN-A4098 (Triazine amine; 4-methoxy-6-methyl-1,3,5-triazin-2-amine)

is a common metabolite of sulfonyl urea herbicides including

Thifensulfuron-methyl. This study describes the environmental fate of

triazine amine. The study was conducted by Syngenta and uses the

Syngenta code CGA 150829. The Applicant considered the results to be

relevant to the conclusions in this Thifensulfuron-methyl EU renewal

dossier.

Overall the UK RMS considered the study to be well conducted and

reported and concluded that the study was acceptable for the purposes of

the regulatory assessment. The study is summarised in detail below

based largely on the Applicants study summary. Since the kinetic

assessment has been reported separately in Section B.8.1.4 the DT50/90

values reported within this study have been removed for simplicity.

Results from this study are used in selecting the overall geometric mean

DT50 of metabolite IN-A4098 for the purposes of exposure modelling.

Executive summary:

The rate of degradation of CGA 150829 was investigated in three different soils:

18 Acres (sandy clay loam), Gartenacker (loam), and Krone (silt loam). For this

purpose, aliquots of all soils were treated at a rate of 0.025 mg a.s./kg soil (dry

weight). Aerobic samples were incubated over 119 days at a soil moisture content

of pF2 in dark conditions at 20°C.


The overall mean recovery comprising the soil extracts, non-extractable residues

and volatile products was between 98.7 and 110.5% (soil 1), 97.3 and 109.2% (soil

2), 97.5 and 107.8% (soil 3) (all values given in percent of applied radioactivity).

CGA 150829 was slowly degraded in Gartenacker, Krone and 18 Acres soils with

a half life of 102.2 to 250.2 days. Very few metabolite fractions were observed.

Formation of bound residues was also a significant pathway for the disappearance

of CGA 150829 with non-extractables ranging from 6.3 to 30.5% during the study.

Volatiles in the form of carbon dioxide ranged from 15.1 to 61.3%.


A. MATERIALS

1. Test material: CGA 150829

Lot/Batch #: 28100012

Purity: 98.0 2.0%

Stability of test compound: The stability of the test substance was determined

by HPLC or TLC using an aliquot of the application

solution before and after the treatment procedure.

2. Soil:

Three soils were used for the study, soils which were chosen to represent arable

farming conditions in respect of soil texture and pH. The characterisation data and

the biomass determinations for the soils are summarised in Table B.8.55 and 56,

respectively.

Table B.8.55 Physical and chemical properties of the soils used

Parameter measured

Soil type

18 Acres Gartenacker Krone

pH measured in CaCl2a 5.0 6.9 4.9

pH measured in watera 5.5 7.3 5.4

Particle size analysisb (%)

Sand 53 41 19

Silt 22 46 58

Clay 25 13 23

Organic matterc (%) (OC%) 5.0 (2.9) 4.2 (2.4) 3.4 (1.97)

Cation Exchange capacityd (meq/100g) 18.4 12.7 15..2

Moisture holding capacitye (%)

pF2 33.8 38.7 30.8

1/3 bar 23.3 28.6 26.3

15 Bar 11.7 8.0 12.4

Soil classificationf Sandy clay loam Loam Silty loam

a pH - by glass electrode in a 1:2 soil : deionised water or 0.01 M CaCl2 slurry (in parentheses).

b Particle size analysis - sand (2-0.05 mm) by sieving; silt (0.05-0.002 mm) and clay (<0.002 mm)

gravimetrically after separation by sedimentation rate when dispersed in sodium hexametaphosphate. c Organic matter - determined as organic carbon by oxidation with potassium dichromate, followed by titration

of excess dichromate with ferrous sulphate based on Walkley-Black wet oxidation method. d Cation exchange capacity - by sodium saturation at pH 7 and flame photometry.

e Moisture holding capacity determined using ceramic pressure technique for 1/3 and 15 bar, pF2 determined by

Haines method. f

Soil classification based on USDA scale (USA Soil Survey Triangle Method).


Table B.8.56 Microbial biomass of soil

Soil name

Microbial biomass carbon (mg/100 g soil)

Start of study End of study

18 Acres 85.6 32.9

Gartenacker 62.1 51.9

Krone 64.0 21.1

Levels of microbial biomass throughout were considered within the limits stated by OECD 307 (i.e. at least 1%

of organic carbon)

B. Study Design and Methods

Aliquots of the moisture adjusted soil (equivalent to 200 g dry weight soil) were

dispensed into glass vessels. The soils were adjusted to approximately pF2

moisture tension.

The radioactivity content of the application solution was determined by LSC as

follows: Three aliquots of 100 L were measured by LSC. Based on the specific

radioactivity of 2.36 MBq/mg and the measured average activity of 773662 dpm

per 100 L dilution, the concentration of the test substance in the application

solution was calculated to be 0.0545 mg/mL. Aliquots of approximately 100 L of

the application solution (for 200 g soil dry weight) were transferred to HPLC vials

previously tarred. The vials were weighed and the residual radioactivity in the vial

was measured by LSC and subtracted from the amount weighed in the vials. The

application rate was approximately 0.025 mg a.s./kg soil. After application, the

soil samples were mixed thoroughly and incubated in a climate chamber at a mean

value of 19.6 0.4C in the dark for up to 119 days.

Duplicate soil vessels from all three soil types were removed from the incubation

system at 0 (1-Gartenacker), 7, 14, 28, 56, 90, and 119 days after treatment. The

soil samples for the determination of the microbial biomass were taken before

application and on Day 120.

After extraction at room temperature, the soil sample was extracted with 250 mL

acetonitrile under reflux for 1 hour. In addition, an acidic harsh extraction was

carried out on several samples using 50 g aliquots (dry weight) of the soil (after

extraction with acetonitrile under reflux) and re-extracting twice with ca. 100 mL

acetonitrile/0.1 N HCl (9:1 v/v) under reflux for 1 hour. The radioactivity was

determined by LSC to check that the mass balance of the preparation step was

between 90% and 110%. Thereafter, aliquots of the concentrated extracts were

directly submitted to HPLC and/or 2D-TLC analysis. The residual radioactivity

remaining in the soil after the last extraction step was determined by combustion

and LSC. The radioactivity in the trapping solutions (NaOH) was determined by

LSC without further preparation of the samples.

II. RESULTS and DISCUSSION

Throughout the study the overall mean recovery at each time point comprising the

soil extracts, non-extractable residues and volatile products was between 98.7 and


110.5% (Gartenacker), 97.3 and 109.2% (18 Acres), 97.5 and 107.8% (Krone) (all

values given in percent of applied radioactivity).

All values are given as mean values of two replicates.

The extractable radioactivity (cold and reflux) decreased from 98.2% at the

beginning of the study to 42.7% at the end of the experiment Day 119 (soil 1),

from 98.3 to 68.3% (soil 2) and from 97.1 to 65.5% (soil 3) - all values given as

mean of two replicates.

Non-extractable residues reached a maximum of 6.3% (soil 1) at the end of the

study, 22.0% (soil 2) and 30.5% (soil 3) at the 90 days sampling. Volatiles in the

form of carbon dioxide increased almost steadily during the study and reached

61.3% (soil 1, Day 119), 15.1% (soil 2, Day 119) and 16.8% (soil 3, Day 119).

Table B.8.57 Summary of the degradation of CGA 150829 in 18 Acres soil

Time point

(DAT) Soil duplicate

CGA 150829

(% of applied

radioactivity)

Mean

(%)

0 A 98.46

98.31 B 98.16

7 A 89.04

90.16 B 91.28

14 A 80.12

83.89 B 87.65

28 A 83.85

83.09 B 82.32

56 A 75.96

76.32 B 76.68

90 A 72.22

72.25 B 72.77

119 A 67.65

68.34 B 69.02

Values given as sum of the amount found in the cold and reflux extracts by 2D-TLC analysis.

Limit of detection = 0.29-3.0% of applied


Table B.8.58 Summary of the degradation of CGA 150829 in Gartenacker soil

Time point


CGA 150829

(% of applied

radioactivity)

Mean

(%)

0 A 97.55

98.18 B 98.81

7 A 77.78

83.71 B 89.65

14 A 88.05

88.88 B 89.70

28 A 81.06

81.07 B 81.07

56 A 65.61

65.69 B 65.76

90 A 50.05

50.25 B 50.45

119 A 42.89

42.67 B 42.46



Table B.8.59 Summary of the degradation of CGA 150829 in Krone soil

Timepoint


CGA 150829

(% of applied

radioactivity)

Mean

(%)

0 A 97.05

96.72 B 96.39

7 A 82.14

83.84 B 85.53

14 A 84.46

84.24 B 84.03

28 A 79.79

80.24 B 80.69

56 A 71.60

71.09 B 70.58

90 A 61.21

62.53 B 63.85

119 A 62.43

62.64 B 62.86




III. CONCLUSION

CGA 150829 was slowly degraded in Gartenacker, Krone and 18 Acres soils.

Formation of bound residues was also a significant pathway for the disappearance

of CGA 150829 with non-extractables ranging 6.3 to 30.5% during the study.

Volatiles in the form of carbon dioxide ranged 15.1 to 61.3%.

(Jungmann, V., Nicollier, G., 2006)

Report: Möndel, M. (2001); Degradation and metabolism of AE F059411 in one

soil under standard conditions

DuPont Report No.: Aventis AGR15 (M-202633-01-1)

Guidelines: SETAC Europe (1995), U.S. EPA 162-1 Deviations: None

Testing Facility: Staatliche Lehr - und Forschungsanstalt fur Landwirtschaft,

Weinbau und Gartenbau (SLFA), Neustadt/Weinstrasse, Germany

Testing Facility Report No.: AGR15

GLP: Yes

Certifying Authority: Landesanstalt fur Pflanzenbau und Pflanzenschutz

Rheinland-Pfalz (Mainz, Germany)

Previous

evaluation:

None: Submitted by DuPont for the purpose of renewal under


IN-A4098 (Triazine amine; 4-methoxy-6-methyl-1,3,5-triazin-2-amine)

is a common metabolite of sulfonyl urea herbicides including

Thifensulfuron-methyl. This study describes the environmental fate of

triazine amine. The study was originally conducted by Aventis and uses

the Aventis code AE F059411. The Applicant considered the results to

be relevant to the conclusions in this Thifensulfuron-methyl EU renewal

dossier.



the regulatory assessment. The study is summarised in detail below


assessment has been reported separately in Section B.8.1.4 the DT50/90

values reported within this study have been removed for simplicity.

Results from this study are used in selecting the overall geometric mean

DT50 of metabolite IN-A4098 for the purposes of exposure modelling.

Executive summary:

A dose rate of 0.35 g AE F059411/100 g dry soil was calculated. Due to

analytical reasons the calculated dose rate was multiplied by the factor 3. AE

F059411 was applied to soil using an application rate corresponding to 1.00 g/100

g air-dried soil. The soil was incubated for 1-2 hours, 7, 4, 21, 28, 42, 56, 70, 84,

96, 112, 126, and 140 days. The material balance (sum of trapped 14

CO2, extracted

and non-extracted radioactivity) for the individual test vessels was between 92 and


104% of the radioactivity applied. At the end of the incubation period 46.1% of

the applied radioactivity were found in the soil extract and could be assigned to be

the unchanged test item. In the course of the experimental phase no metabolite was

found. The amount of extractable radioactivity decreased in the first half of the

incubation period (Day 70) up to 54.3% of applied radioactivity. After that period

the extractable radioactivity remained nearly constant within a range of 51.0 and

46.1% of the applied radioactivity. Non-extractable radioactivity was increasing

for about 40 days. After that period the non-extractable radioactivity remained

almost constant within a range of 38.1 to 45.7% of the applied activity. The

amount of volatile compounds and 14

CO2 increased continuously and reached on

Day 140 a maximum value of 5.2% of the applied activity.

I. MATERIAL AND METHODS

A. MATERIALS

1. Test material: [Triazine-2-14

C] AE F059411

Specific radioactivity: 14.33 MBq/mg

Radiochemical purity: >99%

2. Soil The soil sample as characterised in Table B.8.60 and

was collected freshly from the field and stored cool.

Two weeks prior application the soil was transferred

in a glasshouse and kept at 20°C and daylight.

Within the following 7 days the soil moisture was

adjusted 3 times in order to maintain a natural

moisture content. One week prior to the

application, the amount of soil which was needed

for the study was sieved through a 2 mm sieve. The

soil was stored again in a plastic bag at room

temperature. The bag was closed with a cotton

wool stopper in order to guarantee a gas exchange.


Table B.8.60 Characteristics of test soil

B. Study design

1. In-life initiated/completed

21-September-1999 to 20-March-2000


Subsamples of 10 g air-dried soil were treated with the test substance, and mixed

into 90 g fresh soil after evaporation of the application solvent, yielding a total of

100 g soil per test vessel (dry weight equivalents, each). After soil moisture

adjustment to 40% of the maximum water holding capacity, incubation was in the

dark at ca. 20°C. The flasks were equipped with appropriate traps to collect

volatiles and 14

CO2.

For each sample the soil was extracted in triplicate, using 150 mL portions of

aqueous acetonitrile (ACN/water, 4/1 v/v). The pooled extracts were carefully

concentrated by rotary evaporation and were analysed by reversed-phase HPLC

with radiodetection. Identity of AE F059411 was confirmed by coelution with

non-labelled reference substance. Non-extractable residues were quantified by

combustion of the dried soils after extraction.

3. Sampling

Duplicate samples were taken for analysis at 0, 7, 14, 21, 28, 42, 56, 70, 84, 96,

112, 126, and 140 days after application of the test substance.

4. Analytical procedures

For each sample the soil was extracted in triplicate, using 150-mL portions of

aqueous acetonitrile (ACN/water, 4/1 v/v). The pooled extracts were carefully

concentrated by rotary evaporation and were analysed by reversed-phase HPLC

with radiodetection. Identity of AE F059411 was confirmed by coelution with

non-labelled reference substance. Non-extractable residues were quantified by

combustion of the dried soils after extraction.

Designation/Batch ID

Units

Honville/960119 a

Origin Chateaudun (F)

Texture Loamy silt (silt loam)

Sand (0.063–2.000 mm) [%] 4.8

Silt (0.002–0.063 mm) [%] 79.8

Clay (<0.002 mm) [%] 15.4

Bulk density [g/cm3] n.d.

pH (water) 6.7

Organic carbon [%] 0.77

Organic matter [%] 1.32

Cation exchange capacity [mval/100 g soil] 13

Maximum water holding capacity [g/100 g soil] 46.9

Field capacity at pF = 2.5 [g/100 g soil] n.d.

Microbial biomass (start) [mg Cmicro/100 g] 10.5

Microbial biomass (end) [mg Cmicro/100 g] 13.3


II. Results and Discussion

A. Data

The results of aerobic biotransformation of [Triazine-2-14

C] AE F059411 in one

European soil are summarised in Table B.8.61.

Table B.8.61 Degradation of metabolite [2-14

C]AE F059411 after application

to soil Honville and aerobic incubation at 20C / 40% maximum water holding

capacity (data are given in % of applied radioactivity; mean of duplicate samples)

Sampling times [days]

0 7 14 21 28 42 56 70 84 96 112 126 140

AE F059411 97.0 90.6 74.6 67.2 64.4 57.5 57.6 54.3 51.0 50.3 47.0 51.5 46.1

Total

extractable 97.0 90.6 74.6 67.2 64.4 57.5 57.6 54.3 51.0 50.3 47.0 51.5 46.1

14CO2

0.1 0.8 1.2 1.4 1.8 2.0 2.9 3.2 3.9 4.0 4.6 4.1 5.2

Non-

extractable 6.5 9.0 22.6 29.0 33.1 38.2 38.1 38.1 36.6 42.4 45.7 38.7 41.2

Total recovery 103.7 100.4 98.4 97.6 99.2 97.7 98.6 95.6 91.5 96.7 97.2 94.3 93.2

B. Mass balance

The overall mean recovery of radioactivity was 97.7%. All individual values were

91.5%.

C. Bound and extractable residues

Extractable radioactivity declined from 97.0% of applied radioactivity on Day 0 to

46.1% on Day 140. The non-extractable residues increased from 6.5% on Day 0 to

41.9% on Day 140.

D. Volatile radioactivity

Mineralisation to 14

CO2 was moderate, accounting for 5.2% and 20.3% of applied

radioactivity at the end of the incubation phase. Other volatile radioactivity was

detected only in negligible amounts (<0.05%).

E. Transformation of parent compound

Chromatographic analysis of the soil extracts showed AE F059411 as the only

extractable compound throughout the study period. No extractable metabolic

downstream products were formed, breakdown therefore led directly to non-

extractable residues and carbon dioxide.

III. Conclusion


The soil metabolite AE F059411 was shown to be degradable in aerobic soil. The

compound undergoes direct transformation to non-extractable residues and is

mineralised to carbon dioxide, with no extractable downstream intermediates.

(Möndel, M., 2001)

Report: G. Morlock (2006a) Degradation of 2-amino-4-methoxy-6-methyl-1,3,5-

triazine (MM-TA) in 3 different soils under aerobic conditions at 20°C

in the dark. GAB Biotechnologie GmbH & GAB Analytik GmbH

[Cheminova A/S], Unpublished Report No. 20051104/01-CABJ [CHA

Doc. No.189 MEM]

Guidelines: OECD 307; SETAC 1995

GLP: Statement of compliance with OECD Principles of Good Laboratory

Practice and The Principles of Good Laboratory Practice (GLP).

Previous

evaluation:

None: Submitted by Task Force for the purpose of renewal under


The following rate of degradation study with IN-A4098 was provided by

the Task Force. The study was evaluated by the UK RMS and

considered acceptable. Kinetics were assessed in line with the FOCUS

kinetics guidance and this additional assessment has been included in the

study summary provided by the Task Force below. The degradation

rates from this study are combined with those from the DuPont studies

in Section B.8.1.4 and are used in selecting the overall geometric mean

DT50 for the purposes of exposure modelling.

Non-radiolabelled IN-A4098 (MM-TA, triazine amine) was applied to 3 soils (German

standard soils 2.2, 3A, and 6S) at a rate equivalent to 200 g/ha and incubated for up to 120

days under aerobic conditions at 20°C in the dark and a soil moisture content of 45% WHC.

Samples were taken at pre-determined intervals and analysed for IN-A4098 using an HPLC-

MS/MS method. The method was validated in accordance with SANCO/3029/99 rev.4 and

was considered acceptable. The recovery of samples fortified with the test item at the time of

sampling of treated soils ranged from 96 to 111%. Degradation of IN-A4098 under the

conditions of the study was moderate to slow. Single first order kinetics provided an

acceptable fit to the data from all three soils with calculated DT50s of 67.3 to 333.2 days

(mean 196.3 days, DT90s 223.6 to 1107 days (mean 652.1 days), r2 = 0.7703-0.9523).

The UK RMS evaluation confirmed that the SFO partial differential equations and associated

initial starting parameters used to derive DT50 and DT90 value were appropriate.


Materials:


1. Test Material: IN-A4098 (MM-TA, triazine amine)

Description: white solid

Lot/Batch #: 921301

Purity: 99.5%

CAS #: Not stated

Stability: Not stated

2. Soils Three German soils supplied by LUFA Speyer.


Soil name pH

(H2O)

OC

%

Sand1

%

Silt1

%

Clay1

%

CEC

mEq/100g

Initial/

End

Biomass

mg C/g

soil2

Classification1

MWHC

%

2.2 5.7 2.21 77.5 14.6 7.9 12.1 23.9/12.0 Loamy sand 39.4

3A 7.3 2.47 47.3 39.1 17.6 23.4 53.8/39.5 Sandy loam 38.3

6S 7.1 2.02 22.0 36.1 42.0 20.5 23.0/19.9 Clay loam 36.6

1 USDA;

2 Prior to application; CEC = Cation exchange capacity, OC = Organic carbon, MWHC = Maximum

water holding capacity

Study Design:


Duplicate 50 g samples of 3 soils (German standard soils 2.2, 3A, and 6S, soil characteristics

given in Table 7.2.3/02-01) were acclimatised in the dark at 202°C for 7 to 14 days. After

this acclimatisation period non-radiolabelled IN-A4098 was applied to the soil samples at a

rate equivalent to 200 g/ha (13.33 µg/sample, based on a uniform distribution in a 5 cm soil

layer and a soil bulk density of 1.5 g/cm3) and incubated under aerobic conditions in the dark

for up to 120 days at 202°C with a soil moisture content of 45% WHC. Soil samples were

taken 0 (after 1 hour), 1, 3, 7, 14, 20, 29, 58, 90 and 120 days after treatment. Soil samples

were extracted immediately after sampling with acetonitrile/water. Extracts were refrigerated

for up to 35 days prior to analysis (extracts were demonstrated to be stable over this period)

and analysis was performed using an HPLC-MS/MS method, which was validated as

required by the SANCO/3029/99 rev.4 guideline. Further method validation was performed

in parallel with the analysis of the samples.

The soil biomass was also monitored over the period of the study to confirm the presence of a

viable microbial community throughout the experiment.


Calculation of half-lives for IN-A4098 according to FOCUS guidance

The IN-A4098 data from the three soils were analysed using CAKE version 1.4 software

package following the guidance provided by FOCUS (2006, 2011). The SFO model

produced acceptable fits to the data both visually and statistically in all soils (Table B.8.63)

and modelling DT50s were calculated from the SFO model accordingly. The calculated DT50

values were essentially the same as those derived in the original study report.

Table B.8.63 Kinetic model fits IN-A4098 laboratory soil degradation data

Soil Model χ2 error (%) Parameter

confidence

(t-test)

Visual fit DT50

Soil 2.2 SFO 5.68 k: p < 0.05 Good 67.3

Soil 3A SFO 5.64 k: p < 0.05 Intermediate 188.4

Soil 6S SFO 1.00 k: p < 0.05 Good 333.2

Results and Discussion:

No significant difference between biomass of the treated and untreated samples was observed

during the conduct of the study.

Recoveries during method validation were 86 to 103%. Procedural recoveries during

analysis of the samples were 96 to 111%.

It was found that degradation of IN-A4098 under the conditions of the study was moderate to

slow. Degradation was modelled using first order kinetics, which provided an acceptable fit

to the data from all three soils with correlation coefficients of > 0.9 in two soils and >0.7 in

the other.

Table B.8.64 Results of the analysis of IN-A4098 in the three soils

Time

[days after

treatment]

Experimental values ([µg/ 50 g dry soil] mean of duplicate samples, recovery

corrected)

Soil 2.2 Soil 3A Soil 6S

0 13.46 13.03 12.7

1 12.78 13.00 12.34

3 11.88 13.22 12.18

7 10.97 12.39 12.35

14 10.56 11.24 12.35

20 8.95 10.07 11.9

29 8.37 10.20 11.75

58 6.68 9.83 11.04

90 5.40 8.82 10.27

120 4.30 8.92 9.8


Conclusions:

Degradation of IN-A4098 under the conditions of the study was moderate to slow.

Calculated DT50s were 67.3 to 333.2 days (mean 196.3 days, DT90s 223.6 to 1107 days (mean

652.1 days), r2 = 0.7703-0.9523). The slow observed DT50 values in all soils (>60 days)

triggered further field-based dissipation studies.

(Morlock, 2006a)

Metabolite IN-A5546

Report: Bell, S. (2011); Rate of degradation of [14

C]-IN-A5546 in five aerobic

soils

DuPont Report No.: Dupont-29146

Guidelines: OECD 307 (2002), OPPTS 835.4100, SETAC Europe (1995)

Deviations: None

Testing Facility: Charles River Laboratories (UK), Tranent, Scotland, UK


GLP: Yes


Previous



In the original DAR the IN-A5546 metabolite appeared to be considered

a non-major transient metabolite due to its short half life. It was not

included in the original PECsoil exposure assessment or in the

groundwater assessment. The transient nature of this metabolite is

supported by the new rate of degradation study submitted by DuPont

below (and also supported by the new study submitted by the Task Force

and reported further below). In the study of DuPont, the IN-A5546

metabolite was not detectable at the first sample point after day 0 (i.e. 3

d). The study supports the original conclusions of the DAR that this

metabolite is transient in microbially viable aerobic soil. However

the data were not sufficient to support any level of detailed kinetic

analysis. The information in this study has been used qualitatively

to confirm that the IN-A5546 metabolite would not require a full

formal quantitative groundwater assessment due to its rapid

degradation. However for completeness the IN-A5546 metabolite

has been included in the soil, groundwater and surface water

exposure assessments. For groundwater, a limited set of modelling was

conducted simulating the worst-case GAPs and based on a conservative

DT50 of 3 d (supported by this study and the new study from the Task

Force, see Brice and Gilbert, 2011b below). This modelling confirmed

PECgw values <<0.001μg/l and no further assessment was considered

necessary. The detailed study summary from DuPont is provided below.


Executive summary: The rate of degradation of [14

C]-IN-A5546 was studied in

five agricultural soils at 20 2C for 120 days in the dark. [14

C]-IN-A5546 was

applied at the rate of 0.51 mg a.s./kg oven dry soil. Samples were maintained in

darkness under aerobic conditions at ca 50% of maximum water holding capacity

(0 bar moisture).

Under laboratory conditions there was rapid degradation of [14

C]-IN-A5546 in all

soils. The test item was not detected in any Day 3 samples, therefore the DT50 and

DT90 are reported as 3 days without kinetic fitting.

Overall mean material balance ranged from 94.67 to 97.87% of the applied

radioactivity. Non-extractable 14

C-residues increased from a mean maximum

2.16% of the applied radioactivity at zero time to a maximum value of 32.70% of

the applied radioactivity at the end of the study. At study termination, evolved 14

CO2 accounted for a maximum of 67.91% of the applied radioactivity. One

major degradation product co-chromatographed with IN-L9223. The major

component accounted for a maximum of 91.06% of the applied radioactivity in all

soils. Total combined unidentified components accounted for a maximum of

4.27% of the applied radioactivity.


A. MATERIALS


C]-IN-A5546 technical metabolite


C]-IN-A5446: 3631068

Radiochemical purity: 99.9%

Specific activity: 18.76 Ci/mg

Description: Solid, powder

Stability of test compound: Shown to be stable under the conditions of the test

2. Soils

The study was conducted with five different soil types (three European and two

from the U.S.). These were freshly collected from the top 0–20 cm layer of

agricultural fields. A summary of the physical and chemical properties of the soils

is provided in Table B.8.65. The percent sand, silt, and clay are quoted on the

basis of the USDA classification.


Table B.8.65 Soil characteristics (Dupont-29146)

Soil identity Sassafras Tama Lleida Speyer 2.2 Nambsheim

Geographic origin USA USA Spain Germany France

USDA texture class Sand Silty clay

loam Silty clay Loamy sand Sandy loam

% Sand 87 11 11 87 72

% Silt 12 56 42 9 19

% Clay 1 33 47 4 9

pH (water) 5.3 6.1 7.9 6.3 7.7

pH (0.01M CaCl2) 4.7 5.6 7.7 5.8 7.4

Organic carbon (%) 1.4 2.3 1.8 2.0 2.2

CEC (meq/100 g) 5.3 17.4 16.9 8.3 10.7

Microbial biomassa

(mg C/100g soil) 3.62 21.95 16.91 19.36 24.25

Moisture content (%) 10.98 18.83 19.77 11.33 18.81

Water

Holding

Capacity

(%)

0-bar 36.62 67.49 56.61 51.83 53.44

0.1 bar 12.3 47.5 38.7 14.1 32.7

1/3-bar 9.0 34.6 31.7 9.8 18.9

15-bar 3.4 16.7 17.6 6.6 8.1

Bulk density (g/cm3) 1.22 1.08 1.07 1.25 1.03 a Following 120 days aerobic incubation at 20 2C

B. STUDY DESIGN


Portions of sieved soils (50 g oven dry-soil equivalent) were adjusted to moisture

contents of 18.31% (Sassafras), 33.75% (Tama), 28.31% (Lleida), 25.92% (Speyer

2.2), and 26.72% (Nambsheim), equivalent to 50% of their respective maximum

water holding capacities at 0 bar applied pressure. A solution of radiolabelled test

substance, dissolved in water containing a final concentration of ca 0.6%

acetonitrile, was prepared and applied to soil samples, in separate 250 mL conical

flasks, at a rate of 0.51 mg a.s./kg oven dry soil. Additional samples for



replaced and soils were incubated in the dark at 20 2C under aerobic conditions

for up to 120 days in a flow through system which allowed the trapping of evolved

carbon dioxide and volatile organic compounds.

2. Sampling

Microbial biomass was determined at zero time and Day 120 (the last sampling

point). Soil samples were taken for analysis at zero time and 3, 7, 15, 30, 59, 90

and 120 days after application.


Sodium hydroxide solutions used to trap volatile components, and ethanediol used

to trap organic volatiles, were replenished and analysed at regular intervals. Soil

samples were subjected to the following extraction sequence:

a. Soil samples were transferred into plastic bottles and acetone: 0.1 M

ammonium carbonate (90:10 v/v) was added. The bottles were ultrasonicated at

50C for ca 30 minutes before being centrifuged for ca 15 minutes at ca 4000 rpm.

The supernatant was decanted and its volume made up to 130 mL with acetone:

0.1 M ammonium carbonate (90:10 v/v).


b. A second extraction was carried out as described above.

c. 0.1 M ammonium carbonate (100 mL) was then added to each vessel and the

vessels ultrasonicated at 50C for ca 1 hour. The vessels were then centrifuged for

ca 15 minutes at ca 4000 rpm. The supernatants were decanted and made up to

130 mL with 0.1 M ammonium carbonate.

d. A fourth extraction was carried out by adding 100 mL acetone to each vessel.

The samples were then ultrasonicated at 50C for ca 30 minutes before being

centrifuged for ca 15 minutes at ca 4000 rpm. The supernatant was decanted and

its volume made up to 130 mL with acetone.

The radioactivity levels in extracts were measured using LSC. Extracts were

stored in separate jars, but were combined for analysis. The volume of the

combined extract was measured and triplicate aliquots were taken and submitted

for LSC to determine the radioactive content.

Soil samples were combusted and 14

C levels were measured using LSC. The soil

extracts were analysed using reverse phase HPLC with a gradient of acetonitrile

and water containing 10 mM ammonium formate. The effluent was passed through

a UV detector (254 nm) to detect reference standards and a radiodetector to detect

radiolabelled components. The limit of quantification for radiolabelled

components, using representative blank samples, was determined as 1% AR.



A. DATA

Table B.8.66 Degradation of [14

C]-IN-A5546, expressed as percentage of applied

radioactivity, in Sassafras soil

Component Rep. No.

Sampling interval (Days)

0 3 7

[14

C]-IN-A5546

1 81.92 nda nd

2 84.73 nd nd

Mean 83.33 nd nd

IN-L9223

1 12.13 87.94 85.74

2 9.83 91.06 86.53

Mean 10.98 89.50 86.14

Unidentified radioactivity

1 nd 1.22 nd

2 nd 1.30 nd

Mean nd 1.26 nd

Non-extractable residue

1 LOQb 1.70 4.30

2 LOQ 1.74 4.83

Mean LOQ 1.72 4.57

14CO2

1 nsc 1.65 4.94

2 ns 1.65 4.94

Mean ns 1.65 4.94

Volatile organics

1 ns LOQ LOQ

2 ns LOQ LOQ

Mean ns LOQ LOQ

Total % recovery

1 96.72 93.00 95.59

2 97.23 96.43 96.92

Mean 96.98 94.72 96.26 a Not detected

b LOQ = data derived from counts below LOQ

c No sample




radioactivity, in Tama soil

Component Rep. No.


0 3 7

[14

C]-IN-A5546

1 83.87 nda nd

2 85.92 nd nd

Mean 84.90 nd nd

IN-L9223

1 10.32 73.88 43.11

2 9.29 72.81 39.97

Mean 9.81 73.35 41.54


1 nd nd 1.46

2 0.57 nd 2.74

Mean 0.29 nd 2.10


1 1.97 11.82 28.05

2 1.96 12.60 25.30

Mean 1.97 12.21 26.68

14CO2

1 nsb 10.19 26.76

2 ns 10.19 26.76

Mean ns 10.19 26.76

Volatile organics

1 ns LOQc LOQ

2 ns LOQ LOQ

Mean ns LOQ LOQ

Total % recovery

1 97.71 97.16 100.81

2 99.13 97.11 97.43


b No sample

c LOQ = data derived from counts below LOQ




radioactivity, in Lleida soil

Component Rep. No.


0 3 7

[14

C]-IN-A5546

1 78.06 nda nd

2 73.57 nd nd

Mean 75.82 nd nd

IN-L9223

1 13.35 82.62 66.67

2 18.63 81.69 65.88

Mean 15.99 82.16 66.28


1 nd nd 0.97

2 nd nd 1.04

Mean nd nd 1.01


1 1.58 6.97 12.52

2 2.74 8.15 16.44

Mean 2.16 7.56 14.48

14CO2

1 nsb 3.61 11.95

2 ns 3.61 11.95

Mean ns 3.61 11.95

Volatile organics

1 ns LOQc LOQ

2 ns LOQ LOQ

Mean ns LOQ LOQ

Total % recovery

1 99.62 96.14 95.84

2 97.98 96.08 98.49


b No sample

c LOQ = data derived from counts below LOQ.




radioactivity, in Speyer 2.2 soil

Component Rep. No.


0 3 7

[14

C]-IN-A5546

1 87.47 nda nd

2 85.66 nd nd

Mean 86.57 nd nd

IN-L9223

1 6.69 82.11 61.85

2 8.95 79.56 62.71

Mean 7.82 80.84 62.28


1 nd 0.81 1.61

2 nd 1.24 nd

Mean nd 1.03 0.81


1 LOQb 6.91 15.02

2 LOQ 7.10 16.09

Mean LOQ 7.01 15.56

14CO2

1 nsc 6.40 16.32

2 ns 6.40 16.32

Mean ns 6.40 16.32

Volatile organics

1 ns LOQ LOQ

2 ns LOQ LOQ

Mean ns LOQ LOQ

Total % recovery

1 98.20 97.34 96.03

2 98.44 95.20 96.37


b LOQ = data derived from counts below LOQ.

c No sample




radioactivity, in Nambsheim soil

Component Rep. No.


0 3 7

[14

C]-IN-A5546

1 78.89 nda nd

2 74.04 nd nd

Mean 76.47 nd nd

IN-L9223

1 12.63 74.91 45.00

2 17.71 74.53 38.76

Mean 15.17 74.72 41.88


1 nd nd 3.34

2 nd nd 4.27

Mean nd nd 3.81


1 LOQb 9.49 20.46

2 LOQ 10.11 21.00

Mean LOQ 9.80 20.73

14CO2

1 nsc 9.60 27.16

2 ns 9.60 27.16

Mean ns 9.60 27.16

Volatile organics

1 ns LOQ LOQ

2 ns LOQ LOQ

Mean ns LOQ LOQ

Total % recovery

1 97.06 95.63 97.44

2 96.43 96.15 93.18


b LOQ = data derived from counts below LOQ.

c No sample

b. MASS BALANCE

Overall mean material balance for [14

C]-IN-A5546 ranged from 94.67% to 97.87%

applied radioactivity.

c. BOUND AND EXTRACTABLE RESIDUES

The percentage of radioactivity in the extractable fraction decreased from Day 0 to

Day 120 for all five soils. The level of bound residue increased over the course of

the study in all of the soils. Extractability values ranged from mean values of

96.98% AR (zero time) to 7.68% AR (Day 120) for the Sassafras soil, 96.46% AR

(zero time) to 4.49% AR (Day 90) for the Tama soil, 96.64% AR (zero time) to

4.34% AR (Day 120) for Lleida, 98.32% AR (zero time) to 6.31% AR (Day 120)

for the Speyer 2.2 soil, and 96.75% AR (zero time) to 4.79% AR (Day 90) for the

Nambsheim soil.

Bound residue values ranged from below quantifiable levels (zero time) to 27.79%

AR (Day 120) for the Sassafras soil, 1.97% AR (zero time) to 38.91% AR (Day


15) for the Tama soil, 2.16% AR (zero time) to 33.65% AR (Day 30) for Lleida

soil, below quantifiable levels (zero time) to 36.86% AR (Day 30) for the Speyer

2.2 soil, and below quantifiable levels (zero time) to 32.19% AR (Day 30) for the

Nambsheim soil.

d. VOLATILISATION

Volatile radioactivity identified as 14

CO2 represented 57.44, 62.15, 61.74, 60.72,

and 67.91% applied radioactivity at Day 120 in the Sassafras, Tama, Lleida,

Speyer 2.2, and Nambsheim soils, respectively. Any other 14

C-organic volatiles

were lower than quantifiable levels.

e. TRANSFORMATION OF PARENT COMPOUND

HPLC analysis of soil extracts demonstrated that [14

C]-IN-A5546 was degraded in

each soil type, with none of the parent test item remaining by Day 3. Results from

HPLC analyses of soil extracts from Day 15 onwards are not reported as no

[14

C]-IN-A5546 was detected in any of these samples.

Meaningful kinetic fits for IN-A5546 degradation could not be derived due to rapid

degradation in all soils. The test item was detected in Day 0 samples but not in any

subsequent sampling interval for all five soils. The DT50 and DT90 are therefore

reported without kinetic fitting as 3 day, as the first sampling interval following

Day 0 was Day 3.

One major degradation product was formed in soil. IN-L9223 accounted for 10.98,

9.81, 15.99, 7.82, and 15.17% of applied radioactivity at zero time in the Sassafras,

Tama, Lleida, Speyer 2.2, and Nambsheim soils, respectively. At Day 3, IN-L9223

accounted for 89.50, 73.35, 82.16, 80.84, and 74.72% of applied radioactivity in

the Sassafras, Tama, Lleida, Speyer 2.2, and Nambsheim soils, respectively.

Unidentified compounds, accounted for maximum values of 1.26, 2.10, 1.01, 1.03,

and 3.81% of applied radioactivity in the Sassafras, Tama, Lleida, Speyer 2.2, and

Nambsheim soils, respectively, by the Day 7 sampling interval.

III. CONCLUSION

This study demonstrated the rapid degradation of [14

C]-IN-A5546 in five aerobic

soils incubated at 20 2C . The DT50 and DT90 in all five soils were <3 days.

The major degradation product was IN-L9223, accounting for between 73.35 to

89.50% of applied radioactivity after 3 days incubation. The majority of the

applied radioactivity was detected as 14

CO2.

(Bell, S., 2011)


Report: A. Brice, J. Gilbert (2011b) Thifensulfonamide: Aerobic soil

degradation. Covance Laboratories Ltd. [Cheminova A/S], Unpublished report

No.: 8235715 [CHA Doc. No. 199 TIM]

Guidelines: OECD 307

GLP: Yes (certified laboratory)

Previous



This new rate of degradation study conducted with IN-A5546 has

been provided by the Task Force and supports the conclusions of

the new study from DuPont above (Bell, 2011). In the original DAR

the IN-A5546 metabolite appeared to be considered a non-major

transient metabolite due to its short half life. This original conclusion is

fully supported by the new data. Since the Task Force study supports

the original conclusions of the DAR, the UK RMS has not reviewed the

study in detail. The improved sampling did allow for a more detailed

kinetic assessment. However since the half-lives were clearly only

around 6 hours and the substance had degraded to ≤ 5% within 24 hours,

the UK RMS has not performed a detailed evaluation of this study. The

information in this study has been used qualitatively to confirm that the

IN-A5546 metabolite would not require a full formal quantitative

groundwater assessment due to its rapid degradation. However for

completeness the IN-A5546 metabolite has been included in the soil,

groundwater and surface water exposure assessments. For groundwater,

a limited set of modelling was conducted simulating the worst-case

GAPs and based on a conservative DT50 of 3 d (supported by the study

from DuPont, see Bell, 2011 above). This modelling confirmed PECgw

values <<0.001μg/l and no further assessment was considered necessary.

The detailed study summary from the Task Force is provided below.

Executive Summary:

The rate of degradation of IN-A5546 (thifensulfonamid, 2-ester-3-sulfonamide) has

been studied in three soils at 20 ± 2ºC and at pF 2 over a period of 72 hours.

Samples of the 2 mm sieved soils (50 g dry weight equivalent) were dispensed into

individual vessels on three separate occasions in order to generate a complete set of

data. The units were maintained in the dark for up to 4 days at 20 ± 2°C to

acclimatise. IN-A5546 (50 μg) was applied by pipette dropwise in acetonitrile (100

μL) on to the soil surface. The soil was mixed thoroughly before incubation in the

dark at 20 ± 2°C. The treatment rate was 1 mg/kg.

Microbial biomass determinations confirmed that all soils remained viable during

incubation.

An analytical procedure for the determination of IN-A5546 in test soils was

validated successfully over the range 0.05 to 1.00 mg/kg.

Recovery of IN-A5546 from procedural fortifications to control soil samples was

within the acceptance criteria of 70 to 110% in all batches with an overall mean of

95% obtained.


Immediately after application, IN-A5546 was recovered at 94 to 96% of applied

treatment. During the incubation period, concentrations of IN-A5546 declined to

between 0.5 to 1.2% of initial applied treatment remaining after 72 hours.

The concentrations of IN-A5546 were analysed by single first-order (SFO) kinetics

following the recommendations of the FOCUS work group and using KinGUI 1.1

in order to determine the values for 50% (DT50) and 90% (DT90) degradation in

all soil types.

The DT50 values for IN-A5546 were between 5.04 and 6.74 hours depending on

the soil type. DT90 values were between 16.75 and 22.40 hours. The test

substance, IN-A5546, degraded in a similar rapid manner when applied to all three

soils.

Table B.8.71 Kinetic summary for IN-A5546 (hours)

Soil name Model DT-50 DT-90

Longwoods SFO 5.04 16.75

Chelmorton SFO 6.26 20.79

Lockington SFO 6.74 22.40


Materials:

1. Test Material: IN-A5546 (Thifensulfonamid, 2-ester-3-sulfonamide)

Description: Solid

Lot/Batch #: 1265-JKV-84-3

Purity: 99.5%

CAS #: Not stated


2. Soils Three UK soils were provided by the Land Research Associates.


Soil name pH

(H2O)

OM

%

(OC

%)

Sand1

%

Silt1

%

Clay1

%

CEC

mEq/100g

Biomass

µg C/g

soil2

Classification MWHC

%

Longwoods 7.9 2.2

(1.3) 77 9 14 13.8 313.1 Sandy loam 12.6

Chelmorton 7.3 5.7

(3.3) 23 57 20 25.8 451.1 Clay loam 33.6

Lockington 6.5 4.3

(2.5) 42 24 34 35.4 668.0 Clay loam 30.7

1 UK Particle Size Distribution and Classification, 2 Prior to study,


Study Design:

Experimental conditions


Soil samples (50 g dry weight equivalent) were weighed into individual glass

vessels on three separate occasions. Initially, a sufficient number of soil samples

were dispensed to allow duplicate analysis at 0 (immediately after treatment), 1, 3

(± 1), 7 (± 1), 14 (± 1), 30 (± 2), and 60 (± 2) days after treatment plus a minimum

of four spare units per soil type. For repeat dose occasion 1, a sufficient number of

units were dispensed for each dose group to enable analysis at 0, 0.5, 1 and 3 hours

after treatment plus a minimum of two spare units per soil type. For repeat dose

occasion 2, a sufficient number of units were dispensed for each dose group to

allow duplicate analysis at up to four further sampling intervals per soil type. Soil

units were acclimatised under experimental conditions for up to 4 days at 20 ± 2°C,

in the dark prior to test substance application.

The application rate selected for IN-A5546 was 50 μg/50 g soil (1.0 mg/kg). The

treated soils were mixed thoroughly by hand prior to the initiation of the incubation

period.

At each sampling time duplicate units were analysed. Soil samples were extracted

three times with acetonitrile : water : acetic acid (3:1:0.25, v/v/v). Aliquots (10

mL) of the combined extracts were concentrated to ca 2 mL under nitrogen and

diluted to 10 mL with methanol : water (1:1, v/v). Analysis was by ultra

performance liquid chromatography (UPLC) with tandem mass spectrometry

detection (MS/MS) (UPLC-MS/MS). The LOQ for this procedure was 0.05

mg/kg.

The analytical method was validated by fortifying sub-samples (50 g dry weight

equivalent) of each untreated control soil, in duplicate, with IN-A5546 at

concentrations of 0.05 and 1.0 mg/kg.


All soils had a viable microbial biomass for up to 18 hours. Considering the short

incubation period, and the fact that approximately 90% IN-A5546 degradation had

been achieved in each incubation group by 18 hours, this was sufficient evidence to

demonstrate viable biomass over the most significant period of incubation.

The LOD of 0.0013 mg/kg was equivalent to 0.1% of the nominally applied

treatment concentration of IN-A5546.

Mean recoveries of IN-A5546 obtained from control soil systems fortified at 0.05

and 1.0 mg/kg, when using the confirmatory transition 222.2 – 189.7, were 91 and

93%, respectively. Overall mean recovery was within the acceptable range of 70 to

110%.

Immediately after application, IN-A5546 was recovered at 94 to 96% of applied

treatment (mean values of four replicates). During the incubation period,

concentrations of IN-A5546 declined to between 0.5 to 1.2% of initial

concentration remaining after 72 hours.


Table B.8.73 Mean concentration of IN-A5546 and percentage of dosed amount in soil

Sampling

interval

(hours)

Longwoods Chelmorton Lockington

Concentration

measured

(mg/kg)

% of dosed

Concentration

measured

(mg/kg)

% of dosed

Concentration

measured

(mg/kg)

% of dosed

0 0.95298 95.3 0.94422 94.4 0.96277 96.3

0.5 0.90525 90.5 0.91173 91.2 0.90847 90.8

1 0.88693 88.7 0.89162 89.2 0.87778 87.8

3 0.60062 60.1 0.67178 68.2 0.66297 66.3

6 0.44955 45.0 0.50137 50.1 0.55917 55.9

18 0.07411 7.4 0.13423 13.4 0.15741 15.7

24 0.01148 1.1 0.03755 3.8 0.04959 5.0

72 0.00537 0.5 0.00645 0.6 0.01221 1.2

Using SFO kinetics, DT50 values for IN-A5546 were between 5.04 and 6.74 hours

depending on the soil type. DT90 values were between 16.75 and 22.4 hours.

Table B.8.74 Kinetic data for IN-A5546

Soil name Model DT-50 (hours) DT-90 (hours) Chi2

Longwoods SFO 5.04 16.75 3.73

Chelmorton SFO 6.26 20.79 2.43

Lockington SFO 6.74 22.40 3.42

Conclusions:

The DT50 values for IN-A5546 in three soils were between 5.04 and 6.74 hours

depending on the soil type. DT90 values were between 16.75 and 22.40 hours.

Consequently, the test substance, IN-A5546, degraded in a similar rapid manner

when applied to all three soils.

(Brice and Gilbert, 2011b)


Metabolite IN-L9223

Report: Cleland, H. (2011); Rate of degradation of [14

C]-IN-L9223 in five aerobic

soils

DuPont Report No.: DuPont-29895, Revision No. 2

Guidelines: OPPTS 835.4100, OECD 307 (2002), SETAC Europe (1995)

Deviations: None



GLP: Yes


Previous

evaluation:



In the original DAR the IN-L9223 metabolite was not included in the

exposure assessments in soil or groundwater and no degradation (or

sorption) endpoints were available. However in the original route of

degradation study, this metabolite was not separated from the IN-L9225

metabolite. IN-L9223 has now been identified as a major soil

metabolite in the acceptable route of degradation study from the Task

Force (Simmonds, 2012a). Therefore the UK RMS accepted that new

data on its rate of degradation in soil was necessary and the separate

studies from DuPont (and the Task Force) are summarised below.


reported and concluded that the study was acceptable for the

purposes of the regulatory assessment. Minor deviations or points to

note are highlighted below. The study report stated that replicate

samples were analysed at each sample point. However the final report

only provided results as the mean of the two replicates and these data

have been used in the separate kinetics fitting reported at Section

B.8.1.4. Mass balance was low (<90% AR) in the 15 and 30 d sampling

points in the Nambsheim soil. This was plausibly attributed by the study

author to escape of evolved 14

CO2. Since approximately 23% AR

remained as parent IN-L9223 at the 30 d sampling point in the Sassafras

soil, sampling of this soil could have been continued beyond 30 d. Since

no further analysis of later time points was conducted, the DT90 for this

soil is extrapolated beyond study duration. Overall degradation rates

were broadly comparable and this minor deviation does not affect the

acceptability of the study. The study is summarised in detail below


assessment has been reported separately the DT50/90 values reported

within this study have been removed for simplicity. Although this study

was considered acceptable, degradation rates were noted to be

significantly shorter than were observed for this metabolite in the parent

dosed route of degradation study. The route of degradation study

provided linked formation fractions and degradation rates. In addition,

in the opinion of the UK RMS, the route study was likely to better

mimic the actual formation of this metabolite in situ in soil. For these


reasons, the degradation rates from this separately dosed metabolite rate

of degradation study have not actually been used in the final

environmental exposure assessment. The detailed study summary from

DuPont is provided below.

Executive summary:

The rate of degradation of [14

C]-IN-L9223 was studied in five agricultural soils at

20 2C for 120 days. [14

C]-IN-L9223 was applied to the soil at a rate of

0.5 g a.s./g oven dry soil. Samples were maintained in darkness under aerobic

conditions at ca 50% of maximum water holding capacity (0 bar moisture).

Under laboratory conditions there was rapid degradation of [14

C]-IN-L9223 in all

soils, which represented less than 1% of applied radioactivity in the final sampling

point (30 d) in 4 out of 5 soils.

Material balance, calculated as the percent of applied radioactivity (% AR), was

maintained at 90% throughout the study except in Nambsheim soil which was

marginally out of range on days 30 and 60. Volatile organics were not produced in

any significant levels in any of the soils. 14

CO2 was evolved in all soils, reaching a

maximum of ca 60% by Day 60 in Sassafras soil. The mean amounts of

radioactivity in each of the components of the system are summarised in Table

B.8.75.

HPLC analysis of the soil extracts demonstrated that [14

C]-IN-L9223 declined in

each soil type over the course of the study. [14

C]-IN-L9223 decreased from

quantitative levels at Day 0 (immediately after application) to values of 0.99% AR

in Nambsheim soil, 0.73% AR in Lleida soil, 0.89% AR in Speyer, 0.74% AR in

Tama and 22.51% AR in Sassafras soil at Day 30. At Day 60, [14

C]-IN-L9223

residues were below the limit of detection in all soils. Biotransformation data is

presented in Table B.8.77 to B.8.81.


Table B.8.75 Radioactivity mass balance at study termination

Soil name

Texture

(USDA)

Extractable at

Day 60

(% AR)

Non-

extractable at

Day 60

(% AR)

Evolved 14

CO2 at Day

60 (% AR)

Overall mean

mass balance

(% AR)

Nambsheim Sandy loam 7.84 23.64 39.36 89.48 19.66

Lleida Clay 8.36 28.71 61.60 100.66 4.26

Speyer 2.2 Loamy sand 8.76 28.53 52.71 97.22 7.56

Tama Silty clay loam 6.77 27.37 57.27 100.11 9.13

Sassafras Sandy loam 8.96 34.27 62.15 101.64 3.80


A. MATERIALS


C]-IN-L9223 technical metabolite

Lot/Batch #: 3631069


Specific activity: 20 Ci/mg

Description: Solid

Stability of test compound: Radiochemical purity tested prior to test system application

3. Soils

The study was conducted with five soil types with varying characteristics. The soil

was freshly collected from the top 20 cm layer of agricultural land and stored

refrigerated prior to use. A summary of the physical and chemical properties of the

soils is provided in Table B.8.76. The percent sand, silt, and clay are reported on

the basis of USDA classification.


Table B.8.76 Soil characteristics (DuPont-29895, Revision No. 2)

Parameter Results/Units

Soil Identity Nambsheim Lleida Speyer 2.2 Tama Sassafras

Geographic Location France Spain Germany USA USA

USDA textural class Sandy loam Clay Loamy sand

Silty clay

loam Sandy loam

Sand (%) 68 17 83 9 57

Silt (%) 21 35 14 60 32

Clay (%) 11 48 3 31 11

pH (in water) 7.8 8.0 6.0 6.7 5.7

pH (in 0.01 M CaCl2 ) 7.4 7.7 5.6 6.3 5.1

Organic Carbon (%)a 1.7 2.1 2.2 2.4 0.9

Bulk Density (g/cm3) 1.09 1.04 1.22 0.96 1.16

Cation Exchange Capacity

(meq/100g) 9.1 15.9 7.6 17.0 6.5


Microbial Biomass

pre-incubation

(g/g dry soil)

156.00 128.93 93.40 111.67 70.53

Microbial biomass

Post-Incubation

(g/g dry soil)

241.40 205.27 171.00 177.93 129.60

Water holding

capacity (%) at

applied pressures

0 Bar 53.7 61.2 48.9 78.3 46.1

1/10 Bar 29.6 36.9 14.2 40.6 23.1

1/3 Bar 14.9 29.5 10.8 30.0 15.1

15 Bar 6.4 18.4 7.6 17.3 5.5

Note: Soil characterisation data (except moisture content) was provided by the Sponsor and was conducted by

Agvise Laboratories as a separate GLP study. Soil moisture content and microbial biomass of the soil was

conducted at Charles River. a Organic Carbon (%) = Organic Matter (%) by Walkley-Black Method/ 1.72

B. STUDY DESIGN


Portions of sieved soil (50 g oven dry soil equivalent) were adjusted to a moisture

content equivalent to ca 50% of their respective maximum water holding capacities at

0 bar applied pressure. A solution of radiolabelled test substance, dissolved in water

with 1% acetonitrile, was prepared and applied to soil samples, in separate test

vessels, at a rate of 0.5 mg a.s./kg oven dry soil. Additional samples for



replaced and soils were incubated in the dark at 20 2C under aerobic conditions for

up to 120 days in a flow through system which allowed the trapping of evolved

carbon dioxide and volatile organic compounds.

2. Sampling

Microbial biomass was determined at zero time and Day 120. Soil samples were

taken for analysis at zero time and 3, 7, 15, 30, 60 days after application.



Sodium hydroxide solutions used to trap volatile components, and ethanediol used to

trap organic volatiles, were replenished, and analysed at each sampling intervals. Soil

samples were subjected to the following extraction sequence:

The soil was transferred to a pre-weighed plastic pot with 100 mL of acetone:

aqueous 0.1 M ammonium carbonate (9:1 v/v). Samples were then placed on the end

over end shaker (ca 1 hour). The supernatant was then separated by centrifugation

(ca 4,000 rpm for ca 15 minutes). Residues were extracted a second time with

100 mL of 0.1 M ammonium carbonate followed by placing on the end over end

shaker (ca 1 hour) and again the supernatant was then separated by centrifugation.

The residues were extracted a third time with 100 mL of acetone: 0.1% formic acid

(aq) (9:1 v/v), placed on an end over end shaker (ca 1 hour). The supernatant was

then separated by centrifugation. From Day 30 onwards, a fourth extraction was

carried out in 100 mL of 0.1 M ammonium carbonate, placed on an end over end

shaker (ca 2 hours at Day 30, ca 1 hour at Day 60). The supernatant was then

separated by centrifugation. Volumes of individual extract solutions were made up to

fixed volumes of 100 mL with the appropriate extractant and triplicate aliquots taken

from each extract for LSC.

Extracts were stored separately, with a portion combined for analysis. The volume of

the combined extract was measured and triplicate aliquots were taken and submitted

for LSC to determine the radioactive content.

Soil sample aliquots were combusted and 14

C levels were measured using LSC. The

soil extracts were analysed using reverse phase HPLC (Agilent Zorbax ODS, 5 m,

250 mm 4.6 mm id) eluted with a gradient of acetonitrile and water adjusted to

pH 2.2 with trifluoroacetic acid. The eluent was passed through an UV detector

(254 nm) to detect reference standard and a radiodetector to detect radiolabelled

components. The limit of quantification for radiolabelled components, using

representative blank samples, was determined as 0.53% AR.


A. DATA


C]-IN-L9223, expressed as % AR, in Nambsheim sandy

loam soil

Component


0 3 7 15 30

IN-L9223 97.76 87.67 68.64 29.55 0.99

Unknown ca 3 min nda nd 1.48 2.88 4.56

Unknown ca 7 min nd nd nd nd 0.17

Unknown ca 15 min 3.82 nd 3.48 nd nd

Total extractable radioactivity 101.58 87.67 73.59 32.42 11.38 14

CO2 nsb 5.07 14.65 29.04 34.07

Non-extractable residue 0.96 5.57 15.78 28.09 26.21

Material balance 102.54 98.30 104.01 89.55 71.65 a Not determined

b No sample



C]-IN-L9223, expressed as % AR, in Lleida clay soil

Component


0 3 7 15 30

IN-L9223 98.09 82.85 55.45 18.64 0.73

Unknown ca 3 min nda 1.35 3.54 5.61 4.14


Unknown ca 15 min 2.20 4.14 3.59 nd nd


CO2 nsb 5.20 18.53 45.27 57.36


Material balance 102.76 100.43 101.24 103.03 97.76 a Not detected

b No sample

All values are the mean of two replicates.


C]-IN-L9223, expressed as % AR, in Speyer loamy

sand

Component


0 3 7 15 30

IN-L9223 100.84 89.07 65.25 34.32 0.89


Unknown ca 15 min nd nd 1.03 0.62 nd


CO2 nsb 5.50 15.75 34.05 47.13



b No sample


C]-IN-L9223, expressed as % AR, in Tama silty clay

loam

Component


0 3 7 15 30

IN-L9223 100.60 81.48 48.26 11.69 0.74


Unknown ca 7 min nd nd nd 1.62 0.32

Unknown ca 10 min nd nd nd 0.63 nd

Unknown ca 15 min nd nd 4.81 0.33 nd


CO2 nsb 9.41 24.49 46.38 57.00



b No sample




C]-IN-L9223, expressed as % AR, in Sassafras

sandy

Component

Sampling times ( Days)

0 3 7 15 30

IN-L9223 97.05 96.59 84.56 59.88 22.51

Unknown ca 3 min nda nd nd nd 2.64


Unknown ca 15 min 4.86 nd nd 0.74 nd

Minor non-polar nd nd nd nd 1.82


CO2 nsb 2.11 6.97 21.41 45.63



b No sample


III. CONCLUSION

The results of this study demonstrate that IN-L9223 is rapidly degraded in soil.

(Cleland H., 2011)

Report: A. Brice, J. Gilbert (2011a) 2-acid-3-sulfonamide: Aerobic soil

degradation. Covance Laboratories Ltd. [Cheminova A/S], Unpublished

report No.: 8235717 [CHA Doc. No. 201 TIM]


GLP: Study director authentication and GLP compliance statement

Previous



This new rate of degradation study conducted with IN-L9223 has

been provided by the Task Force and largely supports the

conclusions of the new study from DuPont above (Cleland, 2011). The detailed study summary from the Task Force is provided below.

Although this study was considered acceptable, degradation rates were

noted to be significantly shorter than were observed for this metabolite

in the parent dosed route of degradation study. The route of degradation

study provided linked formation fractions and degradation rates. In

addition, in the opinion of the UK RMS, the route study was likely to

better mimic the actual formation of this metabolite in situ in soil. For

these reasons, the degradation rates from this separately dosed

metabolite rate of degradation study have not actually been used in the

final environmental exposure assessment.


The rate of degradation of IN-L9223 (2-acid-3-sulfonamide) has been studied in three soils

(Table B.8.83) at 20 ± 2ºC and at a mean of the WHC at pF 2 over 119 days.

Samples of the sieved soils (50g) were dispensed into individual glass vessels. The units

were maintained in the dark at 20 ± 2ºC for 4 days to enable an equilibrium to be established.

IN-L9223 (50 μg) was applied by syringe dropwise in acetonitrile (100 μL) onto the soil

surface. The soil was mixed thoroughly before incubation in the dark at 20 ± 2°C. The

treatment rate was 1 mg/kg. Microbial biomass was determined at dosing and study

termination. Duplicate soil samples were taken for analysis of IN-L9223 for dose groups

(DG) A, B and C, at 0, 1, 3, 7, 14, 30, 65, 90 and 119 days after application.

Recovery of IN-L9223 from procedural fortifications to control soil samples was within the

acceptance criteria of 70 to 110% in all batches with an overall mean of 96% obtained.

Immediately after application, IN-L9223 was recovered at 92 to 101% of applied treatment.

During the incubation period, concentrations of IN-L9223 declined to between 0.2 (< limit of

detection, LOD) to 51.3% of initial concentration remaining after 119 days. The

concentrations of IN-L9223 were analysed by single first-order (SFO) kinetics following the

recommendations of the FOCUS work group and using KinGUI 1.1 in order to determine the

values for 50% (DT50) and 90% (DT90) degradation in all soil types.

The DT50 values for IN-L9223 in three soils were between 27.1 and 122.3 days depending on

the soil type. DT90 values were between 89.9 and 406.2 days (Table B.8.82).

RMS evaluations confirmed that the SFO partial differential equations and associated initial

starting parameters used to derive DT50 and DT90 value were appropriate.

Table B.8.82 Kinetic summary for IN-L9223 (days)

Soil name Model DT-50 DT-90

Longwoods SFO 122.3 406.2

Chelmorton SFO 39.3 130.7

Lockington SFO 27.1 89.9


Materials:

1. Test Material: IN-L9223 (2-acid-3-sulfonamide)

Description: Solid

Lot/Batch #: 929-MC-41-1

Purity: 97.7%

CAS #: Not stated


2. Soils Three UK soils were provided by the Land Research Associates.



Soil name pH

(H2O)

OM

%

(OC

%)

Sand1

%

Silt1

%

Clay1

%

CEC

mEq/100g

Initial

Biomass

µg C/g

soil2

(% OC)

End

Biomass

µg C/g soil2

(% OC)

Classification MWHC

%

Longwoods 7.9 2.2

(1.3) 77 9 14 13.8

313.1

(2.4)

274.6 (2.1)

Sandy loam 12.6

Chelmorton 7.3 5.7

(3.3) 23 57 20 25.8

451.1

(1.4)

484.9 (1.5) Clay loam 33.6

Lockington 6.5 4.3

(2.5) 42 24 34 35.4

668.0

(2.7)

661 (2.2) Clay loam 30.7

1 UK Particle Size Distribution and Classification, 2 On arrival at Covance,


Study Design:


Soil samples (50 g dry weight equivalent) were weighed into individual glass vessels on one

occasion. Soil units were acclimatised under experimental conditions for 4 days at 20 ± 2°C,

in the dark prior to test substance application. In addition, seventeen untreated incubation

units (50 g dry weight equivalent) of each soil type were prepared in the same way. These

units were used for control samples and for procedural recovery fortifications during the

sample analysis. After the initial moisture adjustment, these soil samples were transferred to

freezer storage (< -10°C, nominally -20°C) until required.

Soil samples were dosed at 50 µg/50 g soil (1.0 mg/kg). The treated soils were mixed

thoroughly by hand prior to the initiation of the incubation period.

At each sampling time duplicate units were analysed. Soil samples were extracted three times

with acetonitrile: water: acetic acid (3:1:0.01, v/v/v). Aliquots (10 mL) of the combined

extracts were concentrated to ca 2 mL, transferred to a 10 mL volumetric flask with 1%

formic acid (1 mL) and diluted to volume with water. An aliquot (0.9 mL) of sample extract

was diluted with methanol (0.1 mL) in an HPLC vial. Analysis was by HPLC-MS/MS. The

LOQ for this procedure was 0.05 mg/kg.

The analytical method was validated by fortifying sub-samples (50 g dry weight equivalent)

of each untreated control soil, in duplicate, with IN-L9223 at concentrations of 0.05 and 1.0

mg/kg.


Recovery of IN-L9223 from procedural fortifications to control soil samples was within the

acceptance criteria of 70 to 110% in all batches with an overall mean of 96% obtained.

The LOD of 0.0075 mg/kg was equivalent to 0.75% of the nominally applied treatment

concentration of IN-L9223.


Immediately after application, IN-L9223 was recovered at 92 to 101% of applied treatment

(mean values of two replicates). During the incubation period, concentrations of IN-L9223

declined to between 0.2 to 51% of initial concentration remaining after 119 days.

In three instances, fresh aliquots of selected samples were analysed in order to confirm the

initial results obtained as three samples gave higher than expected results. The original high

results from dose group A, 30 days, and dose group C, 14 days, were attributed to inaccuracy

during analysis or contamination. However, because there was no clear reason to discount

these original values, the mean value of all three results from each sample was used in the

kinetic determinations.

Table B.8.84 Mean concentration of IN-L9223 and percentage of dosed amount in soil

Sampling

interval

(days)

Longwoods (A) Chelmorton (B) Lockington (C)

Concentration

measured

(mg/kg)

% of dosed

Concentration

measured

(mg/kg)

% of dosed

Concentration

measured

(mg/kg)

% of dosed

0 0.99904 99.9 1.00549 100.5 0.92054 92.1

1 1.00106 100.1 0.88867 88.9 0.87859 87.9

3 1.08171 108.2 0.94872 94.9 0.91079 91.1

7 0.98869 98.9 0.93789 93.8 0.90407 90.4

14 0.94765 94.8 0.81880 81.9 0.91676 91.7

14b NA NA NA NA 0.73278 73.3

14b NA NA NA NA 0.70601 70.6

30 1.03879 103.9 0.64829 64.8 0.53211 53.2

30a 0.83844 83.8 NA NA NA NA

30 a 0.82243 82.2 NA NA NA NA

65 0.67008 67.0 0.26865 26.9 0.05907 5.9

65b NA NA NA NA 0.05649 5.6

90 0.66004 66.0 0.18301 18.3 0.03265d 3.3

119 0.51274 51.3 0.10648 10.6 0.00225d c

0.2 a further units analysed. The mean value from each unit was used for the kinetic evaluations.

b further aliquots analysed. The mean value from each unit was used for the kinetic evaluations.

c Concentration <LOD (0.0075 mg/kg) therefore a value of 0.0038 mg.kg (0.5 x LOD) used for the kinetic

evaluations dnoted to be < the validated LOQ

NA – Not applicable

Using SFO kinetics, DT50 values for IN-L9223 were between 27 and 122 days depending on

the soil type. DT90 values were between 90 and 406 days. RMS evaluations confirmed that

the SFO partial differential equations and associated initial starting parameters used to derive

DT50 and DT90 value were appropriate.


Table B.8.85 Kinetic data for IN-L9223

Soil name Model DT-50 DT-90 Chi2

Longwoods SFO 122.3 406.2 3.22

Chelmorton SFO 39.3 130.7 5.82

Lockington SFO 27.1 89.9 11.22

Conclusions:

The DT50 values for IN-L9223 in three soils were between 27.1 and 122.3 days depending on

the soil type. DT90 values were between 89.9 and 406.2 days.

The test substance, IN-L9223, degraded in a similar manner when applied to the Chelmorton

and Lockington clay loam soils. Degradation of the test substance was slower when applied

to the Longwoods sandy loam soil.

(Brice and Gilbert, 2011a)

Metabolite IN-L9225 and IN-L9226

Report: Manjunatha, S. (2000); Rates of degradation of IN-L9225 and IN-L9226

(metabolites of Thifensulfuron-methyl) in three aerobic soils


Guidelines: EC Directive 95/36/EC (1995), SETAC (1995)

Test

material:

IN-L9225

technical

metabolite

IN-L9226 technical

metabolite

Lot/Batch #: L9225-5 L9226-2

Purity: 98.8% 95.1%

GLP: Yes

Previous

evaluation: In DAR for original approval (DAR Addendum2000).


fully meets the current guidelines OECD 307 and US EPA OPPTS

835.4100. The UK RMS accepts that the original study is sufficient to

meet current guidelines. The study has been re-evaluated in line with

the current FOCUS kinetics guidance, and results of the new kinetic

analysis are presented in separate reports summarised in Section

B.8.1.4. Results from this study for the IN-L9225 metabolite are

combined with additional information from the route of degradation

study in determining an overall geometric mean DT50 for the purposes

of the environmental exposure assessment. For IN-L9226, the

information is used qualitatively to exclude this metabolite from a full

formal quantitative groundwater assessment due to its rapid

degradation. However the leaching risk of IN-L9226 has been

effectively addressed in the groundwater section based on the


assessment of IN-A5546 (see Section B.8.6 for further details).

The original text of the study summary from the 2000 DAR Addenda

has been included below. Since the kinetics assessment has been

completely updated, original DT50/90 values have been removed using

strikethrough text.

Methods : The metabolites IN-L9225 and IN-L9226 (purity > 95 %) in acetonitrile

were applied at 1 mg/kg to 3 soils (50 g samples). Soil characteristics given in table

below. Incubation was at 20° C and at 40 % MWHC. For IN-L9225, duplicate

samples (3 on day 0) were removed at 0, 3, 7, 14, 21, 30, 45, 60, 90 and 120 DAT.

Soils were extracted with 0.1 M ammonium carbonate, extracts were acidified and

partitioned with ethyl acetate and the organic phase was concentrated and analysed

by HPLC-UV. For IN-L9226, duplicate samples (3 on day 0) were removed at 0, 3,

7, 10, 14, 21 and 30 DAT. Soils were extracted with acetonitrile and extracts were

concentrated and analysed by HPLC-UV. Analytical methods were validated using

spiked soil samples (0.05, 0.1 and 1 mg/kg).

Table B.8.86 Soil characteristics (degradation of IN-L9225 and IN-L9226)

Origin Drummer Glenville Gross-Umstadt

Soil texture silty clay loam sandy loam silt loam

Sand % 5.6 69 8.8

Silt % 57.2 22 74.4

Clay % 37.2 9 16.8

pH 5.9 7.3 7.5

OM % 5.1 2.0 1.9

CEC meq/100 g 33.3 4.7 10.3

MWHC (0 bar) 56.7 36.6 45.3

Soil biomass (mg C/100 g soil)* 77.4 65.6 67.5

* fumigation extraction method, initial value

Results : Analytical recoveries were 86 - 102 % (93 - 105 % during the experiment)

for IN-L9225 and 98 - 109 % (94 - 105 % during the experiment) for IN-L9226

and the LOQ was determined to be 0.05 mg/kg for both compounds. For IN-

L9225, DT50 and DT90 values were calculated to be 20.4 - 157 d (mean 73.8 d) and

67.9 - 522 d (mean 245 d), respectively, using 1st order kinetics. For IN-L9226, the

corresponding values were 0.9 - 2.9 d (mean 1.9 d) and 2.9 - 9.6 d (mean 6.4 d).


Table B.8.87 Degradation of IN-L9225 and IN-L9226 in 3 soils

mg/kg (mean of 2/3 replicates)

IN-L9225 (acid) IN-L9226 (O-desmethyl)

Drummer Glenville G-Umstadt Drummer Glenville G-Umstadt

0 1.01 1.06 1.04 1.04 1.07 1.04

3 0.77 0.94 1.02 0.37 0.61 0.1

7 0.68 0.93 1.03 0.08 0.13 < 0.05

10 - - - 0.05 0.09 -

14 0.66 0.82 0.86 < 0.05 < 0.05 -

21 0.62 0.50 0.82 - - -

30 0.55 0.32 0.81 - - -

45 0.51 0.21 0.80 - - -

60 0.41 0.14 0.79 - - -

90 0.15 0.06 0.66 - - -

120 0.08 0.05 0.63 - - -

R2 0.92 0.97 0.86 0.99 0.99 -

DT50 (day) 44.1 20.4 157 2.0 2.9 0.9

DT90 (day) 146 67.9 522 6.6 9.6 2.9

Conclusions : The metabolite IN-L9225 (Thifensulfuron acid) is slowly degraded

in 3 soils (OM 1.9 - 5.1 %, pH 5.9 - 7.5) with DT50 and DT90 values in the range

20.4 - 157 d (mean 73.8 d) and 67.9 - 522 d (mean 245 d), respectively. This highly

variable persistence is not clearly related to soil properties. The metabolite IN-

L9226 (O-desmethyl thifensulfuron) is rapidly degraded in the 3 soils with DT50 <

2.9 d and DT90 < 9.6 d.

(Manjunatha, 2000)

Metabolite IN-L9226

Report: E. Knoch (2012c) Aerobic Soil Degradation of O-Desmethyl

Thifensulfuron-methyl. SGS Institute Fresenius GmbH, [Cheminova A/S],

Unpublished

Report No.IF-11/02083022, [CHA Doc. No. 299 TIM]



Previous



This new rate of degradation study conducted with IN-L9226 has been

provided by the Task Force and largely supports the conclusions of the

original DAR study above (Manjunatha, 2000). In the original DAR IN-

L9226 was included in the exposure assessment in soil and groundwater.

However it was shown to be transient metabolite with a short half life

and demonstrated no leaching risk to groundwater (PECgw <0.001μg/l).


No risks were identified for this metabolite in the original DAR. The

new study below from the Task Force clearly just supports the

original conclusions of the DAR with DT50 values ranging from 0.3

to 3.3 days. Metabolite IN-L9226 is no longer identified as a major soil

metabolite from the acceptable route of degradation studies summarised

above. However the information in this study has been used

qualitatively to exclude the IN-L9226 metabolite from a full formal

quantitative groundwater assessment due to its rapid degradation. The

leaching risk of IN-L9226 has been effectively addressed in the

groundwater section based on read across from the assessment of IN-

A5546 (see Section B.8.6 for further details).

As a result the UK RMS has not reviewed the study in detail. The

detailed study summary from the Task Force is provided below.

Executive Summary:

The degradation of IN-L9226 (O-Desmethyl Thifensulfuron-methyl) was

investigated under aerobic conditions at 20 °C in the dark for a maximum of 30

days. Three German soils were used for the experiment (USDA classification:

LUFA 2.2 / loamy sand, LUFA 2.3 / sandy loam and LUFA 6S / clay). The soil

moisture was adjusted to 45 % maximum water holding capacity.

The target rate of 0.1 mg/kg dry soil for IN-L9226 was selected for the aerobic soil

degradation experiments. The soil systems were acclimatized under a dynamic

atmosphere of air to maintain aerobic conditions. The test period consisted of

sampling intervals at: LUFA 2.2 and LUFA 2.3: zero-time (initial value), 1, 2, 3, 7

and 14 days; LUFA 6S: zero-time (initial value), 2, 4, 7, 14 and 30 days. The

recoveries of IN-L9226 for the initial time specimens ranged from 88 to 95 % of

the applied test item. For the experimental end specimens the recoveries of IN-

L9226 decreased by aerobic degradation and accounted for < 10 % for LUFA 2.2

(days-14), < 10 % for LUFA 2.3 (days-14) and < 10 % for LUFA 6S (days-30).

The modelling followed first order kinetics. The following DT50 and DT90 values

were calculated:


Soil name Model DT-50 (days) DT-90 (days) Chi2

LUFA 2.2 SFO 0.6 2.1 18.5

LUFA 2.2 FOMC 0.6 2.1 20.4

LUFA 2.3* SFO 0.3 0.9 7.6

LUFA 6S SFO 3.3 10.8 12.5

* day 2 not included in the kinetic calculation


Materials:

1. Test Material: IN-L9226 (O-Desmethyl Thifensulfuron-methyl)

Description: White Solid

Lot/Batch #: 957-PEJ-2


Purity: 93.1%

CAS #: 150258-68-7


2. Soils Three German soils were provided by the LUFA Speyer.


Soil name

pH

(0.1 M

CaCl2)

OC

%

Sand1

%

Silt1

%

Clay1

%

CEC

mEq/100g

Biomass

mg C/g

soil2

Classification MWHC

%

LUFA 2.2 5.5 1.87 80.6 12.6 6.8 9.9 32 Loamy sand 44.4

LUFA 2.3 6.8 0.94 63.7 27.6 8.7 10.7 20 Sandy loam 35.6

LUFA 6S 7.1 1.64 22.2 36.8 41.0 23.7 84 Clay 38.9 1 USDA Particle Size Distribution and Classification, 2 Prior to study,

CEC = Cation exchange capacity, OC = Organic carbon, MWHC = Maximum water holding capacity at pF 0

Study Design:


The soils (100 g dry weight) were moistened to 45% MWHC and incubated at 20 ±

2ºC in the dark. Application of the test substance (0.1 mg a.s./kg soil) was made to

the soil surface and mixed by manual shaking. Following application the soil units

were incubated until sampling.

Sampling was at: LUFA 2.2 and LUFA 2.3: zero-time (initial value), 1, 2, 3, 7 and

14 days; LUFA 6S: zero-time (initial value), 2, 4, 7, 14 and 30 days. At each

sampling interval replicate specimens were taken and assayed for IN-L9226.

Within the course of the experiments (> 0-time) the analytical method was proved

to be valid. Therefore, laboratory procedural recovery specimens were performed,

using two fortification levels for the analyte and soil type: 0.01 mg a.s./kg dry soil

(10 % target rate) and 0.1 mg a.s./kg dry soil (100 % target rate).

The samples were extracted four times with 100-140 mL 0.5 mol/L ammonium

carbonate and methanol (60:40 v/v) by shaking, followed by centrifugation and

filtration. The extracts were combined and the final volume was made up to 500

mL with extraction solvent. 200 µL of the extract was diluted with 800 µL of pure

water. Final extracts were then subjected to LC-MS/MS analysis.

Standard solutions of IN-L9226 were prepared freshly for each set of soil samples

analysed.

The kinetic modelling followed the guidance of FOCUS kinetics employing the

software tool for kinetic evaluation FOCUS_DEGKIN v2.


The limit of quantification (LOQ) was 0.01 mg/kg dry soil for IN-L9226. All the

recovery data of IN-L9226 in the three soil systems are acceptable (mean recovery

between 70 and 110 % and a relative standard deviation less than 20 %).

The recoveries of IN-L9226 for the initial time specimens ranged from 88 to 95 %

of the applied test item. For the experimental end specimens the recoveries of IN-

L9226 decreased by aerobic degradation and accounted for < 10 % for LUFA 2.2

(days-14), < 10 % for LUFA 2.3 (days-14) and < 10 % for LUFA 6S (days-30).


Table B.8.90 Concentration of IN-L9226 and percentage of dosed amount in

soil

Sampling

interval

(hours)

LUFA 2.2 LUFA 2.3 LUFA 6S

Concentration

measured

(mg/kg)

% of dosed

Concentration

measured

(mg/kg)

% of dosed

Concentration

measured

(mg/kg)

% of dosed

0 0.0886

0.0896

92

93

0.0917

0.0899

95

93

0.0856

0.0849

89

88

1 0.0213

0.0252

21

25

0.0068

0.0088

7

9 NA NA

2 0.0211

0.0195

22

20

0.0091

0.0126

9

13

0.0649

0.0725

67

75

3 (0.0018)

(0.0021)

(2)

(2)

(0.0029)

0.0036

(3)

4 NA NA

4 NA NA NA NA 0.0306

0.0323

31

32

7 (0.0021)

(0.0023)

(2)

(2)

0.0029

0.0031

3

3

0.0189

0.0195

20

20

14 (0.0004)

(0.0005)

(0)

(1)

(0.0008)

(0.0008)

(1)

(1)

0.0058

0.0051

6

5

30 NA NA NA NA (0.0025)

(0.0023)

(3)

(2)

(..) below 30% LOQ

Conclusions:

Using SFO kinetics, DT50 values for IN-L9226 were between 0.3 and 3.3 days

depending on the soil type. DT90 values were between 0.9 and 10.8 days.



LUFA 2.2 SFO 0.6 2.1 18.5

LUFA 2.2 FOMC 0.6 2.1 20.4

LUFA 2.3* SFO 0.3 0.9 7.6

LUFA 6S SFO 3.3 10.8 12.5

* day 2 not included in the kinetic calculation

(Knoch, 2012c)


Metabolite IN-RDF00

Report: Wardrope, L. (2011); Rate of degradation of [14

C]-IN-RDF00 in five

aerobic soils


Guidelines: OPPTS 835.4100, OECD 307 (2002), SETAC Europe (1995)

Deviations: None



GLP: Yes


Previous

evaluation:



A new rate of degradation study conducted with IN-RDF00 has been

provided by DuPont. However the IN-RDF00 metabolite has not been

identified as a major soil metabolite and has not been included in the

exposure assessments in soil and groundwater. It was included

conservatively as a major aqueous metabolite on the basis of its

formation in sterile buffer solutions at pH 4 and has been included in the

revised aquatic exposure assessment in this RAR. However since a soil

DT50 is not required for this metabolite this study has not been reviewed

in detail. For completeness the detailed study summary from DuPont is

provided below. Since this information is not relied on, it has been

greyed out.

Executive summary:

The rate of degradation of [14

C]-IN-RDF00 was studied in five agricultural soils at

20 2C for 30 days. [14

C]-IN-RDF00 was applied to the soil at a rate of

0.542 mg a.s./kg oven dry soil. Samples were maintained in darkness under

aerobic conditions at ca 50% of maximum water holding capacity (0 bar moisture).

Under laboratory conditions there was very rapid degradation of [14

C]-IN-RDF00

in all soils. The test item was not detected in any Day 1 samples; therefore the

DT50 and DT90 are reported as 1 day with no kinetic fitting.

Material balance, calculated as the percent of applied radioactivity (% AR), was

maintained 90% throughout the study (except for Lleida Day 7 and Day 14,

Replicate 1 samples with mass balances of 88.45 and 89.98% AR, respectively).

At initiation the extractability of IN-RDF00 from all soils ranged between 93.67%

and 99.69% AR. Over the duration of the study, extractability decreased while the

non-extractable residues generally increased. Evolution of 14

CO2 was significant

and increased throughout the duration of the study in all five soils to 76.03, 60.23,

74.63, 64.07, and 90.29% AR at Day 30 in Speyer 2.2, Nambsheim, Sassafras,

Lleida, and Tama soils, respectively.



A. MATERIALS


C]IN-RDF00 technical metabolite

Lot/Batch #: 3620295

Radiochemical purity: 97.72–99.50%


Description: Solid


2. Soils

The study was conducted with five soil types. These were freshly collected from

the top 20 cm layer from agricultural fields and stored refrigerated prior to use. A

summary of the physical and chemical properties of the soils is provided in Table

B.8.92. The percent sand, silt, and clay are quoted on the basis of the USDA

classification.

Table B.8.92 Soil characteristics (DuPont-29894)

Parameter Results

Soil identity Speyer 2.2 Nambsheim Sassafras Lleida Tama

Geographic location Germany France USA Spain USA

USDA texture class Loamy sand Sandy loam Sandy loam Clay Silty clay loam

Sand (%) 83 68 57 17 9

Silt (%) 14 21 32 35 60

Clay (%) 3 11 11 48 31

pH (in water) 6.0 7.8 5.7 8.0 6.7

pH (in 0.01 M CaCl2) 5.6 7.4 5.1 7.7 6.3

Organic Carbon (%)a 2.2 1.7 0.9 2.1 2.4

Bulk Density (g/cm3) 1.22 1.09 1.16 1.04 0.96

Initial soil biomass

(as % soil organic carbon) 0.80 1.13 1.10 0.62 1.09

Final soil biomass

(as % soil organic carbon) 0.60 1.39 0.41 0.74 0.71

CEC (meq/100g) 7.6 9.1 6.5 15.9 17.0


Water holding

capacity (%) at

applied pressures

0-Bar 46.2 46.1 38.5 60.0 65.1

0.1-Bar 14.2 29.6 23.1 36.9 40.6

1/3-Bar 10.8 14.9 15.1 29.5 30.0

15-Bar 7.6 6.4 5.5 18.4 17.3 a Organic carbon (%) = organic matter (%) by Walkley-Black Method/1.724

B. STUDY DESIGN


Portions of sieved soil (50 g oven dry-soil equivalent) were adjusted to moisture

contents of 14.3% (Speyer 2.2), 10.7% (Nambsheim), 13.1% (Sassafras), 17.3%

(Lleida), and 22.6% (Tama) equivalent to ca 50% of their respective maximum

water holding capacities at 0 bar applied pressure. A solution of radiolabelled test

substance, dissolved in water with 1% acetonitrile was prepared and applied to soil

samples, in separate test vessels, at a rate of 0.542 g a.s./kg oven dry soil.

Additional samples for determination of biomass were prepared and incubated

following application of an equal amount of blank application solution. Water lost


due to evaporation was replaced and soils were incubated in the dark at 20 2C

under aerobic conditions for up to 30 days in a flow through system which allowed

the trapping of evolved carbon dioxide and volatile organic compounds.

2. Sampling

Microbial biomass was determined near time zero and after Day 30 (the last

sampling point). Soil samples were taken for analysis at zero time and 1, 2, 3, 5, 7,

14, 21, and 30 days after application.


Sodium hydroxide solutions used to trap volatile components, and ethanediol used

to trap organic volatiles, were replenished, and analysed at each sampling intervals.

Day 0 to Day 7 soil samples were subjected to the following extraction sequence:

a. Soil was transferred into extraction vessels with extractant and extracted twice

with acetonitrile: 0.1 M ammonium carbonate, 9:1 v/v (Extracts 1 and 2).

b. Then twice with acetonitrile: 0.1 M ammonium carbonate, 3:1 v/v (with the

exception of Day 0 samples, not including second Lleida replicate) (Extracts 3 and

4).

c. Then once with acetonitrile: 0.1 M ammonium carbonate, 3:1 v/v (All Day 1

soils plus Day 3 Lleida replicates) (Extract 5).

d. Each extract was separated by centrifugation and the volume of each extract

taken to 110 mL. Triplicate aliquots were taken for LSC.

Day 14 to Day 30 soil samples were subjected to the following extraction

sequence:

a. Soil was transferred into extraction vessels with extractant and extracted once

with acetonitrile: 0.1 M ammonium carbonate, 9:1 v/v (Extract 1).

b. Then three times with acetonitrile: 0.1 M ammonium carbonate, 3:1 v/v

(Extracts 3, 4 and 5).

c. Each extract was separated by centrifugation and the volume of each extract

taken to 110 mL. Triplicate aliquots were taken for LSC.

The radioactivity levels in extracts were measured using LSC. Extracts were

stored in separate jars until those extracts containing 5% AR were combined for

concentration prior to HPLC analysis. The pH of the pooled extracts was adjusted

to ca pH 7 and the volume of the combined extracts measured and triplicate

aliquots taken and submitted for LSC to determine the radioactive content. Pooled

extracts were concentrated and triplicate aliquots submitted for LSC. The

procedural recovery was calculated by comparing the amount of radioactivity prior

to and following concentration.

Soil samples were combusted and 14

C levels were measured using LSC. The soil

extracts were analysed using reverse phase HPLC eluted with a gradient of 10 mM

ammonium formate (adjusted to pH 4 with formic acid) and acetonitrile. The

effluent was passed through an UV detector (254 nm) to detect reference standards

and a radiodetector to detect radiolabelled components. The limit of quantification

for radiolabelled components, using representative blank samples, was determined

as 1% AR.



A. DATA


C]-IN-RDF00, expressed as a percentage of applied

radioactivity, in Speyer 2.2 soil

Component

Rep.

No.


0 1 2 3 5 7 14 21 30

IN-RDF00

1 80.97 nda nd nd nd nd nd nd nd

2 83.55 nd nd nd nd nd nd nd nd

Mean 82.26 nd nd nd nd nd nd nd nd

Unknown

ca 6.5

minutes

1 0.95 82.05 70.82 67.80 55.14 44.54 16.99 5.10 nd

2 0.57 83.78 69.75 68.55 55.89 44.84 14.57 4.89 nd

Mean 0.76 82.92 70.29 68.18 55.52 44.69 15.78 5.00 nd

Unknown

ca 15.5

minutes




Other

unidentified

radioactivityb

1 2.36 7.49 3.17 2.78 2.67 2.31 1.73 0.99 nd

2 2.92 7.62 3.88 2.97 2.74 2.75 1.81 0.43 nd

Mean 2.64 7.56 3.53 2.88 2.71 2.53 1.77 0.71 nd

Total

extractable

residuec

1 96.42 89.53 77.71 70.57 57.82 46.85 23.72 11.61 5.94

2 99.00 91.39 77.54 71.53 58.63 47.60 21.63 10.12 5.82

Mean 97.71 90.46 77.63 71.05 58.23 47.23 22.68 10.87 5.88

Non-

extractable

residue

1 4.07 3.67 11.51 11.09 11.70 12.12 14.89 17.31 16.91

2 3.14 3.53 10.61 10.10 11.74 12.35 16.74 16.86 16.28

Mean 3.61 3.60 11.06 10.60 11.72 12.24 15.82 17.09 16.60

14CO2

1 nsd 4.94 10.70 16.20 28.13 36.88 60.96 70.26 76.03

2 ns 4.94 10.70 16.20 28.13 36.88 60.96 70.26 76.03

Mean ns 4.94 10.70 16.20 28.13 36.88 60.96 70.26 76.03

Volatile

organics

1 ns 0.00 0.00 0.01 0.01 0.01 0.01 0.01 0.01

2 ns 0.00 0.00 0.01 0.01 0.01 0.01 0.01 0.01

Mean ns 0.00 0.00 0.01 0.01 0.01 0.01 0.01 0.01

Total %

recovery

1 100.49 98.14 99.92 97.87 97.66 95.86 99.58 99.19 98.89

2 102.14 99.86 98.85 97.84 98.51 96.84 99.34 97.25 98.14

Mean 101.32 99.00 99.39 97.86 98.09 96.35 99.46 98.22 98.52

Overall mean mass balance 98.69

Standard deviation 1.48 a Not detected (below LOQ)

b No individual other unidentified component accounts for 5% AR.

c The total values may differ slightly from the sum of the individual values due to rounding.

d No sample



C]-IN-RDF00, expressed as percentage of applied

radioactivity, in Nambsheim soil

Component

Rep.

No.


0 1 2 3 5 7 14 21 30

IN-RDF00




Unknown

ca 6.5

minutes

1 nd 85.08 72.53 70.37 65.26 54.73 28.59 11.60 nd

2 nd 86.53 71.39 72.71 66.00 61.42 27.71 11.27 nd

Mean nd 85.81 71.96 71.54 65.63 58.08 28.15 11.44 nd

Unknown

ca 15.5

minutes




Other

unidentified

radioactivityb

1 1.97 4.48 1.95 3.58 2.81 3.44 3.70 1.02 nd

2 2.08 4.14 6.27 3.36 2.77 3.17 3.77 1.28 nd

Mean 2.03 4.31 4.11 3.47 2.79 3.31 3.74 1.15 nd

Total

extractable

residuec

1 95.46 89.56 77.42 73.96 68.07 58.17 34.20 20.71 6.87

2 96.42 90.67 80.45 76.07 68.76 64.59 33.19 20.00 7.94

Mean 95.94 90.12 78.94 75.02 68.42 61.38 33.70 20.36 7.41

Non-

extractable

residue

1 3.64 3.74 11.72 13.11 15.67 17.55 23.98 27.59 30.67

2 3.62 3.59 11.65 13.30 16.76 17.62 23.80 30.64 31.17

Mean 3.63 3.67 11.69 13.21 16.22 17.59 23.89 29.12 30.92

14CO2

1 nsd 5.17 8.40 10.25 15.90 21.13 38.08 50.96 60.23

2 ns 5.17 8.40 10.25 15.90 21.13 38.08 50.96 60.23

Mean ns 5.17 8.40 10.25 15.90 21.13 38.08 50.96 60.23

Volatile

organics

1 ns 0.00 0.00 0.01 0.01 0.02 0.03 0.03 0.03

2 ns 0.00 0.00 0.01 0.01 0.02 0.03 0.03 0.03

Mean ns 0.00 0.00 0.01 0.01 0.02 0.03 0.03 0.03

Total %

recovery

1 99.10 98.47 97.54 97.33 99.65 96.87 96.29 99.29 97.80

2 100.04 99.43 100.50 99.63 101.43 103.36 95.10 101.63 99.37

Mean 99.57 98.95 99.02 98.48 100.54 100.12 95.70 100.46 98.59





d No sample




radioactivity, in Sassafras soil

Component

Rep.

No.


0 1 2 3 5 7 14 21 30

IN-RDF00




Unknown

ca 6.5

minutes

1 nd 74.84 76.68 73.80 63.64 53.14 28.65 13.59 nd

2 nd 73.64 75.72 72.26 64.25 58.49 29.48 17.16 nd

Mean nd 74.24 76.20 73.03 63.95 55.82 29.07 15.38 nd

Unknown

ca 14.5

minutes

1 nd 15.29 1.53 0.55 nd nd nd nd nd

2 nd 14.29 2.55 0.45 nd nd nd nd nd

Mean nd 14.79 2.04 0.50 nd nd nd nd nd

Unknown

ca 15.5

minutes




Other

unidentified

radioactivityb

1 2.52 3.10 2.95 3.55 3.96 3.32 5.19 2.79 nd

2 1.58 4.35 3.30 4.10 3.67 3.16 4.67 2.24 nd

Mean 2.05 3.73 3.13 3.83 3.82 3.24 4.93 2.52 nd

Total

extractable

residuec

1 100.92 93.24 81.14 77.91 67.60 56.46 35.61 21.20 11.42

2 98.45 92.28 81.57 76.81 67.92 61.65 35.83 24.75 11.05

Mean 99.69 92.76 81.36 77.36 67.76 59.06 35.72 22.98 11.24

Non-

extractable

residue

1 0.62 2.86 8.47 8.09 9.39 10.69 12.69 13.53 12.86

2 0.52 3.54 8.42 8.40 10.31 10.17 12.41 13.36 13.75

Mean 0.57 3.20 8.45 8.25 9.85 10.43 12.55 13.45 13.31

14CO2

1 nsd 3.93 8.06 12.70 21.67 29.94 51.46 62.41 74.63

2 ns 3.93 8.06 12.70 21.67 29.94 51.46 62.41 74.63

Mean ns 3.93 8.06 12.70 21.67 29.94 51.46 62.41 74.63

Volatile

organics

1 ns 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.02

2 ns 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.02

Mean ns 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.02

Total %

recovery

1 101.54 100.03 97.67 98.70 98.66 97.09 99.76 97.15 98.93

2 98.97 99.75 98.05 97.91 99.20 101.76 99.70 100.53 99.45

Mean 100.26 99.89 97.86 98.31 99.28 99.43 99.73 98.84 99.19





d No sample




radioactivity, in Lleida soil

Component

Rep.

No.


0 1 2 3 5 7 14 21 30

IN-RDF00




Unknown

ca 6.5 minutes

1 nd 75.29 75.35 64.57 67.44 51.50 39.24 16.76 nd

2 nd 79.43 73.31 69.69 69.59 61.20 47.12 19.24 nd

Mean nd 77.36 74.33 67.13 68.52 56.35 43.18 18.00 nd

Unknown

ca 15.5

minutes




Other

unidentified

radioactivity

1 1.96 9.51 2.41 3.03 1.90 2.03 3.53 1.24 nd

2 2.25 9.63 5.03 2.07 2.14 2.00 3.59 1.52 nd

Mean 2.11 9.57 3.72 2.55 2.02 2.02 3.56 1.38 nd

Total

extractable

residueb

1 97.30 84.81 79.42 69.23 70.77 54.64 42.77 23.67 11.95

2 98.70 89.06 80.07 76.44 73.18 64.47 50.70 26.63 13.08

Mean 98.00 86.94 79.75 72.84 71.98 59.56 46.74 25.15 12.52

Non-

extractable

residuec

1 5.54 9.82 14.94 22.69 17.03 16.77 19.07 22.14 17.84

2 4.70 8.10 14.67 13.13 17.82 17.15 18.71 20.61 20.49

Mean 5.12 8.96 14.81 17.91 17.43 16.96 18.89 21.38 19.17

14CO2

1 nsd 3.03 5.52 7.82 11.59 17.03 28.12 50.55 64.07

2 ns 3.03 5.52 7.82 11.59 17.03 28.12 50.55 64.07

Mean ns 3.03 5.52 7.82 11.59 17.03 28.12 50.55 64.07

Volatile

organics

1 ns 0.00 0.00 0.00 0.00 0.01 0.02 0.03 0.04

2 ns 0.00 0.00 0.00 0.00 0.01 0.02 0.03 0.04

Mean ns 0.00 0.00 0.00 0.00 0.01 0.02 0.03 0.04

Total %

recovery

1 102.84 97.66 99.88 99.74 99.39 88.45 89.98 96.39 93.90

2 103.40 100.19 100.26 97.39 102.59 98.66 97.55 97.82 97.68

Mean 103.12 98.93 100.07 98.57 100.99 93.56 93.77 97.11 95.79





d No sample




radioactivity, in Tama soil

Component

Rep.

No.


0 1 2 3 5 7 14 21 30

IN-RDF00




Unknown

ca 6.5

minutes

1 nd 50.65 33.24 12.73 15.32 11.80 nd nd nd

2 nd 53.85 30.21 16.26 10.41 9.68 nd nd nd

Mean nd 52.25 31.73 14.50 12.87 10.74 nd nd nd

Unknown

ca 15.5

minutes




Other

unidentified

radioactivityb

1 2.70 7.28 1.52 1.12 1.40 1.11 nd nd nd

2 2.11 4.69 1.95 1.40 0.68 1.80 nd nd nd

Mean 2.41 5.99 1.74 1.26 1.04 1.46 nd nd nd

Total

extractable

residuec

1 94.82 57.94 35.71 20.23 19.47 14.79 6.48 3.29 1.40

2 92.52 58.55 33.05 23.45 13.45 13.38 7.20 2.89 1.10

Mean 93.67 58.25 34.38 21.84 16.46 14.09 6.84 3.09 1.25

Non-

extractable

residue

1 7.35 16.72 19.84 25.91 12.59 11.57 9.16 8.51 8.51

2 7.45 15.99 20.43 23.57 19.08 11.19 9.05 8.66 8.49

Mean 7.40 16.36 20.14 24.74 15.84 11.38 9.11 8.59 8.50

14CO2

1 nsd 23.66 42.09 51.00 66.01 72.83 83.79 88.14 90.29

2 ns 23.66 42.09 51.00 66.01 72.83 83.79 88.14 90.29

Mean ns 23.66 42.09 51.00 66.01 72.83 83.79 88.14 90.29

Volatile

organics

1 ns 0.01 0.02 0.03 0.04 0.05 0.05 0.06 0.06

2 ns 0.01 0.02 0.03 0.04 0.05 0.05 0.06 0.06

Mean ns 0.01 0.02 0.03 0.04 0.05 0.05 0.06 0.06

Total %

recovery

1 102.17 98.33 97.66 97.17 98.11 99.24 99.48 100.00 100.26

2 99.97 98.21 95.59 98.05 98.58 97.45 100.09 99.75 99.94

Mean 101.07 98.27 96.63 97.61 98.35 98.35 99.79 99.88 100.10





d No sample

III. CONCLUSION

This study demonstrated that IN-RDF00 was very rapidly degraded in all five soils

tested with degradation starting immediately upon contact with each soil. The

aerobic DT50 and DT90 of IN-RDF00 at 20 2C in all five soils was 1 day. The

majority of the applied radioactivity was detected as 14

CO2.

(Wardrope, L., 2011)


Metabolite IN-V7160

Report: Tunink, A. (2009); 14

C-IN-V7160: Rate of degradation in five soils

DuPont Report No.: DuPont-27641, Revision No. 1

Guidelines: OECD 307 (2002), U.S. EPA 162-1 (1982), SETAC Europe (1995),

OPPTS 835.4100 (2008) Deviations: None

Testing Facility: ABC Laboratories, Inc. (Missouri), Columbia, Missouri, USA


GLP: Yes

Certifying Authority: Laboratories in the USA are not certified by any

governmental agency, but are subject to regular inspections by the U.S. EPA.

Previous

evaluation:



A new rate of degradation study conducted with IN-V7160 has been

provided by DuPont. The IN-V7160 metabolite was identified as a

potential major soil metabolite in their new aerobic soil route of

degradation study (Cleland, 2011). However the UK RMS has rejected

that study due to concerns over the validity of the analytical method and

the ability to identify the various metabolites, including IN-V7160. This

metabolite was not identified as a major metabolite in the new,

acceptable route of degradation study provided by the Task Force.

However metabolite IN-V7160 was also identified in the irradiated

samples of the DuPont soil photolysis study at up to 9.6% AR. This

metabolite was not identified as a major metabolite in the new

photolysis study submitted by the Task Force. However the analytical

methods in both studies, and more specifically the chromatography used,

did appear to be acceptable and sufficient to separate and identify the

major metabolites in both studies. Although there are some doubts over

whether the IN-V7160 metabolite should be considered as a major

metabolite, based on the level found in the Task Force studies, it has

been included in the environmental exposure assessment in soil and

groundwater to ensure the assessment is conservative. It was also a

major aqueous metabolite identified in the original water sediment study

considered in the DAR (see Section B.8.4.4, Spare, 2000) and included

in the revised aquatic exposure assessment in this RAR.

This new rate of degradation study conducted with IN-V7160 has been

reviewed by the UK RMS and considered acceptable. The detailed

study summary from DuPont is provided below. Since the kinetics have

been reassessed in line with the FOCUS kinetics guidance, the DT50/90

values derived during the study have been removed from the study

summary below to avoid confusion. The modern kinetic assessment is

reported in Section B.8.1.4. Results from this study are used to derive a

geometric mean DT50 for the IN-V7160 metabolite for the purposes of

the environmental exposure assessment.


Executive summary:

The aerobic biotransformation of radiolabelled IN-V7160, was studied in five

different soil systems under aerobic conditions. The five soils were a sandy loam

from Chesapeake Farms, Maryland, U.S.A. (Mattapex #25), a heavy clay from the

Lleida region of Spain, a sandy clay loam from Nambsheim, France, a sandy loam

from Goch, Germany, and a sandy loam from Suchozebry, Poland. The organic

matter content (Walkley-Black method) for these soils was 1.5, 3.1, 2.7, 3.1, and

1.3%, while the pH (1:1 soil:0.01 M CaCl2) was 4.35, 7.50, 7.01, 5.13, and 5.04,

respectively.

The test soils were treated with [triazine-2-14

C]IN-V7160 at a concentration of

0.298 g a.s./g dry weight soil and incubated in darkness at approximately

20 2C. The samples were incubated under aerobic conditions in flow-through

systems to maintain soil moistures at 40 to 60% of its 0-bar moisture, yet

remaining as close as possible to 75% of 1/3 bar during the course of the study.

The flow-through systems were designed to trap evolved carbon dioxide (CO2) and

volatile organic compounds. Soil samples were extracted with a mixture of

aqueous and organic solvents at 0, 1, 3, 7, 15, 30, 60, 91, and 120 days after

treatment and analysed for [14

C]IN-V7160.

The recovery of total radioactivity was within 91.6 to 105.4% of the applied

radioactivity for all soils at all sampling points. Mean extractability values were at

100.1% to 102.1% AR at Day 0 in the five soils, then decreased to a minimum of

70.2% AR (Day 120), 71.7% AR (Day 120), 76.2% AR (Day 120), 60.5% AR

(Day 120), and 78.5% AR (Day 120) in the Mattapex #25, Lleida, Nambsheim,

Goch, and Suchozebry soils, respectively. During the course of the study, the

amount of [14

C]IN-V7160 in the extracts decreased from approximately 95% AR to

<10% AR by Day 60 in the Mattapex #25 soil, <4% AR by Day 30 in the Lleida

soil, <5% AR by Day 14 in the Nambsheim soil, approximately 20% AR at

Day 120 in the Goch soil, and approximately 33% AR at the Day 120 in the

Suchozebry soil.

As the level of extractable radioactivity decreased, the level of unextractable

residue (non-extractable residues - NER) slowly increased in the soils during the

course of the study. At Day 120, the mean NER for the Mattapex #25, Lleida,

Nambsheim, Goch, and Suchozebry soils were 20.0, 14.4, 10.0, 29.7, and

20.7% AR, respectively.

The amount of 14

CO2 collected increased with time in each soil. Mean recovery of 14

CO2 collected at Day 120 was 8.1% AR, 11.8% AR, 12.5% AR, and 4.2% AR for

Mattapex #25, Lleida, Nambsheim, Goch, and Suchozebry soils, respectively. No

radioactivity above the limit of detection was seen in the volatile organic traps

throughout the study.


A. MATERIALS



C-IN-V7160 technical metabolite

Lot/Batch #: [triazine-2-14

C]IN-V7160: 3612231

Radiochemical purity: [triazine-2-14

C]IN-V7160: 97%

14

C specific activity: [triazine-2-14

C]IN-V7160: 48.67 Ci/mg

Description: White solid

Stability of test compound: Not determined

2. Soils

The study was conducted with five different soil types (four European and one

from the USA). The soil were a sandy loam from Chesapeake Farms, Maryland,

U.S.A. (Mattapex #25), a heavy clay from the Lleida region of Spain, a sandy clay

loam from Nambsheim, France, a sandy loam from Goch, Germany, and a sandy

loam from Suchozebry, Poland. The organic matter content (Walkley-Black

method) for these soils was 1.5, 3.1, 2.7, 3.1, and 1.3%, while the pH (1:1 soil:0.01

M CaCl2) was 4.35, 7.50, 7.01, 5.13, and 5.04, respectively (Table B.8.98).

Table B.8.98 Soil characteristics (DuPont-27641, Revision No. 1)

Soil name Mattapex #25 Lleida Nambsheim Goch Suchozebry

Geographic

location

Chesapeake

Farms,

Maryland, USA

39º11.93’ N and

76º12.03’ W

Lleida region

of Spain

41º 39.236’N

and

0º34.290’E

Nambsheim,

France

47º56’52.15”N

and

7º35’11.06”E

Goch,

Germany

51º43’33”N

and

06º07’10”E

Suchozebry,

Poland

52º16’N and

22º15’E

Textural class

(USDA) Sandy loam Silty clay Sandy loam Silt loam Sandy loam

% Sand 57 5 53 35 73

% Silt 32 43 29 54 18

% Clay 11 52 18 11 9

CEC (meq/100 g) 5.7 16.6 9.7 10.1 6.3

% Organic matter

(Walkley Black) 1.5 3.1 2.7 3.1 1.3

% Organic carbona 0.9 1.8 1.6 1.8 0.8

pHb 5.0 7.6 7.6 5.6 5.4

pHc 4.35 7.50 7.01 5.13 5.04

Microbial biomass

at initiation (μg/g

dry weight)

46.0 266.3 242.7 34.6 56.8

Microbial biomass

at termination (μg/g

dry weight)

65.3 258.8 127.6 40.1 34.5

Moisture at 0 bar

(%) 40.7 63.1 56.0 54.5 45.7

Moisture at 1/10

bar (%) 18.3 31.7 19.0 28.6 10.0

Moisture at 1/3 bar

(%) 14.2 25.3 14.7 18.9 8.3

a Organic carbon = Organic matter / 1.72

b pH in 1:1 soil:water ratio

c pH in 1:1 soil:0.01 M CaCl2 (aq) ratio performed at ABC Laboratories.

B. STUDY DESIGN



The test soils were treated with [triazine-2-14

C]IN-V7160 at a concentration of

0.298 g a.s./g dry weight soil and incubated in darkness at approximately

20 2C. The samples were incubated under aerobic conditions in flow-through

systems to maintain soil moistures at 40 to 60% of its 0-bar moisture, yet

remaining as close as possible to 75% of 1/3 bar during the course of the study.

The flow-through systems were designed to trap evolved carbon dioxide (CO2) and

volatile organic compounds. Soil samples were extracted with a mixture of

aqueous and organic solvents at 0, 1, 3, 7, 15, 30, 60, 91, and 120 days after

treatment and analysed for [14

C]-IN-V7160.

Aerobic conditions were maintained in all samples by drawing humidified air

through the series containing the representative samples. During incubation,

systems were maintained in the dark (except during general use of the chamber or

when the samples were removed during moisture content maintenance). The test

temperature in the chamber was set to 20C. Throughout the study (typically every

two weeks), representative test bottles were weighed. Any weight loss relative to

Day 0 was attributed to moisture loss, and the appropriate amount of reagent water

was added to bring the moisture content to 40 to 60% of 0-bar moisture, yet

remaining as close as possible to 75% of 1/3 bar.

2. Sampling

Main Study: Two samples for each soil system were withdrawn immediately after

treatment (Day 0), and 1, 3, 7, 15, 30, 60, 91, and 120 days after application. The

soil systems were extracted and prepared for analysis. The volatile traps for each

sample train were collected at the same time intervals (excluding Day 0), analysed

for the presence of radioactive volatiles, and replenished.

Biomass Soil: Neither CO2 nor volatile organics were collected from soils

intended for soil microbial viability measurements. Soils were harvested for

analysis at the beginning of the study and after Day 120 of the study.

All soil extracts were stored in a freezer as quickly as possible after sampling. The

soils were extracted on the day of sampling and analysed by LSC. The extracts

were then prepared for analysis and analysed typically within approximately one to

two weeks of sampling. Repeat analyses of some of the soil extracts were

conducted up to 6 weeks after the initial extraction. An aliquot of the dose control

was analysed at initiation and after study termination to verify stability during

storage and processing. A dilution of the radioactive stock solution of the test

substance was also analysed with each set to show stability. The KOH traps for

collecting 14

CO2 produced by the systems were collected at each sampling day

after Day 0 and replaced with fresh material at each sampling event. Triplicate

aliquots from the KOH volatile traps were taken at each sampling point to

determine trapped volatiles by LSC analyses. Since mass accountability was

maintained throughout the study, the air sampling tubes for collecting organic

volatiles were maintained on the system and not sampled.

3. Description of analytical procedure

The air flow through the test systems was ceased, and the bottles for that specific

timepoint were removed from incubation in the environmental chamber set at

20C. The bottle weights were taken to verify the soil moistures for the test


systems were within the desired ranges. If low, water was added to all samples to

keep them in the desired moisture range.

The treated soils were extracted four times, three times by adding 125 mL of

90:10 acetone:0.1M ammonium carbonate (aq) and once by adding 125 mL of

10:90 acetone:0.1M ammonium carbonate (aq) to the Nalgene bottles, and shaking

at high speed for 60 minutes. Following shaking, the samples were centrifuged for

20 minutes. Following centrifugation, successive supernatants were decanted into

a 500-mL mixing cylinder. After decanting the supernatant from the final

extraction into the cylinder, the combined extract volume was diluted to 460 mL

with acetone. Aliquots of the combined extracts were analysed by LSC.

The soil extract samples were then typically concentrated for analysis using the

following process. A 100-mL aliquot of each extract was concentrated to dryness

using a rotary evaporator. To facilitate the removal of water, acetonitrile was

periodically added to the flasks. Each flask was reconstituted with 5 mL of 95:5

0.01 M ammonium acetate (aq):acetonitrile (added with a class A volumetric pipet)

and sonicated for at least 10 minutes. The concentrated extracts were transferred

into 15-mL polypropylene centrifuge tubes that were centrifuged for 10 minutes.

Aliquots of this sample were analysed by LSC (to verify that mass balance was

maintained at 90 to 100% throughout the process) and also by HPLC. If recoveries

were not within the acceptable range, the process was repeated. All samples were

stored in a freezer when not in use.

Excess solvent left in the previously extracted soil samples was evaporated under a

gentle stream of nitrogen, as needed. Samples were homogenised and triplicate

aliquots of the extracted soil samples (approximately 0.5 g) were analysed by

combustion followed by LSC to determine the amount of non-extractable residue

(NER).

Since the test substance showed significant breakdown (i.e., <10% AR in the

extracts for three soils in the first month), it was determined that the residues not

extracted would not be associated with the test substance. Thus, further analysis of

the non-extractable residues (e.g., humin/fulvic extraction) was deemed not

necessary.

Since mean mass balance was maintained between 90 and 110% for all test

systems, the absorbent tubes were not sampled. For the KOH traps, where the total

activity detected was >10% AR (from Lleida and Nambsheim spoil), a barium

chloride test performed on these systems confirmed that the activity trapped was

due to the presence of 14

CO2.

Untreated biomass samples were taken from each soil system at the beginning of

the study and 128 days after the initiation, biomass samples were harvested and

analysed by the fumigation-extraction method for biomass determination.



A. DATA

Table B.8.99 Material balance of radioactivity for Mattapex #25 soil treated with

[14

C]IN-V7160

Days

post

dose Rep.

% Applied radioactivity

Soil NER Total in

soil

Organic

volatiles

14CO2

traps

Total

volatiles

Mass

balance

0

1 100.7 0.9 101.6 N/A N/A N/A 101.6

2 100.7 1.3 102.0 N/A N/A N/A 102.0

Mean 100.7 1.1 101.8 N/A N/A N/A 101.8

1

1 86.5 6.8 93.3 N/A 0.0% 0.0 93.3

2 86.0 5.6 91.6 N/A 0.0% 0.0 91.6

Mean 86.3 6.2 92.5 N/A 0.0 0.0 92.5

3

1 87.7 8.7 96.4 N/A 0.0 0.0 96.4

2 86.3 9.2 95.4 N/A 0.0 0.0 95.4

Mean 87.0 8.9 95.9 N/A 0.0 0.0 95.9

7

1 89.8 10.9 100.6 N/A 0.2 0.2 100.8

2 89.9 10.8 100.7 N/A 0.4 0.4 100.9

Mean 89.9 10.8 100.7 N/A 0.3 0.3 100.9

15

1 84.9 13.1 98.0 N/A 0.5 0.5 98.5

2 84.2 14.2 98.4 N/A 1.0 1.0 98.9

Mean 84.5 13.7 98.2 N/A 0.7 0.7 98.7

30

1 77.1 15.8 92.9 N/A 3.0 3.0 95.8

2 79.3 14.1 93.4 N/A 4.2 4.2 97.6

Mean 78.2 15.0 93.1 N/A 3.6 3.6 96.7

60

1 75.7 19.8 95.5 N/A 5.3 5.3 100.7

2 72.3 19.7 92.0 N/A 6.4 6.4 98.4

Mean 74.0 19.7 93.7 N/A 5.8 5.8 99.6

91

1 75.0 16.9 92.0 N/A 5.6 5.6 97.6

2 72.1 16.8 88.9 N/A 6.7 6.7 95.6

Mean 73.6 16.9 90.4 N/A 6.2 6.2 96.6

120

1 70.2 18.4 88.5 N/A 7.4 7.4 96.0

2 70.2 21.6 91.8 N/A 8.7 8.7 100.5

Mean 70.2 20.0 90.2 N/A 8.1 8.1 98.2

Overall mean 97.9

Standard deviation 2.9

NER = non-extractable residues, N/A = not applicable (no volatile traps, or traps not sampled)

Note: Values were not rounded during spreadsheet calculations.


Table B.8.100 Material balance of radioactivity for Lleida soil treated with [14

C]IN-V7160

Days

post

dose Rep.


Soil NER Total in

soil

Organic

volatiles

14CO2

traps

Total

volatiles

Mass

balance

0

1 100.7 0.9 101.5 N/A N/A N/A 101.5

2 100.8 0.6 101.4 N/A N/A N/A 101.4

Mean 100.7 0.7 101.5 N/A N/A N/A 101.5

1

1 89.2 2.7 91.9 N/A 0.0 0.0 91.9

2 89.8 2.6 92.4 N/A 0.0 0.0 92.4

Mean 89.5 2.6 92.2 N/A 0.0 0.0 92.2

3

1 92.5 4.0 96.5 N/A 0.0 0.0 96.5

2 93.9 4.1 98.0 N/A 0.0 0.0 98.0

Mean 93.2 4.1 97.3 N/A 0.0 0.0 97.3

7

1 99.1 4.3 103.4 N/A 0.1 0.1 103.5

2 99.2 4.5 103.7 N/A 0.0 0.0 103.8

Mean 99.2 4.4 103.6 N/A 0.1 0.1 103.7

15

1 96.4 6.3 102.7 N/A 0.3 0.3 102.9

2 94.2 6.5 100.7 N/A 0.2 0.2 100.9

Mean 95.3 6.4 101.7 N/A 0.2 0.2 101.9

30

1 91.1 8.7 99.8 N/A 2.0 2.0 101.8

2 86.4 8.7 95.1 N/A 1.9 1.9 97.0

Mean 88.8 8.7 97.5 N/A 1.9 1.9 99.4

60

1 85.9 10.4 96.3 N/A 6.4 6.4 102.7

2 85.1 10.0 95.1 N/A 6.2 6.2 101.3

Mean 85.5 10.2 95.7 N/A 6.3 6.3 102.0

91

1 75.2 12.5 87.7 N/A 7.5 7.5 95.3

2 76.1 11.2 87.4 N/A 7.2 7.2 94.6

Mean 75.7 11.9 87.6 N/A 7.4 7.4 94.9

120

1 70.3 12.9 83.1 N/A 11.9 11.9 95.0

2 73.2 16.0 89.1 N/A 11.7 11.7 100.9

Mean 71.7 14.4 86.1 N/A 11.8 11.8 97.9

Overall mean 99.0





Table B.8.101 Material balance of radioactivity for Nambsheim soil treated with

[14

C]IN-V7160

Days

post

dose Rep.


Soil NER Total in

soil

Organic

volatiles

14CO2

traps

Total

volatiles

Mass

balance

0

1 101.5 0.5 102.0 N/A N/A N/A 102.0

2 101.6 0.5 102.0 N/A N/A N/A 102.0

Mean 101.5 0.5 102.0 N/A N/A N/A 102.0

1

1 91.3 1.9 93.2 N/A 0.0 0.0 93.2

2 91.9 2.1 94.0 N/A 0.0 0.0 94.0

Mean 91.6 2.0 93.6 N/A 0.0 0.0 93.6

3

1 93.6 3.3 96.9 N/A 0.0 0.0 96.9

2 96.2 3.0 99.2 N/A 0.0 0.0 99.2

Mean 94.9 3.1 98.0 N/A 0.0 0.0 98.1

7

1 100.0 3.6 103.5 N/A 0.1 0.1 103.6

2 99.7 3.6 103.3 N/A 0.1 0.1 103.4

Mean 99.9 3.6 103.4 N/A 0.1 0.1 103.5

15

1 94.7 5.4 100.1 N/A 0.4 0.4 100.5

2 95.9 5.0 100.9 N/A 0.3 0.3 101.3

Mean 95.3 5.2 100.5 N/A 0.4 0.4 100.9

30

1 90.4 6.7 97.1 N/A 3.0 3.0 100.2

2 85.7 6.5 92.3 N/A 2.9 2.9 95.1

Mean 88.1 6.6 94.7 N/A 3.0 3.0 97.7

60

1 85.6 8.7 94.2 N/A 8.1 8.1 102.3

2 87.3 7.9 95.2 N/A 7.7 7.7 102.9

Mean 86.4 8.3 94.7 N/A 7.9 7.9 102.6

91

1 77.6 8.8 86.4 N/A 9.0 9.0 95.4

2 79.5 8.8 88.3 N/A 8.6 8.6 96.9

Mean 78.6 8.8 87.4 N/A 8.8 8.8 96.2

120

1 75.1 10.2 85.3 N/A 12.7 12.7 98.0

2 77.2 9.8 87.0 N/A 12.3 12.3 99.3

Mean 76.2 10.0 86.2 N/A 12.5 12.5 98.7

Overall mean 99.2





Table B.8.102 Material balance of radioactivity for Goch soil treated with [14

C]IN-V7160

Days

post

dose Rep.


Soil NER Total in

soil

Organic

volatiles

14CO2

traps

Total

volatiles

Mass

balance

0

1 101.5 1.3 102.9 N/A N/A N/A 102.9

2 102.1 1.6 103.8 N/A N/A N/A 103.8

Mean 101.8 1.5 103.3 N/A N/A N/A 103.3

1

1 95.5 9.0 104.4 N/A 0.0 0.0 104.4

2 92.5 9.3 101.9 N/A 0.0 0.0 101.9

Mean 94.0 9.1 103.1 N/A 0.0 0.0 103.1

3

1 87.9 11.9 99.8 N/A 0.0 0.0 99.8

2 88.5 11.3 99.8 N/A 0.0 0.0 99.8

Mean 88.2 11.6 99.8 N/A 0.0 0.0 99.8

7

1 90.3 15.0 105.3 N/A 0.1 0.1 105.4

2 89.7 14.3 104.0 N/A 0.1 0.1 104.1

Mean 90.0 14.7 104.6 N/A 0.1 0.1 104.7

15

1 78.3 19.9 98.2 N/A 0.1 0.1 98.3

2 79.9 17.4 97.4 N/A 0.1 0.1 97.5

Mean 79.1 18.7 97.8 N/A 0.1 0.1 97.9

30

1 71.5 22.1 93.6 N/A 0.7 0.7 94.3

2 81.2 20.8 101.9 N/A 0.8 0.8 102.7

Mean 76.3 21.4 97.8 N/A 0.7 0.7 98.5

60

1 69.1 27.2 96.3 N/A 2.2 2.2 98.5

2 70.1 27.3 97.4 N/A 2.5 2.5 99.9

Mean 69.6 27.2 96.9 N/A 2.3 2.3 99.2

91

1 65.3 33.0 98.3 N/A 2.5 2.5 100.8

2 68.2 29.2 97.4 N/A 2.9 2.9 100.3

Mean 66.7 31.1 97.8 N/A 2.7 2.7 100.5

120

1 59.5 31.7 91.2 N/A 4.0 4.0 95.2

2 61.6 27.7 89.3 N/A 4.4 4.4 93.7

Mean 60.5 29.7 90.2 N/A 4.2 4.2 94.4

Overall mean 100.2





Table B.8.103 Material balance of radioactivity for Suchozebry soil treated with

[14

C]IN-V7160

Days

post

dose Rep.


Soil NER Total in

soil

Organic

volatiles

14CO2

traps

Total

volatiles

Mass

balance

0

1 100.9 1.1 102.1 N/A N/A N/A 102.1

2 100.1 0.9 101.0 N/A N/A N/A 101.0

Mean 100.5 1.0 101.5 N/A N/A N/A 101.5

1

1 99.1 4.4 103.5 N/A 0.0 0.0 103.5

2 97.1 4.6 101.7 N/A 0.0 0.0 101.7

Mean 98.1 4.5 102.6 N/A 0.0 0.0 102.6

3

1 93.7 6.4 100.1 N/A 0.0 0.0 100.1

2 95.9 6.8 102.6 N/A 0.0 0.0 102.6

Mean 94.8 6.6 101.4 N/A 0.0 0.0 101.4

7

1 96.6 8.0 104.6 N/A 0.1 0.1 104.7

2 95.6 7.5 103.1 N/A 0.2 0.2 103.3

Mean 96.1 7.8 103.9 N/A 0.2 0.2 104.0

15

1 86.6 11.8 98.4 N/A 0.3 0.3 98.7

2 84.1 11.8 95.9 N/A 0.3 0.3 96.2

Mean 85.4 11.8 97.1 N/A 0.3 0.3 97.4

30

1 88.2 14.1 102.4 N/A 0.8 0.8 103.2

2 89.1 14.6 103.7 N/A 0.9 0.9 104.6

Mean 88.7 14.4 103.0 N/A 0.8 0.8 103.9

60

1 82.1 19.7 101.8 N/A 1.3 1.3 103.2

2 81.4 21.4 102.8 N/A 1.6 1.6 104.4

Mean 81.7 20.6 102.3 N/A 1.5 1.5 103.8

91

1 81.5 21.1 102.6 N/A 1.4 1.4 104.0

2 79.2 22.3 101.5 N/A 1.7 1.7 103.3

Mean 80.4 21.7 102.1 N/A 1.6 1.6 103.6

120

1 78.8 21.6 100.4 N/A 1.9 1.9 102.3

2 78.1 19.9 98.0 N/A 2.3 2.3 100.3

Mean 78.5 20.7 99.2 N/A 2.1 2.1 101.3

Overall mean 102.2





Table B.8.104 Distribution of extractable residues in Mattapex #25 soil under aerobic

conditions treated with IN-V7160 (20C)

Days post dose

IN-V7160

(% AR)

Sum unassigned peaks

(% AR)

Largest unassigned

peak (% AR)

Rep 1 Rep 2 Mean Rep 1 Rep 2 Mean Rep 1 Rep 2

0 94.6 94.1 94.3 6.1 6.7 6.4 3.7 3.7

1 77.1 79.9 78.5 9.4 6.1 7.8 4.6 3.0

3 70.8 71.2 71.0 16.9 15.1 16.0 8.7 7.8

7 51.8 68.3 60.1 37.9 21.6 29.8 32.5 15.4

15 28.0 22.0 25.0 56.8 62.2 59.5 50.0 55.2

30 13.3 13.1 13.2 63.7 66.2 65.0 56.7 60.5

60 9.5 7.1 8.3 66.2 65.2 65.7 57.8 59.1

91 9.1 5.9 7.5 65.9 66.2 66.1 56.3 58.8

120 5.9 6.2 6.0 64.3 64.0 64.1 54.5 55.2 Note: Values were not rounded during spreadsheet calculations.

AR = Applied Radioactivity

Table B.8.105 Distribution of extractable residues in Lleida soil under aerobic conditions

treated with IN-V7160 (20C)

Days post dose

IN-V7160

(% AR)


(% AR)

Largest unassigned

peak (% AR)


0 95.6 95.2 95.4 5.0 5.6 5.3 3.4 3.4

1 81.9 80.6 81.2 7.3 9.2 8.3 3.4 3.6

3 70.6 71.2 70.9 21.9 22.8 22.3 17.4 17.5

7 47.3 48.0 47.7 51.8 51.2 51.5 47.8 47.3

15 16.2 16.2 16.2 80.2 78.0 79.1 76.0 74.3

30 3.3 3.1 3.2 87.8 83.3 85.5 83.7 79.8

60 1.2 1.4 1.3 84.8 83.7 84.2 81.1 78.7

91 1.0 0.9 0.9 74.2 75.2 74.7 70.0 71.1




Table B.8.106 Distribution of extractable residues in Nambsheim soil under aerobic

conditions treated with IN-V7160 (20C)

Days post dose

IN-V7160

(% AR)


(% AR)

Largest

unassigned peak

(% AR)


0 94.7 95.2 94.9 6.8 6.4 6.6 3.6 3.8

1 74.8 76.3 75.6 16.5 15.5 16.0 7.8 9.4

3 46.8 51.4 49.1 46.9 44.8 45.8 41.3 36.8

7 16.2 29.4 22.8 83.7 70.3 77.0 78.7 65.7

15 2.9 4.6 3.8 91.8 91.4 91.6 86.9 87.7

30 1.1 1.0 1.0 89.4 84.8 87.1 85.0 81.4

60 0.6 0.5 0.5 85.0 86.8 85.9 79.7 80.7

91 0.4 0.3 0.3 77.3 77.3 77.3 75.0 76.1



Table B.8.107 Distribution of extractable residues in Goch soil under aerobic conditions


Days post dose

IN-V7160

(% AR)


(% AR)

Largest unassigned

peak (%AR)


0 96.2 95.2 95.7 5.4 6.9 6.2 3.4 3.8

1 89.8 85.3 87.5 5.7 7.3 6.5 3.1 3.3

3 78.1 74.5 76.3 9.8 14.0 11.9 5.7 6.7

7 72.1 47.0 59.5 18.2 42.7 30.4 14.5 35.2

15 51.6 51.8 51.7 26.7 28.1 27.4 22.7 23.8

30 38.8 40.1 39.4 32.7 41.1 36.9 29.5 36.3

60 29.7 27.0 28.3 39.4 43.1 41.3 34.5 39.0

91 24.6 24.9 24.8 40.7 40.3 40.5 35.6 38.6




Table B.8.108 Distribution of extractable residue in Suchozebry soil under aerobic conditions


Days post dose

IN-V7160

(% AR)


(% AR)

Largest unassigned

peak (% AR)


0 95.9 93.5 94.7 5.0 6.5 5.8 3.5 3.9

1 90.2 90.7 90.5 8.9 6.4 7.7 4.3 3.4

3 79.5 77.9 78.7 14.2 18.0 16.1 6.6 8.1

7 73.4 70.1 71.7 23.2 25.5 24.4 16.9 18.5

15 57.0 50.7 53.8 29.6 33.4 31.5 21.6 24.9

30 48.1 44.1 46.1 40.1 44.9 42.5 29.7 32.8

60 38.9 35.6 37.2 43.2 45.8 44.5 28.7 32.2

91 37.7 32.5 35.1 43.8 46.7 45.3 28.2 30.2



III. CONCLUSION

IN-V7160 degraded in all aerobic test soils incubated at 20C by several

mechanisms including microbial degradation, sequestration to non-extractable

residue and mineralisation to CO2 over the course of the study.

The mass balance was quantitative in all soils ranging from 91.6 to 105.4% of the

applied radioactivity at all sampling points.

The amount of [14

C]IN-V7160 extracted from the soils declined steadily over the

course of the study ranging from 96.2% AR at Day 0 to 0.3% AR at Day 120.

Non-extractable residues increased steadily over the course of the study ranging

from 10.0 to 29.7% AR at Day 120. Carbon dioxide formation also increased

steadily ranging from 2.1% to 12.5% AR by Day 120 showing that the compound

was available for mineralisation by microorganisms.

(Tunink, A., 2009)

Metabolite IN-W8268

Report: Fang, C. (2000); Rates of degradation of IN-W8268, a metabolite of

Thifensulfuron-methyl, in three aerobic soils


Guidelines: SETAC-Europe (1995), OECD (1999)

Test

material:

IN-W8268 technical metabolite

Lot/Batch

#:

W8268-550

Purity: >95%

Previous In DAR for original approval (DAR Addendum2000).


evaluation:


following study did fully meet current guidelines (OECD 307 and US

EPA OPPTS 835.4100). The UK RMS agreed that the study provided

useful and acceptable information on the rate of degradation of

metabolite IN-W8268. Although mass balance dropped below 90%

towards the end of the sampling period in all three soils, the degradation

rates for IN-W8268 from this study appeared to be significantly longer

than from the additional new study supplied by the Task Force.

Therefore excluding results from this study due to lower than optimal

mass balance would have actually resulted in selecting a significantly

shorter DT50. Since this may lead to an underestimation of the

peristence of this metabolite the mass balance was considered

acceptable. It should be noted that the IN-W8268 metabolite has only

been identified as a major soil metabolite in the original route of

degradation study presented in the original DAR, which has now been

considered as unacceptable. It has not been identified in either of two

new route of degradation studies reviewed above. Technically the IN-

W8268 metabolite could be excluded from the soil and groundwater

exposure assessment. However it was included in the original exposure

assessment and the original non-FOCUS groundwater exposure

assessment indicated concentrations close to 0.1μg/l (i.e. <0.06μg/l

based on PRZM-3 simulating a non-FOCUS Hamburg scenario). For

completeness and to ensure a conservative assessment has been

performed, the UK RMS accepted that IN-W8268 should be included in

the groundwater exposure assessment. However the uncertainty over its

actual occurrence based on acceptable soil route of degradation studies

should be noted. The study has been re-evaluated in line with the

current FOCUS kinetics guidance, and results of the new kinetic

analysis are presented in separate reports summarised in Section

B.8.1.4. Results from this study are used to derive a geometric mean

DT50 for the IN-W8268 metabolite for the purposes of the

environmental exposure assessment.

The original text of the study summary from the 2000 DAR Addenda

has been included below. Since the kinetics assessment has been

completely updated, original DT50/90 values have been removed using

strikethrough text.

Methods: [Thiophene-2-14

C]IN-W8268 (purity 99.7 %) in acetonitrile was applied

at 1 mg/kg to 3 soils (50 g samples). Soil characteristics are given in table below.

Incubation was at 20° C and 40-50 % MWHC. Duplicate samples were removed at

0, 3, 7, 14, 30, 45, 60, 90 and 120 DAT. Soils were extracted with acetonitrile/0.1

N ammonium carbonate, extracts were concentrated and analysed by HPLC.

Extracted soils were combusted. Volatiles were trapped.


Table B.8.109 Soil characteristics (degradation of IN-W8268)

Origin Drummer Glenville Gross-Umstadt

Soil texture silty loam sandy loam silt loam

Sand % 25.0 53.0 5.6

Silt % 46.0 34.0 77.2

Clay % 29.0 13.0 17.2

pHw 7.7 5.7 7.8

OM % 6.7 1.5 2.1

CEC meq/100 g 35.4 7.3 9.6

MWHC (0 bar) 74.1 39.3 50.0

Soil biomass (mg C/100 g soil)* 51.3 15.9 33.8

* fumigation extraction method, initial value

Results : RA was not fully recovered at the end of the experiment. That could be

due to CO2 losses and results are deemed to be acceptable. IN-W8268 was the only

major compound found in soil extracts. It degraded with DT50 in the range 40.7 -

68.6 d (mean 55.8 d) and DT90 in the range 135.2 - 228.0 d (mean 185 d). After 90

d, the thiophene ring was significantly mineralized (about 25 %) and bound

residues were 22 - 30 %.

Table B.8.110 Degradation of IN-W8268 (referred to as IN-W in table) in 3

soils

DAT % of applied radioactivity (mean of 2 replicates)

Drummer Glenville Gross-Umstadt

IN-W CO2 Bound Recov. IN-W CO2 Bound Recov. IN-W CO2 Bound Recov.

0 89.4 8.2 99.2 98.8 0.7 101.0 97.7 0.7 100.0

3 92.7 0.4 5.5 100.4 95.0 0.4 5.2 101.7 97.1 0.3 2.6 101.4

7 85.6 1.4 9.9 98.5 88.3 1.4 7.8 100.0 93.6 1.0 3.5 100.3

14 79.5 3.6 13.3 98.0 80.8 4.3 11.8 99.1 86.1 2.5 6.9 96.8

21 72.6 6.4 15.3 96.4 71.6 7.5 17.2 99.7 77.3 4.7 9.4 95.1

30 64.5 10.4 18.7 95.3 62.9 11.1 20.3 98.0 68.9 7.4 12.5 91.5

45 53.3 15.0 23.6 93.6 57.0 15.3 22.8 98.8 54.6 12.2 16.5 85.6

60 47.2 19.1 25.2 92.7 49.1 20.8 22.2 96.4 43.8 18.8 19.3 84.8

90 32.2 24.1 30.1 88.0 39.6 28.7 22.5 94.3 26.8 26.3 24.7 79.9

120 21.7 26.7 33.3 83.0 29.3 31.8 22.2 86.3 11.6 30.2 27.6 71.8

Conclusions: The metabolite IN-W8268 (thiophene sulfonimide) is slowly

degraded in 3 soils (OM 1.5 - 6.7 %, pH 5.7 - 7.8) with DT50 in the range 40.7 -

68.6 d (mean 55.8 d) and DT90 in the range 135.2 - 228.0 d (mean 185 d).

(Fang, 2000)


Report: E. Knoch (2012d) Aerobic Soil Degradation of Thiophene sulfonimide.

SGS Institute Fresenius GmbH, [Cheminova A/S], Unpublished Report

No.IF-11/02039256; [CHA Doc. No. 297 TIM]



Previous



This new rate of degradation study conducted with IN-W8268 has been

provided by the Task Force and largely supports the conclusions of the

original study from the DAR above (Fang, 2000). The detailed study

summary from the Task Force is provided below. Results from this

study are used to derive an overall geometric mean DT50 for the IN-

W8268 metabolite for the purposes of the environmental exposure

assessment.

The degradation of IN-W8268 (thiophene sulfonimide) was investigated under aerobic

conditions at 20 °C in the dark for a maximum of 94 days. Three German soils were used for

the experiment (USDA classification: LUFA 2.2 / loamy sand, LUFA 2.3 / sandy loam and

LUFA 6S / clay, Table B.8.112). The soil moisture was adjusted to 45 % maximum water

holding capacity.

The target rate of 0.1 mg/kg dry soil for IN-W8268 was selected for the aerobic soil degradation

experiments. The soil systems were acclimatized under a dynamic atmosphere of air to

maintain aerobic conditions. The test period consisted of sampling intervals at: LUFA 2.2:

zero-time (initial value), 3,5, 7, 14 and 30 days; LUFA 2.3: zero-time (initial value), 3, 7, 14, 30

and 60 days; LUFA 6S: zero-time (initial value), 3, 7, 14, 30, 60 and 94 days. The recoveries of

IN-W8268 for the initial time specimens ranged from 79 to 91 % of the applied test item. For

the experimental end specimens the recoveries of IN-W8268 decreased by aerobic

degradation and accounted for < 10 % for LUFA 2.2 (days-14), < 10 % for LUFA 2.3 (days-

30) and < 10 % for LUFA 6S (days-94). The modelling followed first order kinetics. The

following DT50 and DT90 values were calculated:

Table B.8.111 Kinetic data for IN-W8268


LUFA 2.2 SFO 2.6 8.6 14.0

LUFA 2.3 SFO 9.7 32.3 7.8

LUFA 6S SFO 24.5 81.3 8.9



Materials:

1. Test Material: IN-W8268 (Thiophene sulfonimide)


Lot/Batch #: P1966-OSJ-TFM-03-D

Purity: 99.6%

CAS #: 59337-94-9




Soil name

pH

(0.1 M

CaCl2)

OC

%

Sand1

%

Silt1

%

Clay1

%

CEC

mEq/100g

Initial/

End

Biomass

mg

C/100g

soil2

Classification MWHC

%

LUFA 2.2 5.5 1.87 80.6 12.6 6.8 9.9 32/26 Loamy sand 44.4

LUFA 2.3 6.8 0.94 63.7 27.6 8.7 10.7 20/26 Sandy loam 35.6

LUFA 6S 7.1 1.64 22.2 36.8 41.0 23.7 84/75 Clay 38.9 1 USDA Particle Size Distribution and Classification, 2 Prior to study,

CEC = Cation exchange capacity, OC = Organic carbon, MWHC = Maximum water holding capacity

Study Design:


The soils (100 g dry weight) were moistened to 45% MWHC and incubated at 20 ± 2ºC in the

dark. Application of the test substance (0.1 mg a.s./kg soil) was made to the soil surface and

mixed by manual shaking. Following application the soil units were incubated until sampling.

Sampling was at: LUFA 2.2: zero-time (initial value), 3, 5, 7, 14 and 30 days; LUFA 2.3: zero-

time (initial value), 3, 7, 14, 30 and 60 days; LUFA 6S: zero-time (initial value), 3, 7, 14, 30, 60

and 94 days. At each sampling interval replicate specimens were taken and assayed for IN-

W8268. Within the course of the experiments (> 0-time) the analytical method was proved to

be valid. Therefore, laboratory procedural recovery specimens were performed, using two

fortification levels for the analyte and soil type: 0.01 mg a.s./kg dry soil (10 % target rate)

and 0.1 mg a.s./kg dry soil (100 % target rate).

The samples were extracted twice with 100-140 mL 0.5 mol/L ammonium carbonate and

methanol (60:40 v/v) by shaking, followed by centrifugation and filtration. The extracts were

combined and the final volume was made up to 250 mL with extraction solvent. 100 µL of


the extract was diluted with 900 µL of pure water. Final extracts were then subjected to LC-

MS/MS analysis.

Standard solutions of IN-W8268 were prepared freshly for each set of soil samples analysed.

The kinetic modelling followed the guidance of FOCUS kinetics employing the software tool

for kinetic evaluation FOCUS_DEGKIN v2.


The limit of quantification (LOQ) was 0.01 mg/kg dry soil for IN-W8268. All the recovery

data of IN-W8268 in the three soil systems are acceptable (mean recovery between 70 and

110 % and a relative standard deviation less than 20 %).

The recoveries of IN-W8268 for the initial time specimens ranged from 79 to 91 % of the

applied test item. For the experimental end specimens the recoveries of IN-W8268 decreased

by aerobic degradation and accounted for < 10 % for LUFA 2.2 (days-14), < 10 % for LUFA

2.3 (days-30) and < 10 % for LUFA 6S (days-94).

Table B.8.113 Concentration of IN-W8268 and percentage of dosed amount in soil

Sampling

interval

(hours)


Concentration

measured

(mg/kg)

% of dosed

Concentration

measured

(mg/kg)

% of dosed

Concentration

measured

(mg/kg)

% of dosed

0 0.0877

0.0909

88

91

0.0890

0.0905

89

90

0.0795

0.0798

79

80

3 0.0505

0.0446

50

45

0.0678

0.0715

68

71

0.0724

0.0741

72

74

5 0.0122

0.0160

12

16 NA NA NA NA

7 0.0200

0.0121

20

12

0.0619

0.0555

62

55

0.0701

0.0752

70

75

14 0.0050

0.0032

5

3

0.0417

0.0318

42

32

0.0689

0.0633

69

63

30 -

-

(0)

(0)

0.0042

0.0015

4

1

0.0322

0.0388

32

39

60 NA NA -

-

(0)

(0)

0.0112

0.0087

11

9

94 NA NA NA NA -

-

(0)

(0)

(..) below 30% LOQ

Conclusions:


Using SFO kinetics, DT50 values for IN-W8268 were between 2.6 and 24.5 days depending

on the soil type. DT90 values were between 8.6 and 81.3 days.

Table B.8.114 Kinetic data for IN-W8268


LUFA 2.2 SFO 2.6 8.6 14.0

LUFA 2.3 SFO 9.7 32.3 7.8

LUFA 6S SFO 24.5 81.3 8.9

(Knoch, 2012d)

Metabolite IN-JZ789

Report: E. Knoch (2012a) Aerobic Soil Degradation of O-Desmethyl

thifensulfuron acid. SGS Institute Fresenius GmbH, [Cheminova A/S],

Unpublished Report No.IF-11/02082955[CHA Doc. No. 298 TIM]



Previous

evaluation:



This new rate of degradation study conducted with IN-JZ789 has been

provided by the Task Force. This metabolite was not considered in the

original DAR but has been identified as a new major soil metabolite in

the new route of degradation study provided by the Task Force. Since

this is a new metabolite, the UK RMS accepted that information on its

rate of degradation in soil was relevant. The detailed study summary

from the Task Force is provided below. A separate kinetic assessment is

provided in Section B.8.1.4.











The degradation of IN-JZ789 (O-Desmethyl thifensulfuron acid) was investigated under

aerobic conditions at 20 °C in the dark for a maximum of 119 days. Three German soils were

used for the experiment (USDA classification: LUFA 2.2 / loamy sand, LUFA 2.3 / sandy loam

and LUFA 6S / clay, Table B.8.116). The soil moisture was adjusted to 45 % maximum water

holding capacity.

The target rate of 0.1 mg/kg dry soil for IN-JZ789 was selected for the aerobic soil degradation

experiments. The soil systems were acclimatized under a dynamic atmosphere of air to

maintain aerobic conditions. The test period consisted of sampling intervals at: LUFA 2.2:

zero-time (initial value), 2, 4, 7, 14 and 30 days; LUFA 2.3: zero-time (initial value), 2, 7, 16, 30

and 58 days; LUFA 6S: zero-time (initial value), 2, 7, 16, 30, 58, 90 and 119 days. The

recoveries of IN-JZ789 for the initial time specimens ranged from 83 to 98 % of the applied

test item. The modelling followed first order kinetics. The following DT50 and DT90 values

were calculated:

Table B.8.115 Kinetic data for IN-JZ789


LUFA 2.2 SFO 2.1 7.1 5.6

LUFA 2.3 SFO 4.2 14.1 1.8

LUFA 6S SFO 56.7 188.5 3.8


Materials:

1. Test Material: IN-JZ789 (O-Desmethyl thifensulfuron acid)

Description: White/Beige Solid

Lot/Batch #: P1265-OSJ-THF-01-A

Purity: 94.2%

CAS #: 171628-02-7




Soil name

pH

(0.1 M

CaCl2)

OC

%

Sand1

%

Silt1

%

Clay1

%

CEC

mEq/100g

Initial/

End

Biomass

mg C/g

soil2

Classification MWHC

%

LUFA 2.2 5.5 1.87 80.6 12.6 6.8 9.9 32/26 Loamy sand 44.4

LUFA 2.3 6.8 0.94 63.7 27.6 8.7 10.7 20/ 26 Sandy loam 35.6


Soil name

pH

(0.1 M

CaCl2)

OC

%

Sand1

%

Silt1

%

Clay1

%

CEC

mEq/100g

Initial/

End

Biomass

mg C/g

soil2

Classification MWHC

%

LUFA 6S 7.1 1.64 22.2 36.8 41.0 23.7 84/51 Clay 38.9 1 USDA Particle Size Distribution and Classification, 2 Prior to study,


Study Design:




mixed by manual shaking. Following application the soil units were incubated until sampling.

Sampling was at: LUFA 2.2: zero-time (initial value), 2, 4, 7, 14 and 30 days; LUFA 2.3: zero-

time (initial value), 2, 7, 16, 30 and 58 days; LUFA 6S: zero-time (initial value), 2, 7, 16, 30, 58,

90 and 119 days. At each sampling interval replicate specimens were taken and assayed for IN-

JZ789. Within the course of the experiments (> 0-time) the analytical method was proved to

be valid. Therefore, laboratory procedural recovery specimens were performed, using two

fortification levels for the analyte and soil type: 0.01 mg a.s./kg dry soil (10 % target rate)

and 0.1 mg a.s./kg dry soil (100 % target rate).

The samples were extracted four times with 100-140 mL 0.5 mol/L ammonium carbonate and

methanol (60:40 v/v) by shaking, followed by centrifugation and filtration. The extracts were

combined and the final volume was made up to 500 mL with extraction solvent. 50 µL of the

extract was diluted with 950 µL of pure water: methanol:formic acid (900:100:0.45 v/v/v).

Final extracts were then subjected to LC-MS/MS analysis.

Standard solutions of IN-JZ789 were prepared freshly for each set of soil samples analysed.


for kinetic evaluation FOCUS_DEGKIN v2. RMS evaluations confirmed that the SFO partial

differential equations and associated initial starting parameters used to derive DT50 and DT90

value were appropriate.


The limit of quantification (LOQ) was 0.01 mg/kg dry soil for IN-JZ789. All the recovery

data of IN-JZ789 in the three soil systems are acceptable (mean recovery between 70 and 110

% and a relative standard deviation less than 20 %).

The recoveries of IN-JZ789 for the initial time specimens ranged from 83 to 98 % of the

applied test item (table 7.2.3/05-03). For the experimental end specimens the recoveries of

IN-JZ789 decreased by aerobic degradation and accounted for < 10 % for LUFA 2.2 (days-

30), < 10 % for LUFA 2.3 (days-58) and 18 – 24 % for LUFA 6S (days-119).


Table B.8.117 Concentration of IN-JZ789 and percentage of dosed amount in soil

Sampling

interval

(hours)


Concentration

measured

(mg/kg)

% of dosed

Concentration

measured

(mg/kg)

% of dosed

Concentration

measured

(mg/kg)

% of dosed

0 0.0920

0.0902

95

93

0.0890

0.0949

92

98

0.0814

0.0805

84

83

2 0.0455

0.0465

47

48

0.0660

0.0672

68

70

0.0755

0.0743

78

77

4 0.0327

0.0257

33

26 NA NA NA NA

7 0.0052

0.0070

5

7

0.0290

0.0276

30

29

0.0683

0.0670

71

69

14 0.0012

0.0010

(1)

(1) NA NA NA NA

16 NA NA 0.0072

0.0075

7

8

0.0630

0.0629

65

65

30 -

-

nd

nd

0.0027

0.0021

(3)

(2)

0.0554

0.0576

57

60

58 NA NA -

-

nd

nd

0.0389

0.0395

40

41

90 NA NA NA NA 0.0222

0.0220

23

23

119 NA NA NA NA 0.0228

0.0171

24

18

(..) below 30% LOQ

Conclusions:

Using SFO kinetics, DT50 values for IN-JZ789 were between 2.1 and 56.7 days depending on

the soil type. DT90 values were between 7.1 and 188.5 days (Table B.8.118).

Table B.8.118 Kinetic data for IN-JZ789


LUFA 2.2 SFO 2.1 7.1 5.6

LUFA 2.3 SFO 4.2 14.1 1.8

LUFA 6S SFO 56.7 188.5 3.8

(Knoch, 2012a)


Metabolite IN-B5528

Report: E. Knoch (2012b) Aerobic Soil Degradation of O-Desmethyl triazine

amine. SGS Institute Fresenius GmbH, [Cheminova A/S], Unpublished Report

No.IF-11/02132772; [CHA Doc. No. 300 TIM]



Previous



This new rate of degradation study conducted with IN-B5528 has been

provided by the Task Force. However this metabolite has not been

identified as a major metabolite in any compartment. Although it

reached 8.7% AR at the end of the new anaerobic soil degradation study,

it was not found in significant levels (>3%) over the first 90 d of that

study. Such prolonged durations of anaerobic soil conditions are

unlikely to be typical in agricultural soils and this metabolite has

therefore been excluded from the environmental exposure assessment.

Since a soil DT50 is not required for this metabolite this study has not

been reviewed in detail. For completeness the detailed study summary

from the Task Force is provided below. Since this information is not

relied on, it has been greyed out.

Executive Summary:

The degradation of IN-B5528 (O-desmethyl triazine amine) was investigated under

aerobic conditions at 20 °C in the dark for a maximum of 27 days. Three German

soils were used for the experiment (USDA classification: LUFA 2.2 / loamy sand,

LUFA 2.3 / sandy loam and LUFA 6S / clay). The soil moisture was adjusted to 45

% maximum water holding capacity.

The target rate of 0.1 mg/kg dry soil for IN-B5528 was selected for the aerobic soil

degradation experiments. The soil systems were acclimatized under a dynamic

atmosphere of air to maintain aerobic conditions. The test period consisted of

sampling intervals at: LUFA 2.2: zero-time (initial value), 2, 5, 14 and 20 hours, 1,

2, 5 and 7 days; LUFA 2.3: zero-time (initial value), 1, 2, 3, 5, 7 and 13 days;

LUFA 6S: zero-time (initial value), 1, 2, 5, 7, 13 and 27 days. The recoveries of

IN-B5528 for the initial time specimens ranged from 82 to 87 % of the applied test

item. The recoveries of IN-B5528 decreased with time and accounted for < 10 %

for LUFA 2.2 (days-1), < 10 % for LUFA 2.3 (days-5) and < 10 % for LUFA 6S

(days-13).

The modelling followed first order kinetics. The following DT50 and DT90 values

were calculated:


Table B.8.119 Kinetic data for IN-B5528


LUFA 2.2 SFO 0.2 0.7 5.8

LUFA 2.3 SFO 1.7 5.5 5.0

LUFA 6S SFO 3.8 12.5 7.4


Materials:

1. Test Material: IN-B5528 (O-Desmethyl triazine amine)


Lot/Batch #: 194694

Purity: 97.3%

CAS #: 16352-06-0




Soil name

pH

(0.1 M

CaCl2)

OC

%

Sand1

%

Silt1

%

Clay1

%

CEC

mEq/100g

Biomass

mg C/g

soil2

Classification MWHC

%

LUFA 2.2 5.5 1.87 80.6 12.6 6.8 9.9 32 Loamy sand 44.4

LUFA 2.3 6.8 0.94 63.7 27.6 8.7 10.7 20 Sandy loam 35.6

LUFA 6S 7.1 1.64 22.2 36.8 41.0 23.7 84 Clay 38.9 1 USDA Particle Size Distribution and Classification, 2 Prior to study,

CEC = Cation exchange capacity, OC = Organic carbon, MWHC = Maximum water holding capacity at pF 2.0

Study Design:


The soils (100 g dry weight) were moistened to 45% MWHC and incubated at 20 ±

2ºC in the dark. Application of the test substance (0.1 mg a.s./kg soil) was made to

the soil surface and mixed by manual shaking. Following application the soil units

were incubated until sampling.

Sampling was at: LUFA 2.2: zero-time (initial value), 2, 5, 14 and 20 hours, 1, 2, 5

and 7 days; LUFA 2.3: zero-time (initial value), 1, 2, 3, 5, 7 and 13 days; LUFA

6S: zero-time (initial value), 1, 2, 5, 7, 13 and 27 days. At each sampling interval

replicate specimens were taken and assayed for IN-B5528. Within the course of the

experiments (> 0-time) the analytical method was proved to be valid. Therefore,

laboratory procedural recovery specimens were performed, using two fortification

levels for the analyte and soil type: 0.01 mg a.s./kg dry soil (10 % target rate) and

0.1 mg a.s./kg dry soil (100 % target rate).

The LUFA 2.2 and 2.3 soil samples were extracted twice with 100-140 mL 0.5

mol/L ammonium carbonate and methanol (70:30 v/v) by shaking, followed by

centrifugation and filtration. The extracts were combined and the final volume was

made up to 250 mL with extraction solvent. 100 µL of the extract was diluted with

900 µL of pure water. The LUFA 6S soil samples were extracted four times with

100-140 mL 0.5 mol/L ammonium carbonate and methanol (70:30 v/v) by shaking,


followed by centrifugation and filtration. The extracts were combined and the final

volume was made up to 500 mL with extraction solvent. 200 µL of the extract was

diluted with 800 µL of pure water. Final extracts were then subjected to LC-

MS/MS analysis.

The kinetic modelling followed the guidance of FOCUS kinetics employing the

software tool for kinetic evaluation FOCUS_DEGKIN v2.


The working solutions of IN-B5528 were found to be stable for at least 3 months

when stored at 2 to 8 °C in the refrigerator. The limit of quantification (LOQ) was

0.01 mg/kg dry soil for IN-B5528. All the recovery data of IN-B5528 in the three

soil systems are acceptable (mean recovery between 70 and 110 % and a relative

standard deviation less than 20 %).

The recoveries of IN-B5528 for the initial time specimens ranged from 82 to 87 %

of the applied test item. The recoveries of IN-B5528 decreased with time and

accounted for < 10 % for LUFA 2.2 (days-1), < 10 % for LUFA 2.3 (days-5) and

< 10 % for LUFA 6S (days-13).


Table B.8.121 Concentration of IN-B5528 and percentage of dosed amount in soil

Sampling

interval

(hours)


Concentration

measured

(mg/kg)

% of dosed

Concentration

measured

(mg/kg)

% of dosed

Concentration

measured

(mg/kg)

% of dosed

0

0.0870

0.0871

0.0827

0.0832

87

87

83

83

0.0840

0.0824

84

82

0.0854

0.0855

86

86

2 hours 0.0594

0.0583

59

58 NA NA NA NA

5 hours 0.0438

0.0448

44

45 NA NA NA NA

14 hours 0.0155

0.0109

16

11 NA NA NA NA

20 hours 0.0045

0.0023

5

(2) NA NA NA NA

1 day 0.0031

0.0033

3

3

0.0594

0.0521

0.0538

0.0534

60*

52*

54

54

0.0635

0.0623

64

62

2 days - - 0.0384

0.0411

38

41

0.0645

0.0625

65

63

3 days NA NA 0.0205

0.0212

21

21 NA NA

5 days - - 0.0091

0.0095

9

9

0.0309

0.0306

31

31

7 days - - 0.0080

0.0050

8

5

0.0242

0.0241

24

24

13 days NA NA 0.0006

0.0006

(1)

(1)

0.0088

0.0070

9

7

27 days NA NA NA NA 0.0022

0.0018

(2)

(2)

(..) below 30% LOQ; * not used for kinetic calculation

Conclusions:

Using SFO kinetics, DT50 values for IN-B5528 were between 0.2 and 3.8 days

depending on the soil type. DT90 values were between 0.7 and 12.5 days.


Table B.8.122 Kinetic data for IN-B5528


LUFA 2.2 SFO 0.2 0.7 5.8

LUFA 2.3 SFO 1.7 5.5 5.0

LUFA 6S SFO 3.8 12.5 7.4

(Knoch, 2012b)

2-acid-3-triuret

Report: E. Knoch (2012e) Aerobic Soil Degradation of TIM 2-acid-3-triuret.

SGS Institute Fresenius GmbH, [Cheminova A/S], Unpublished Report

No.IF-12/02251384; [CHA Doc. No.: TIM 315]



Previous

evaluation:



This new rate of degradation study conducted with 2-acid-3-triuret has

been provided by the Task Force and evaluated by the UK RMS. The











Executive Summary:

The degradation of TIM 2-acid-3-triuret was investigated under aerobic conditions at 20 °C

in the dark for a maximum of 66 hours (2.75 days). Three German soils were used for the

experiment (USDA classification: LUFA 2.2 / loamy sand, LUFA 2.3 / sandy loam and LUFA

2.4/ loam). The soil moisture was adjusted to 45 % maximum water holding capacity.

The target rate of 0.1 mg/kg dry soil for TIM 2-acid-3-triuret was selected for the aerobic soil

degradation experiments. The soil systems were acclimatized under a dynamic atmosphere of

air to maintain aerobic conditions. The test period consisted of sampling intervals at: LUFA

2.2: zero-time (initial value), 0.5, 0.75, 1, 1.5, 3, 5, 8;14 and24 hours; LUFA 2.3: zero-time

(initial value), 1, 2, 3, 5, 8, 14 and 24 hours; LUFA 2.4: zero-time (initial value), 1, 3, 5, 8, 14,

24, 44 and 66 hours. The recoveries of TIM 2-acid-3-triuret for the initial time specimens

ranged from 79 to 88 % of the applied test item. The recoveries of TIM 2-acid-3-triuret

decreased with time and accounted for < 10 % for LUFA 2.2 (days-0.063), < 10 % for LUFA

2.3 (days-0.333) and < 10 % for LUFA 6S (day-1).


The modelling followed first order kinetics. The following DT50 and DT90 values were

calculated:

Table B.8.123 Kinetic data for TIM 2-acid-3-triuret


LUFA 2.2 SFO 0.0182 0.0604 13.6

LUFA 2.3 SFO 0.0663 0.2201 4.3

LUFA 2.4 SFO 0.2360 0.7839 3.1


Materials:

1. Test Material: TIM 2-acid-3-triuret

Description: Beige solid

Lot/Batch #: P1265HRM-TFSM-17

Purity: 96.0%

CAS #: 171628-03-8

Stability: Expiration date April 03 2015



Soil name

pH

(0.1 M

CaCl2)

OC

%

Sand1

%

Silt1

%

Clay1

%

CEC

mEq/100g

Biomass

mg C/g

soil2

Classification MWHC

%

LUFA 2.2 5.5 1.77 78.9 13.8 7.3 10.1 42 Loamy sand 41.8

LUFA 2.3 6.8 0.94 63.1 28.4 8.5 10.9 49 Sandy loam 37.3

LUFA 2.4 7.2 2.26 33.6 40.5 25.9 31.4 74 Loam 44.4 1 USDA Particle Size Distribution and Classification, 2 Prior to study,


Study Design:




mixed by manual shaking. Following application the soil units were incubated until

sampling.

Sampling was at: LUFA 2.2: zero-time (initial value) 0.5, 0.75, 1, 1.5, 3, 5, 8, 14 and 24 hours;

LUFA 2.3: zero-time (initial value), 1, 2, 3, 5, 8, 14 and 24 hours; LUFA 2.4: zero-time (initial


value), 1, 3, 5, 8, 14, 24, 44 and 66 hours. At each sampling interval replicate specimens were

taken and assayed for TIN 2-acid-3-triuret. Within the course of the experiments (> 0-time)

the analytical method was proved to be valid. Therefore, laboratory procedural recovery

specimens were performed, using two fortification levels for the analyte and soil type: 0.01

mg test item/kg dry soil (10 % target rate) and 0.1 mg test item/kg dry soil (100 % target rate).

The soil samples (LUFA 2.2, 2.3 and 2.4) were extracted four times with a mixture of ultra

pure water, methanol and acetic acid (60/40/2 v/v/v) by shaking, followed by centrifugation

and filtration. The extracts were combined and the final volume was made up to 5000 mL

with extraction solvent. 100 µL of the extract was diluted with 900 µL of methanol/pure

water (10/90/v/v). Final extracts were then subjected to LC-MS/MS analysis.


for kinetic evaluation FOCUS_DEGKIN v2.


The working solutions of TIM 2-acid-3-triuret were found to be stable for at least 2 weeks

since the concentration of test item in old solution was in the range of 90-110% of the

concentration in freshly prepared solution. The limit of quantification (LOQ) was 0.01

mg/kg dry soil for TIM 2-acid-3-triuret. All the recovery data of TIM 2-acid-3-triuret in the

three soil systems are acceptable (mean recovery between 70 and 110 % and a relative

standard deviation less than 20 %). The recoveries of TIM 2-acid-3-triuret for the initial time

specimens ranged from 79 to 88 % of the applied test item. The recoveries of TIM 2-acid-3-

triuret decreased with time and accounted for < 10 % for LUFA 2.2 (days-0.063), < 10 % for

LUFA 2.3 (days-0.333) and < 10 % for LUFA 2.4 (day-1).


Table B.8.125 Concentration of TIM 2-acid-3-triuret and percentage of dosed amount in soil

Sampling

interval

(hours)

LUFA 2.2 LUFA 2.3 LUFA 2.4

Concentration

measured

(mg/kg)

% of dosed

Concentration

measured

(mg/kg)

% of dosed

Concentration

measured

(mg/kg)

% of dosed

0

0.0803

0.0803

0.0845

0.0836

80

80

84

83

0.0873

0.0856

0.0788

0.0882

87

85

79

88

0.0869

0.874

87

87

0.5 hours 0.0352

0.0333

35

33 N/A N/A N/A N/A

0.75 hours 0.0194

0.0194

19

19 N/A N/A N/A N/A

1 hour 0.0244

0.0241

24

24

0.0558

0.0564

56

56

0.0752

0.0773

75

77

1.5 hours 0.0085

0.0094

8

9 N/A N/A N/A N/A

2 hours 0.0594

0.0583

59

58

0.0332

0.0336

33

33 NA NA

3 hours 0.0031

0.0081 8

0.0229

0.0209

23

21

0.0624

0.0606

62

60

5 hours 0.0028

0.0013

3

(1)

0.0118

0.0143

12

14

0.0454

0.0436

45

46

8 hours -

-

(0)

(0)

0.0038

0.0035

4

3

0.0339

0.0359

34

36

14 hours -

-

0

0

-

-

(0)

(0)

0.0122

0.0143

12

14

24 hours -

-

(0)

(0)

-

-

(0)

(0)

0.0068

0.0061

7

6

44 hours N/A N/A N/A N/A -

-

(1)

(0)

66 hours N/A N/A N/A N/A -

-

(0)

(0)

(..) below 30% LOQ;

Conclusions:

TIM 2-acid-3-triuret degraded rapidly in aerobic soils. The modelling followed first order

kinetics.

Using SFO kinetics, DT50 values for TIM 2-acid-3-triuret were between 0.0182 and 0.236

days depending on the soil type. DT90 values were between 0.0604 and 0.7839 days.


Table B.8.126 Kinetic data for TIM 2-acid-3-triuret


LUFA 2.2 SFO 0.0182 0.0604 13.6

LUFA 2.3 SFO 0.0663 0.2201 4.3

LUFA 2.4 SFO 0.2360 0.7839 3.1

(Knoch, 2012e)

B.8.1.4 Rate of degradation

DuPont rate of degradation studies

Previous

evaluation:



DuPont summarised their kinetic assessment of existing and new studies

in three separate reports (Jagtap, 2011; Snyder, 2012 and Weber, 2011).

In some cases the Applicant provided kinetic assessments of studies that

were subsequently rejected by the UK RMS as being unreliable. The

study summaries below therefore only presents the kinetic fitting of

study considered reliable by the UK RMS. To simplify the presentation

of the kinetic analysis, only the modelling endpoints have been shown.

Persistence endpoints are considered less important in this specific case

for the reasons explained below. The active substance has a short half

life in soil and clearly does not breach any of the relevant persistence

triggers specified in Regulation 1107/2009. Peak metabolite PECsoil

values are calculated using the total dose approach and conservatively

assume no degradation between applications for the multiple application

GAPs. Given the very large margins of safety on the terrestrial risk

assessment for all metabolites, this simple approach is considered

sufficient to demonstrate the low risk of these substances. In general the

Applicants kinetics reports were clearly reported and conducted in

accordance with FOCUS kinetics guidance. The kinetic fits have been

independently verified by the UK RMS. In some cases, to verify the

goodness of fit, the UK RMS has supplemented the Applicants original

study summary with additional details and graphical plots from the

original study report. Since the three separate reports covered different

studies, all three have been reviewed below in a single section.

Report: Jagtap, S. (2011); Soil degradation of Thifensulfuron-methyl - kinetic calculations

following FOCUS kinetics guidelines

DuPont Report No.: DuPont-18742 EU, Revision No. 1, Supplement No. 1

Guidelines: FOCUS kinetics guidelines (FOCUS, 2006) Deviations: None

Testing Facility: Simulogic Environmental Consulting Pvt. Ltd., Pune, India

Testing Facility Report No.: DuPont-18742 EU, Revision No. 1, Supplement No. 1

GLP: No

Certifying Authority: Not applicable


Report: Snyder, N.J. (2012); Soil degradation of Thifensulfuron-methyl - kinetic

calculations following FOCUS kinetics guidelines

DuPont Report No.: DuPont-18742 EU, Revision No. 2

Guidelines: FOCUS kinetics guidelines (FOCUS, 2005) Deviations: None

Testing Facility: Waterborne Environmental, Inc, Leesburg, Virginia, USA

Testing Facility Report No.: DuPont-18742 EU, Revision No. 2

GLP: No



Report: Weber, D. (2011); Aminotriazin: Calculation of endpoints from aerobic soil

degradation studies for use in fate modelling kinetic analysis according to the FOCUS

guidance

DuPont Report No.: SYN D09681 (M-411174-01-1)

Guidelines: Not applicable - postion paper Deviations: None

Testing Facility: Harlan Laboratories Ltd., Itingen, Switzerland

Testing Facility Report No.: D09681

GLP: No

Certifying Authority: Not applicable - postion paper

Executive summary:

The three reports above provided estimates of the degradation of Thifensulfuron-methyl and

the formation and decline of metabolites, with the goal of providing modelling endpoints and

persistence triggers for additional ecotoxicological work, as calculated following the FOCUS

kinetics guidelines (FOCUS, 2005). Only modelling triggers are presented in this summary.

Since the UK RMS rejected the original route of degradation study presented in the 2000

DAR as well as the new route of degradation study proved by DuPont, the kinetic assessment

for DuPont was simplified to a single rate of degradation study performed with thifensulfuron

and separate metabolite dosed rate of degradation studies. The description of fitting

performed on the studies that have subsequently been rejected have been removed from this

summary. For the purposes of the groundwater exposure assessment, formation fractions

have been derived from the acceptable route of degradation study provided by the Task Force

(see evaluation of Ford, 2012 below).


Following the UK RMS review of new and existing rate of degradation studies performed

with Thifensulfuron-methyl, only a single study on two soils remained that was considered

acceptable in the DuPont submission. Although only 4 or 5 time points were available

(which included a final sample point where residues were below the LOD) in general the

visual and statistical fit using SFO kinetics was considered acceptable by the Applicant and

agreed by the UK RMS. The chi2 error values were low (3 or 4) and the t-test on the rate

constant confirmed it was statistically different from zero. A summary of the DT50/90

values under study conditions and normalised to reference conditions is provided in Table

B.8.127 below. These two DT50 values have been combined with acceptable data from the


Task Force route of degradation study on a further 4 soils (Simmonds, 2012a). This has bene

used to derive an overall geometric mean DT50 for exposure modelling. Since the derivation

of parent DT50 values from the Task Force route of degradation study was more complex,

including sequential metabolite fitting, only the DT50 values are shown here. Please refer to

the summary of Ford, 2012 further below for full details of the kinetic assessment .

Table B.8.127: Summary of modelling degradation parameters for Thifensulfuron-methyl

(DuPont data)

Parent Aerobic conditions

Study

reference

Soil type pH t. oC / % MWHC

DT50 /DT90

(d)

DT50 (d)

20C

pF2/10kPa1

chi2

Method of

calculation

Allen, 1987 Speyer 2.2;

loamy sand

5.7 22oC / 40%

MWHC 1.7 / 5.7 2.0 3 SFO


loamy sand

7.0 22oC / 40%

MWHC 2.6 / 8.6 3.1 4 SFO

Simmonds,

2012a

Longwood;

sandy loam 7.5 20° / pF 2 -2.5 0.99 0.99

3.742 SFO

Simmonds,

2012a

Farditch;

loam 6.5 20° / pF 2 -2.5 1.12 1.12

6.782 SFO

Simmonds,

2012a

Lockington;

sandy clay 5.5 20° / pF 2 -2.5 1.23 1.23

10.02 SFO

Simmonds,

2012a

Kenslow;

loam 5.5 20° / pF 2 -2.5 0.85 0.85

5.662 SFO

Geometric mean - 1.39 - - 1DT50 values only corrected for temperature since soil moisture estimated to be greater than pF2 based on

measured MWHC from original study report and default values for pF2 from FOCUS groundwater report 2the DT50 represents the geometric mean of values from separate radiolabelled samples (e.g. triazine and

thiophene samples). The chi2 is the highest value from either radiolabel.

IN-A4098

Following the UK RMS review of new and existing rate of degradation studies performed

with metabolite IN-A4098, three studies on a total of five soils remained that were considered

acceptable in the DuPont submission. In addition a further study on 3 soils was considered

acceptable from the Task Force submission. Kinetic fitting for the study of Rhodes (1987)

was performed by the UK RMS using the FOCUS DEGKIN spreadsheet since this study was

excluded by DuPont. In general the visual and statistical fits for the remaining soils using

SFO kinetics were considered acceptable by the Applicants and agreed by the UK RMS. The

chi2 error values were low and the t-test on the rate constant confirmed they were statistically

different from zero. In one soil (Honville) a clearer bi-phasic pattern of decline was observed

and fitting using the HS model was selected. A summary of the DT50/90 values under study

conditions and normalised to reference conditions is provided in Table B.8.128 below.


Table B.8.128: Summary of modelling degradation parameters for IN-A4098 (DuPont and

Task Force data)

IN-A4098 Aerobic conditions

Study

reference

Soil type pH t. oC / %

MWHC DT50 (d)

DT50 (d)

20C

pF2/10kPa

chi2

Method of

calculation

Rhodes,

1987a

(Dupont)

Keyport; silt

loam

4.3

25oC / 70% FC 208 254 6.2 SFO

Möndel,

2001

(Dupont)

Honville,

loamy silt

6.7

(H2O) 20°C / 40%

MWHC

260.1 K1 = 0.01772

K2 = 0.00266

Tb = 25.9

201.6 3.0

HS (DT50

calculated

from slow

phase)

Jungmann,

Nicollier,

2006

(Dupont)

Gartenacker;

Loam,

6.9

(CaCl2) 20°C / pF2 102.2 102.2 3.5 SFO

Jungmann,

Nicollier,

2006

(Dupont)

18 Acres;

sandy clay

loam,

5.0

(CaCl2) 20°C / pF2 249.4 249.4 3.2 SFO

Jungmann,

Nicollier,

2006

(Dupont)

Krone; silt

loam,

4.9

(CaCl2) 20°C / pF2 190.8 190.8 3.7 SFO

Morlock

(2006a)

Task Force

Soil 2.2; loamy

sand

5.7

(H2O) 20°C / 45%

MWHC 67.3 67.3 5.68 SFO

Morlock

(2006a)

Task Force

Soil 3A; sandy

loam

7.3

(H2O) 20°C / 45%

MWHC 188.4 175.7 5.645 SFO

Morlock

(2006a)

Task Force

Soil 6S; clay

loam

7.1

(H2O) 20°C / 45%

MWHC 333.2 230.1 1.00 SFO

Geometric mean - 180.2 169.4 - - aKinetic fitting for the study of Rhodes (1987) was performed by the UK RMS using the FOCUS DEGKIN

spreadsheet since this study was excluded by DuPont

To enable reviewers to confirm the acceptability of the kinetic fits, the graphical fits of the

Honville soil is shown below (see Figure B.8.4). As can be seen the SFO fit does not provide

an acceptable visual fit and therefore the applicant tested DFOP and HS fits (FOMC excluded

as DT90 not reached within the duration of the study). The HS fit was selected on basis of

lowest chi2 error percentage and best residual fit. The DT50 was taken from the slow phase

of the HS kinetic. Since metabolite IN-A4098 is a terminal metabolite, the use of this simple

work around to derive a pseudo SFO DT50 for this soil is acceptable. Overall the UK RMS

accepted the use of the geometric mean DT50 of 169.4 d for the purposes of the exposure

assessment.

As a result of the EFSA peer review the UK RMS was asked to update the dataset for the IN-

A4098 metabolite to take account of additional DT50 endpoints available in peer reviewed

RARs for other sulfonyl urea active substances for which IN-A4098 was a common

metabolite. This resulted in an additional 4 DT50 values being added to the dataset. In order

to address the requirement identified in Open Points 4.4 and 4.5 of the Evaluation Table, the


UK RMS has updated Table B.8.128 as Table B.8.128a below. The new data are included in

the final 4 rows of the following table.

Table B.8.128a: Summary of modelling degradation parameters for IN-A4098 (DuPont and

Task Force data plus data taken from other peer reviewed active substances)


Study

reference


MWHC DT50 (d)

DT50 (d)

20C

pF2/10kPa

chi2

Method of

calculation

Rhodes, 1987

(Dupont)

Keyport; silt

loam 4.3 25

oC / 70% FC 208 254 6.2 SFO

Möndel, 2001

(Dupont)

Honville,

loamy silt 6.7

(H2O)

20°C / 40%

MWHC

260.1 K1 = 0.01772

K2 = 0.00266

Tb = 25.9

201.6 3.0

HS (DT50

calculated

from slow

phase)

Jungmann,

Nicollier, 2006

(Dupont)

Gartenacker;

Loam, 6.9

(CaCl2) 20°C / pF2 102.2 102.2 3.5 SFO

Jungmann,

Nicollier, 2006

(Dupont)

18 Acres;

sandy clay

loam,

5.0

(CaCl2) 20°C / pF2 249.4 249.4 3.2 SFO

Jungmann,

Nicollier, 2006

(Dupont)

Krone; silt

loam, 4.9

(CaCl2) 20°C / pF2 190.8 190.8 3.7 SFO

Morlock

(2006a)

Task Force

Soil 2.2; loamy

sand 5.7

(H2O)

20°C / 45%

MWHC 67.3 67.3 5.68 SFO

Morlock

(2006a)

Task Force

Soil 3A; sandy

loam 7.3

(H2O)

20°C / 45%

MWHC 188.4 175.7 5.645 SFO

Morlock

(2006a)

Task Force

Soil 6S; clay

loam 7.1

(H2O)

20°C / 45%

MWHC 333.2 230.1 1.00 SFO

Scott

(2000)b

Arrow; sandy

loam 5.7

20°C / 50%

MWHC 44.7 22.5 14 HS

d

Wonders and

Melkebeke

(2002)c

Speyer 2.1;

sand 5.5 20°C / pF2 112.5 112.5 2.9 SFO

Wonders and

Melkebeke

(2002)c

Soil 115; clay

loam 8.6 20°C / pF2 175.2 175.2 3.1 SFO

Wonders and

Melkebeke

(2002)c

Soil 243;

sandy loam 5.6 20°C / pF2 96.4 96.4 6.2 SFO

Geometric mean - 146.1 132.4 - - bAccepted in the RARs for metsulfuron methyl, prosulfuron and triasulfuron

cAccepted in the RAR for metsulfuron methyl

dCalculated from slow phase rate constant (k1=0, fixed lag phase, k2 = 0.03082, tb = 22.25 d)

The revised dataset accounting for the additional 4 DT50 values is noted to result in a

geometric mean DT50 of 132.4 d (at 20°C and pF 2; n=12). Since this is lower than the value

used by the UK RMS in the groundwater exposure assessment in this RAR (i.e. 169.4 d based

on Table B.8.128 above; n = 8) the existing modelling for this terminal metabolite can be

considered conservative. As a result of the PRAPeR 126 meeting the experts considered it


appropriate to add 4 more DT50 values from the thifensulfuron methyl route of degradation

study (Simmonds, 2012a) in selecting a final modelling input parameter. These additional 4

DT50 values increased the geometric mean DT50 to 167.9 d, which is the endpoint that has

been used in updated FOCUSgw modelling for this metabolite.

Figure B.8.4 Graphical fit for IN-A4098 for the Honville soil (Möndel, 2001)

Based on the combined data sets from both Applicants, the UK RMS proposed the use of a

geometric mean DT50 of 169.4 days for the purposes of FOCUS modelling for metabolite

IN-A4098. Including information on this common metabolite from other RARs and the

parent dosed study (Simmonds, 2012a), the amended geometric mean DT50 for modelling

purposes is 167.9 132.4 d.


IN-A5546

One rate of degradation study performed with metabolite IN-A5546 was considered

acceptable in the DuPont submission and one rate of degradation study was considered

acceptable in the Task Force submission. In the original DAR the IN-A5546 metabolite

appeared to be considered a non-major transient metabolite due to its short half life. It was

not included in the original PECsoil exposure assessment or in the groundwater assessment.

The transient nature of this metabolite was supported by the new rate of degradation study

submitted by DuPont. In the study of DuPont, the IN-A5546 metabolite was not detectable at

the first sample point after day 0 (i.e. 3 d). Since the study clearly supported the original

conclusions of the DAR and the data was not sufficient to support any level of kinetic

analysis, the UK RMS has not reviewed the study in detail and kinetic analysis was not

performed (only a single data point, day 0, was available). For the purposes of modelling

DuPont proposed DT50 of 3 days (based on the first sampling point post day 0). In the Task

Force study, the degradation rate in all three soils was determined to be less than 7 hours.

Again this confirms the very transient nature of this metabolite and justified its exclusion

from a full consideration in the exposure assessments in groundwater and surface water due

to its rapid degradation. However for completeness the IN-A5546 metabolite has been

included in the soil, groundwater and surface water exposure assessments. For groundwater,

a limited set of modelling was conducted simulating the worst-case GAPs and based on a

conservative DT50 of 3 d (supported by the study from DuPont).

IN-L9223

One rate of degradation study performed with metabolite IN-L9223 was considered

acceptable in the DuPont submission. An additional rate of degradation study was performed

by the Task Force and was considered acceptable. In general the visual and statistical fits

using SFO kinetics were considered acceptable by the Applicants and agreed by the UK

RMS. The chi2 error values were low and the t-test on the rate constant confirmed they were

statistically different from zero. A summary of the DT50/90 values under study conditions

and normalised to reference conditions is provided in Table B.8.129 below.


Table B.8.129 Summary of modelling degradation parameters for IN-L9223 (DuPont and

Task Force data)

IN-L9223 Aerobic conditions

Study

reference


MWHC DT50 /DT90

(d)

DT50 (d)

20C

pF2/10kPa

chi2

Method of

calculation

Cleland,

2011

(DuPont)

Nambsheim,

sandy loam

7.4

(CaCl2) 20°C / 50%

MWHC 9.0 / 30 8.4 9 SFO

Cleland,

2011

(DuPont)

Lleida, clay

7.7

(CaCl2) 20°C / 50%

MWHC 7.1 / 23.7 6.2 8 SFO

Cleland,

2011

(DuPont)

Speyer 2.2,

loamy sand

5.6

(CaCl2) 20°C / 50%

MWHC 9.0 / 30.1 9.0 8 SFO

Cleland,

2011

(DuPont)

Tama, silty

clay loam

6.3

(CaCl2) 20°C / 50%

MWHC 6.0 / 19.9 5.8 8 SFO

Cleland,

2011

(DuPont)

Sassafras,

sandy loam

5.1

(CaCl2) 20°C / 50%

MWHC 16.9 / 56.1 16.9 7 SFO

Brice and

Gilbert,

2011a

(Task Force)

Longwoods;

sandy loam

7.9

(H2O) 20°C / pF 2

122.3 /

406.2 122.3 3.22 SFO

Brice and

Gilbert,

2011a

(Task Force)

Chelmorton;

clay loam

7.3

(H2O) 20°C / pF 2 39.3 / 130.7 39.3 5.82 SFO

Brice and

Gilbert,

2011a

(Task Force)

Lockington,

clay loam

6.5

(H2O) 20°C / pF 2 27.1 / 89.9 27.1 11.22 SFO

Geometric mean - 17.2

(DT50) 16.7 - -


Nambsheim soil are shown below (soil selected as the SFO fit had the highest chi2 error

percentage from the DuPont studies as an example). As can be seen the SFO fit provides an

acceptable visual fit and there was no improvement with the FOMC fit. The FOMC fit gave

identical DT50 and DT90 values and high confidence intervals were associated with the

alpha and beta values. Hence the SFO fit was considered acceptable (chi2 9% and rate

constant significant at P = 0.05).

Although the degradation rates from these studies were considered acceptable, degradation

rates were noted to be significantly shorter than were observed for this metabolite in the

parent dosed route of degradation study. The route of degradation study provided linked

formation fractions and degradation rates. In addition, in the opinion of the UK RMS, the

route study was likely to better mimic the actual formation of this metabolite in situ in soil.

For these reasons, the degradation rates from these separately dosed metabolite rate of

degradation study have not actually been used in the final environmental exposure

assessment. Degradation rates for IN-L9223 have been conservatively derived from the

kinetic analysis of the parent route of degradation study (see Ford, 2012 below).


Figure B.8.5 Graphical fit for the Nambsheim soil (Cleland, 2011)

IN-L9225

The original rate of degradation study performed with metabolite IN-L9225 in the 2000 DAR

was considered acceptable in the DuPont submission. The study was re-evaluated in line

with FOCUS kinetics. In general the visual and statistical fits using SFO kinetics were

considered acceptable by the Applicant and agreed by the UK RMS. The chi2 error values

were low and the t-test on the rate constant confirmed they were statistically different from

zero. A summary of the DT50/90 values under study conditions and normalised to reference

conditions is provided in Table B.8.130 below.


Table B.8.130: Summary of modelling degradation parameters for IN-L9225 (DuPont data)


Study

reference


MWHC DT50 /DT90

(d)

DT50 (d)

20C

pF2/10kPa

chi2

Method of

calculation

Manjanutha,

2000

Drummer, silty

clay loam

5.9 20°C / 40%

MWHC 42.5 / 141.2 34.9 11 SFO

Manjanutha,

2000

Glenville,

sandy loam

7.3 20°C / 40%

MWHC 20.6 / 68.5 17.2 9 SFO

Manjanutha,

2000

Gross-

Umstadt, silt

loam

7.5 20°C / 40%

MWHC 154.4 / 513 119.9 5 SFO

Geometric mean 51.3 41.6


Drummer soil are shown below (see Figure B.8.6). This soil was selected as the SFO fit had

the highest chi2 error percentage as a representative example. As can be seen the SFO fit

provides a reasonable visual fit and, importantly, there was no improvement with the FOMC

fit. The FOMC fit gave identical DT50 and DT90 values and high confidence intervals were

associated with the alpha and beta values. Hence the SFO fit was considered acceptable (chi2

11% and rate constant significant at P = 0.05).

The DT50 data from this study was combined with additional data from four further soils

from the parent route of degradation study (see evaluation of kinetics report of Ford, 2012

below). These two data sets were combined to derive an overall geometric mean DT50 for

the purposes of the exposure assessment.


Figure B.8.6 Graphical fit for the Drummer soil (Manjanutha, 2000)

IN-L9226

The original rate of degradation study performed with metabolite IN-L9226 in the 2000 DAR

was considered acceptable in the DuPont submission. The study was re-evaluated in line

with FOCUS kinetics. In addition a new rate of degradation study with this metabolite was

provided in the Task Force submission. In general the visual and statistical fits using SFO

kinetics were considered acceptable by the Applicants and agreed by the UK RMS. The chi2

error values were low for the DuPont study and higher for the Task Force study, and the t-test

on the rate constant confirmed they were statistically different from zero. Visually all fits

were accepted. A summary of the DT50/90 values under study conditions and normalised to

reference conditions is provided in Table B.8.131 below. Overall these data confirm the very

transient nature of this metabolite and justified its exclusion from detailed consideration in


the exposure assessments in groundwater due to its rapid degradation. However the leaching

risk of IN-L9226 has been effectively addressed in the groundwater section based on the

assessment of IN-A5546 (see Section B.8.6 for further details).

Table B.8.131 Summary of modelling degradation parameters for IN-L9226 (DuPont and

Task Force data)


Study

reference


MWHC DT50 /DT90

(d)

DT50 (d)

20C

pF2/10kPa

chi2

Method of

calculation

Manjanutha,

2000

(DuPont)

Drummer, silty

clay loam

5.9 20°C / 40%

MWHC 2.0 1.6 5 SFO

Manjanutha,

2000

(DuPont)

Glenville,

sandy loam

7.3 20°C / 40%

MWHC 2.9 2.4 13 SFO

Manjanutha,

2000

(DuPont)

Gross-

Umstadt, silt

loam

7.5 20°C / 40%

MWHC 0.9 0.7 3 SFO

Knoch,

2012c

(Task Force)

LUFA 2.2;

loamy sand

5.5

(CaCl2) 20°C / 45%

MWHC 0.6 0.6 18.5 SFO

Knoch,

2012c

(Task Force)

LUFA 2.3;

sandy loam

6.8

(CaCl2) 20°C / 45%

MWHC 0.3 0.27 7.6 SFO

Knoch,

2012c

(Task Force)

LUFA 6S; clay

7.1

(CaCl2) 20°C / 45%

MWHC 3.3 1.63 12.5 SFO

Geometric mean 1.2 0.95 - -

IN-V7160

The IN-V7160 metabolite was not considered in the original DAR. A new rate of

degradation study with this metabolite was provided in the DuPont submission. The visual

and statistical fits using SFO kinetics were considered acceptable by the Applicant in all 5

soils tested. The UK RMS agreed with the selection of the SFO kinetic in 3 of the 5 soils. In

these soils the chi2 error values were low, the t-test on the rate constant confirmed they were

statistically different from zero and visually the fits were considered acceptable. However in

the other 2 soils (Goch and Suchozebry) the UK RMS rejected the selection of SFO kinetics

based on poor visual fit. In these soils, the DFOP kinetic was selected for the purposes of

deriving a modelling input parameter, based on the slow phase rate constant. The DFOP


kinetic was considered appropriate by the UK RMS for the purposes of a conservative first

tier exposure assessment. In these two soils, the IN-V7160 metabolite represented >10%

initial at the end of the study, hence the FOMC kinetic was not considered the most

appropriate choice. The use of the conservative endpoint from the DFOP slow phase was

acceptable in this case as the IN-V7160 metabolite was modelled as a terminal metabolite. A

summary of the DT50/90 values under study conditions and normalised to reference

conditions is provided in Table B.8.132 below. Note that in the Applicants (DuPont)

exposure assessment, a geometric mean DT50 from the SFO fits only was selected, and was

calculated to be 12.6 d. Therefore the rejection of the SFO fits in the Goch and Suchozebry

soils lead to a more conservative geomean DT50 of 19.4 d.

Table B.8.132: Summary of modelling degradation parameters for IN-V7160 (DuPont data)

IN-V7160 Aerobic conditions

Study

reference

Soil type pH

(CaCl2)

t. oC / %

MWHC DT50 /DT90

(d)

DT50 (d)

20C

pF2/10kPaa

chi2

Method of

calculation

Tunink,

2009

(DuPont)

Mattapex,

sandy loam

4.35 20°C / 40 of 0

Bar 9.8 9.0 11 SFO

Tunink,

2009

(DuPont)

Lleida, silty

clay

7.50 20°C / 40 of 0

Bar 6.6 5.6 5 SFO

Tunink,

2009

(DuPont)

Nambsheim,

sandy loam

7.01 20°C / 40 of 0

Bar 3.3 3.3 2 SFO

Tunink,

2009

(DuPont) Goch, silt loam

5.13

20°C / 40 of 0

Bar

16.1/204.1

M0 = 95.3

K1 = 0.008

K2 = 0.175

g = 0.5

71.6

(based on

slow phase

rate constant)

3 DFOP

Tunink,

2009

(DuPont) Suchozebry,

sandy loam

5.04

20°C / 40 of 0

Bar

24.8/542.8

M0 = 94.2

K1 = 0.003

K2 = 0.097

g = 0.5

231

(based on

slow phase

rate constant)

2 DFOP

Geometric mean - - 19.4 - - amoisture correction was performed based on measured data for both study and reference conditions


Goch and Suchozebry soils are shown below in Figure B.8.7 and 8.8 (soils where Applicant

accepted SFO and UK RMS selected DFOP as appropriate for modelling). As can be seen in

both soils, although the SFO fit gave χ2 values less than 15%, SFO provided a relatively poor

visual fit, with a systematic deviation in the pattern of residuals. The DFOP gave a very good

visual fit, much improved chi2 values and small and random scatter of residuals. In addition

all DFOP rate constant were significant at P = 0.05. As a terminal metabolite the use of the

conservative slow phase rate constant as a pseudo-SFO DT50 in these soils was selected by

the UK RMS. This lead to an overall geometric mean DT50 of 19.4 days that was selected as

the appropriate input parameter for the exposure assessment.


Applicants kinetic fitting for metabolite IN-V7160 in the Mattapex soil using both SFO and

FOMC kinetics. In the original evaluation the Applicant and UK RMS accepted SFO fitting

for this soil. However Open Point 4.6 requested further consideration of the FOMC kinetic


fit, as this specific fit had been previously accepted for this soil during the EU evaluation of

the active substance metsulfuron methyl. The graphical fitting is provided in Figure B.8.8a

below. In this case the UK RMS still considers the SFO fit to be acceptable for modelling

purposes. The chi2 value is less than 15% and the rate constant is statistically significant.

The fit to time zero residues is good and the description of the residue decline up to the DT90

period (i.e. describing the decline of 90% of applied material) is also visually acceptable. A

marginal improvement of the fit for the residues after the DT90 point (i.e. the final 10% of

applied material) is achieved with the FOMC kinetic. However given the acceptability of the

other statistical and visual criteria based on SFO kinetics, the UK RMS accepted the SFO

kinetic fit. In contrast, the UK RMS rejected the SFO fits for the Goch and Suchozebry soils

because even though chi2 values were less than 15%, the fit to initial residues was poor and

the visual fit up to the DT90 time point was also visually unacceptable in the opinion of the

UK RMS. Overall we consider that a clear and consistent approach to accepting and

rejecting SFO fits has been made for this study and that the choice of endpoints is consistent

with the FOCUS kinetics guidance. The geometric mean DT50 of 19.4 d is likely to be

conservative because of the inclusion of the two values derived from the slow phase rate

constants for the DFOP fits for the Goch and Suchozebry soils. No change to the endpoints is

therefore proposed.

Based on the proposed modelling values listed in Table B.8.132 above, it can be seen that

there is a large spread of values (from 3.3 d in the Nambsheim soil up to a 231 d in the

Suchozebry soil). Considering the soils tested (see Table B.8.132), there is no obvious

correlation between degradation and soil properties such as pH. However it is noted that

microbial biomass in the Goch and Suchozebry soils were relatively low, and actually below

the 1% of total organic carbon recommended on OECD 307. Mineralisation in the form of

evolved 14

CO2 was also noted to be lowest in these two soils, which may also be indicative of

low microbial activity/viability. Although the higher persistence in these soils might have

been an artefact of low microbial viability, for the purposes of a conservative assessment, all

soils have been retained in the calculation of the geometric mean.


Figure B.8.7 Graphical fit for the Goch soil (Tunink, 2009; kinetic fitting reported in

Jagtap, 2011)


Figure B.8.8 Graphical fit for the Suchozebry soil (Tunink, 2009; kinetic fitting reported in

Jagtap, 2011)


Figure B.8.8a Graphical fit for the Mattapex soil (Tunink, 2009; kinetic fitting reported in

Jagtap, 2011)


IN-W8268

The original rate of degradation study performed with metabolite IN-W8268 in the 2000

DAR was considered acceptable in the DuPont submission. The study was re-evaluated in

line with FOCUS kinetics. In addition a new rate of degradation study with this metabolite

was provided in the Task Force submission. In general the visual and statistical fits using

SFO kinetics were considered acceptable by the Applicants and agreed by the UK RMS. The

chi2 error values were low and the t-test on the rate constant confirmed they were statistically

different from zero. A summary of the DT50/90 values under study conditions and

normalised to reference conditions is provided in Table B.8.133 below. Comparing the

results from the two studies, there appears to be some relatively large differences in the DT50

values (e.g. normalised values of 43.5 to 61.1 d in the DuPont study of Fang, 2000 and only

2.6 to 12.1 d in the Task Force study of Knoch, 2012d). The UK RMS therefore re-examined

the original study reports to determine whether there were likely to be any systematic reason

for these differences. Fang (2000) used radiolabelled material and was thus able to determine

a mass balance at each sampling point. Knoch (2012d) used cold material, but the method

and extraction was acceptably validated within the study. The application rate to test soils in

Fang (2000) were higher (1mg/kg compared to 0.1mg/kg in Knock, 2012d). Extraction was

via acetonitrile/ammonium carbonate in Fang (2000) and by methanol/ammonium carbonate

in Knoch (2012d). Initial microbial biomass in each study was broadly comparable. Overall

no obvious reason for the differences were observed and both sets of values were retained for

the purposes of selecting an overall mean value. This leads to an overall geometric mean

DT50 of 18.7 days that was selected as the appropriate input parameter for the exposure

assessment.

Table B.8.133 Summary of modelling degradation parameters for IN-W8268 (DuPont and

Task Force data)

IN-W8268 Aerobic conditions

Study

reference


MWHC DT50 /DT90

(d)

DT50 (d)

20C

pF2/10kPa

chi2

Method of

calculation

Fang, 2000

(DuPont)

Drummer, silty

clay loam

7.7 20°C / 40-50%

MWHC 59.0 59.0 2 SFO

Fang, 2000

(DuPont)

Glenville,

sandy loam

5.7 20°C / 40-50%

MWHC 64.2 61.1 4 SFO

Fang, 2000

(DuPont)

Gross-

Umstadt, silt

loam

7.8 20°C / 40-50%

MWHC 48.1 43.5 4 SFO

Knoch,

2012d

(Task Force)

LUFA 2.2;

loamy sand

5.5

(CaCl2) 20°C / 45%

MWHC 2.6 2.6 14 SFO

Knoch,

2012d

(Task Force)

LUFA 2.3;

sandy loam

6.8

(CaCl2) 20°C / 45%

MWHC 9.7 8.6 7.8 SFO



Study

reference


MWHC DT50 /DT90

(d)

DT50 (d)

20C

pF2/10kPa

chi2

Method of

calculation

Knoch,

2012d

(Task Force)

LUFA 6S; clay

7.1

(CaCl2) 20°C / 45%

MWHC 24.5 12.1 8.9 SFO

Geometric mean - 22.0 18.7 - -

IN-JZ789

One rate of degradation study performed with metabolite IN-JZ789 was considered

acceptable in the Task Force submission. In general the visual and statistical fits using SFO

kinetics were considered acceptable by the Applicant and agreed by the UK RMS. The chi2

error values were low and the t-test on the rate constant confirmed they were statistically

different from zero. A summary of the DT50/90 values under study conditions and

normalised to reference conditions is provided in Table B.8.134 below.

Table B.8.134: Summary of modelling degradation parameters for IN-JZ789 (Task Force

data)

IN-JZ789 Aerobic conditions

Study

reference


MWHC DT50 (d)

DT50 (d)

20C

pF2/10kPa

chi2

Method of

calculation

Knoch,

2012a

(Task Force)

LUFA 2.2;

loamy sand

5.5

(CaCl2) 20°C / 45%

MWHC 2.1 2.1 5.6 SFO

Knoch,

2012a

(Task Force)

LUFA 2.3:

sandy loam

6.8

(CaCl2) 20°C / 45%

MWHC 4.2 3.7 1.8 SFO

Knoch,

2012a

(Task Force)

LUFA 6S; clay

7.1

(CaCl2) 20°C / 45%

MWHC 56.7 28.0 3.8 SFO

Geometric mean 7.9 6.0

Although the degradation rates from this study were considered acceptable, degradation rates

were noted to be significantly shorter than were observed for this metabolite in the parent

dosed route of degradation study provided by the Task Force. The route of degradation study

provided linked formation fractions and degradation rates. In addition, in the opinion of the

UK RMS, the route study was likely to better mimic the actual formation of this metabolite in

situ in soil. For these reasons, the degradation rates from these separately dosed metabolite

rate of degradation study have not actually been used in the final environmental exposure


assessment. Degradation rates for IN-JZ789 have been conservatively derived from the

kientic analysis of the parent route of degradation study (see Ford, 2012 below).

Task Force studies

Previous

evaluation: None: Submitted by Task Force for the purpose of renewal under


The Task Force summarised their kinetic assessment of the new route of

degradation in aerobic soil study for parent Thifensulfuron-methyl and

major metabolites in a separate stand alone report (Ford, 2012). This

kinetic report has been independently validated by the UK RMS. In

general the report was considered acceptable and all deviations are fully

described in the relevant sections below. For simplicity and to aid

combining the Task Force data with that derived from the DuPont study,

this report will first summaise the results for parent Thifensulfuron-

methyl below. Separate sections will deal with the derivation of kinetic

input parameters for the combined metabolites. In order to derive

combined modelling input parameters, additional tables combining the

acceptable data already summarised above from DuPont and the Task

Force are provided for each substance.

In general the Applicants kinetics reports were clearly reported and

conducted in accordance with FOCUS kinetics guidance. The kinetic

fits have been independently verified by the UK RMS. In some cases, to

verify the goodness of fit, the UK RMS has supplemented the

Applicants original study summary with additional details and graphical

plots from the original study report. Although the Applicants study

report was acceptably conducted and reported, the UK RMS disagreed

with the final approach taken to selecting input parameters for most of

the major metabolites. The Applicant proposed combining the

formation fractions from the route study with degradation rates from

stand alone metabolite dosed studies (previously reported above). The

Applicant rejected the DT50 values derived for IN-L9223, IN-JZ789,

IN-A4098 and 2-acid-3-triuret from the route of degradation study. The

UK RMS had a number of reservations about this approach. The

principal reservation was that this approach when used in exposure

modelling could significantly underestimate the pattern of formation of

the major metabolites observed in the parent route of degradation study.

This was because degradation rates in the metabolite dosed studies were

often significantly shorter than observed in the route of degradation

study. Since the route of degradation study should, in theory, more

closely reflect the actual formation of the metabolites in situ in soil, the

UK RMS preferred to use data from this study wherever possible.

Overall, the UK RMS proposed retaining the more conservative DT50

values from the route of degradation study, even though these were often

associated with high levels of uncertainty that would not normally be

considered acceptable according to the FOCUS kinetics criteria. This


was considered the most appropriate approach in this case, to ensure a

conservative first tier exposure assessment could be conducted. This is

more fully explored in the detailed assessment provided below.

An open point was identified at PRAPeR meeting 126 for the UK RMS

to add a concise summary at the start of the kinetic assessment to better

describe the rationale behind the approach taken to selecting modelling

endpoints. This was considered useful due to the relatively large

number of MS comments received on the non-standard kinetic

assessment. This was also considered useful to indicate the aspects of

the original assessment that were accepted by the meeting of experts and

which aspects were rejected in favour of alternative approaches.

Firstly it should be noted that the existing route of degradation

information in the original DAR could not be used to derive modelling

endpoints in accordance with current guidance. The original study

(Rapisarda, 1984) did not investigate the route of thifensulfuron methyl

labelled in the triazine ring and the analytical method was unable to

separate the primary metabolites. Hence the data was not suitable for

robust kinetic analysis following FOCUS guidelines. The new route of

degradation study submitted by DuPont (Cleland, 2011) was rejected

due to major analytical issues and was therefore also unsuitable for

further kinetic analysis. The only reliable study from which key

endpoints such as metabolite formation fractions could be derived was

the new study from the Task Force (Simmonds, 2012a). This study was

subject to detailed kinetic analysis in the report of Ford (2012) below.

Even in the study of Simmonds (2012a) there were issues associated

with the reliability of the degradation rates for the major metabolites

(IN-JZ789, 2-acid-3-triuret, IN-L9223 and IN-A4098). The kinetic fits

for these metabolites were associated with high χ2 error percentages and

the confidence in the parameter estimates for the degradation rate

parameters assessed by t-test were poor. Much of the uncertainty

associated with these metabolite endpoints was due to the data not

necessarily well describing the pattern of formation, peak and in

particular the decline phase for these secondary and tertiary metabolites.

However since this study represented the only data from which

formation fractions (and associated DT50 values) could be derived, the

UK RMS chose a non-standard approach to selecting and justifying the

choice of modelling endpoints. The approach is best illustrated in

Figures such as B.8.22 (for IN-JZ789), B.8.25 (for 2-acid-3-triuret) and

B.8.27 (for IN-L9223). Essentially the approach was based on plotting

different combinations of DT50 and formation fractions against the entire

combined dataset from all soils from the study of Simmonds (2012a)

and selecting the combination that resulted in a conservative description

of the metabolite residue pattern. Due to the uncertainties in the data,

formation fractions were conservatively selected based on the upper 95th

percentile confidence limits of the Applicant fitting to ensure the residue

pattern was conservatively described by the selected parameter

combinations. In some cases this resulted in the UK RMS rejecting the

additional (shorter) DT50 values that were available from separate


metabolite dosed studies, because combining these data with endpoints

from the study of Simmonds led to an apparent underestimation of the

metabolite profile. This approach is acknowledged by the UK RMS to

be non-standard and not explicitly included in the FOCUS degradation

kinetics guidance. However the UK RMS considered that this approach

was at least in the spirit of section B.8.4.2.1 of the kinetics guidance

which recommends the use of ‘alternative but conservative estimates

…to better describe the observed patterns’. This approach was

considered by the UK RMS to be the best way to treat the existing data.

It was regarded as being preferable to either rejecting the study

completely (leading to a major data gap), or simply accepting the

endpoints from the standard fitting procedure where these were

associated with high levels of uncertainty. This approach is more fully

outlined in the detailed study summary below.

The outcome of the PRAPeR Meeting 126 was to accept the

conservative UK RMS approach for endpoint selection for metabolites

IN-JZ789, 2-acid-3-triuret and IN-L9223. However for IN-A4098 the

meeting considered that a more standard approach to accepting

endpoints from the kinetic fitting would be suitable. The meeting

considered that for this metabolite, although endpoints were uncertain,

the quality of the visual fits would allow the standard endpoints to be

selected for modelling purposes. After the Expert meeting the UK

RMS therefore updated the approach taken to selecting endpoints for IN-

A4098. Changes to the kinetic assessment and the new endpoints for

IN-A4098 are highlighted in green in the following section. The

groundwater assessment for IN-A4098 has also been updated.

Report: S. Ford (2012) Thifensulfuron-methyl: Calculation of Kinetic Endpoints

for Modelling Purposes from a Study on Four Laboratory Soils. JSC

International Limited [Cheminova A/S], Unpublished report No.:

RCH/02/02/KIN1

Guidelines: Guidance document on estimating persistence and degradation kinetics

from environmental fate studies on pesticides in EU registration. Report

of the Workgroup on degradation kinetics in FOCUS, EC Document

Reference SANCO/10058/2005, rev. 2, June 2006 and 2011

GLP: Not applicable

Executive Summary:

The degradation behaviour of Thifensulfuron-methyl and the rates of formation and

degradation of the soil metabolites IN-L9225, IN-JZ789, 2-Acid-3-triuret, IN-L9223 and

IN-A4098 have been studied in four soils under laboratory conditions by Simmonds (2012a).

This route of degradation study submitted by the Task Force was considered acceptable by

the UK RMS.


This report described the calculation of modelling endpoints to allow the appropriate choice

of half-lives (DT50) for Thifensulfuron-methyl and its primary soil metabolite IN-L9225 and

formation fractions for the soil metabolites IN-L9225, IN-JZ789, 2-Acid-3-triuret, IN-L9223

and IN-A4098 for the purposes of calculating predicted environmental concentrations

(PECs). Note that on the basis of the Applicants kinetic assessment, they considerd that it

was only possible to derive estimates of the formation fractions of metabolites IN-JZ789, 2-

Acid-3-triuret, IN-L9223 and IN-A4098 and no reliable DT50 values could be obtained in the

opinion of the Applicant. The acceptability of this approach has been considered in detail by

the UK RMS. However in general the UK RMS notes that since DT50 and formation

fraction are highly correlated, and both values are needed to accurately describe the pattern of

formation and decline of a metabolite, selecting one value and rejecting the other may not be

appropriate.

Kinetic modelling input data were generated according to the data handling recommendations

made in the FOCUS guidance for degradation kinetics (FOCUS, 2006, 2011) and kinetic

models were fitted using KinGUI v1.1 (2006) by the Applicant following the flowcharts for

deriving modelling endpoints presented in the FOCUS (2006, 2011) guidance on kinetic

analysis.

In the first instance, the data were directly fitted, un-weighted, with the complete data set and

unconstrained initial concentration (M0). The acceptability of kinetic fits was judged both

visually and according to the χ2 error% and the t-test functions as recommended by FOCUS

Kinetics (2006, 2011).

The fits of the models to the thifensulfuron-methyl and IN-L9225 data assuming SFO

kinetics were good visually and statistically and the UK RMS was able to accept the

Applicant derived DT50 and formation fractions for the parent to IN-L9225 pathway. The

UK RMS confirmed the acceptability of the fits using repeat simulations with KINGUI v.II

and ModelMaker v4.0. The degradation rates for parent and IN-L9225 metabolite from this

study have been combined with acceptable data from other studies (where soils were dosed

with either Thifensulfuron-methyl or IN-L9225 as parent material) in order to determine

overall average input parameters for the purposes of exposure modelling.

The Applicant considered that the fits of the SFO models to the other metabolites were

acceptable visually. However the Applicant noted that the χ2 error percentages of the fits

were high and the confidence in the parameter estimates for the degradation rate parameters

assessed by t-test were poor. Therefore, the Applicant proposed that no further half-lives

suitable for use in modelling could be derived from this study. Much of the magnitude of the

χ2 error percentages and the lack of parameter confidence for some of the secondary

metabolite fits could be accounted for by data scatter and apparent lag in the formation of the

secondary metabolites. The overall fit of the models to the formation and decline of all the

metabolites was good in the opinion of the Applicant and the analysis demonstrated that the

estimated formation fractions were statistically different from 1.0 (95% upper confidence

limits < 1.0); therefore, the use of worst-case formation fractions (i.e. formation fractions of

1.0) in modelling would result in a severe overestimation of the metabolite residues in soil.

Considering the visual quality of the fits to the overall formation and decline and the high

levels of confidence in the parameter estimates for the primary metabolite, IN-L9225, the

formation fractions calculated for the other metabolites could be used as realistic inputs in the

opinion of the Applicant. Degradation rates for these other metabolites were proposed by the

Applicant to be derived from the separate metabolite dosed rate of degradation studies

summarised earlier in this section.


The UK RMS replication of the model workflows in KinGUI v.II and ModelMaker V4.0

identified several issues with the Applicant modelling. The Applicant used KinGUI v1.1 in

their kinetic assessment. Although the repeat kinetic assessments performed by the UK RMS

resulted in the same basic parameter estimates (e.g. for DT50 and formation fraction

combinations), it was noted that in the KinGUI v.II outputs, the formation fractions for the

flows A1 to A2 and A1 to B1 were the reverse of those formation fractions for the same

flows in the Applicants modelling using v1.1 of KinGUI. The UK RMS repeated the

simulations in ModelMaker and confirmed that there appears to be a systematic error in

version 1.1 of KinGUI, with formation fraction for these two flows incorrectly reported in the

results summary files. A simple graphical illustration of this error can be seen with the

Applicants fits for the Farditch soil (see Figures B.8.14 and B.8.15 for the thiophene and

triazine labels respectively). For example, for the thiophene label the Applicant reported

formation fractions for IN-JZ789 (O-desmethyl thifensulfuron acid) of 0.22 and for IN-L9223

(2-acid-3-sulfonamide) of 0.09. The UK RMS obtained the same numerical values but for

the opposite flows (i.e. 0.09 for IN-JZ789 and 0.22 for IN-L9223). In Figure B.8.14 it can be

clearly seen that the Applicant model gave peak predicted residues of close to 14% for IN-

L9223 and 6% for IN-JZ789. The peak residue of IN-L9223 of 14% could not have been

achieved with a formation fraction of only 0.09 (since peak residues must never exceed

formation fraction in this type of model). This error introduced into the Applicants kinetic

assessment has been corrected by the UK RMS in the relevant summary tables below.

A further issue with the Applicant kinetic assessment was that in the opinion of the UK RMS,

based on the visual assessment for some soil and metabolite combinations, the Applicant

approach may have not adequately described the peak formation of metabolites. There is also

uncertainty in the approach of deriving formation fractions from soils where the DT50 was

determined to be unreliable. In determining the most appropriate approach to take, the UK

RMS has referred to Section 8.4.2.1 of FOCUS kinetics which provides the following

guidance:-


In most cases a clear decline phase could not always be reliably determined for the secondary

metabolites. Therefore the derivation of conservative estimates of DT50 from the decline

phase as recommended by FOCUS could not be calculated. The absence of clear decline

phases in most cases would also partially explain the high confidence intervals and failure of

the t-test for parameter significance. In addition, the use of conservative DT50 values such as

1000 d for intermediate metabolites such as IN-JZ789 would not have been appropriate since

this may have led to an underestimation of the formation of the subsequent metabolite (i.e. 2-

acid-3-triuret) in the groundwater modelling simulations. In addition, the use of conservative

default DT50 values was not supported by data on the rate of degradation of these

metabolites from the separate metabolite dosed studies. Since the Applicant derived

formation fractions clearly differed from 1.0 (95% upper confidence limits were less than

1.0) in most cases, the use of a conservative formation fraction of 1 as recommended by

FOCUS may also be inappropriate (i.e. the kinetic modelling did demonstrate that formation

fractions were statistically less than 1). The UK RMS therefore considered that the approach

suggested in the final paragraph from FOCUS kinetics above may be the most appropriate

option i.e. where there would be “a clear overestimation of observed metabolite residues

using default assumptions of formation fraction of 1 and DT50 of 1000 d, alternative but

conservative estimates should be allowed to better describe the observed patterns”. In order

to ensure the reasonable worst-case nature of the selected estimates, the UK RMS explored

the use of the 95% upper confidence limits for the formation fractions, in combination with

DT50 values derived from either this study or from the separate metabolite dosed studies.

The UK RMS considered this to be in line with the FOCUS recommendation to use

‘alternative but conservative estimates’ to ‘better describe the observed patterns’. The UK

RMS therefore repeated the kinetic fitting, fixing the parameters to those proposed by the


Applicant, except that the formation fractions for the secondary metabolites were set to the

upper 95% confidence limits that were read directly from the Applicants KinGUI output.

The derivation of the upper 95% confidence intervals is further explained in Figure B.8.21a.

The error in the KinGUI v.1.1 outputs where the formation fractions for A1 to A2 and A1 to

B1 were transposed was corrected in the UK RMS fitting. A visual assessment of the fits was

then performed to confirm the appropriateness of this approach, and in selecting whether

DT50 values should be derived from the metabolite dosed studies or selected from the values

derived for the metabolites from the Thifensulfuron-methyl route of degradation study.

Whilst the approach used by the UK RMS is recognised as being conservative, in this case it

was considered to be the most appropriate and robust method to derive conservative first tier

input parameters in the absence of reliable combinations of DT50 and formation fraction that

fully met the FOCUS kinetics guidance criteria. Full graphical outputs from the UK RMS

kinetic assessment have been provided below in order that the acceptability of this approach

can be confirmed visually at least. In order to present the data in the most useful and clear

format, the UK RMS has combined the data from all 4 soils and radiolabels into single

graphical outputs for parent and each metabolite. These were compared with the different

combinations of formation fraction and modelling DT50 before selecting the most

appropriate combination. These graphical outputs do not represent the results of typical

optimised kinetic fitting in accordance with FOCUS guidance. However in the opinion of the

UK RMS they do provide a clear visual illustration of how well the RMS proposed endpoints

describe the whole data sets. When compared with the alternative combinations that would be

chosen based on the Applicant approach, the UK RMS considers that the graphical outputs

clearly support the values chosen.

A further issue with the Applicant approach is related to the correlation between DT50 and

formation fraction. As an example, in the Longwood soil the rate constants for IN-JZ789,

IN-L9223, 2-acid-3-triuret amd IN-A4098 all failed the t-test for significance to varying

degrees. In the cases of IN-L9223 (thiophene label) and IN-A4098 (triazine label) the DT50

optimised to >1000 d. Due to the correlation between degradation rate and formation

fraction, where the kinetic model optimised the rate constant to a very low value (i.e. a long

DT50) the corresponding formation fraction may have been reduced to compensate during

the optimisation steps. This would not normally be a problem where both DT50 and

formation fraction are retained for the purposes of selecting modelling input parameters.

However in this case the DT50 values are excluded in the Applicant approach due to their

uncertainty. This may lead to the selection of lower formation fractions by the Applicant

which may underestimate metabolite formation when the degradation rate in exposure

modelling is set to a faster value derived from metabolite dosed studies. The approach to

utilising the upper 95% confidence limits of the formation fractions in combination with

DT50 values from this study is considered by the UK RMS to add an appropriate level of

conservatism to the input parameter selection in this case. This approach was accepted by

PRAPeR Meeting 126 for IN-JZ789, IN-L9223 and 2-acid-3-triuret. However the meeting

considered that the standard kinetic endpoints for IN-A4098 should be accepted. To resolve

the issue over the >1000 d DT50 value for IN-A4098 in the Longwood soil (where formation

fraction may optimise to an artificially low value), the meeting requested that the UK RMS

repeat the kinetic fitting for this metabolite in this soil with a fixed DT50 of 1000 d to derive a

new formation fraction. This open point has been completed and further details are provided

in the relevant sections below.

A final issue with the Applicant approach is that they effectively disregard the DT50 values

derived from this study in favour of values derived from separate metabolite dosed studies.


In principle the UK RMS considers that mixing formation fractions from parent dosed studies

with degradation rates from metabolite dosed studies can be an acceptable approach in certain

circumstances. However the UK RMS also considers it important to consider whether the

degradation rates from the metabolite dosed studies are broadly representative of the

behaviour seen in the parent dosed studies (where metabolites are formed in situ). In this

case, for metabolites IN-JZ789, 2-acid-3-triuret and IN-L9223 there appeared to be very large

differences between the Applicant derived DT50 values from the Thifensulfuron-methyl

route study and from the separate metabolite dosed studies. For example for the 2-acid-3-

triuret metabolite the geometric mean DT50 derived in the study of Ford, 2012 (i.e. from the

parent applied study of Simmonds, 2012a) was 73 d compared to <0.1 days from the separate

metabolite dosed study of Knoch (2012). The summary results in Table B.8.147 are presented

to allow the two sets of values to be compared. As stated above, the UK RMS considered

that the simplest way to determine the appropriateness of different DT50 and formation

fraction combinations was to check the visual fit of the proposed modelling input parameters

against the combined soil residue data from the Thifensulfuron-methyl route of degradation

study. These figures are presented in Figures B.8. 20 to B.8.30 and discussed further below.

A detailed consideration of the input parameters proposed by the Applicant and the

alternative values proposed by the UK RMS is included in the tables below. Representative

graphical outputs from the Applicant fitting and the UK RMS approach are also provided in

Figures B.8.12 to B.8.19 (Applicant) and B.8.20 to B.8.30 (UK RMS).

The final schemes fitted in KinGUI for each label are shown in Figures B.8.9 and B.8.10.

The proposed degradation scheme from the route and rate of degradation study in soil has

been shown previously in Figure B.8.2. It was not possible to fit all the pathways in the

proposed degradation scheme due to the limitations of the kinetic modelling software.

However the pathways available in KinGUI were compatable with FOCUS PELMO (and

FOCUS PEARL). The proposed pathway was refined through the fitting procedure to

remove minor pathways that would allow it to be modelled in KinGUI and to provide a

conservative set of input parameters for the purposes of the groundwater exposure

assessment.


Figure B.8.9 Modelled kinetic pathway for the thiophene label

Figure B.8.10 Modelled kinetic pathway for the triazine label

The data from the thiophene and triazine labelled samples were treated separately in the

kinetic analysis. This enabled the sequential metabolite fitting to be performed, where the

IN-L9223 and IN-A4098 metabolites were only seen in samples treated with one of the two

Parent : Thifensulfuron-methyl

A1 : IN-L9225

A2: IN-JZ789

B1: IN-L9223

B2: 2-Acid-3-triuret

Parent : Thifensulfuron-methyl

A1 : IN-L9225

A2: IN-JZ789

B1: IN-A4098

B2: 2-Acid-3-triuret


radio labelled positions. Technically it would have been possible to combine the different

radiolabels to perform a single kinetic fit for the parent and common metabolites. However

the UK RMS considered this would have further complicated the kinetic assessment, with

separate DT50s for parent from the combined fitting of common metabolites and separate

fittings to accomdate the label specific metabolites. In general the parent DT50’s were short,

and the impact of handling the data separately is likely to be minimal in the opinion of the

UK RMS. Therefore the UK RMS accepted the approach used by the Applicant. Individual

soil geometric mean DT50’s were calculated prior to deriving an overall geometric mean.

This was considered necessary to avoid introducing a bias to soils tested with both

radiolabels, because for Thifensulfuron-methyl, the results from the Task Force study of

Simmonds (2012a) was combined with an earlier study from DuPont (Allen, 1987).

Results:

The route of degradation study by Simmonds (2012a) was conducted at a temperature of

20°C and at a soil moisture content between pF2 and pF2.5. However the exact moisture

content of each soil relative to field capacity was not reported. Therefore half-lives

calculated were not normalised for use in the regulatory models. This approach was

considered the most appropriate and conservative method in this case. The modelling half

lives derived for Thifensulfuron-methyl from this study are summarised in Table B.8.135.

These results represent the final fits following the sequential kinetic fitting of parent and

metabolites for each separate radiolabel position.

Table B.8.135 Thifensulfuron-methyl modelling endpoints

Soil Label

SFO DT50 (days)

Chi2

t-test

Thifensulfuron-

methyl

Longwoods

Thiophene 0.83 3.74 k < 0.05

Triazine 1.19 3.11 k < 0.05

Soil geomean 0.99 - -

Farditch

Thiophene 0.71 3.58 k < 0.05

Triazine 1.78 6.78 k < 0.05


Lockington

Thiophene 0.97 9.61 k < 0.05

Triazine 1.55 10.0 k < 0.05


Kenslow

Thiophene 0.59 5.66 k < 0.05

Triazine 1.23 1.22 k < 0.05


Visually and statistically the UK RMS was able to confirm the acceptability of the SFO

kinetic fits for parent thifensulfuron. To illustrate the acceptability of the kinetic fits here, the

UK RMS has reproduced the kinetic fit from the Lockington, triazine soil in Figure B.8.11

below. This soil and label position was selected as it represented the soil with the highest


chi2 error percentage. Similar visual fits were observed in all other soil/label combinations

and to simplify the presentation of the kinetic fitting graphical representations of the fits in

other soils have been omitted here. However all graphical outputs from the Applicant kinetic

fitting have been reproduced in Figures B.8.12 to B.8.19 at the end of this section for

completeness.

Figure B.8.11: Graphical plots of the SFO fit for the Lockington soil, triazine label (SFO

DT50 = 1.55 d, chi2 = 10.0%)

Combining the data above on 4 soils with the acceptable data from the DuPont submission

(single study of Allen, 1987 on two further soils) resulted in a geometric mean SFO DT50 of

1.39 days (Allen, 1987 was normalised to pF 2 and 20°C; see Table B.8.136 for combined

data set). This endpoint will be used in the FOCUS groundwater and surface water modelling

prepared by the UK RMS.


Table B.8.136 Combined modelling DT50 values for parent Thifensulfuron-methyl

Study reference Soil type SFO DT50 (20°C and

pF 2)

Allen, 1987 Speyer 2.2; loamy sand 2.0

Allen, 1987 Speyer 2.3; loamy sand 3.1

Simmonds, 2012a Longwood; sandy loam 0.99

Simmonds, 2012a Farditch; loam 1.12

Simmonds, 2012a Lockington; sandy clay 1.23

Simmonds, 2012a Kenslow; loam 0.85


The following tables and figures provide summary results of the Applicants kinetic fitting.

Note that results for all steps of the sequential fitting procedure are provided for

completeness. However only results from the final sequential fit (Step 3) have been relied on

for selecting regulatory endpoints.

The UK RMS has also presented an additional graphical fit of data for Thifensulfuron-methyl

from all soils from Simmonds (2012a) together with the proposed geometric mean DT50 of

1.39 d (see Figure B.8.20). This figure is intended to show the good fit to the combined data.

This approach has been used particularly in selecting appropriate combinations of metabolite

DT50 and formation fractions. However for completeness the combined figure for

Thifensulfuron-methyl has also been provided.


Table B.8.137 Kinetic modelling flowchart steps for Longwoods Soil – thiophene label

Compartment Model χ2 error % t-test DT50 (days) Visual

assessment

Step 1: Fit Thifensulfuron-methyl (TIM)

Thifensulfuron-

methyl SFO 2.31 k < 0.05 0.79 Good

Step 2: Add primary metabolite: IN-L9225 (TIA) to acceptable parent model

Thifensulfuron-


IN-L9225 SFO 8.87 k < 0.05 74.3 Good

Step 3: Add secondary metabolites: IN-JZ789 (DTIA), 2-Acid-3-triuret (AT) and IN-L9223 (AS) to acceptable

primary metabolite model

Thifensulfuron-


IN-L9225 SFO 8.87 k < 0.05 74.4 Good

IN-JZ789 SFO 49.8 k = 0.44 362 Intermediate

2-Acid-3-triuret SFO 61.1 k = 0.49 122 Intermediate

IN-L9223 SFO 39.2 k = 0.50 1000 Intermediate

As discussed above, the UK RMS was concerned that for some soils the Applicant approach

may have underestimated the peak of metabolite formation levels. An example of this can be

seen in Figure B.8.12 below. For the O-desmethyl Thifensulfuron-methyl (IN-JZ789) and 2-

acid-3-triuret metabolites it can be seen that visually the Applicants modelled fit does not

necessarily describe the peak occurrence of these metabolites. This was one of the reasons

that the UK further explored the use of the upper 95% confidence intervals for the formation

fractions, to ensure the combination of selected DT50 and formation fraction was

conservative. Visual presentation of the UK RMS selected values is shown further below in

Figures B.8.20 to B.8.30.


Figure B.8.12 Graphical output for the Applicants kinetic fitting for the

Longwood soil (thiophene label)


Table B.8.138 Kinetic modelling flowchart steps for Longwoods Soil – triazine label


assessment

Step 1: Fit Thifensulfuron-methyl (TIM)

Thifensulfuron-


Step 2: Add primary metabolites: IN-L9225 (TIA) and IN-A4098 (TA) to acceptable parent model

Thifensulfuron-


IN-L9225 SFO 8.22 k < 0.05 85.2 Good

IN-A4098 SFO 31.9 k = 0.48 820 Intermediate

Step 3: Add secondary metabolites: IN-JZ789 (DTIA) and 2-Acid-3-triuret (AT) to primary metabolite model

Thifensulfuron-


IN-L9225 SFO 8.21 k < 0.05 85.1 Good


IN-JZ789 SFO 57.7 k = 0.14 51.5 Intermediate

2-Acid-3-triuret SFO 43.6 k = 0.17 57.9 Intermediate

Again in Figure B.8.13 it can be seen that the fit to the O-desmethyl thifensulfuron acid (IN-

JZ789) may be slightly underestimated by the Applicant fitting.

An open point was identified at PRAPeR 126 to repeat the fitting for IN-A4098 using a fixed

DT50 of 1000 d (this was specifically requested to ensure that a conservative estimate of

formation was derived). However the UK RMS checked and confirmed that fixing the DT50

for IN-A4098 had no impact on other substance endpoints. This is as expected since the IN-

A4098 is a terminal metabolite in the modelling scheme used by the Applicant and does not

therefore significantly influence other kinetic flows. The revised kinetic fitting with a fixed

DT50 of 1000 d for IN-A4098 is shown in Figure B.8.13a (although it is noted that visually no

difference is seen compared to the fitting in Figure B.8.13 when this parameter was free

fiteed by the Applicant). A slight improvement in χ2 error % to 26.6% was noted in the re-

fitting (compared to 31.9% in the free fitted assessment). This may simply be an artefact of

increased degrees of freedom due to fixing this one parameter in the model.


Figure B.8.13 Graphical output for the Applicants kinetic fitting for the Longwood

soil (triazine label)


Figure B.8.13a Graphical output for the additional UK RMS kinetic fitting for IN-

A4098 (triazine amine) with a fixed DT50 of 1000 d for the Longwood soil (triazine

label; χ2 error % to 26.6%)


Table B.8.139 Kinetic modelling flowchart steps for Farditch Soil – thiophene label


assessment

Step 1: Fit Thifensulfuron-methyl

Thifensulfuron-


Step 2: Add primary metabolite: IN-L9225 to acceptable parent model

Thifensulfuron-


IN-L9225 SFO 10.9 k < 0.05 20.7 Good

Step 3: Add secondary metabolites: IN-JZ789, 2-Acid-3-triuret and IN-L9223 to acceptable primary metabolite

model

Thifensulfuron-


IN-L9225 SFO 10.9 k < 0.05 20.7 Good


2-Acid-3-triuret SFO 34.3 k < 0.05 46.1 Good

IN-L9223 SFO 27.7 k < 0.05 107 Good


Figure B.8.14 Graphical output for the Applicants kinetic fitting for the Farditch soil

(thiophene label)

[Note this graphical output illustrates the systematic error in the KinGUI v1.1 report. Formation fractions were reported for

IN-JZ789 (O-desmethyl thifensulfuron acid) of 0.22 and for IN-L9223 (2-acid-3-sulfonamide) of 0.09. The peak residue of

IN-L9223 of 14% could not have been achieved with a formation fraction of only 0.09 (since peak residues must never

exceed formation fraction in this type of model). This error introduced into the Applicants kinetic assessment has been

corrected by the UK RMS in the relevant summary tables above and in selecting final average formation fractions.]


Table B.8.140 Kinetic modelling flowchart steps for Farditch Soil – triazine label


assessment


Thifensulfuron-


Step 2: Add primary metabolites: IN-L9225 and IN-A4098 to acceptable parent model

Thifensulfuron-


IN-L9225 SFO 12.0 k < 0.05 25.4 Good

IN-A4098 SFO 27.3 k = 0.21 118 Good

Step 3: Add secondary metabolites: IN-JZ789 and 2-Acid-3-triuret to primary metabolite model

Thifensulfuron-


IN-L9225 SFO 12.0 k < 0.05 25.4 Good





Figure B.8.15 Graphical output for the Applicants kinetic fitting for the Farditch soil

(triazine label)


Table B.8.141 Kinetic modelling flowchart steps for Lockington Soil – thiophene label


assessment


Thifensulfuron-



Thifensulfuron-


IN-L9225 SFO 11.2 k < 0.05 17.5 Good


model

Thifensulfuron-


IN-L9225 SFO 11.2 k < 0.05 17.5 Good



IN-L9223 SFO 29.1 k = 0.07 194 Intermediate


Figure B.8.16 Graphical output for the Applicants kinetic fitting for the Lockington

soil (thiophene label)


Table B.8.142 Kinetic modelling flowchart steps for Lockington Soil – triazine label


assessment


Thifensulfuron-



Thifensulfuron-


IN-L9225 SFO 10.0 k < 0.05 20.4 Good

IN-A4098 SFO 21.5 k = 0.38 546 Good


Thifensulfuron-


IN-L9225 SFO 10.0 k < 0.05 20.3 Good



2-Acid-3-triuret SFO 36.3 k = 0.32 115 Good



Lockington soil (triazine label)


Table B.8.143 Kinetic modelling flowchart steps for Kenslow Soil – thiophene label


assessment


Thifensulfuron-



Thifensulfuron-


IN-L9225 SFO 13.5 k < 0.05 14.4 Good


model

Thifensulfuron-


IN-L9225 SFO 13.5 k < 0.05 14.4 Good



IN-L9223 SFO 23.9 k = 0.11 272 Good



Kenslow soil (thiophene label)


Table B.8.144 Kinetic modelling flowchart steps for Kenslow Soil – triazine label


assessment


Thifensulfuron-



Thifensulfuron-


IN-L9225 SFO 5.55 k < 0.05 15.4 Good

IN-A4098 SFO 8.59 k = 0.06 206 Good


Thifensulfuron-


IN-L9225 SFO 5.55 k < 0.05 15.4 Good

IN-A4098 SFO 8.59 k = 0.03 208 Good


2-Acid-3-triuret SFO 53.0 k = 0.35 132 Intermediate


Figure B.8.19 Graphical output for the Applicants kinetic fitting for the Kenslow soil

(triazine label)


Figure B.8.20 Graphical output for the UK RMS kinetic fitting for Thifensulfuron-

methyl (all soils) assuming a modelling DT50 of 1.39 d. Overall this choice of

DT50 was accepted by the UK RMS.


The modelling half lives and formation fractions derived for IN-L9225 are summarised in

Table B.8.145. Visual fits for all soils from the Applicants kinetic report are as previously

shown in Figures B.8.12 to B.8.19 to illustrate the goodness of fit for IN-L9225. The

combined graphical fit for all soils from Simmonds (2012a) assuming modelling input

parameters of a DT50 of 32.3 dand formation fraction of 0.95 is presented in Figure B.8.21.

For the parent to IN-L9225 pathway the UK RMS fully accepted the values proposed by the

Applicant as they were derived in accordance with FOCUS kinetics and complied with the

general principles of acceptable visual and statistical fitting criteria.

Table B.8.145 IN-L9225 modelling endpoints

Soil Label DT50 (days) Formation fraction

IN-L9225

Longwoods

Thiophene 74.4 1.00

Triazine 85.1 0.95

Soil mean 79.6 -

Farditch

Thiophene 20.7 0.97

Triazine 25.4 0.98

Soil mean 22.9 -

Lockington

Thiophene 17.5 1.00

Triazine 20.3 0.94

Soil mean 18.8 -

Kenslow

Thiophene 14.4 0.93

Triazine 15.4 0.84

Soil mean 14.9 -

Geometric mean of soils from Simmonds (2012a) 26.8 0.95 (arithmetic mean)

Combining the data above on 4 soils with the acceptable data from the DuPont submission

(single study of Manjunatha on three further soils) resulted in a geometric mean SFO DT50

of 32.3 days (DT50s from Manjunatha normalised to pF 2 and 20°C; see Table B.8.146 for

combined data set). The combination of data from parent and metabolite dosed studies was

considered reasonable in this case given the good agreement in DT50 values from the different

study types. However it was noted that across the combined set of 7 soils there was a

reasonably large spread of DT50 values (i.e. 14.9 to 119.9 d). This did not appear to be

related to the study type. No obvious correlation between degradation and soil properties

could be determined by the UK RMS (e.g. DT50 and soil pH, OC content, microbial biomass

etc). The variable peristence was commented on in the original DAR consideration of the

Manjunatha study, although no correlation with soil properties could be determined then

either. Overall the UK RMS considered the use of the geometric mean from both studies to

be appropriate. This endpoint will be used in the FOCUS modelling prepared by the UK

RMS, in combination with a formation fraction of 0.95.


Table B.8.146 Combined modelling DT50 values for IN-L9225

Study reference Soil type Soil pH SFO DT50

(20°C and pF 2)

Manjunatha, 2000 Drummer, silty clay

loam 5.9 34.9

Manjunatha, 2000 Glenville, sandy loam 7.3 17.2

Manjunatha, 2000 Gross-Umstadt, silt

loam 7.5 119.9

Simmonds, 2012a Longwood; sandy

loam

7.5 79.6

Simmonds, 2012a Farditch; loam 6.5 22.9

Simmonds, 2012a Lockington; sandy clay 5.5 18.8

Simmonds, 2012a Kenslow; loam 5.5 14.9



Figure B.8.21 Graphical output for the UK RMS kinetic fitting for IN-L9225

(all soils) assuming a modelling DT50 of 32.3d and formation fraction of 0.95 (from

Thifensulfuron-methyl). Overall this choice of formation fraction and DT50 was

accepted by the UK RMS.


The following summary table outlines the DT50 values derived for IN-JZ789, IN-L9223, IN-

A4098 and 2-acid-3-triuret from the Applicants kinetic fitting. As highlighted above, the

Applicant proposed not to use these values in their exposure assessment. They proposed to

use a combination of formation fractions from this kinetic modelling study combined with

DT50 values derived from the separate standalone metabolite dosed studies. As previously

stated, in principle the UK RMS considers that mixing formation fractions from parent dosed

studies with degradation rates from metabolite dosed studies can be an acceptable approach.

However the UK RMS also considers it important to consider whether the degradation rates

from the metabolite dosed studies are representative of the behaviour seen in the parent dose

studies (where metabolites are formed in situ). The summary results in Table B.8.147 are

presented to allow the two sets of values to be compared. Results are presented for the

geometric mean of all soils from the route study of Simmonds (2012a). In addition, a

geometric mean excluding results from soils where the DT50 optimised to a value > 1000 d

was derived. It should be noted that although results are presented as >1000 d in most cases

the fitted DT50 values were far in excess of 1000 d and therefore highly uncertain. The

impact of including or excluding the 1000 d DT50 values has been fully considered in the UK

RMS kinetic assessment and graphical outputs are presented for comparative purposes. The

final row of Table B.8.147 presents the geometric mean of the combined metabolite dosed

studies for direct comparison (these results have been previously summarised in this section).

Table B.8.147 Summary of DT50 values derived from the Applicants kinetic analysis of

Simmonds (2012a).

Soil Label IN-JZ789

DT50 (days)

2-acid-3-triuret

DT50 (days)

IN-L9223

DT50 (days)

IN-A4098

DT50 (days)

Longwoods Thiophene 362 122 >1000 -

Triazine 51.5 57.9 - >1000

Farditch Thiophene 128 46.1 107 -

Triazine >1000 74.4 - 118

Lockington Thiophene 39.5 38.4 194 -

Triazine 8.06 115 - 562

Kenslow Thiophene >1000 57.0 272 -

Triazine >1000 132 - 208

Geometric mean 172 73 274 343

Geometric mean

(excluding soils with

DT50 >1000 d)

60 73 178 240

Geometric mean

from metabolite

dosed studies

6.0 0.07 16.7 169.4a

aIncluding information on this common metabolite from other RARs, the updated geometric mean is 132.4 d for

modelling purposes. PRAPeR meeting 126 agreed that for IN-A4098 the entire data set from metabolite dosed

studies plus the 4 DT50 values from Simmonds (2012a) should be combined in selecting an overall modelling

input value. This gave an overall geometric mean DT50 of 167.9 d (n = 16). This value has been used in

updated groundwater modelling.

As can be seen from the summary results in Table B.8.147 above, for metabolites IN-JZ789,

2-acid-3-triuret and IN-L9223 there appeared to be very large differences between the

Applicant derived DT50 values from the Thifensulfuron-methyl route study and from the

separate metabolite dosed studies. For example for the 2-acid-3-triuret metabolite the

geometric mean DT50 derived in the study of Ford (2012) was 73 d compared to <0.1 days

from the separate metabolite dosed study of Knoch (2012). Although the magnitude of


difference was smaller for IN-JZ789 and IN-L9223 there was still at least an order of

magnitude reduction in DT50’s seen in the metabolite dosed studies compared to that derived

from the kinetic fitting of the thifensulfuron dosed study. Only the IN-A4098 metabolite

gave broadly comparable DT50 values from the thifensulfuron and metabolite dosed studies

(i.e. values within a factor of 2). In this case, the UK RMS was concerned that utilising the

shorter DT50 values from the metabolite dosed studies for IN-JZ789, 2-acid-3-triuret and IN-

L9223 may significantly underestimate persistence based on the behaviour observed in parent

dosed study. The UK RMS considered that the simplest way to determine the

appropriateness of different DT50 and formation fraction combinations was to check the

visual fit of the proposed modelling input parameters against the combined soil residue data

from the Thifensulfuron-methyl route of degradation study. These figures are presented in

Figures B.8.20 to B.8.28 30 for different combinations and discussed further below.

The following summary table (Table B.8.148) outlines the formation fractions for IN-L9225

and IN-A4098 forming from parent Thifensulfuron-methyl. The results were noted to be

very consistent across the 4 soils and confirmed that the major pathway of parent degradation

was via the IN-L9225 metabolite. A more minor route was via the IN-A4098 metabolite.

The major pathway for the formation of the IN-A4098 metabolite was via the IN-L9225

metabolite. However for the purposes of a conservative groundwater exposure assessment

both routes of formation of the IN-A4098 have been retained.


Table B.8.148 Formation fractions for metabolites forming from Thifensulfuron-methyl

Soil Label Fraction forming

IN-L9225 IN-A4098

Longwoods Thiophene 1.00 -

Triazine 0.95 0.02*

Farditch Thiophene 0.97 -

Triazine 0.98 0.02

Lockington Thiophene 1.00 -

Triazine 0.94 0.06

Kenslow Thiophene 0.93 -

Triazine 0.84 0.08

Arithmetic mean 0.95 0.05

*The formation fraction for IN-A4098 from parent thifensulfuron methyl remained at 0.02 even when the DT50

for this metabolite was fixed at 1000 d in the additional UK RMS fitting performed in response to the Open

Point identified at PRAPeR 126. Therefore no change to the arithmetic mean was required.

The following Table B.8.149 provides a summary of the Applicant derived formation

fractions for the metabolites formed from IN-L9225. In addition, the values proposed for use

by the UK RMS based on the Applicant derived upper 95% confidence limits are also

included for comparison. Representative graphical plots of all data from Simmonds (2012a)

have also been included below to demonstrate the visual quality of the Applicant fits and the

conservatism introduced with the UK RMS proposed values. Since the Applicant values

have not been used in the groundwater exposure assessment they have been greyed out.

PRAPeR meeting 126 accepted the use of upper 95th

percentile confidence limits for IN-

JZ789, 2-acid-3-triuret and IN-L9233. However the meeting rejected this approach for IN-

A4098 in favour of using the actual fitted formation fractions. Therefore Table B.8.149 has

been updated with an additional column representing the values proposed by the Expert

Meeting. Since the UK RMS values for this metabolite have not been used in the

groundwater exposure assessment they have also been greyed out.


Table B.8.149 Formation fractions for metabolites forming from IN-L9225 [note UK RMS

values represent 95% confidence limits taken from the Applicant KinGUI modelling report]

Soil Label Formation fractions

IN-JZ789 2-Acid-3-triuret IN-L9223 IN-A4098

Applicant UK

RMS Applicant

UK

RMS Applicant

UK

RMS Applicant

UK

RMS

PRAPeR 126

Longwoods Thiophene 0.16 0.36 0.29 0.53 0.13 0.34 - - -

Triazine 0.12 0.58 0.17 0.32 - - 0.27 0.45 0.13*

Farditch Thiophene 0.22 0.17 0.20 0.25 0.09 0.29 - - -

Triazine 0.14 0.14 0.10 0.19 - - 0.05 0.29 0.14

Lockington Thiophene 0.22 0.19 0.13 0.18 0.08 0.29 - - -

Triazine 0.10 0.41 0.05 0.09 - - 0.09 0.20 0.10

Kenslow Thiophene 0.22 0.11 0.09 0.15 0.05 0.28 - - -

Triazine 0.17 0.09 0.05 0.07 - - 0.04 0.25 0.17

Arithmetic mean 0.17 0.26 0.14 0.22 0.09 0.30 0.11 0.30 0.14

Note that due to the apparent error in reporting formation fractions in KinGui v1.I the values for the flows

between IN-L9225 and IN-JZ789 and either IN-L9225 and IN-L9223 (thiophene labelled soils) or IN-L9225 and

IN-A4098 (triazine labelled soils) should be reversed in the Applicant values. The values listed by the UK RMS

do provide the correct upper 95% confidence intervals for the appropriate flow listed.

*The value of 0.13 was derived from the additional UK RMS fitting for IN-A4098 when the DT50 was fixed to

1000 d (required as part of an Open Point from PRAPeR 126). This was slightly higher than the Applicant

value of 0.12 (see column 3 in Table B.9.149) when all parameters were free fitted. All other formation

fractions for IN-A4098 are from the Applicant fitting (but incorrectly reported for the flow to IN-JZ789 in the

Applicants report and listed in Column 3 in the table above).

To illustrate where the upper 95% confidence intervals have been derived from, the

UK RMS has included a screenshot from the Applicants KinGUI modelling report in

Figure B.8.21a below. This example is for the fitting to the Longwoods thiophene

data. Note that for flows A1 to A2 and A1 to B1 the error in the KinGUI reporting

has been corrected by the UK RMS. For example for the flow to IN-JCZ789

(compartment A2) the Applicant used a formation fraction from IN-L9225

(compartment A1) of 0.16 (i.e. read from the report for A1_FFA2). For the same

flow, the UK RMS used a upper 95% confidence interval of 0.36, which the

UKRMS took from the A1 to B1 flow (i.e. A1_FFB1).


Figure B.8.21a: Screenshot from Applicants KinGUI modelling report to show the

derivation of 95% confidence intervals

Figure B.8.22 Graphical output for the UK RMS kinetic fitting for IN-JZ789

(all soils) assuming a modelling DT50 of 60 d and formation fraction of 0.26 (from

IN-L9225). Overall this choice of formation fraction and DT50 was accepted by the

UK RMS.


Figure B.8.23 Graphical output for the UK RMS kinetic fitting for IN-JZ789 (all soils)

assuming a modelling DT50 of 6 d and formation fraction of 0.26 (from IN-L9225). This

combination was not accepted by the UK RMS

Note this graphical output is presented to demonstrate the potential underestimation

of IN-JZ789 when combining formation fractions from the Thifensulfuron-methyl

route of degradation study with DT50 values from the separately dosed IN-JZ789

rate of degadation studies. The UK RMS considered the fits with the longer DT50

of 60 d in Figure B.8.22 above to be more appropriate.


Figure B.8.24 Graphical output for the UK RMS kinetic fitting for IN-JZ789

(all soils) assuming a modelling DT50 of 172 d and formation fraction of 0.26 (from

IN-L9225). This combination was not accepted by the UK RMS

Note this graphical output is presented to demonstrate the potential overestimation of IN-

JZ789 when combining formation fractions from the Thifensulfuron-methyl route of

degradation study with the geometric mean DT50 value including values >1000 d from the

same route of degadation study. The UK RMS considered the fits with the shorter DT50 of

60 d (excluding the 1000 d values) in Figure B.8.22 above to be a sufficiently conservative

appropriate.


The following Table B.8.150 provides the Applicant derived formation fractions for the

pathway between IN-JZ789 and 2-acid-3-triuret. The UK RMS noted that where a positive

flow pathway between these two substances was included, the upper 95% confidence

intervals always included 1. Where a value of 0 is reported, this was as a result of the

original modelled flow being optimised to a very small value, and subsequently being

excluded from the final fitting procedure. In these cases it was assumed that IN-JZ789 only

degraded to the sink. The UK RMS noted that results between label positions within the

same soil were sometimes quite inconsistent. For example in the Lockington soil, the

formation fraction was 1.0 in the thiophene label and 0 in the triazine label. The UK RMS

considered this added a degree of uncertainty to the values derived, since in theory this

pathway should be unaffected by label position. In order to ensure a conservative

assessment, and in line with the approach taken with the other formation fractions outlined

above, the UK RMS proposed to use a simple conservative formation fraction of 1 for the IN-

JZ789 to 2-acid-3-triuret pathway.

Table B.8.150 Formation fractions for metabolites forming from IN-JZ789

Soil Label Fraction forming

2-Acid-3-triuret

Longwoods Thiophene 0.95

Triazine 1.00

Farditch Thiophene 0.00

Triazine 0.57

Lockington Thiophene 1.00

Triazine 0.00

Kenslow Thiophene 0.32

Triazine 1.00

Arithmetic mean

0.61

(UK RMS proposed to use a

conservative value of 1.0)


Figure B.8.25 Graphical output for the UK RMS kinetic fitting for 2-acid-3-

triuret (all soils) assuming a modelling DT50 of 73 d and formation fractions of 0.22

(from IN-L9225) and 1.0 (from IN-JZ789). Overall this choice of formation fraction

and DT50 was accepted by the UK RMS.


Figure B.8.26 Graphical output for the UK RMS kinetic fitting for 2-acid-3-triuret (all soils)

assuming a modelling DT50 of 0.07 d and formation fractions of 0.22 (from IN-L9225) and

1.0 (from IN-JZ789) [note the modelled fit is barely visible above the origin]. The

combination was not accepted by the UK RMS.

Note this graphical output is presented to demonstrate the potential underestimation of 2-

acid-3-triuret when combining formation fractions from the Thifensulfuron-methyl route of

degradation study with DT50 values from the separately dosed 2-acid-3-triuret rate of

degadation studies. The UK RMS considered the fits with the longer DT50 of 73 d in Figure

B.8.25 above to be clearly more appropriate.


Figure B.8.27 Graphical output for the UK RMS kinetic fitting for IN-L9223 (all soils)

assuming a modelling DT50 of 178 d and formation fractions of 0.30 (from IN-L9225).

Overall this choice of formation fraction and DT50 was accepted by the UK RMS.


Figure B.8.28 Graphical output for the UK RMS kinetic fitting for IN-L9223 (all soils)

assuming a modelling DT50 of 16.7 d and formation fractions of 0.30 (from IN-L9225). This

combination was not accepted by the UK RMS.

Note this graphical output is presented to demonstrate the potential underestimation of IN-

L9223 when combining formation fractions from the Thifensulfuron-methyl route of

degradation study with DT50 values from the separately dosed IN-L9223 rate of degadation

studies. The UK RMS considered the fits with the longer DT50 of 178 d in Figure B.B.27

above to be clearly more appropriate.

Similar Tables of fitting for IN-A4098 have been removed since PRAPeR 126 did not

support the UK RMS approach for this metabolite.


Figure B.8.29 Graphical output for the UK RMS kinetic fitting for IN-A4098 (all soils)

assuming a modelling DT50 of 169.4 d (from the combined separately dosed metabolite rate

of degradation studies) and formation fractions of 0.30 (from IN-L9225) and 0.05 (from

Thifensulfuron-methyl). Overall this choice of formation fraction and DT50 was accepted by

the UK RMS.

In response to Open Points 4.4 and 4.5 the UK RMS updated the dataset for IN-A4098 to

take account of 4 additional DT50 values for this common metabolite from other peer

reviewed RARs. This led to a revised geometric mean DT50 of 132.4 d. To check whether

this revised DT50 in combination with the previously agreed formation fractions (i.e. 0.30

from IN-L9225 and 0.05 from thifensulfuron methyl) the UK RMS repeated the visualisation

procedure with all data. This new fitting is presented in Figure B.8.29a below. The only

diffference between this figure and Figure B.8.29 above is that the IN-A4098 DT50 has been

fixed to 132.4 d (compared to 169.4 d as in Figure B.8.29 above).


Figure B.8.29a Graphical output for the UK RMS kinetic fitting for IN-A4098 (all

soils) assuming a modelling DT50 of 132.4 d (from the combined separately dosed

metabolite rate of degradation studies supplied by both Notifiers and 4 additional DT50s from

others RARs) and formation fractions of 0.30 (from IN-L9225) and 0.05 (from

Thifensulfuron-methyl). Overall this choice of formation fraction and DT50 was also

accepted by the UK RMS.

Visually the fit was considered comparable to that previously accepted in Figure B.8.129 and

therefore the UK RMS also accepted this revised choice of DT50 and formation fraction for

IN-A4098.


Figure B.8.30 Graphical output for the UK RMS kinetic fitting for IN-A4098 (all soils)

assuming a modelling DT50 of 343 d (geometric mean DT50 of all soils from the route of

degradation study) and formation fractions of 0.30 (from IN-L9225) and 0.05 (from

Thifensulfuron-methyl). This combination was not accepted by the UK RMS.

Note this graphical output is presented to demonstrate the potential overestimation of IN-

A4098 when combining formation fractions from the Thifensulfuron-methyl route of

degradation study with the geometric mean DT50 value including values >1000 d from the

same route of degadation study. The UK RMS considered the fits with the shorter DT50 of

169.4 d (from the separately dosed metabolite rate of degradation studies) in Figure B.8.29 or

the revised geometric mean DT50 of 132.4 d based on additional data from other RARs in

Figure B.8.29a above to be a sufficiently conservative.


Conclusions:

Modelling half-lives for Thifensulfuron-methyl and IN-L9225 and formation fractions for IN-

L9225 were acceptably derived based on the Applicants kinetic fitting report. Summary

graphical outputs from the Applicants fitting are provided in Figures B.8.12 to B.8.19 to

confirm the acceptability of fitting for parent and IN-L9225. For IN-JZ789, 2-Acid-3-triuret

and IN-L9223 the UK RMS selected formation fractions from the Applicant fitting but

conservatively used the upper 95% confidence limits. For these three metabolites the UK

RMS also investigated the impact of selecting DT50 values from the route study or from the

separate metabolite dosed studies. Based on the graphical outputs presented in Figure B.8.22

(for IN-JZ789), Figure B.8.25 for (2-acid-3-triuret) and Figure B.8.27 (for IN-L9223), the

UK RMS conservatively used geometric mean DT50’s (excluding values above 1000 d) from

the Applicants kinetic fitting of the parent route of degradation study. This approach was

used in preference to using DT50 values from the separately dosed metabolite rate of

degradation studies due to the significant difference in behaviour observed in each study type.

The graphical fits of these metabolites for all soils combined are presented in Figures B.8.20

to B.8.28; these fits confirm the appropriateness of using geometric mean DT50 excluding

values >1000 days in combination with the upper limit 95% confidence interval formation

fraction. For IN-A4098 the UK RMS approach was rejected by the experts at PRAPeR 126.

For IN-A4098 the experts considered it appropriate to combine the metabolite dosed and

parent dosed DT50 values (revised geometric mean DT50 of 167.9 d, n=16) and the standard

formation fractions from the original Applicant fitting (0.05 from thifensulfuron methyl and

0.14 from IN-L9225). used the geometric mean DT50 from metabolite dosed studies, since

for this metabolite there was reasonable agreement between the thifensulfuron and metabolite

dosed studies with regards to metabolite DT50. The graphical fit of this metabolite is

presented in Figures B.8.29, 29a and 30. For comparison, for metabolites IN-JZ789, 2-acid-

3-triuret and IN-L9223 additional graphical fits for all soils have been produced combining

the Applicant derived formation fractions with the shorter DT50 values from the metabolite

dosed studies. This was the approach recommended by the Applicant. However in the

figures based on this approach it can be seen that this approach may lead to significant

underestimation of metabolite levels and was therefore rejected by the UK RMS in selecting

the final proposed parameters.

Table B.8.151 summarises the geometric mean DT50 values and arithmetic mean formation

fractions proposed by the UK RMS and agreed at PRAPeR 126 for use in FOCUS

groundwater and surface water modelling. These have also been graphically illustrated in

Figure B.8.30a. Although this approach was not based on typical optimised kinetic fitting for

IN-JZ789, IN-L9223 and 2-acid-3 triuret, the UK RMS considered that the approach was

consistent with the general principles of FOCUS kinetics. Based on the graphical fits of the

accepted parameter combinations (i.e Figure B.8.22 for IN-JZ789, Figure B.8.25 for 2-acid-

3-triuret, Figure B.8.27 for IN-L9223 and Figure B.8.29 for IN-A4098) the UK RMS and

PRAPeR 126 considered the selected parameters to be acceptable for the purposes of the first

tier exposure assessment.


Table B.8.151 Summary of the geometric mean DT50 values for Thifensulfuron-methyl and

IN-L9225 and the arithmetic mean formation fractions for modelling for metabolites IN-

L9225, IN-JZ789, 2-Acid-3-triuret, IN-L9223 and IN-A4098

Values for FOCUS modelling inputs

DT50 (days) Fraction formed

Thifensulfuron-methyl 1.39 -

IN-L9225 32.3 0.95 (from Thifensulfuron-methyl)

IN-JZ789 60a 0.26 (from IN-L9225)

2-Acid-3-triuret 73 a

0.22 (from IN-L9225)

1.0 (from IN-JZ789)

IN-L9223 178 a 0.30 (from IN-L9225)

IN-A4098 169.4

b

167.9b

0.30 0.14 (from IN-L9225)

0.05 (from Thifensulfuron-methyl) a geometric mean of Applicant derived DT50 values from Ford (2012) excluding values >1000 d

b geometric mean of all metabolite and parent dosed studies (n=16). A lower geometric mean of 132.4 d was derived based

on additional DT50 values from other peer reviewed RARs.

Figure B.8.30a: Proposed modelling degradation scheme and formation

fractions (proposed by UK RMS)

(based on Ford, 2012)


B.8.1.5 Field studies

Field dissipation

Report: Rapisarda, C., Scott, M.T. (1986); Field dissipation studies with [thiophene-2-14

C]DPX-M6316 in U.S. and Canadian soils


Guidelines: U.S. EPA PB83-153973 (1982)

Test

material:

14C-Thifensulfuron-methyl technical


C]-Thifensulfuron-methyl Lot# 1788-151

Purity: Radiochmical purity >98%

Report: Naidu, M.V. (1989a); Field soil dissipation study of [thiophene-2-14

C]DPX-M6316

and [triazine-2-14

C]DPX-M6316 at Madera, California

DuPont Report No.: AMR 1105-88, Revision No. 1


Test

material:



C]M6316-206, [Triazine-2-14

C]M6316-227

Purity: Radiochemical purity 97% for both

Report: Naidu, M.V. (1989b); Terrestrial field dissipation study of DPX-M6316 in

Canadian soils

DuPont Report No.: AMR 835-87, Revision No. 1


Test

material:



C]DPX-M6316, [triazine-2-14

C]DPX-M6316;

lot numbers not provided

Purity: Radiochemical purity: 97, 97.5%

Previous



original field dissipation studies do not meet current guidelines. In the

DuPont submission these studies have been superseded by new field

dissipation studies. However in the environmental exposure assessment

DuPont proposed retaining information on the maximum soil formation

levels of metabolites IN-V7160 and IN-L9223 from the original studies,

as they represented the highest and most conservative values from all

studies. It should be noted that for IN-L9223 higher levels of formation

were observed in the new acceptable route of degradation study

supplied by the Task Force (see Simmonds, 2012a). For IN-V7160, it

was only detected at a single time point in one of the 4 North American

field trials. It was not included in the list of metabolites analysed for in

the new field dissipation studies of DuPont. It was not detected in the

acceptable aerobic route of degradation study supplied by the Task

Force. However on the basis that this metabolite occurred at close to

10% at the end of the new laboratory soil photolysis study from


DuPont, the IN-V7160 metabolite has been included as metabolite in

the soil and groundwater exposure assessment. However effectively no

information from these old field dissipation studies is actually used in

the revised exposure assessment presented in the RAR.

Furthermore it should be noted that field dissipation studies would not

be triggered based on the parent DT50 << 60 d. Although under the

new data requirements field dissipation studies could be triggered by

metabolite persistence, these new data requirements do not apply to

substances under the AIR 2 renewal program. The environmental

exposure assessment is based on degradation under laboratory

conditions, utilising peak occurrence or formation fraction of

metabolites also under laboratory conditions. No attempt to derive

degradation rates for the active or metabolites using modern FOCUS

kinetics methods was attempted by either Applicant. Therefore the UK

RMS concluded that field dissipation studies were neither required nor

used in the environmental exposure assessment. On this basis, the UK

RMS has not reviewed in detail the existing or new information

provided by DuPont. Since this information is not relied upon, it has

been greyed out to show that it has not been relied on. Note this grey

text in this case does not imply that the studies are invalid, merely that

they have not been used int he regulatory assessment.

In the Task Force submission, they propose simply referencing the old

field dissipation trials and have not submitted any new data. Since no

data would actually be required, this approach was also considered

acceptable by the UK RMS


DAR and 2000 DAR Addenda has been included below. Since this

information is not now relied on, it has been greyed out.

Field studies took place in 3 US and 1 Canadian location (AMR 460-85, started 05/1984 and reported by

C. Rapisarda and M.T. Scott (1986), no GLP statement), 4 Canadian locations (AMR 835-87, started 04/1987,

reported by V. Naidu, Motupalli (1988), no GLP statement) and Madera, California (AMR 1105-88, started

03/1988, reported by V. Naidu, Motupalli (1989), no GLP statement). Guideline US EPA, Pesticide Assessment

Guidelines: Environmental Fate 164-1 was used. The studies were conform to the guideline except batch, purity

and lot numbers of non-labelled test materials were not provided, DT90s were recalculated to meet current

reporting criteria, and a freezer storage stability study was not reported. The studies were found acceptable.

Protocol - [thiophene-2-14C]Thifensulfuron-methyl (radiochemical purity >98%) and [triazine-2-

14C]Thifensulfuron-methyl (radiochemical purity 97.5%) were applied at 80 g a.s./ha to stainless steel cylinders

(10 cm diameter, 38 cm length) driven into the soil at 9 sites. Soil columns were periodically removed, cut in

four sections. Radioactivity in soil segments was determined by combustion. When > 5%, the radioactive

compounds were extracted and analysed by HPLC and/or TLC. Bound residues were determined by

combustion. DT50 and DT90 were calculated using linear first order and non linear kinetics. Soil characteristics


were given in Table B.8.152. Experimental conditions were given in Table B.8.153. Rainfall were not

representative of north European countries.

Table B.8.152 Soil characteristics

Location Textural class Sand (%) Silt (%) Clay (%) OM (%) pH

Akron, Colorado Loam 40 43 17 1.2 6.5

Moscow, Idaho Silt Loam 2 75 23 2.1 6.4

Fargo, Dakota Silty Clay Loam 0 67 33 5.3 7.3

Fisher, Manitba Silty Clay Loam 1 59 40 6.4 7.9

Saskatoon, Saskatchwan Loamy Sand 82.4 12 5.6 2.3 6.3

Calgary, Alberta Loam 48.4 30 21.6 4.1 7.9

London, Ontario Sandy Loam 74.4 16 9.6 3 7.5

Kentville, Nava Scotia Sandy Loam 72 18 10 3.2 6.5

Madera, California Sandy Loam 61 26 13 1.6 7.3

Table B.8.153 Experimental conditions

Location Treatment

date

14C

position

Duration

(months)

AirTemp.

*(°C)

Rainfall

(mm)

Akron, Colorado may 84 thiophene 18 11-32 201

Moscow, Idaho april 84 thiophene id 1-37 215

Fargo, Dakota june 84 thiophene id 12-30 208

Fisher, Manitba june 84 thiophene id 9-27 283

Saskatoon,

Saskatchwan

may 87 thiophene (S) id 15.9 46

Calgary, Alberta may 87 triazine (S) id 9.6 71

London, Ontario may 87 thiophene (S) id 18.7 286

triazine (S) id id id

Kentville,

Nova Scotia

may 87 thiophene (S) id 8.8 177


Madera,

California

march 88 thiophene (S) 8 35.4 60


(S) with normal surfactants. * daily range or daily average maximum

Results - Radioactivity was in the 15 cm top layer of soils (22 cm at Fargo and Fisher; London and

Kentville for 14

C-labelled triazine) (Table B.8.154).


Table B.8.154 Distribution of radioactivity in soil cylinders at London (Ontario) treated with

[triazine-2-14C] Thifensulfuron-methyl. Percent of applied radioactivity recovered

(concentration, ppm*)

Soil

Segment

cm

(inches)

0

Day

3

Day

1

Week

2

Week

1

Month

2

Month

4

Month

10

Month

14

Month

18

Month

0-7.6

(0-3)

75.4

(0.079)

96.7

(0.079)

89.3

(0.066)

82.8

(0.081)

91.2

(0.079)

65.7

(0.062)

57.6

(0.050)

27.7

(0.026)

32.0

(0.031)

29.4

(0.023)

7.6-15.2

(3-6)

0.0**

(0.0)

0.1

(<0.001

0.2

(<0.001

0.2

(<0.001

0.2

(<0.001

1.4

(0.001)

13.8

(0.012)

14.9

(0.011)

15.5

(0.012)

8.6

(0.007)

15.2-22.9

(6-9)

0.0

(0.0)

0.0

(0.0)

0.0

(0.0)

0.1

(<0.001

0.1

(<0.001

0.2

(<0.001

8.0

(0.007)

6.5

(0.004)

2.8

(0.002)

2.8

(0.002)

22.9-35.6

(9-14)

0.0

(0.0)

0.0

(0.0)

0.0

(0.0)

0.1

(<0.001

0.1

(<0.001

0.1

(<0.001

6.6

(0.002)

2.4

(0.001)

0.0

(0.0)

0.6

(<0.001

Total

Recovery

(%)

75.4

96.8

89.5

83.2

91.6

67.4

86.0

51.5

50.3

41.4

*: Values given in parentheses are the concentration of radioactivity in the air-dried soil reported as parts per

million (ppm) Thifensulfuron-methyl equivalents.**: 0.0 not detected above background.

The total recovered radioactivity decreased from about 100% to 37-91 % of applied (may be due to

14CO2 production). Maximum value of bound residues in each soil was in the range 17-47 %. Thifensulfuron-

methyl was rapidly degraded in every site with linear DT50 and DT90 in the range 3-20 days and 10-66 days

respectively (Table B.8.155).


Table B.8.155 Persistence in soils

Location 14

C

position

DT50*

(days)

DT90*

(days)

Akron, Colorado thiophene 3 <1 10 <1

Moscow, Idaho thiophene 20 7 66 50

Fargo, Dakota thiophene 14 1.2 47 26

Fisher, Manitba thiophene 6 0.4 20 7.4

Saskatoon,

Saskatchwan

thiophene (S) 12.8 3.4 42.6 23

Calgary, Alberta triazine (S) 11.7 3.8 38.7 29

London, Ontario thiophene (S) 10.5 5.1 34.7 28

triazine (S) 16.1 3.4 53.5 20

Kentville,

Nova Scotia

thiophene (S) 5.8 0.6 19.4 5.7

triazine (S) 6.2 0.4 20.7 3.8

Madera,

California

thiophene (S) 8.3 6.4 27.6 40

triazine (S) 7.3 10.9 24.4 50

(S) with normal surfactants.

* first and second column: linear and non linear degradation kinetic, respectively

Degradation route (triazine 14C) was in accordance with aerobic pathway (Figure B.8.31).

Thifensulfuron acid, O-demethyl Thifensulfuron-methyl and triazine amine were the main degradation products:

amounts increased over the first weeks then decreased. Highest amounts (and concentrations) were in the range

<5-62% (<59 ppb), <1-47% and 10-30 % (8-22 ppb) respectively. [thiophene-2-14C]Thifensulfuron-methyl

degradates showed a predominance of Thifensulfuron acid with minor amounts (<10 ppb) of 2-ester-3-

sulfonamide, 2-acid-3-sulfonamide, thiophene sulfonimide, and O-demethyl Thifensulfuron-methyl metabolites.

After 8-12 months, residual amounts of each compound were in the range not detected - 3% (< 2 ppb)

except for Thifensulfuron acid at Calgari (14 %, 14 ppb) and Madera (36 %, 32 ppb), triazine amine (10-23 %,

6-22 ppb) at all sites and triazine urea at Calgary (7%, 7 ppb) and Madera (15 %, 12 ppb) (table 7.1.15). After

60 - 70 days post treatment, the residual Thifensulfuron-methyl was less than 10% in all study sites.


Figure B.8.31 Proposed metabolic pathway of [triazine-2-14

C]Thifensulfuron-methyl in field

soil dissipation studies

S CO2CH3

SO2NHCNH

O

N

N

N

OCH3

CH3

Thifensulfuron methyl

*

S CO2H

SO2NHCNH

O

N

N

N

OCH3

CH3

Thifensulfuron acid

N

N

N

OCH3

CH3H2N

Triazine amine

S CO2CH3

SO2NHCNH

O

N

N

N

OH

CH3

O-demethyl

Thifensulfuron

methyl

N

N

N

OCH3

CH3H2NOCNH

Triazine urea

demethylation

deesterification

hydrolysis

hydrolysis


Table B.8.156 Composition of radioactivity in soil cylinders at London (Ontario), treated

with [triazine-2-14C] Thifensulfuron-methyl. Percent of applied radioactivity recovered

(concentration, ppm*)

Sampling

Time

Soil

Segment

(cm)

Thifen-

sulfuron

methyl

Thifen-

sulfuron

acid

O-Demethyl

Thif. meth.

Triazine

Urea

Triazine

Amine

Bound

0-Day

0-7.6

52.1

(0.054)

8.7

(0.009)

0.1

(<0.001)

0.3

(<0.001)

0.6

(<0.001)

1.3

(0.001)

3-Days

0-7.6

49.8

(0.041)

12.4

(0.010)

3.9

(0.003)

2.4

(0.002)

2.7

(0.002)

2.7

(0.002)

1-Week

0-7.6

21.6

(0.016)

40.1

(0.030)

2.2

(0.002)

1.0

(<0.001)

2.5

(0.002)

6.6

(0.005)

2-Weeks

0-7.6

20.1

(0.020)

24.6

(0.024)

4.2

(0.004)

4.9

(0.005)

8.0

(0.008)

8.5

(0.008)

1-Month

0-7.6

14.4

(0.012)

22.7

(0.020)

3.8

(0.003)

2.5

(0.002)

13.4

(0.012)

12.0

(0.010)

2-Months

0-7.6

1.5

(0.001)

14.7

(0.014)

1.2

(<0.001)

9.2

(0.009)

17.2

(0.016)

13.4

(0.013)

4-Months

0-7.6

0.3

(<0.001)

0.2

(<0.001)

<0.2

(<0.001)

1.3

(0.001)

21

(0.019)

10.5

(0.009)

7.6-15.2

<0.1

(<0.001)

0.2

(<0.001)

<0.1

(<0.001)

0.2

(<0.001)

6.2

(0.005)

0.4

(<0.001)

15.2-22.9

0.0

(0.0)

<0.1

(<0.001)

0.0

(0.0)

<0.1

(<0.001)

2.7

(0.002)

2.3

(0.002)

22.9-35.6

0.0

(0.0)

0.0

(0.0)

0.0

(0.0)

0.0

(0.0)

0.0

(0.0)

0.1

(<0.001)

10-Months 0-7.6 0.2

(<0.001)

0.9

(0.001)

0.2

(<0.001)

0.6

(<0.001)

9.3

(0.009)

13.0

(0.012)

7.6-15.2 0.0

(0.0)

0.0

(0.0)

0.0

(0.0)

0.1

(<0.001)

7.6

(0.006)

4.5

(0.003)

15.2-22.8 0.2

(<0.001)

0.0

(0.0)

0.0

(0.0)

0.0

(0.0)

3.0

(0.002)

1.8

(0.001)

14-Months 0-7.6 0.1

(<0.001)

0.6

(0.001)

0.2

(<0.001)

0.7

(<0.001)

8.6

(0.008)

13.7

(0.013)

7.6-15.2 0.0

(0.0)

0.0

(0.0)

0.0

(0.0)

0.0

(0.0)

7.8

(0.006)

3.9

(0.003)

18-Months 0-7.6 0.0

(0.0)

0.0

(0.0)

0.1

(0.001)

0.2

(<0.001)

7.4

(0.006)

17.1

(0.013)

7.6-15.2 0.0

(0.0)

0.0

(0.0)

0.0

(0.0)

0.0

(0.0)

5.4

(0.005)

3.0

(0.003)

*: Values given in parentheses are the concentration of radiolabelled compound in the air-dried soil

reported as parts per million (ppm) Thifensulfuron-methyl equivalents.

In conclusion, Thifensulfuron-methyl was rapidly degraded in soils from US. and Canadian location

treated in the spring to early summer. Half-lives ranged from 3 to 20 days. DT90 values were estimated to be

less than 90 days. Thifensulfuron-methyl degradates showed a predominance of Thifensulfuron acid and triazine

amine with minor amounts of 2-ester-3-sulfonamide, 2-acid-3-sulfonamide, thiophene sulfonimide, and O-

demethyl Thifensulfuron-methyl metabolites. The leachability of Thifensulfuron-methyl and its degradation

products was moderate. No significant concentrations of parent compound or metabolites were found below 23

cm. Thifensulfuron-methyl and its degradation products do not accumulate in soil.


Additional text from 2000 DAR Addenda

No additional data were submitted but because metabolites were studied in the field

experiments carried out in USA and Canada with radiolabel Thifensulfuron-methyl, and

results were only briefly presented in the monograph, more exhaustive information is given in

the following table (see Table B.8.157). For IN-L9225, DT50f values were calculated by the

RMS from data of the Canadian field studies using first order decline of the formation

degradation curves.

Table B.8.157 Metabolites of 14

C-Thifensulfuron-methyl in field experiments carried out in

USA and Cananda

Location Label Metabolites

Moscow

(USA)

Thiophene No major metabolite

Akron

(USA)

Thiophene No major metabolite

Fargo (USA) Thiophene IN-L9225+IN-L9223+IN-W8268 max. about 30 % (not

separated)

IN-L9226 max. about 25 %

Fisher (Can.) Thiophene IN-L9225+IN-L9223+IN-W8268 max. about 30 % (not

separated)

Saskatoon Thiophene IN-L9225 (acid) max. 32 % (2 w), DT50 26 d (R2 0.98)

(Canada) IN-L9226 (O-desmethyl) max. 10 % (1 w)

IN-W8268 (thiophene sulfonimide) max. 4 %

London Thiophene IN-L9225 max. 32.6 % (1 mo), DT50 49 d (R2 0.97)

(Canada) IN-W8268 max. 2 %

Triazine IN-L9225 max. 40 % (1 w), DT50 16 d (R2 0.95)

IN-A4098 (triazine amine) max. 30 % (4 mo)

Kentville Thiophene IN-L9225 max. 27.4 % (3 d), DT50 9 d (R2 0.93)

(Canada) IN-W8268 max. 3.6 %

Triazine IN-L9225 max. 30.1 % (3 d), DT50 8 d (R2 0.96)

IN-A4098 max. 15.5 % (1-4 mo)

Calgary Triazine IN-L9225 max. 55.7 % (1 mo)

(Canada) IN-A4098 max. 23 % (12 mo)

Madera Thiophene IN-L9225 max. 60 % (2 mo)

(California) IN-W8268 max. 1.4 %

Triazine IN-L9225 max. 61.5 % (14 d)

IN-A4098 max. 9.6 %

IN-V7160 (triazine urea) detected once at 14.7 %


Conclusions : IN-L9225 (thifensulfuron acid) is the primary metabolite of Thifensulfuron-

methyl found in soil under field conditions (max. 56 % at the canadian sites and

61.5 % in California). For this metabolite, typical DT50f are in the range 8 - 49 d (5

Canadian sites) although slower degradation is observed at Calgary and Madera.

Thus degradation of IN-L9225 is faster under field conditions than under

laboratory conditions. The metabolite IN-A4098 (triazine amine) is usually found

in amounts > 10 % (max. 30 %). The metabolite IN-L9226 (O-desmethyl

Thifensulfuron-methyl) is detected only once above 10 % (max. about 25 %). The

metabolite IN-W8268 (thiophene sulfonimide) is always < 4 %. Because higher

concentrations are found under laboratory conditions (up to 28 %) degradation is

thought to be faster under field conditions than under laboratory conditions. The

metabolite IN-V7160 (triazine urea) is detected only once above 10 % but it has

never been found under laboratory conditions thus it it is deemed to be not

relevant.

(Rapisarda and Scott, 1986; Naidu, 1989a and b)

Report: Aitken, A., Doig, A., Just, G., Cairns, S. (2012); Terrestrial field dissipation study of

Thifensulfuron-methyl (DPX-M6316) following a single application to bare ground - France

2009


Guidelines: EU 7029/VI/1995 Rev 5 (1997), SETAC Europe (1995), SANCO/3029/99 rev.

4 (2000), U.S. EPA 164-1 (1982) Deviations: None



GLP: Yes

Certifying Authority: Department of Health (U.K.), Groupe Interministeriel des Produits

Chimiques (GIPC) (Paris, France)

Previous

evaluation:



DuPont submitted new field dissipation trials at 4 EU locations to

supersede data available in the original DAR (Aitken et al., 2012, 2012a,

2012b, 2012c).

As highlighted above, it should be noted that field dissipation studies

would not actually be triggered based on the parent DT50 << 60 d under

laboratory conditions. The environmental exposure assessment is based

on degradation under laboratory conditions, utilising peak occurrence or

formation fraction of metabolites also under laboratory conditions.

Degradation rates and metabolite formation levels from the field are

therefore not used in the assessment. Therefore the UK RMS concluded

that field dissipation studies were neither required nor used in the

environmental exposure assessment. On this basis, the UK RMS has not

reviewed in detail the existing or new information provided by DuPont.

It should also be noted that in accordance with the AIR2 Regulation

(Commission Regulation (EU) No 1141/2010) new data is required to


reflect changes in either the data requirements or changes in scientific

knowledge since the first inclusion, or to support specific representative

uses. The UK RMS concluded that none of these aspects warranted the

submission or evaluation (in detail) of new field dissipation studies.

From a brief review of the new data provided, the new information

largely supported the conclusions of the laboratory route and rate of

degradation studies. Parent Thifensulfuron-methyl was observed to

degrade rapidly at all locations, with the major degradation products

being essentially the same as observed under laboratory conditions.

Degradation products identified in field dissipation studies were IN-

L9225 (major), IN-L9226, IN-A4098 (major), IN-L9223, IN-A5546,

and IN-W8268. Levels of formation were lower than observed under

laboratory conditions. This supported the use of laboratory data in the

environmental exposure assessment performed by the UK RMS. Since

this information is not relied upon for the regulatory assessment, it has

been greyed out. Note this grey text in this case does not imply that the

studies are invalid, merely that they have not been used int he regulatory

assessment.

Executive summary:

This report describes the soil dissipation of a single application of Thifensulfuron-methyl (lot number

DPX-M6316-280, formulated as a water soluble granule (SG) containing 500 g of active ingredient per

kilogram of formulation (nominal)) to bare ground studied under field conditions in Wagnonville, France, for

ca. 18 months after application on 05 October 2009.

The study design consisted of three replicate treated bare soil plots and a control (untreated) bare soil plot. The

test site soil was characterised as silt loam in horizons 0-5, 5-15, 15-30, 30-50, 50-70, and 70-90 cm. The test

item was applied at a nominal rate of 41 g a.s./ha which was the highest proposed use rate for Thifensulfuron-

methyl for autumn applications. Actual application based on the amount of spray solution applied and the

output from calibrated spray equipment used indicated application at 100.9-103.3% of the targeted application

rate in all three treated plots. The application method was representative of the proposed commercial use of this

product.

Plastic Petri dish bottom halves were used as application monitors to verify the amount applied at application.

Analysis of the contents from the Petri dishes indicated an average recovery of 28.2 g/ha representing 70.5% of

the nominal application rate. Analysis of the soil samples collected immediately after the application had been

applied (Day 0 samples) was also used to verify the application rate. Average recovery of Thifensulfuron-

methyl in Day 0, 0-5 cm soil horizon was 25.9 g/ha (64.8% of nominal applied). However the cumulative total

of residues at Day 0 inclusive of all metabolite residues detected was ca 100% of the nominal application rate

(41 g peq/ha). Soil samples for soil characterisation and biomass were taken. Post treatment soil samples were

collected for 15 sampling intervals on Days +0, 3, 16, 21, 30, 52, 115, 136, 157, 196, 245, 295, 353, 457, and

540 following application of the test item. Five replicate cores were taken from each of the treated replicate

areas at each sampling event. Soil cores were collected in the field at 0-5, 5-15, 15-30, 30-50, 50-70, and

70-90 cm soil depths (except Days 0 and 3, where samples down to 30 cm only were collected).

Soil samples were analysed for residues of Thifensulfuron-methyl and soil metabolites, IN-A4098, IN-A5546,

IN-L9223, IN-L9225, IN-L9226, and IN-W8268, according to the soil residue analytical method described in

Charles River Analytical Method No. 9502 (provided in the report), which was based on analytical method

report DuPont-29189 (summarised in Thifensulfuron-methyl EU Renewal Dossier, Annex IIA, Document M-II,

Section 2, DuPont-32991 EU). Soil samples were extracted using 3 extraction solutions: acetone:0.1M

ammonium carbonate (90:10, v/v); 0.1M ammonium carbonate and acetone: 0.1% formic acid (aq) (90:10, v/v).

An aliquot of the extracts was evaporated to a volume of less than 1 mL and then made to a final volume of 2

mL using 1M ammonium formate: formic acid (100:1, v/v) prior to analysis. These samples were then

analysed using reverse phase UPLC separation coupled to tandem mass spectrometry (LC-MS/MS). The Limit

of Quantification (LOQ) for all analytes was 1.0 ppb.


Fresh fortified samples of control soil were analysed concurrently with each set of treated samples. Each

analysis set included fresh fortifications ranging from the LOQ level of 1 ppb up to 10 ppb. The average

recoveries of the fresh fortification samples analysed concurrently with the analysis of the field samples are

summarised in the Table B.8.158 below.

Table B.8.158 Average recoveries of fresh fortified samples analysed concurrently with the field samples

Analyte

Average recovery

[%]

Relative standard

deviation [%]

Thifensulfuron-methyl 99 8.6

IN-A4098 104 16.5

IN-A5546 97 11.7

IN-L9223 102 15.0

IN-L9225 90 12.3

IN-L9226 99 13.8

IN-W8268 105 10.2

Note: The LOQ and LOD were 1.0 and 0.5 ppb, respectively, for each component

Soil samples from all sampling events were generally analysed to the depth increment at which the residues

found indicating no reasonable expectation of residues in lower depths. Residues were determined in ppb and

then converted to g peq/ha for every sample analysed. Post application (Day 0) soil residues in the 0-5 cm

samples ranged from 21.5 to 28.7 g peq/ha for Thifensulfuron-methyl. When combined with the metabolites

detected on Day 0 the cumulative total of ca. 40 g peq /ha verified the nominal amount of test material applied.

The entire applied test item remained in the uppermost soil segments 0-15 cm, throughout the study.

Residues of Thifensulfuron-methyl declined rapidly throughout this study. The average Day 0 residue,

25.9 g peg/ha (summed for all soil depths) declined to about 17% of the applied amount (4.5 g peq/ha) by Day 3

and to less than 1% of applied (0.3 g peq/ha) by Day 30. Beyond Day 30, there were no residues of

Thifensulfuron-methyl detected. Thus 100% of the applied test substance had degraded by the end of the study.

Five of the six metabolites monitored were detected at some sampling intervals during this study with only

IN-W8268 undetected at any sampling interval. The first three metabolites in the sequence of degradation of

Thifensulfuron-methyl, viz. IN-L9225, IN-L9226, and IN-A4098 were found almost immediately after the

application. IN-L9225 reached an average peak level of 23.7 g peq/ha by Day 3 and declined thereafter, while

IN-L9226 reached an average peak level of 1.7 g peq/ha ca 6 hours after application on Day 0 and then

declined. IN-A4098 reached its highest average total amount 10.0 g peq/ha on Day 52 and then declined to

4.5 g peq/ha by Day 540. A clear decline pattern for the remaining two metabolites, IN-L9223 and IN-A5546

was not established during this study. These metabolites reached a peak average level of 0.4 and 0.2 g peq/ha,

respectively, and these amounts were less than 1% of the applied amount.

The test item and its degradation products remained primarily in the upper 0-15 cm of soil. A single detection

below 15 cm only occurred at one sampling interval (Day 16) and accounted for less than 5% of the applied

amount

Per FOCUS (2006) guidance, the soil data set was assessed using the single first-order (SFO), first-order

multicompartment (FOMC) and double first-order in parallel (DFOP) models for decline rates. Soil

concentrations of Thifensulfuron-methyl in units of % mass of applied parent equivalents (% peq) were used to

compute DT50 and DT90 values using ModelMaker 4 software (Cherwell Scientific). The first-order multi-

compartment (FOMC) model provided the best fit for the decline data as well as for Day 0 residues, and the

statistical evaluation was acceptable based on 2. All

2 error evaluations were well below the 15% requirement

defined in FOCUS guidance. The calculated DT50 and DT90 for Thifensulfuron-methyl were 0.5 and 3.4 days,

respectively.

The storage period between sampling in the field and analyte extraction did not exceed 596 days for all samples

analysed. Freezer storage stability of the soil residues will be documented in a separate study, DuPont-28979

IM, summarised in this document. The results obtained in this study to date indicates acceptable stability of all

residues during frozen storage.



A. MATERIALS

1. Test material: Thifensulfuron-methyl 50SG

Lot/Batch #: M6316-280

Purity: 500 g a.s./kg

Description: Brown solid granule

CAS #: None for the formulation

79277-27-3 for the active substance

Stability of test compound: Shown to be stable at normal conditions

2. Test site

Test site description is detailed in Table B.8.159.

Table B.8.159 Test site description, France

Location: Wagnonville

Country: France

GPS coordinates N5023’23.7”, E00304’17.6”

Representative crop region: Cereal.

Site selection criteria: The field site was flat and level and allowed soil sampling down

to 90 cm.

The site was free from flooding risk.

The site had good security and was readily able to be remarked if

required.

Weather station: 0.2 km from trial site.

Pretreatment exclusion criteria: No other chemical of similar structure applied during the past

3 years.

Plot history, crops grown Grass lawn 2008, grass lawn 2007, grass lawn 2006.

Pesticides used in preceding 3 years No other chemical of similar structure applied during the past

3 years.

Location/Identification of weather station Douai weather station

Distance of weather station from test site 0.2 km

Depth to ground water table Not defined

3. Soils

Soil samples for soil characterisation were taken and data are included in Table

B.8.160.


Table B.8.160 Soil properties at the French site

Soil property

Soil depth (cm)

0-5 5-15 15-30 30-50 50-70 70-90

Sand %

(0.05-2 mm)a

29 27 23 18 19 19

Silt %

(0.05-0.002 mm)a

55 55 59 68 63 63

Clay %

(<0.002 mm)a

16 18 18 14 18 18

pH (water, 1:1)

6.1 5.9 6.4 6.7 6.8 6.9

% Organic matterb

3.5 3.2 2.1 0.6 0.4 0.5

C.E.C [meq/100g]c 11.8 11.9 12.1 10.9 10.4 10.9

Bulk density (g cm-3

) 1.07 1.08 1.16 1.16 1.18 1.21

% Moisture at 1/3 bar 24.4 23.6 21.2 20.7 22.3 22.4

% Moisture at 15 bar 8.7 8.7 7.9 6.7 6.8 7.0

Soil classificationd

Silt loam Silt loam Silt loam Silt loam Silt loam Silt loam

Microbial biomass carbon 155.6 g/g dry basis a Particle size

b Walkley-Black method

c Cation Exchange Capacity (C.E.C)

d Soil classification according to USDA system

B. EXPERIMENTAL DESIGN

1. Experimental design

The experimental details for the test substance application, application rate,

application method etc., are included in Table B.8.161.


Table B.8.161 Experimental design, plot set up and application details

Details Wagnonville, France

Duration of study 540 days

Uncropped (bare) or cropped Bare, maintained weed free

Controls used Yes

Number of plot(s): 3 treated (Replicates I, II, and III) and 1 untreated

control

Treated plot dimensions: 3 m 24 m

Distance between treated plots 3 m

Application rate used (g a.s./ha) 41 g a.s./ha, nominal, Application by two passes in

opposite directions

Was the maximum label rate per ha used in study? Yes

Application date (s) 05-October-2009

Application method Ground-directed boom broadcast spray

Type of spray equipment Backpack sprayer with Lurmark 03F110 nozzles,

6 spray nozzles, 3 m swath width.

Volume of spray solution applied/plot 401-412 L/ha

Identification and volume of carrier (e.g., water), if

used Water

Monthly weather reports included (yes/no) Yes, also daily weather data

Pan evaporation data available? No

Meteorological conditions during application

Cloud cover (%) 100

Temperature (air) 13.1C

Relative Humidity (%) 95

Wind speed 0.6 meters/sec

Sunlight (hr)

[time required for application] Unknown

Rainfall (05 October 2009 – 18 October 2009) 52.7 mm

Verification of application Plastic Petri dishes (approximately 8.7 cm diameter)

and Day 0 soil cores

Field spikes (Transit stability samples) None; Day 0 sample and application monitor analyses

confirmed transit stability

Additional modules added to study: run-off, leaching,

volatilisation

None; however, test placed on flat site with little risk

of flooding to control run-off. Soil sampling to 90 cm

(36 in.) to measure movement in soil

2. Soil sampling

Soil sampling intervals and the sampling depths, and number of cores collected are

listed in Table B.8.162.


Table B.8.162 Soil sampling details

Details Wagnonville

Method of sampling (random or

systematic) Random

Sampling intervals (days ) -1a, +0

b, 3, 16, 21, 30, 52, 115, 136, 157, 196, 245, 295, 353, 457, and

540

Method of soil collection The 0-5 cm segment was sampled using a metal cylinder with an inner

diameter of 9.5 cm driven 5 cm into the soil and the soil was then

scooped out by hand using a spoon. The metal cylinder remained in

place during collection of the lower depths to prevent treated soil from

falling onto the sampling area and potentially contaminating the lower

depths. Soil cores for the 5-90 cm depths were taken with a Humax

coring system. This allowed sampling of the lower depths in

increments of 5-15, 15-30, 30-50, 50-70, and 70-90 cm segments.

Sampling depth Nominally to 90 cm depth

Number of cores collected per plot 5 per replicate plot, 15 per time point total

Depth and diameter of segments 0-5 cm (9.5 cm diameter)

5-15 cm (5 cm diameter)





Storage conditions Frozen

Maximum storage length 596 days a Control soil.

b Immediately after application

3. Description of analytical methods

All soil samples were analysed for Thifensulfuron-methyl and its degradation

products, (IN-A4098, IN-A5546, IN-L9223, IN-L9225, IN-L9226, and IN-W8268)

using Charles River Analytical Method No. 9502, which was based on DuPont-29189

(summarised in Thifensulfuron-methyl EU Renewal Dossier, Annex IIA, Document

M-II, Section 2, DuPont-32991 EU), and validated during this study.

The final purified extracts were quantified for Thifensulfuron-methyl and its

metabolites by ultra performance liquid chromatography (UPLC) with tandem mass

spectrometry employing turbo ion spray ionisation in positive and negative mode.

The instrumentation used for sample analysis, along with the operating conditions

used are detailed in Charles River Analytical Method No. 9502 (provided in the

report).

The Thifensulfuron-methyl, IN-A4098, IN-A5546, IN-L9223, IN-L9225, IN-L9226,

and IN-W8268 peak areas were calculated for the target ion for each of the matrix-

matched calibration standards, quality control samples, control samples, and unknown

test samples. A matrix-matched calibration curve was then obtained by weighted

least squares linear regression analysis (1/x) of the plot peak area versus the

concentration of Thifensulfuron-methyl, IN-A4098, IN-A5546, IN-L9223, IN-L9225,

IN-L9226, and IN-W8268 in each matrix-matched calibration standard. The

concentrations (ppb) of Thifensulfuron-methyl and its degradation products were

calculated using the matrix-matched calibration curve. On some occasions it was

necessary to use matrix-matched calibration standards interspersed throughout the

analytical run to quantify test samples, controls and quality control samples. The

peak areas were calculated for target ion for Thifensulfuron-methyl, IN-A4098,

IN-A5546, IN-L9223, IN-L9225, IN-L9226, and IN-W8268, for each of the matrix-


matched calibration standards, quality control samples, control samples and unknown

test samples in two separate analytical runs. The concentrations (ppb) of

Thifensulfuron-methyl and its degradation products in treated field soil samples were

calculated on a dry weight basis.

The limit of quantification (LOQ) for Thifensulfuron-methyl and its metabolites (IN-

A4098, IN-A5546, IN-L9223, IN-L9225, IN-L9226, and IN-W8268) was 1.0 ppb

since this was the lowest validated level. The limit of detection (LOD) was

determined to be 0.5 ppb for Thifensulfuron-methyl and its metabolites (IN-A4098,

IN-A5546, IN-L9223, IN-L9225, IN-L9226, and IN-W8268). The LOD was

determined as the sample concentration equivalent to the lowest calibration standard

(0.5 ppb = 0.25 ng/mL based upon the dilution factor of sample analysis).

Soil moisture was determined for each sample extracted by drying the sample to at

110C and determining the loss of weight. Moisture data were used to convert wet

weight ppb residues into dry weight ppb.

The ppb residues for parent compound and each degradation product in each sample

were converted to g/ha parent equivalents by multiplying the molar amounts of each

analyte by the parent compound molecular weight to obtain parent equivalent mass.

The parent equivalent masses were further multiplied by the total calculated soil in

one hectare at each depth for conversion to g a.s./ha for the parent and each

degradation product at each depth.


A. APPLICATION VERIFICATION

Application was targeted at a rate of 41 g a.s./ha. The mean actual application rate was

40.84 g a.s./ha (99.6% of the intended application rate, calculated from the sprayer

output). The test material application rate was monitored with the aid of Petri dishes

placed in randomly chosen locations in each of the treated plots. The mean recovery of

Thifensulfuron-methyl on the application monitors, was 28.2 g peq/ha, or 70.5% of the

expected nominal application rate.

In addition to the application monitors, the residues in soil on Day 0 also served to

confirm the actual application rate. Averaged residue of Thifensulfuron-methyl in 0-5

cm soil on Day 0 of 25.9 g peq/ha in the three replicate soil cores, represented 64.8% of

the nominal applied amount. However the cumulative total of residues at Day 0 inclusive

of all metabolite residues detected was ca 100% of the nominal application rate (41 g

peq/ha).

B. RESIDUE DECLINE

Residues in ppb dry weight basis are listed in Tabl.

Post application (Day 0) soil residues in the 0-5 cm samples averaged 56.7 ppb (25.7 g

a.s./ha) for Thifensulfuron-methyl. Residues of Thifensulfuron-methyl declined rapidly

to less than 10% of the applied amount, 6.5 ppb by Day 3 and to less than 1% of applied

amount, 0.8 ppb by Day 30. Beyond Day 30, there were no residues of Thifensulfuron-

methyl detected. Only a small portion of Thifensulfuron-methyl residue moved to lower

depths, showing a maximum of 1.5 ppb in 5-15 cm on Day 3. No residues of

Thifensulfuron-methyl were detected below 15 cm.


Five of the six metabolites monitored were detected during this study with only IN-

W8268 undetected at any sampling interval. The first three metabolites in the sequence

of degradation of Thifensulfuron-methyl, viz., IN-L9225, IN-L9226, and IN-A4098 were

found ca. 4 hours after the application. IN-L9225 reached its highest average level of

23.2 ppb in 0-5cm depth by Day 3 and declined gradually after, while IN-L9226 reached

its average peak level 3.7 ppb in 0-5 cm immediately after application and then declined.

IN-A4098 reached its highest average level of 3.3 ppb in 0-5 cm by Day 30 and then

declined to 1 ppb by Day 540.

IN-A5546 was only detected at one interval at a level of about 0.6 ppb immediately after

application in 0-5 cm and was not detected at any other timepoint or horizon after Day 0.

IN-L9223 was also only detected at one interval at a level of 1 ppb on Day 3 and was not

detected at any other sampling event.

Almost all of the applied test item and its degradation products remained in the upper 0-

15 cm of soil. Detection below 15 cm happened on only one occasion for one

degradation product (IN-L9225) on Day 16 and was less than the LOQ at a level of 0.7

ppb in the 15-30 cm depth.

It can be concluded from these data that Thifensulfuron-methyl degraded rapidly in soil

with the formation of major metabolites that also degraded rapidly. Residues of

Thifensulfuron-methyl and its metabolites were confined to the upper 0–15 cm horizons

except for two isolated detections in the 15–30 cm horizon. Thus, loss of applied

material via leaching did not contribute to the dissipation of residue in this study.

C. MASS BALANCE

In order to quantify the rate of decline of the applied test item, the concentrations of

Thifensulfuron-methyl as well as all metabolites, measured in ppb, were converted to

mass in grams per unit area (g/ha parent equivalents), for each soil segment.

Residues summed for the entire soil column, and averaged for the three replicates are

summarised in Table B.8.164.

D. DISSIPATION KINETICS

The soil data set was assessed using the single first-order (SFO), first-order

multicompartment (FOMC) and double first-order in parallel (DFOP) models for decline

rates. Soil concentrations of Thifensulfuron-methyl in units of percent mass of applied

parent equivalents were used to compute DT50 and DT90 values using ModelMaker 4

software (Cherwell Scientific). The FOMC model provided the best fit for the decline

data as well as for Day 0 residues, and the statistical evaluation was acceptable based on

χ2. The calculated DT50 and DT90 for Thifensulfuron-methyl were 0.5 and 3.4 days,

respectively.

247 Thifensulfuron-methyl - Volume 3, Annex B.8 : Environmental fate and behaviour July 2014 Table B.8.163 Average residues at each depth (ppb dry weight basis)

DAT

(Days) Rep

Depth

(cm)

% Moist

(dwb)


(ppb)

IN-A4098

(ppb)

IN-A5546

(ppb)

IN-L9223

(ppb)

IN-L9225

(ppb)

IN-L9226

(ppb)

IN-W8268

(ppb)

-1a

I 0-5 24.6 <LOD <LOD <LOD <LOD <LOD <LOD <LOD

II 0-5 22.3 <LOD <LOD <LOD <LOD <LOD <LOD <LOD

III 0-5 22.6 <LOD <LOD <LOD <LOD <LOD <LOD <LOD







0b

I 0-5 22.2 43.0 0.881 <LOD <LOD 23.1 2.84 <LOD

II 0-5 23.4 66.5 1.84 <LOD <LOD 22.2 3.98 <LOD

III 0-5 21.9 60.7 1.38 0.618 <LOD 19.0 4.15 <LOD


II 5-15 11.1 0.728 <LOD <LOD <LOD <LOD <LOD <LOD





3

I 0-5 34.1 5.87 1.31 <LOD <LOD 19.3 <LOD <LOD

II 0-5 28.9 7.32 1.76 <LOD 0.992 34.4 0.658 <LOD

III 0-5 31.1 6.24 1.44 <LOD <LOD 15.8 <LOD <LOD

I 5-15 27.9 1.25 <LOD <LOD <LOD 8.78 <LOD <LOD

II 5-15 29.2 <LOD <LOD <LOD <LOD 9.63 <LOD <LOD

III 5-15 27.3 1.48 <LOD <LOD <LOD 9.46 <LOD <LOD





Table B.8.163 Average residues at each depth (ppb dry weight basis) (continued)

DAT

(Days) Rep

Depth

(cm)

% Moist

(dwb)


(ppb)

IN-A4098

(ppb)

IN-A5546

(ppb)

IN-L9223

(ppb)

IN-L9225

(ppb)

IN-L9226

(ppb)

IN-W8268

(ppb)

16

I 0-5 24.1 1.13 2.31 <LOD <LOD 3.29 <LOD <LOD

II 0-5 24.3 1.38 4.19 <LOD <LOD 7.86 <LOD <LOD


I 5-15 26.0 <LOD 1.52 <LOD <LOD 4.42 <LOD <LOD

II 5-15 26.4 <LOD 2.09 <LOD <LOD 4.77 <LOD <LOD

III 5-15 25.0 <LOD 1.22 <LOD <LOD 4.48 <LOD <LOD

I 15-30 18.5 <LOD <LOD <LOD <LOD 0.698 <LOD <LOD



21

I 0-5 28.4 0.964 2.38 <LOD <LOD 2.82 <LOD <LOD

II 0-5 28.1 0.885 2.82 <LOD <LOD 2.99 <LOD <LOD








30

I 0-5 34.9 0.837 2.79 <LOD <LOD 1.24 <LOD <LOD











DAT

(Days) Rep

Depth

(cm)

% Moist

(dwb)


(ppb)

IN-A4098

(ppb)

IN-A5546

(ppb)

IN-L9223

(ppb)

IN-L9225

(ppb)

IN-L9226

(ppb)

IN-W8268

(ppb)

52

I 0-5 29.2 <LOD 1.85 <LOD <LOD <LOD <LOD <LOD

II 0-5 29.9 <LOD 2.93 <LOD <LOD <LOD <LOD <LOD

III 0-5 28.8 <LOD 2.45 <LOD <LOD <LOD <LOD <LOD







115










136












DAT

(Days) Rep

Depth

(cm)

% Moist

(dwb)


(ppb)

IN-A4098

(ppb)

IN-A5546

(ppb)

IN-L9223

(ppb)

IN-L9225

(ppb)

IN-L9226

(ppb)

IN-W8268

(ppb)

157










196










245












DAT

(Days) Rep

Depth

(cm)

% Moist

(dwb)


(ppb)

IN-A4098

(ppb)

IN-A5546

(ppb)

IN-L9223

(ppb)

IN-L9225

(ppb)

IN-L9226

(ppb)

IN-W8268

(ppb)

295










353










457












DAT

(Days) Rep

Depth

(cm)

% Moist

(dwb)


(ppb)

IN-A4098

(ppb)

IN-A5546

(ppb)

IN-L9223

(ppb)

IN-L9225

(ppb)

IN-L9226

(ppb)

IN-W8268

(ppb)

540









III 15-30 22.4 <LOD <LOD <LOD <LOD <LOD <LOD <LOD a Pre-application samples.

b Sampled ca. 6 hours after application had been applied

LOQ = 1 ppb <LOD = <0.5 ppb Quantifiable values >LOD but <LOQ are highlighted in bold.

253 Thifensulfuron-methyl - Volume 3, Annex B.8 : Environmental fate and behaviour July 2014 Table B.8.164 Average residues summed for all depths in g/ha parent equivalents

Days


(g peq/ha)

IN-A4098

(g peq/ha)

IN-A5546

(g peq/ha)

IN-L9223

(g peq/ha)

IN-L9225

(g peq/ha)

IN-L9226

(g peq/ha)

IN-W8268

(g peq/ha)

0*a 25.9 1.7 0.2 0.0 10.2 1.7 0.0

3 4.5 2.2 0.0 0.4 23.7 0.1 0.0

16 0.6 7.9 0.0 0.0 7.8 0.0 0.0

21 0.4 7.6 0.0 0.0 4.5 0.0 0.0

30 0.3 9.3 0.0 0.0 2.0 0.0 0.0

52 0.0 10.0 0.0 0.0 0.0 0.0 0.0

115 0.0 5.1 0.0 0.0 0.0 0.0 0.0

136 0.0 5.6 0.0 0.0 0.0 0.0 0.0

157 0.0 5.0 0.0 0.0 0.0 0.0 0.0

196 0.0 6.2 0.0 0.0 0.0 0.0 0.0

245 0.0 5.4 0.0 0.0 0.0 0.0 0.0

295 0.0 5.6 0.0 0.0 0.0 0.0 0.0

353 0.0 5.2 0.0 0.0 0.0 0.0 0.0

457 0.0 6.6 0.0 0.0 0.0 0.0 0.0

540 0.0 4.5 0.0 0.0 0.0 0.0 0.0 a Samples taken ca 4 hours after application had been applied.

Residues in g/ha parent equivalents.


Table B.8.165 DT50 and DT90 values for Thifensulfuron-methyl in France

Kinetic

model Optimised parameters standard error

2

error r2

DT50

(days)

DT90

(days)

SFO M0 = 100 0.9

k = 0.727 0.058 3 0.993 1.0 3.2

FOMC

Best Fit

M0 = 100 0.9

= 1.332 0.728

= 0.725 0.828

0 0.993 0.5 3.4

DFOP

M0 = 100 + 2

k1 = 0.804 0.262

k2 = 0.045 0.156 (g=1)

0 0.993 0.9 3.2

III. CONCLUSIONS

A field soil dissipation study was conducted with Thifensulfuron-methyl over two seasons on bare ground in a

typical agricultural soil in Wagnonville, France. A nominal 41 g a.s./ha application was made in the autumn

(October), a time that is customary for cereal production.. Soil cores were collected to a depth of 90 cm up to ca

18 months following application. Thifensulfuron-methyl declined rapidly to about 10% of the amount applied,

4.5 g peq/ha by Day 3 and to less than 1% of applied (0.3 g peq/ha) by Day 30. No residues of Thifensulfuron-

methyl were detected after Day 30 of the 540 day study. IN-L9225, IN-L9226 and IN-A4098 were found ca 4

hours after the application. IN-L9225 reached an average peak level of 23.7 g peq/ha by Day 3 and declined

thereafter. IN-L9226 reached an average peak level of 1.7 g peq/ha on Day 0 and declined thereafter.

IN-A4098 reached an average peak level of 10.0 g peq/ha on Day 52 and declined to 4.5 g peq/ha by the end of

the study. Thifensulfuron-methyl and its degradation products were confined to the upper 15 cm of soil.

Detections below 15 cm happened at only one interval and accounted for less than 5% of the applied amount in

any depth segment, and for any individual component. A DT50 of 0.5 days and a DT90 of 3.4 days was

calculated for the parent compound.

Figure B.8.32 Decline of Thifensulfuron-methyl in France

(Aitken, A., Doig, A., Just, G., Cairns, S., 2012)


Report: Aitken, A., Doig, A., Just, G. (2012c); The field soil dissipation of Thifensulfuron-methyl

(DPX-M6316) following a single application to bare ground - Germany 2010


Guidelines: EU 1607/VI/97 Rev 1 (1997), EU 7029/VI/1995 Rev 5 (1997), SETAC Europe (1995),

SANCO/3029/99 rev. 4 (2000), OPPTS 835.6100 (2008) Deviations: None



GLP: Yes


Executive summary:

This study describes the soil dissipation of a single application of Thifensulfuron-methyl 50SG to bare ground

under field conditions in Goch-Nierswalde, Germany for ca 18 months after application on 23 April 2010.

The study design consisted of three replicate treated bare soil plots and a control (untreated) bare soil plot. The

test site soil was characterised as silt loam at 0-5 cm, loam at 5-15 cm, silt loam at 15-70 cm and sand at the

70-90 cm soil horizon. The test item was applied at a nominal rate of 61.5 g a.s./ha which was the highest

proposed annual use rate for spring applications of Thifensulfuron-methyl. Actual application based on the

amount of spray solution applied and the output from calibrated spray equipment used indicated application at

98.3-102.4% of the targeted application rate in all three treated plots. The application method was

representative of the proposed commercial use of this product.

Plastic Petri dish bottom halves were used as application monitors to verify the amount of parent material

applied at application. Analysis of the contents from the Petri dishes indicated an average recovery of

65.4 g peq/ha, representing 106% of the nominal application rate (61.5 g a.s./ha). Analysis of the soil samples

collected immediately after the application had been applied (Day +0 samples) was also used to verify the

application rate. The average calculated recovery of Thifensulfuron-methyl in the 0–5 cm soil layer at Day 0

was 43.6 g/ha (70.9% of nominal applied). However, the cumulative total of residues at Day 0 inclusive of all

depths and all metabolite residues detected was 95.4% of the nominal application rate (61.5 g peq/ha).

Soil samples for soil characterisation and biomass were taken one day before application of the test item. Post

treatment soil samples were collected for 15 sampling intervals on Days +0, 3, 10, 16, 21, 29, 53, 95, 153, 202,

262, 300, 361, 453, and 538 following application of the test item. Five replicate cores were taken from each of

the treated replicate areas at each sampling event. Soil cores were collected in the field at 0-5, 5-15, 15-30,

30-50, 50-70 and 70-90 cm soil depths (except on Day +0 and Day 3, when samples down to 30 cm only were

collected).

Soil samples were analysed for residues of Thifensulfuron-methyl and all significant soil metabolites, IN-

A4098, IN-A5546, IN-L9223, IN-L9225, IN-L9226, and IN-W8268, according to the soil residue analytical

method described in Charles River Analytical Method No. 9535 (provided in the report). Soil samples were

extracted using three extractions solutions: acetone: 0.1M ammonium carbonate (90:10, v/v); 0.1M ammonium

carbonate and acetone: 0.1% formic acid (aq) (90:10, v/v). An aliquot of the extracts was evaporated to a

volume of less than 1 mL and then made to a final volume of 2 mL using 1M ammonium formate: formic acid

(100:1, v/v) prior to analysis. These samples were then analysed using reverse phase UPLC separation coupled

to tandem mass spectrometry (LC-MS/MS). The Limit of Quantification (LOQ) for all analytes was 1.0 ppb

which was sufficient to quantify ≥1.0% of the nominal applied amount based upon the theoretical residue

concentration in the upper soil core (97.8 ppb).

Fresh fortified samples of control soil were analysed concurrently with each set of treated samples. Each

analysis set included fresh fortifications ranging from the LOQ level up to 10 ppb. Residues were routinely

detected above 10 ppb throughout the course of this study therefore additional analyses were performed on a

‘high recovery’ batch containing two control samples fortified at 60 ppb. The average recoveries of the fresh

fortification samples analysed concurrently with the analysis of the field samples, including the ‘high recovery’

batch, are summarised in the Table B.8.166 below.


Table B.8.166 Average recoveries of the fresh fortification samples

Analyte Average recovery [%] Relative standard deviation [%]

Thifensulfuron-methyl 95.5 11.6

IN-A4098 84.9 15.0

IN-A5546 96.6 14.3

IN-L9223 89.7 14.8

IN-L9225 93.0 10.1

IN-L9226 95.6 12.0

IN-W8268 90.2 14.2

The LOQ and LOD were 1.0 and 0.5 ppb, respectively, for each component.

Soil samples from all sampling events were generally analysed to the depth increment at which no detectable

residues were found indicating no reasonable expectation of residues in lower depths. Residues were

determined in ppb and then converted to g peq/ha for every sample analysed. Post application (Day 0) soil

residues in the 0-5 cm samples ranged from 41.4 to 44.9 g peq/ha for Thifensulfuron-methyl; when combined

with the metabolites detected on Day 0 the average total of 58.7 g peq/ha verified the amount of test material

applied. The applied test item remained in the uppermost soil segments 0-15 cm throughout the study, with the

exception of two detections in the 15-30 cm horizon.

Residues of Thifensulfuron-methyl declined rapidly throughout this study. The average Day 0 residue of

Thifensulfuron-methyl, 45.9 g peq/ha (summed for all soil depths) declined to less than half the applied amount,

21.9 g peq/ha by Day 10 and to less than 1% of applied amount (0.3 g peq/ha) by Day 53. Beyond Day 53,

there were no residues of Thifensulfuron-methyl detected except on Day 453 where 1.5 g peq/ha was detected in

one of the replicates in the 15-30 cm horizon.

Five of the six metabolites monitored were detected at some sampling intervals during this study with only

IN-W8268 undetected at any sampling interval. IN-L9225, IN-L9226, IN-A4098, and IN-A5546 were found

immediately after the application. IN-L9225 reached an average peak level of 17.5 g peq/ha on Day 21 and

declined thereafter. IN-L9226 reached an average peak level of 3.7 g peq/ha on Day 3, and then declined to

levels below the LOD by Day 53. IN-A4098 reached its highest average total amount of 9.4 g peq/ha on

Day 453 and was still present at levels of 7.4 g peq/ha by the end of the study at Day 538. IN-A5546 reached an

average peak level of 0.8 g peq/ha on Day 10 declined thereafter. IN-L9223 was detected at a few sampling

intervals with the highest average peak level at 1.8 g peq/ha on Day 95 and was not detected after this time

point.

The applied test item and its degradation products remained primarily in the upper 15 cm of soil. Detections

below 15 cm occurred on two occasions. For those sampling intervals that were analysed below 30 cm, no

residues were detected.

Per FOCUS (2006) guidance, the soil data set was assessed using the single first-order (SFO), first-order

multicompartment (FOMC) and double first-order in parallel (DFOP) models for decline rates. Soil

concentrations of Thifensulfuron-methyl in units of % mass of applied parent equivalents (% peq) were used to

compute DT50 and DT90 values using ModelMaker 4 software (Cherwell Scientific). The SFO model

provided a reasonable visual and statistical fit of the decline data as well as the Day 0 residues. The FOMC and

DFOP models yielded similar results without significant improvements in the visual or statistical fits of the data.

Based on these results, the SFO model is chosen as the appropriate model, yielding a DT50 of 6.4 days and a

DT90 of 21.1 days for Thifensulfuron-methyl dissipation under field conditions.

Components

modelled Kinetic model DT50 (days) DT90 (days) r2

Parent only

kinetics

SFO

6.4 21.1 0.978

FOMC

6.4 21.1 0.978

DFOP

5.8 22.2 0.982


The storage period between sampling in the field and analyte extraction did not exceed 381 days (approximately

13 months) for all samples analysed. Freezer storage stability of the soil residues has been determined to be

acceptable for a period of up to 15 months under a separate on-going storage stability study, DuPont-28979 IM,

summarised in this document.


A. MATERIALS



Purity: 500 g a.s./kg nominal

Description: Brown solid granule

CAS#: None for the formulation



2. Test site

Test site description is detailed in Table B.8.167. Soil samples collected to 90 cm

depth were characterised and the soil characterisation data are included in Table

B.8.168.

Table B.8.167 Test site description, Germany

Location: Berliner Str. 75, 47574, Goch-Nierswalde, Germany

Country: Germany

GPS coordinates 51o 43’ 34” North

6o 7’ 04” East

Representative crop region: Cereal


to 90 cm.



required.

Weather station: Agroplan weather station located 0.3 km from the test site and

Deutscher Wetterdienst weather station located ca 7.0 km from

the test site.


3 years.

Plot history, crops grown Fallow land in 2007, green manuring in 2008 and green

manuring in 2009

Pesticides used in preceding 3 years No other chemical of similar structure applied during the past 3

years.

Location/Identification of weather station Agroplan weather station located 0.3 km from the test site and

Deutscher Wetterdienst weather station located ca 7.0 km from

the test site.

Distance of weather station from test site See above



Table B.8.168 Soil properties at the German site

Soil property

Soil depth (cm)

0-5 5-15 15-30 30-50 50-70 70-90

Sand %

(0.05-2 mm)a

37 49 35 27 37 91

Silt %

(0.002-0.05 mm)a

54 42 54 62 52 5

Clay %

(<0.002 mm)a

9 9 11 11 11 4

pH (soil:water, 1:1)

5.5 5.7 5.9 6.3 6.2 6.1

% Organic matterb

3.8 3.5 2.2 0.52 0.22 0.04

C.E.C [meq/100g]c 7.5 7.7 7.4 5.0 4.4 3.4

Bulk density (gm cc) 1.12 1.11 1.19 1.27 1.33 1.56

% Moisture at 1/3 bar 21.5 23.7 25.8 23.1 20.7 3.7

% Moisture at 15 bar 5.9 6.0 5.1 4.2 3.8 1.7

Soil classificationd

Silt loam Loam Silt loam Silt loam Silt loam Sand

Microbial biomass carbon 98.0 g/g dry basis a Particle size b Walkley-Black method c Cation Exchange Capacity (C.E.C) d Soil classification according to USDA system

B. METHODS




2. Soil sampling






using a method which was based on DuPont-29189 (summarised in Thifensulfuron-

methyl EU Renewal Dossier, Annex IIA, Document M-II, Section 2, DuPont-32991

EU), and validated under this study


metabolites by ultra performance liquid chromatography with tandem mass



used, is detailed in Method No. 9535.

The Thifensulfuron-methyl, (IN-A4098, IN-A5546, IN-L9223, IN-L9225, IN-L9226,

and IN-W8268) peak areas were calculated for the target ion for each of the matrix-

matched calibration standards, quality control samples, control samples, and test

samples. A matrix-matched calibration curve was then obtained by weighted least

squares linear regression analysis (1/) of the plot peak area versus the concentration

of Thifensulfuron-methyl, IN-A4098, IN-A5546, IN-L9223, IN-L9225, IN-L9226,

and IN-W8268 in each matrix-matched calibration standard. The concentrations

(ppb) of Thifensulfuron-methyl and its degradation products were calculated using the


matrix-matched calibration curve. On some occasions it was necessary to use matrix-

matched calibration standards interspersed throughout the analytical run to quantify

test samples, controls and quality control samples. The peak areas were calculated for

target ion for Thifensulfuron-methyl, IN-A4098, IN-A5546, IN-L9223, IN-L9225,

IN-L9226, and IN-W8268, for each of the matrix-matched calibration standards,

quality control samples, control samples and unknown test samples in two separate

analytical runs. The concentrations (ppb) of Thifensulfuron-methyl and its

degradation products in treated field soil samples were calculated on a dry weight

basis.


A4098, IN A5546, IN-L9223, IN-L9225, IN-L9226, and IN-W8268) was 1.0 ppb






Soil moisture was determined for each sample extracted by drying the sample to ca











Details Goch-Nierswalde, Germany



Controls used Yes


control



Application rate used (g a.s./ha) 61.5 g a.s./ha, nominal. Application by two passes in

opposite directions


Application date (s) 23-April-2010


Type of spray equipment Backpack sprayer with Lechler IDK

120-025 POM nozzles, 6 spray nozzles, 3 m swath

width

Volume of spray solution applied/plot 393.1–409.7 L/ha


used Water




Cloud cover (%) 5

Temperature (air) 12.0 C


Wind speed 0.0–1.0 meters/sec

Sunlight (hr)


Supplemental Irrigation Irrigation to supplement natural precipitation

Verification of application Plastic Petri dishes and Day 0 soil cores

Field Spikes (Transit stability samples) None; Day +0 sample and application monitor analyses



volatilisation






Details Goch-Nierswalde, Germany


systematic) Random

Sampling intervals (days) -0, +0 a, 3, 10, 16, 21, 29, 53, 95, 153, 202,

262, 300, 361, 453 and 538 Method of soil collection The 0-5 cm segment was sampled using a metal cylinder with an inner


scooped out. The metal cylinder remained in place during collection of

the lower depths to prevent treated soil from falling onto the sampling

area and potentially contaminating the lower depths. Soil cores for the

5-90 cm depths were taken with a Humax

coring system. This allowed

sampling of the lower depths in increments of 5-15, 15-30, 30-50,

50-70, and 70-90 cm segments.










Maximum storage length 381 days a Immediately after application



Application was targeted at a rate of 61.5 g a.s./ha. The mean actual application rate was

61.4 g a.s./ha (99.8% of the intended application rate, calculated from the sprayer output).

The test material application rate was monitored with the aid of Petri dishes placed in

randomly chosen locations in each of the treated plots. The mean recovery of

Thifensulfuron-methyl as calculated from application monitors was 65.4 g peq/ha, or

106% of the expected nominal application rate.

In addition to the application monitors, the residues in soil on Day +0 also served to


cm soil on Day +0 of 43.6 g peq/ha in the three replicate soil cores, represented 70.9% of

the nominal applied amount and combined with the metabolites detected on Day +0 the

average cumulative total of all depths of 58.7 g peq /ha represented 95.4% of the nominal

applied amount verified the amount of test material applied.

B. RESIDUE DECLINE

Residues in ppb dry weight basis are listed in Table B.8.171.

Post application (Day +0) soil residues in the 0-5 cm samples averaged about 69.4 ppb

for Thifensulfuron-methyl and combined with the metabolites detected on Day +0 the

cumulative average total of 88.4 ppb verified the amount of test material applied.

Residues of Thifensulfuron-methyl declined rapidly to less than 40% of the applied


amount, 36.7 ppb by Day 10 and to less than 1% of applied amount, 0.7 ppb by Day 53.

Beyond Day 53, there were no residues of Thifensulfuron-methyl detected except on Day

453 when a residue of 0.6 ppb was detected in one of the replicates in the 15-30 cm

horizon.


W8268 undetected at any sampling interval. IN-L9225, IN-L9226, IN-A4098, and IN-

A5546 were found immediately after the application. IN-L9225 reached its highest

average level of 26.1 ppb in 0-5cm depth on Day 16 and declined gradually after, while

IN-L9226 reached its average peak level of 5.9 ppb in 0-5 cm on Day 3 after application

and then declined. IN-A4098 reached its highest average level of 4.3 ppb in 0-5 cm by

Day 95 and the total level detected at the end of the study (Day 538) for all depths was

2.9 ppb. IN-A5546 reached its highest total level for all depths of 1.4 ppb on Day 10 and

declined thereafter.

IN-L9223 was first detected on Day 10 with an average level of 1.17 ppb in the 0-5 cm

depth which then rose to an average peak level in the 0-5 cm depth of 1.6 ppb by Day 95

and was not detected at any levels above the LOD after this sampling interval.


15 cm of soil. Detections below 15 cm were infrequent and seldom accounted for more

than 1 ppb in any depth segment, and for any individual component. For those sampling

intervals that were analysed below 30 cm no residues were detected.



Thifensulfuron-methyl were primarily confined to the 0-15 cm horizon, with isolated

detections in the 15–30 cm horizon. Thifensulfuron-methyl was not detected below 30

cm, thus loss of applied material via leaching did not contribute to the dissipation of

residue in this study.

C. MASS BALANCE









rates. Soil concentrations of Thifensulfuron-methyl in units of % mass of applied parent

equivalents (% peq) were used to compute DT50 and DT90 values using ModelMaker 4

software (Cherwell Scientific). The SFO model provided a reasonable visual and

statistical fit of the decline data as well as the Day +0 residues. The FOMC and DFOP

models yielded similar results without significant improvements in the visual or statistical

fits of the data. Based on these results, the SFO model is chosen as the appropriate


model, yielding a DT50 of 6.4 days and a DT90 of 21.1 days for Thifensulfuron-methyl

dissipation under field conditions.


Table B.8.171 Average residues at each depth (ppb dry weight basis)

DAT

(Days) Rep

Depth

(cm)

% Moist

(dwb)


(ppb)

IN-A4098

(ppb)

IN-A5546

(ppb)

IN-L9223

(ppb)

IN-L9225

(ppb)

IN-L9226

(ppb)

IN-W8268

(ppb)

-1










+0a

I 0-5 24.6 70.0 1.37 0.659 <LOD 10.7 4.3 <LOD

II 0-5 26.8 73.1 1.21 <LOD <LOD 12.3 4.8 <LOD

III 0-5 25.7 65.0 1.15 0.670 <LOD 10.2 4.5 <LOD

I 5-15 26.1 1.92 <LOD <LOD <LOD <LOD <LOD <LOD


III 5-15 26.9 0.738 <LOD <LOD <LOD <LOD <LOD <LOD




3

I 0-5 24.4 48.0 2.12 <LOD <LOD 15.4 5.75 <LOD

II 0-5 22.6 59.8 1.93 0.828 <LOD 12.9 5.16 <LOD

III 0-5 24.3 68.7 2.07 0.901 <LOD 13.8 6.71 <LOD

I 5-15 25.9 1.05 <LOD <LOD <LOD <LOD <LOD <LOD








DAT

(Days) Rep

Depth

(cm)

% Moist

(dwb)


(ppb)

IN-A4098

(ppb)

IN-A5546

(ppb)

IN-L9223

(ppb)

IN-L9225

(ppb)

IN-L9226

(ppb)

IN-W8268

(ppb)

10

I 0-5 28.7 29.6 3.15 0.746 1.06 24.5 3.90 <LOD

II 0-5 29.3 35.7 3.02 <LOD 1.29 24.3 4.31 <LOD

III 0-5 28.7 39.6 2.73 <LOD <LOD 17.7 4.55 <LOD


II 5-15 26.9 1.70 <LOD <LOD <LOD 0.860 <LOD <LOD

III 5-15 26.6 <LOD <LOD 0.676 <LOD <LOD <LOD <LOD




16

I 0-5 24.8 15.3 4.34 <LOD 1.41 26.9 2.92 <LOD

II 0-5 25.5 15.9 3.27 <LOD 0.903 28.4 2.41 <LOD

III 0-5 23.9 9.53 4.22 <LOD <LOD 22.9 2.01 <LOD



III 5-15 25.0 <LOD <LOD <LOD <LOD 1.17 <LOD <LOD




21

I 0-5 30.2 9.69 2.79 <LOD 1.15 20.2 0.914 <LOD

II 0-5 31.4 12.1 2.35 <LOD 1.48 26.4 1.07 <LOD

III 0-5 30.5 9.03 2.48 <LOD 0.985 18.3 0.800 <LOD









DAT

(Days) Rep

Depth

(cm)

% Moist

(dwb)


(ppb)

IN-A4098

(ppb)

IN-A5546

(ppb)

IN-L9223

(ppb)

IN-L9225

(ppb)

IN-L9226

(ppb)

IN-W8268

(ppb)

29

I 0-5 22.0 2.96 2.80 <LOD <LOD 7.28 <LOD <LOD

II 0-5 21.9 5.76 3.32 <LOD 0.923 15.2 <LOD <LOD

III 0-5 20.1 5.65 3.63 <LOD 0.841 12.3 0.607 <LOD







53

I 0-5 14.7 0.617 2.49 <LOD <LOD 2.52 <LOD <LOD

II 0-5 17.6 0.716 2.36 <LOD <LOD 3.85 <LOD <LOD








95

I 0-5 24.1 <LOD 3.92 <LOD 0.932 1.57 <LOD <LOD

II 0-5 25.8 <LOD 3.87 <LOD 1.78 1.94 <LOD <LOD

III 0-5 22.6 <LOD 5.15 <LOD 2.11 2.31 <LOD <LOD









DAT

(Days) Rep

Depth

(cm)

% Moist

(dwb)


(ppb)

IN-A4098

(ppb)

IN-A5546

(ppb)

IN-L9223

(ppb)

IN-L9225

(ppb)

IN-L9226

(ppb)

IN-W8268

(ppb)

153










202










262












DAT

(Days) Rep

Depth

(cm)

% Moist

(dwb)


(ppb)

IN-A4098

(ppb)

IN-A5546

(ppb)

IN-L9223

(ppb)

IN-L9225

(ppb)

IN-L9226

(ppb)

IN-W8268

(ppb)

300










361










453












DAT

(Days) Rep

Depth

(cm)

% Moist

(dwb)


(ppb)

IN-A4098

(ppb)

IN-A5546

(ppb)

IN-L9223

(ppb)

IN-L9225

(ppb)

IN-L9226

(ppb)

IN-W8268

(ppb)

538












III 30-50 22.2 <LOD <LOD <LOD <LOD <LOD <LOD <LOD a Sampled immediately after application had dried.

LOQ 1.0 ppb

<LOD = <0.5 ppb

Quantifiable values >LOD but <LOQ are highlighted in bold.


Table B.8.172 Average residues summed for all depths in g/ha parent equivalents

Days


(g peq/ha)

IN-A4098

(g peq/ha)

IN-A5546

(g peq/ha)

IN-L9223

(g peq/ha)

IN-L9225

(g peq/ha)

IN-L9226

(g peq/ha)

IN-W8268

(g peq/ha)

+0* 45.9 2.2 0.5 0.0 7.2 3.0 0.0

3 37.8 3.5 0.6 0.0 8.9 3.7 0.0

10 21.9 4.9 0.8 0.9 14.2 2.7 0.0

16 8.4 6.7 0.0 0.9 17.3 1.6 0.0

21 6.4 4.4 0.0 1.4 17.5 0.6 0.0

29 2.9 5.6 0.0 0.7 7.8 0.1 0.0

53 0.3 3.8 0.0 0.0 1.7 0.0 0.0

95 0.0 7.2 0.0 1.8 1.2 0.0 0.0

153 0.0 4.5 0.0 0.0 0.0 0.0 0.0

202 0.0 3.6 0.0 0.0 0.0 0.0 0.0

262 0.0 5.2 0.0 0.0 0.0 0.0 0.0

300 0.0 4.8 0.0 0.0 0.0 0.0 0.0

361 0.0 4.1 0.0 0.0 0.0 0.0 0.0

453 0.5 9.4 0.0 0.0 0.0 0.0 0.0

538 0.0 7.4 0.0 0.0 0.0 0.0 0.0 a Samples taken immediately after application had dried.


Residue data averaged for three replicate plots at each sampling interval.


Table B.8.173 DT50 and DT90 values for Thifensulfuron-methyl in Germany

Kinetic


2

error r2

DT50

(days)

DT90

(days)

SFO M0 = 97.3 2.7

k = 0.109 0.007 8 0.978 6.4 21.1

FOMC

M0 = 97.3 3

alpha = 118310 991140

beta = 1084900 9039000

9 0.978 6.4 21.1

DFOP

M0 = 99.9 2.9

k1 = 0.098 0.017

k2 = 1 6.355 (g = 0.9)

7 0.982 5.8 22.2

III. CONCLUSIONS

A field soil dissipation study was conducted with Thifensulfuron-methyl over two seasons on

bare ground in a typical agricultural soil in Goch-Nierswalde, Germany. A nominal 61.5 g

a.s./ha application was made in the spring (April) at a time that is customary for cereal

production. Soil cores were collected in a randomised fashion to a depth of 90 cm up to ca.

18 months following application.

Thifensulfuron-methyl declined to less than 0.5% of applied (0.3 g peq/ha) by Day 53. By

the end of the study, (Day 538) no residues of Thifensulfuron-methyl were detected.

IN-L9225, IN-L9226, IN-A4098, and IN-A5546 were found immediately after the

application. IN-L9225 reached an average peak level of 17.5 g peq/ha on Day 21 and

declined thereafter. IN-L9226 reached an average peak level of 3.7 g peq/ha on Day 3 and

declined thereafter. IN-A4098 reached an average peak level of 9.4 g peq/ha on Day 453 and

was still present at levels of 7.4 g peq/ha by the end of the study. IN-A5546 reached an

average peak level of 0.8 g peq/ha on Day 10 and was not detected at any further sampling

time point. IN-L9223 reached an average peak level of 1.8 g peq/ha on Day 95 and no

residues were detected after this time point. Thifensulfuron-methyl and its degradation

products remained in the upper 15 cm of soil. Detections below 15 cm were infrequent. A

DT50 value of 6.4 days and a DT90 value of 21.1 days were calculated for Thifensulfuron-

methyl dissipation under field conditions.

(Aitken, A., Doig, A., Just, G., 2012c)

Report: Aitken, A., Just, G., Doig, A. (2012b); The field soil dissipation of Thifensulfuron-

methyl (DPX-M6316) following a single application to bare ground - Spain 2010


Guidelines: OPPTS 835.6100 (2008), EU 7029/VI/1995 Rev 5 (1997), SETAC Europe

(1995), SANCO/3029/99 rev. 4 (2000) Deviations: None

Testing Facility: Charles River Laboratories (UK), Tranent, Scotland (UK)


GLP: Yes

Certifying Authority: Department of Health (U.K.), Entidad Nacional de Acreditacion

(ENAC) (Spain)


Executive summary:

This study describes the soil dissipation of a single application of Thifensulfuron-methyl

50SG to bare ground studied under field conditions in Termens, Spain for ca 18 months after

application on 06 May 2010.

The study design consisted of three replicate treated bare soil plots and a control (untreated)

bare soil plot. The test site soil was characterised as clay loam at soil horizons from 0–5, 5–

15, 15–30 cm, and as clay at soil horizons from 30–50, 50–70, and 70-90 cm. The test item

was applied at a nominal rate of 61.5 g a.s./ha which was the highest proposed annual use rate

for spring applications of Thifensulfuron-methyl. Actual application based on the amount of

spray solution applied and the output from calibrated spray equipment used indicated

application at 100.8-104% of the targeted application rate in all three treated plots. The

application method was representative of the proposed commercial use of this product.

Plastic Petri dish bottom halves were used as application monitors to verify the amount of

parent material applied at application. Analysis of the contents from the Petri dishes

indicated an average recovery of 90.4 g peq/ha, representing 147% of the nominal application

rate (61.5 g a.s./ha). Analysis of the soil samples collected immediately after the application

had been applied (Day 0 samples) was also used to verify the application rate. The average

calculated recovery of Thifensulfuron-methyl in the 0–5 cm soil layer at Day +0 was 28.2

g/ha (45.9% of nominal applied). However, the cumulative total of residues at Day +0

inclusive of all depths and all metabolite residues detected was 82.0% of the nominal

application rate (61.5 g peq/ha).

Soil samples for soil characterisation and biomass were taken two days before application of

the test item. Post treatment soil samples were collected for 15 sampling intervals on Days

+0, 5, 11, 15, 20, 29, 48, 98, 154, 202, 250, 301, 358, 447 and 533 following application of

the test item. Five replicate cores were taken from each of the treated replicate areas at each

sampling event. Soil cores were collected in the field at 0-5, 5-15, 15-30, 30-50, 50-70 and

70-90 cm soil depths (except on Day +0 and Day 5, when samples down to 30 cm only were

collected).

Soil samples were analysed for residues of Thifensulfuron-methyl and all significant soil

metabolites, IN-A4098, IN-A5546, IN-L9223, IN-L9225, IN-L9226, and IN-W8268,

according to the soil residue analytical method described in Charles River Analytical Method

No. 9536 (provided in the report). Soil samples were extracted using 3 extractions solutions:

acetone: 0.1M ammonium carbonate (90:10, v/v); 0.1M ammonium carbonate and acetone:

0.1% formic acid (aq) (90:10, v/v). An aliquot of the extracts was evaporated to a volume of

less than 1 mL and then made to a final volume of 2 mL using 1M ammonium formate:

formic acid (100:1, v/v) prior to analysis. These samples were then analysed using reverse

phase UPLC separation coupled to tandem mass spectrometry (LC-MS/MS). The Limit of

Quantification (LOQ) for all analytes was 1.0 ppb which was sufficient to quantify ≥1.0% of

the nominal applied amount based upon the theoretical residue concentration in the upper soil

core (97.0 ppb).

Fresh fortified samples of control soil were analysed concurrently with each set of treated

samples. Each analysis set included fresh fortifications ranging from the LOQ level up to 10

ppb. Residues were routinely detected above 10 ppb throughout the course of this study

therefore additional analyses were performed on a ‘high recovery’ batch containing two


control samples fortified at 70 ppb. The average recoveries of the fresh fortification samples

analysed concurrently with the analysis of the field samples, including the ‘high recovery’

batch, are summarised in the Table B.8.174 below.

Table B.8.174 A summary of the average recoveries of the fresh fortification samples

Analyte Average recovery (%) Relative standard deviation (%)


IN-A4098 87.3 13.3

IN-A5546 97.2 10.3

IN-L9223 101 10.1

IN-L9225 98.9 13.7

IN-L9226 94.6 14.0

IN-W8268 101 10.2

Note: The LOQ and LOD were 1.0 and 0.5 ppb, respectively, for each component

Soil samples from all sampling events were generally analysed to the depth increment at

which no detectable residues were found indicating no reasonable expectation of residues in

lower depths. Residues were determined in ppb and then converted to g peq/ha for every

sample analysed. Post application (Day 0) soil residues in the 0-5 cm samples ranged from

13.1 to 47.0 g peq/ha for Thifensulfuron-methyl, when combined with the metabolites

detected on Day 0 the average total of 50.4 g peq/ha verified the amount of test material

applied. The entire applied test item remained in the uppermost soil segments 0-15 cm,

throughout the study.

Residues of Thifensulfuron-methyl declined rapidly throughout this study. The average Day

+0 residue, 30.6 g peq/ha (summed for all soil depths) declined to about 2% of the applied

amount, 1.1 g peq/ha by Day 5 and to 1% of applied amount (0.3 g peq/ha) by Day 20.

Beyond Day 20, there were no residues of Thifensulfuron-methyl detected. Thus 100% of

the applied test substance had degraded by the end of the study.

Five of the six metabolites monitored were detected at some sampling intervals during this

study with only IN-A5546 undetected at any sampling interval. IN-L9225, IN-L9226, and

IN-A4098 were found immediately after the application. IN-L9225 reached an average peak

level of 52.9 g peq/ha on Day 15 and declined to 0.2 g peq/ha by the end of the study (540

DAA). IN-A4098 reached an average peak level of 11.3 g peq/ha on Day 100 and then

declined to 6.7 g peq/ha by the end of the study (Day 540). IN-L9226 was detected on Day 0

with an average of 2.1 g peq/ha but not at any other sampling time point. IN-L9223 reached

an average peak level of 1.0 g peq/ha on Day 30, and then declined to levels below LOD by

Day 150. An average detection of IN-W8268 was found at Day 20 (0.5 g peq/ha), but not at

any other sampling time point.

Almost all of the applied test item and its degradation products remained in the upper 15 cm

of soil. A single detection below 15 cm was observed, for metabolite IN-L9225 (1.8 g

peq/ha) noted at 50 days after application in the 15–30 cm soil horizon. For those sampling

intervals that were analysed below 30 cm, no residues were detected.

Per FOCUS (2006) guidance, the soil data set was assessed using the single first-order (SFO),

first-order multicompartment (FOMC) and double first-order in parallel (DFOP) models for

decline rates. Soil concentrations of Thifensulfuron-methyl in units of % mass of applied


parent equivalents (% peq) were used to compute DT50 and DT90 values using ModelMaker

4 software (Cherwell Scientific).

Reliable dissipation kinetics (SFO, FOMC or DFOP) could not be fitted to the data, due to

very rapid degradation of Thifensulfuron-methyl with only ca 2% of the test item remaining

at the first sampling interval (Day 5) after the day of application (Day 0). Therefore, the

DT50 and DT90 values are assigned as <5 days.

The storage period between sampling in the field and analyte extraction did not exceed 364

days for all samples analysed. Freezer storage stability of the soil residues is documented in

a separate GLP study, DuPont-28979 IM, summarised in this document.


A. MATERIALS



Purity: 500 g a.s./kg

Description: Solid granule

CAS #: None for the formulation



2. Test site

Test site description is detailed in Table B.8.175.

Table B.8.175 Test site description, Spain

Location: Termens, Catalunya, Spain, 25142

Country: Spain

GPS coordinates N 41°42.348’ E 0°47.824’

Representative crop region: Cereal

Site selection criteria:

The field site was flat and level and allowed soil sampling down

to 90 cm.



required.

Weather station:

Cwi Technical weather station located on the test site and

Vallfogna de Balaguer weather station which was <20km away

from the test site.


3 years.

Plot history, crops grown Maize in 2009, Maize in 2008 and no crop in 2007

Pesticides used in preceding 3 years No other chemical of similar structure applied during the past 3

years.

Location/Identification of

weather station

Cwi Technical weather station located on the test site and

Vallfogna de Balaguer weather station which was <20km away

from the test site.

Distance of weather station from test site station on-site; back-up station <20km



3. Soils

Soil samples collected to 90 cm depth were characterised and the soil characterisation

data are included in Table B.8.176 .

Table B.8.176 Soil properties at the Spanish site

Soil property

Soil depth (cm)

0-5 5-15 15-30 30-50 50-70 70-90

Sand %

(0.05-2 mm)a

40 36 34 12 6 10

Silt %

(0.05-0.002 mm)a

30 32 30 36 38 36

Clay %

(<0.002 mm)a

30 32 36 52 56 54

pH (water, 1:1)

7.9 8.0 8.0 8.1 8.2 8.3

% Organic matterb

2.3 2.4 1.4 0.53 0.35 0.35

C.E.C [meq/100g]c 25.2 34.2 40.3 40.9 30.8 24.9

Bulk density (gm cc) 1.11 1.10 1.17 1.13 1.12 1.13

% Moisture at 1/3 bar 21.7 24.0 21.5 26.4 27.1 26.7

% Moisture at 15 bar 12.0 12.8 12.2 16.1 16.1 15.9

Soil classificationd Clay

loam

Clay

loam

Clay

loam Clay Clay Clay





B. EXPERIMENTAL DESIGN






Details Termens, Spain



Controls used Yes


control



Application rate used (g a.s./ha) 61.5 g a.s./ha, nominal. Application by two passes in

opposite directions


Application date (s) 06-May-2010


Type of spray equipment Backpack sprayer with Lurmark 03F110 flat fan

nozzles, 6 spray nozzles, 3 m swath width.



used Water




Cloud cover (%) 30




Sunlight (hr)


Supplemental irrigation Irrigation to supplement natural precipitation

Verification of application Plastic Petri dishes and Day 0 soil cores

Field spikes (Transit stability samples) None; Day 0 sample and application monitor analyses



volatilisation




2. Soil sampling




Table B.8.178 Soil sampling details, Spain

Details Termens, Spain


systematic) Random

Sampling intervals (days) -0, +0 a, 5, 11, 15, 20, 29, 48, 98, 154, 202, 250,

301, 358, 447, and 533






5-90 cm depths were taken with a Humax® coring system. This allowed

sampling of the lower depths in increments of 5-15, 15-30, 30-50,

50-70, and 70-90 cm segments.
















EU), and validated under this study.





used, is detailed in Charles River Method No. 9536 (provided in report).





least squares linear regression analysis (1/x) of the plot peak area versus the

concentration of Thifensulfuron-methyl, (IN-A4098, IN-A5546, IN-L9223, IN-

L9225, IN-L9226, and IN-W8268) in each matrix-matched calibration standard. The







matched calibration standards, quality control samples, control samples and unknown












Soil moisture was determined for each sample extracted by drying the sample to ca

110oC and determining the loss of weight. Moisture data were used to convert wet














Thifensulfuron-methyl on the application monitors was 90.4 g peq/ha, or 147% of the








B. RESIDUE DECLINE


Post application (Day 0) soil residues in the 0-5 cm samples averaged about 47.7 ppb

(28.2 g a.s./ha) for Thifensulfuron-methyl and combined with the metabolites detected on

Day 0 the cumulative average total of 71.1 ppb verified the amount of test material

applied. Residues of Thifensulfuron-methyl declined rapidly to ca. 2% of the applied

amount, 1.6 ppb by Day 5 and to less than LOD, 0.7 ppb by Day 20. Beyond Day 20,

there were no residues of Thifensulfuron-methyl detected. No residues of

Thifensulfuron-methyl were detected in the 15-30 cm soil segment at any sampling

interval, and only on Day 0 were residues of Thifensulfuron-methyl detected in the 5-15

cm soil segment.



A5546 undetected at any sampling interval. IN-L9225, IN-L9226 and IN-A4098, were

found immediately after the application. IN-L9225 reached its highest average level of

70.2 ppb in 0-5cm depth on Day 10 and declined to 0.6 ppb by the end of the study, while

IN-L9226 reached its average peak level of 2.1 ppb in 0-5 cm immediately after

application and was not detected at any further sampling interval. IN-A4098 reached its

highest average level of 4.3 ppb in 0-5 cm by Day 100 and then declined to 2.0 ppb by

the end of the study.

IN-L9223 reached an average level of 0.9 ppb in 0-5 cm on Day 30 and declined

thereafter. IN-W8268 was detected at only one sampling interval (20 DAA) with a value

of 1.2 ppb detected in the 0-5 cm soil segment.


15 cm of soil. There was only one instance of a residue being detected below 15 cm

during the trial conduct. For those sampling intervals that were analysed below 30 cm no

residues were detected.



Thifensulfuron-methyl were primarily confined to the 0–15 cm horizons, with isolated

detections in the 15–30 cm horizon. Thifensulfuron-methyl was not detected below 30

cm, thus, loss of applied material via leaching did not contribute to the dissipation of

residue in this study.

C. MASS BALANCE









rates. Soil concentrations of Thifensulfuron-methyl in units of % mass of applied parent

equivalents were used to compute DT50 and DT90 values using ModelMaker 4 software

(Cherwell Scientific). Reliable dissipation kinetics (SFO, FOMC or DFOP) could not be

fitted to the data, due to very rapid degradation of Thifensulfuron-methyl with only ca.

2% of the test item remaining at the first sampling interval (Day 5) after the day of

application (Day 0). Therefore, the DT50 and DT90 values are assigned as <5 days,

although the actual values are significantly less than 5 days.



DAT

(Days) Rep

Depth

(cm)

% Moist

(dwb)

Thifensulfuron

methyl

(ppb)

IN-A4098

(ppb)

IN-A5546

(ppb)

IN-L9223

(ppb)

IN-L9225

(ppb)

IN-L9226

(ppb)

IN-W8268

(ppb)

0










0a

I 0-5 15.1 73.6 1.18 <LOD <LOD 33.4 3.24 <LOD

II 0-5 21.2 31.2 <LOD <LOD <LOD 10.1 0.930 <LOD

III 0-5 15.5 38.3 0.849 <LOD <LOD 28.6 2.12 <LOD

I 5-15 21.1 3.03 <LOD <LOD <LOD 2.41 <LOD <LOD

II 5-15 22.7 2.14 <LOD <LOD <LOD 0.888 <LOD <LOD





5

I 0-5 20.4 1.59 1.25 <LOD <LOD 66.7 <LOD <LOD

II 0-5 19.2 2.35 1.31 <LOD <LOD 63.0 <LOD <LOD










DAT

(Days) Rep

Depth

(cm)

% Moist

(dwb)

Thifensulfuron

methyl

(ppb)

IN-A4098

(ppb)

IN-A5546

(ppb)

IN-L9223

(ppb)

IN-L9225

(ppb)

IN-L9226

(ppb)

IN-W8268

(ppb)

11

I 0-5 12.9 1.03 2.20 <LOD <LOD 60.3 <LOD <LOD

II 0-5 14.1 1.09 2.45 <LOD <LOD 72.9 <LOD <LOD








15

I 0-5 10.9 0.930 2.55 <LOD <LOD 68.1 <LOD <LOD

II 0-5 12.3 1.24 2.24 <LOD <LOD 50.6 <LOD <LOD








20

I 0-5 7.6 0.562 2.02 <LOD 0.801 69.3 <LOD 1.21

II 0-5 9.2 0.843 2.86 <LOD 0.897 72.1 <LOD <LOD










DAT

(Days) Rep

Depth

(cm)

% Moist

(dwb)

Thifensulfuron

methyl

(ppb)

IN-A4098

(ppb)

IN-A5546

(ppb)

IN-L9223

(ppb)

IN-L9225

(ppb)

IN-L9226

(ppb)

IN-W8268

(ppb)

29

I 0-5 11.0 <LOD 2.43 <LOD 0.621 49.7 <LOD <LOD

II 0-5 12.0 <LOD 2.55 <LOD 0.704 55.6 <LOD <LOD








48













98

I 0-5 9.9 <LOD 4.98 <LOD 0.570 14.7 <LOD <LOD











DAT

(Days) Rep

Depth

(cm)

% Moist

(dwb)

Thifensulfuron

methyl

(ppb)

IN-A4098

(ppb)

IN-A5546

(ppb)

IN-L9223

(ppb)

IN-L9225

(ppb)

IN-L9226

(ppb)

IN-W8268

(ppb)

154










202










250












DAT

(Days) Rep

Depth

(cm)

% Moist

(dwb)

Thifensulfuron

methyl

(ppb)

IN-A4098

(ppb)

IN-A5546

(ppb)

IN-L9223

(ppb)

IN-L9225

(ppb)

IN-L9226

(ppb)

IN-W8268

(ppb)

301










358










447












DAT

(Days) Rep

Depth

(cm)

% Moist

(dwb)

Thifensulfuron

methyl

(ppb)

IN-A4098

(ppb)

IN-A5546

(ppb)

IN-L9223

(ppb)

IN-L9225

(ppb)

IN-L9226

(ppb)

IN-W8268

(ppb)

533









III 15-30 17.7 <LOD <LOD <LOD <LOD <LOD <LOD <LOD a Sampled immediately after application had dried

LOQ 1.0 ppb

<LOD = <0.5 ppb




Days


(g peq/ha)

IN-A4098

(g peq/ha)

IN-A5546

(g peq/ha)

IN-L9223

(g peq/ha)

IN-L9225

(g peq/ha)

IN-L9226

(g peq/ha)

IN-W8268

(g peq/ha)

0a 30.6 1.2 0.0 0.0 17.2 1.4 0.0

5 1.1 2.1 0.0 0.0 44.7 0.0 0.0

11 0.7 4.4 0.0 0.0 52.2 0.0 0.0

15 0.7 5.3 0.0 0.0 52.9 0.0 0.0

20 0.3 3.9 0.0 0.9 45.1 0.0 0.5

29 0.0 4.6 0.0 1.0 42.8 0.0 0.0

48 0.0 5.9 0.0 0.0 22.0 0.0 0.0

98 0.0 11.3 0.0 0.5 11.7 0.0 0.0

154 0.0 7.1 0.0 0.0 5.9 0.0 0.0

202 0.0 7.5 0.0 0.0 5.9 0.0 0.0

250 0.0 7.8 0.0 0.0 5.3 0.0 0.0

301 0.0 7.5 0.0 0.0 4.6 0.0 0.0

358 0.0 8.8 0.0 0.0 3.1 0.0 0.0

447 0.0 5.4 0.0 0.0 0.4 0.0 0.0

533 0.0 6.7 0.0 0.0 0.2 0.0 0.0 a Samples taken immediately after application had dried




Table B.8.181 DT50 and DT90 values for Thifensulfuron-methyl in Spain

Kinetic


2

error r2

DT50

(days)

DT90

(days)

SFOa M0 = 100 11.3

k = 0.757 1.014 4 0.8 0.9 3.0

FOMCb

M0 = 100 11.6

= 0.774 6.783

= 0.032 1.61

1 0.8 0.0 0.7

DFOPc

M0 = 100 12

k1 = 1 9.468

k2 = 0.072 1.362 (g = 1)

2 0.8 0.7 2.6

a Rate constant k fails t-test for statistical significance.

b Poor visual fit.

c Rate constants k1 and k2 fail t-test for statistical significance.

III. CONCLUSIONS


bare ground in a typical agricultural soil in Termens, Spain. A nominal 61.5 g a.s./ha

application was made in the spring (May), a time that is customary for cereal production.

Soil cores were collected in a randomised fashion to a depth of 90 cm up to ca. 18 months

following application.

Thifensulfuron-methyl declined rapidly to about 2% of the amount applied, 1.1 g peq/ha by

Day 5 and to 0.5% of applied (0.3 g peq/ha) by Day 20. By the end of the study (Day 540),

no residues of Thifensulfuron-methyl were detected.

IN-L9225, IN-L9226, and IN-A4098 were found immediately after the application.

IN-L9225 reached an average peak level of 52.9 g peq/ha on Day 15 and declined thereafter.

IN-L9226 was detected only at Day 0 with an average level of 1.4 g peq/ha detected. IN-

A4098 reached an average peak level of 11.3 g peq/ha on Day 100 and declined thereafter.

IN-L9223 reached an average peak level of 1.0 g peq/ha and declined by the end of the study.

IN-W8268 was detected on only one sampling interval with an average level of 0.5 g peq/ha

on Day 20 and was not detected at any other sampling event.

Thifensulfuron-methyl and its degradation products were confined to the upper 15 cm of soil.

A single detection of IN-L9225 was made in the 15-30 cm depth segment. A DT50 and DT90

value of <5 days was assigned for the parent compound.

(Aitken, A., Just, G., Doig, A., 2012b)

Report: Aitken, A., Just, G., Doig, A. (2012a); The field soil dissipation of Thifensulfuron-

methyl following a single application to bare ground - Italy 2010


Guidelines: OPPTS 835.6100 (2008), EU 1607/VI/97 Rev 1 (1997), EU 7029/VI/1995 Rev

5 (1997), SETAC Europe (1995), SANCO/3029/99 rev. 4 (2000) Deviations: None

Testing Facility: Charles River Laboratories (UK), Tranent, Scotland (UK)



GLP: Yes


Executive summary:

This study describes the soil dissipation of a single application of Thifensulfuron-methyl

50SG to bare ground studied under field conditions in Graffignana, Italy, for ca 15 months

after application on 26 April 2010.

The study design consisted of three replicate treated bare soil plots. The test site soil was

characterised as loam in horizons 0-5, 5-15, 15-30, 30-50, 50-70, and 70-90 cm. The test

item was applied at a nominal rate of 61.5 g a.s./ha which was the highest proposed use rate

for spring applications of Thifensulfuron-methyl. Actual application based on the amount of

spray solution applied and the output from calibrated spray equipment used indicated

application at 97.6-99.2% of the targeted application rate in all three treated plots. The

application method was representative of the proposed commercial use of this product.

Plastic Petri dish bottom halves were used as application monitors to verify the amount

applied at application. Analysis of the contents from the Petri dishes indicated an average

recovery of 56.4 g /ha, representing 92% of the nominal application rate (61.5 g a.s./ha).

Analysis of the soil samples collected immediately after the application had been applied

(Day 0 samples) was also used to verify the application rate. The average calculated recovery

of Thifensulfuron-methyl in the 0-5cm soil layer at Day +0 was 26.5 g/ha (43.1% of nominal

applied). However, the cumulative total of residues at Day +0 inclusive of all depths and all

metabolite residues detected was 85.2% of the nominal application rate (61.5 g peq/ha).

Soil samples for soil characterisation and biomass were taken before application of the test

item. Post treatment soil samples were collected for 14 sampling intervals on Days +0, 3, 11,

15, 31, 52, 73, 99, 149, 199, 253, 304, 359, and 452 following application of the test item.

Five replicate cores were taken from each of the treated replicate areas at each sampling

event. Soil cores were collected in the field at 0-5, 5-15, 15-30, 30-50, 50-70, and 70-90 cm

soil depths (except on Day 0 and Day 3, when samples down to 30 cm only were collected).

Soil samples were analysed for residues of Thifensulfuron-methyl and all significant soil

metabolites, IN-A4098, IN-A5546, IN-L9223, IN-L9225, IN-L9226, and IN-W8268,

according to the soil residue analytical method described in Charles River Analytical Method

No. 9537 (provided in the report). Soil samples were extracted using three extractions

solutions: acetone: 0.1M ammonium carbonate (90:10, v/v); 0.1M ammonium carbonate and

acetone: 0.1% formic acid (aq) (90:10, v/v). An aliquot of the extracts was evaporated to a

volume of less than 1 mL and then made to a final volume of 2 mL using 1M ammonium

formate: formic acid (100:1, v/v) prior to analysis. These samples were then analysed using

reverse phase UPLC separation coupled to tandem mass spectrometry (LC-MS/MS). The

Limit of Quantification (LOQ) for all analytes was 1.0 ppb which was sufficient to quantify

≥1.0% of the nominal applied amount based upon the theoretical residue concentration in the

upper soil core.

Fresh fortified samples of control soil were analysed concurrently with each set of treated

samples. Each analysis set included fresh fortifications ranging from the LOQ level up to 10

ppb. Residues were routinely detected above 10 ppb throughout the course of this study

therefore an additional ‘high recovery’ batch containing two fortified control samples at

50 ppb was performed. The average recoveries of the fresh fortification samples analysed


concurrently with the analysis of the field samples, including the ‘high recovery’ batch, are

summarised in the Table B.8.182 below:

Table B.8.182 Average recoveries of the fresh fortification samples analysed concurrently

with the analysis of the field samples

Analyte

Average recovery

[%]

Relative standard

deviation [%]


IN-A4098 84.0 10.7

IN-A5546 89.7 11.5

IN-L9223 94.2 9.0

IN-L9225 89.3 11.3

IN-L9226 93.0 10.2

IN-W8268 97.2 10.5

The LOQ and LOD were 1.0 and 0.5 ppb, respectively, for each component.

Soil samples from S1-S14 sampling events were generally analysed to the depth increment at

which the residues found indicated no reasonable expectation of residues in lower depths.

Residues were determined in ppb and then converted to g peq/ha for every sample analysed.

Post application (Day 0) soil residues in the 0-5 cm samples ranged from 21.2 to 30.1 g

peq/ha for Thifensulfuron-methyl, when combined with the metabolites detected on Day 0

the average total of 52.4 g peq /ha verified the amount of test material applied. The entire

applied test item remained in the uppermost soil segments 0-30 cm, throughout the study.

Residues of Thifensulfuron-methyl declined rapidly throughout this study. Average residue,

27.0 g peq/ha (summed for all soil depths) declined to 24% of the applied amount, 14.9

g peq/ha by Day 3 and to 2.3% of applied amount (1.4 g peq/ha) by Day 15. Beyond Day 31,

there were no residues of Thifensulfuron-methyl detected. Thus 100% of the applied test

substance had degraded by the end of the study.

Four of the six metabolites monitored were detected at some sampling intervals during this

study with only IN-A5546 and IN-W8268 undetected at any sampling interval. IN-L9225,

IN-L9226, and IN-A4098 were found immediately after the application. IN-L9225 reached

an average peak level of 19.9 g peq/ha on Day 0 and declined thereafter, IN-L9226 reached

an average peak level of 2.5 gpeq/ha on Day 0, and then declined to levels below LOD by

Day 11. IN-A4098 reached its highest average total amount (14.2 g peq/ha on Day 15) and

then declined by the end of the study. A detection of IN-L9223 was found at Day 3 (0.6 g

peq/ha), but not at any other sampling time point.

Almost all of the applied test item and its degradation products remained in the upper 15 cm

of soil. Detections below 15 cm were infrequent. For those sampling intervals that were

analysed below 30 cm, no residues were detected.

Per FOCUS (2006) guidance, the soil data set was assessed using the single first-order (SFO),

first-order multicompartment (FOMC) and double first-order in parallel (DFOP) models for

decline rates. Soil concentrations of Thifensulfuron-methyl in units of % mass of applied

parent equivalents (% peq) were used to compute DT50 and DT90 values using ModelMaker

4 software (Cherwell Scientific). The first-order multi-compartment (FOMC) model

provided the best fit for the decline data as well as for Day 0 residues, and the statistical


evaluation was acceptable based on χ2. All χ

2 error evaluations were well below the 15%

requirement defined in FOCUS guidance. The calculated DT50 and DT90 for Thifensulfuron-

methyl were 1.5 and 6.5 days, respectively.

The storage period between sampling in the field and analyte extraction did not exceed 508

days for all samples analysed. Freezer storage stability of the soil residues is documented in

a separate GLP study, DuPont-28979 IM, summarised in this document.


A. MATERIALS



Purity: 500 g a.s./kg nominal

Description: Light brown solid granule

CAS#: None for the formulation



2. Test Site

Test site description is detailed in Table B.8.183. Soil characterisation samples were

taken and data are included in Table B.8.184.

Table B.8.183 Test site description

Location: Graffignana

Country: Italy

GPS Coordinates 009 26’ 631” E, 45 13’ 325” N

Representative crop region: Cereal.


to 90 cm.



required.

Weather station: Cwi Technical weather station located on the test site and ARPA

Lombardia weather station which was 2.82 km away from the

test site.


3 years.

Plot history, crops grown Corn in 2009, Wheat in 2007-2008 and Corn in 2007

Pesticides used in preceding 3 years No other chemical of similar structure applied during the past

3 ears.

Location/Identification of

weather station

Cwi Technical weather station located on the test site and ARPA

Lombardia weather station which was 2.82 km away from the

test site.

Distance of weather station from test site See above



Table B.8.184 Soil properties at the Italian site

Soil property

Soil depth (cm)

0-5 5-15 15-30 30-50 50-70 70-90

Sand %

(0.05-2 mm)a

47 44 46 44 34 36

Silt %

(0.05-0.002 mm)a

39 40 38 38 44 44

Clay %

(<0.002 mm)a

14 16 16 18 22 20

pH (water, 1:1)

6.6 6.2 6.7 6.4 6.5 6.6

% Organic matterb

2.2 1.7 2.0 0.93 0.26 0.22

C.E.C [meq/100g]c 10.7 10.0 10.1 10.6 10.5 10.6

Bulk density (g cm-3

) 1.22 1.20 1.20 1.26 1.22 1.24

% Moisture at 1/3 bar 18.3 19.1 21.6 19.5 21.0 23.2

% Moisture at 15 bar 7.8 7.5 8.0 8.1 9.3 9.1

Soil Classificationd

Loam Loam Loam Loam Loam Loam





B. METHODS



application method, etc., are included in Table B.8.185.

2. Soil sampling








EU), and validated under this study.





used, is detailed in Charles River Method No. 9537 (provided in the report).





least squares linear regression analysis (1/) of the plot peak area versus the

concentration of Thifensulfuron-methyl, (IN-A4098, IN-A5546, IN-L9223, IN-

L9225, IN-L9226 and IN-W8268) in each matrix-matched calibration standard. The



















Soil moisture was determined for each sample extracted by drying the sample to at







one hectare at each depth for conversion to g ai/ha for the parent and each degradation

product at each depth.



Details Graffignana, Italy



Controls used Control samples were collected.

Number of plot(s): 3 treated (Replicates I, II, and III)



Application rate used (g a.s./ha) 61.5 g a.s./ha, nominal, Application by two passes in

opposite directions


Application date (s) 26-April-2010


Type of spray equipment Backpack sprayer with Lurmark 02F110 nozzles, 6

spray nozzles, 3 m swath width.



used

Water




Cloud cover (%) 0




Sunlight (hr)

[time required for application]

Unknown

Supplemental Irrigation Irrigation to supplement natural precipitation

Verification of Application Plastic Petri dishes and Day 0 soil cores

Field Spikes (Transit stability samples) None; Day 0 sample and application monitor analyses



volatilisation






Details Graffignana


systematic)

Random

Sampling intervals (days ) +0a, 3, 11, 15, 31, 52, 73, 99, 149, 199, 253, 304, 359, and 452






5-90 cm depths were taken with a Humax® coring system. This

allowed sampling of the lower depths in increments of 5-15, 15-30,

30-50, 50-70, and 70-90 cm segments.

















Thifensulfuron-methyl on the application monitors, was 56.4 g peq/ha, or 92% of the








B. RESIDUE DECLINE


Post application (Day 0) soil residues in the 0-5 cm samples averaged about 45.2 ppb for

Thifensulfuron-methyl and combined with the metabolites detected on Day 0 the

cumulative average total of 83.5 ppb verified the amount of test material applied.

Residues of Thifensulfuron-methyl declined rapidly to less than 25% of the applied

amount, 24.1 ppb by Day 3 and to less than 3% of applied amount, 2.4 ppb by Day 15.


Beyond Day 15, there were no residues of Thifensulfuron-methyl detected. No residues

of Thifensulfuron-methyl were detected in the 5-15 cm soil segment at any sampling

interval and only one result of 0.9 ppb was detected in 15-30 cm on Day 0.

Four of the six metabolites monitored were detected during this study with only IN-

A5546 and IN-W8268 undetected at any sampling interval. IN-L9225, IN-L9226 and

IN-A4098, were found immediately after the application. IN-L9225 reached its highest

average level of 32.3 ppb in 0-5cm depth on Day 0 and declined gradually after, while

IN-L9226 reached its average peak level of 4.1 ppb in 0-5 cm immediately after

application and then declined. IN-A4098 reached its highest average level of 2.9 ppb in

0-5 cm by Day 15 and then declined gradually thereafter.

IN-L9223 was detected on only one sampling interval with an average level of 0.8 ppb in

0-5 cm on Day 3 and was not detected at any other sampling event.


15 cm of soil. Detections below 15 cm were infrequent and seldom accounted for more

than 3 ppb in any depth segment, and for any individual component. For those sampling

intervals that were analysed below 30 cm no residues were detected.

It can be concluded from these data that Thifensulfuron-methyl and its major metabolites

were all degrading throughout this study at varying rates. In addition, very little residue

moved to depths below 15 cm. Thus, loss of applied material via leaching did not

contribute to the dissipation of residue in this study.

C. MASS BALANCE









rates. Soil concentrations of Thifensulfuron-methyl in units of percent mass of applied

parent equivalents were used to compute DT50 and DT90 values using ModelMaker 4

software (Cherwell Scientific). The FOMC model provided the best fit for the decline

data as well as for Day 0 residues, and the statistical evaluation was acceptable based on

χ2. The calculated DT50 and DT90 for Thifensulfuron-methyl were 1.5 and 6.5 days,

respectively.



DAT

(Days) Rep

Depth

(cm)

% Moist

(dwb)


(ppb)

IN-A4098

(ppb)

IN-A5546

(ppb)

IN-L9223

(ppb)

IN-L9225

(ppb)

IN-L9226

(ppb)

IN-W8268

(ppb)

-4










0a

I 0-5 12.8 53.9 2.17 <LOD <LOD 35.9 5.21 <LOD

II 0-5 12.1 32.8 1.63 <LOD <LOD 31.6 3.11 <LOD

III 0-5 11.1 48.9 1.68 <LOD <LOD 29.4 4.03 <LOD







3

I 0-5 13.1 28.4 2.50 <LOD <LOD 32.2 3.26 <LOD

II 0-5 12.6 21.2 2.17 <LOD 0.783 23.4 2.76 <LOD

III 0-5 12.9 22.7 2.14 <LOD 0.802 24.8 3.22 <LOD









DAT

(Days) Rep

Depth

(cm)

% Moist

(dwb)


(ppb)

IN-A4098

(ppb)

IN-A5546

(ppb)

IN-L9223

(ppb)

IN-L9225

(ppb)

IN-L9226

(ppb)

IN-W8268

(ppb)

11

I 0-5 24.8 2.30 2.44 <LOD <LOD 2.37 <LOD <LOD

II 0-5 25.3 2.87 2.37 <LOD <LOD 2.92 <LOD <LOD














15

I 0-5 24.1 2.55 2.35 <LOD <LOD 2.34 <LOD <LOD

II 0-5 23.9 2.39 2.60 <LOD <LOD 2.08 <LOD <LOD













DAT

(Days) Rep

Depth

(cm)

% Moist

(dwb)


(ppb)

IN-A4098

(ppb)

IN-A5546

(ppb)

IN-L9223

(ppb)

IN-L9225

(ppb)

IN-L9226

(ppb)

IN-W8268

(ppb)

31













52















DAT

(Days) Rep

Depth

(cm)

% Moist

(dwb)


(ppb)

IN-A4098

(ppb)

IN-A5546

(ppb)

IN-L9223

(ppb)

IN-L9225

(ppb)

IN-L9226

(ppb)

IN-W8268

(ppb)

73













99















DAT

(Days) Rep

Depth

(cm)

% Moist

(dwb)


(ppb)

IN-A4098

(ppb)

IN-A5546

(ppb)

IN-L9223

(ppb)

IN-L9225

(ppb)

IN-L9226

(ppb)

IN-W8268

(ppb)

149










199










253












DAT

(Days) Rep

Depth

(cm)

% Moist

(dwb)


(ppb)

IN-A4098

(ppb)

IN-A5546

(ppb)

IN-L9223

(ppb)

IN-L9225

(ppb)

IN-L9226

(ppb)

IN-W8268

(ppb)

304










359









III 15-30 14.4 <LOD <LOD <LOD <LOD <LOD <LOD <LOD a sampled immediately after application had been applied.

LOQ = 1 ppb

<LOD = <0.5 ppb




Days


(g peq/ha)

IN-A4098

(g peq/ha)

IN-A5546

(g peq/ha)

IN-L9223

(g peq/ha)

IN-L9225

(g peq/ha)

IN-L9226

(g peq/ha)

IN-W8268

(g peq/ha)

0a 27.0 3.0 0.0 0.0 19.9 2.5 0.0

3 14.9 3.9 0.0 0.6 17.6 2.0 0.0

11 1.6 8.1 0.0 0.0 7.9 0.0 0.0

15 1.4 14.2 0.0 0.0 2.1 0.0 0.0

31 0.0 6.5 0.0 0.0 0.5 0.0 0.0

52 0.0 6.0 0.0 0.0 0.0 0.0 0.0

73 0.0 4.6 0.0 0.0 0.0 0.0 0.0

99 0.0 2.2 0.0 0.0 0.0 0.0 0.0

149 0.0 1.5 0.0 0.0 0.0 0.0 0.0

199 0.0 0.0 0.0 0.0 0.0 0.0 0.0

253 0.0 0.0 0.0 0.0 0.0 0.0 0.0

304 0.0 0.0 0.0 0.0 0.0 0.0 0.0

359 0.0 0.0 0.0 0.0 0.0 0.0 0.0 a Samples taken immediately after application had been applied.




Table B.8.189 DT50 and DT90 values for Thifensulfuron-methyl in Italy

Kinetic


2

error r2

DT50

(days)

DT90

(days)

SFO M0 = 99.9 2.4

k = 0.413 0.029 4% 0.989 1.7 5.6

FOMC

Best Fit

M0 = 100 2.4

= 3.403 2.689

= 6.743 6.538

2% 0.991 1.5 6.5

DFOP

M0 = 100 2.5

k1 = 0.077 0.208

k2 = 0.463 0.12 (g = 0.1)

1% 0.991 1.6 6.0

III. CONCLUSIONS


bare ground in a typical agricultural soil in Graffignana, Italy. A nominal 61.5 g a.s./ha

application was made in the spring (April 2010), a time that is customary for cereal production.

Soil cores were collected in a randomised fashion to a depth of 90 cm up to ca 15 months

following application.

Thifensulfuron-methyl declined rapidly to about 24% of the amount applied, 14.9 g peq/ha by

Day 3 and to 2.3% of applied (1.4 g peq/ha) by Day 15. By the end of the study, (Day 359) no

residues of Thifensulfuron-methyl were detected. IN-L9225, IN-L9226, and IN-A4098 were

found immediately after the application. IN-L9225 reached an average peak level of 19.9 g

peq/ha on Day 0 and declined thereafter. IN-L9226 reached an average peak level of 2.5 g

peq/ha on Day 0 and declined thereafter. IN-A4098 reached an average peak level of 14.2 g

peq/ha on Day 15 and declined by the end of the study. IN-L9223 was detected on only one

sampling interval with an average level of 0.6 g peq/ha on Day 3. Thifensulfuron-methyl and its

degradation products remained in the upper 15 cm of soil. Detections below 15 cm were

infrequent. A DT50 of 1.5 days and a DT90 of 6.5 days was calculated for the parent compound.

(Aitken, A., Just, G., Doig, A., 2012a)


B.8.1.6 Summary & assessment – Soil studies

Two radio labelled forms of Thifensulfuron-methyl ([thiophene-2-14

C]-Thifensulfuron-

methyl and [triazine-2-14

C]-Thifensulfuron-methyl) were used to evaluate the metabolic fate

of the active substance in soil. These label positions are considered to represent stable

portions of the parent molecule.

The metabolism and degradation of Thifensulfuron-methyl in soil was investigated in a

number of studies from DuPont and the Task Force to supplement information already

presented in the original DAR. Both applicants provided new route of degradation studies

with parent Thifensulfuron-methyl in soil. In addition both Applicants submitted extensive

packages of new soil rate of degradation studies for the metabolites.

The original route of degradation study in the DAR was considered unacceptable upon re-

evaluation due to a number of critical deficiencies (only a single radiolabel position studied,

analysis via a single TLC method with no confirmatory analysis, inadequate separation of

major metabolites, no determination of soil biomass etc). However for the purposes of

conducting a conservative environmental exposure assessment information on peak levels of

metabolites IN-W8268 and IN-L9226 from this study were retained as these metabolties were

found at higher levels in this original study than in any of the subsequent data supplied.

The new route of degradation study supplied by DuPont was also considered unacceptable

upon evaluation due to a significant number of major methodological issues, mainly related

to conduct and interpretation of the analytical method. No information from this study could

be used for the purposes of the environmental exposure assessment. However the new route

of degradation study from the Task Force was considered acceptable and formed the basis of

the assessment of route of degradation in aerobic soils. In total, five metabolites (IN-L9225,

IN-JZ789, 2-Acid-3-triuret, IN-L9223, IN-A4098) breached the relevant trigger criteria

(>10% single time point or, in the case if IN-JZ789 >5% on two consecutive time points and

>5% at the end of the study). Degradation of parent Thifensulfuron-methyl under aerobic

soil conditions was very rapid, with DT50 values typically less than 3 d under study

conditions. In aerobic soil, the primary metabolic pathway proceeds via deesterification of the

parent compound to IN-L9225, the free carboxylic acid analogue of Thifensulfuron-methyl.

IN-L9225 may be demethylated to form IN-JZ789. The thiophene ring of IN-JZ789 may

open to form 2-acid-3-triuret. IN-L9225 may also be hydrolysed at the sulfonylurea bridge to

yield IN-A4098 and IN-L9223, which are comprised of the triazine and thiophene

heterocyclic moieties, respectively. An alternate degradation pathway for Thifensulfuron-

methyl may involve O-demethylation to yield IN-L9226. Hydrolysis of IN-L9226 in turn

yields IN-A5546, which can be deesterified to form IN-L9223. IN-A5546 is also deesterified

and cyclised to form IN-W8268. The IN-L9226 and IN-W8268 metabolites were only

identified in the acceptable route of degradation studies in the original DAR.

Under anaerobic conditions, no new major metabolites were found that were not also found at

comparable levels during the aerobic study. The metabolite IN-B5528 was found at higher

levels in this study compared to the aerobic study, however it was noted that this metabolite

was not found in significant levels over the first 90 d (≤ 3% AR up to day 90) and only

exceeded 5% at the final sampling time of 120 d after prolonged anaerobic conditions (peak

of 8.7% at 120 d). Since maintenance of anaerobic conditions for such prolonged periods is

not considered likely in typical agricultural soils, this metabolite is not considered to be of

relevance for the environmental exposure assessment and has not been considered further.


New soil photolysis studies were provided by both Applicants. The study from DuPont

indicated that the IN-V7160 metabolite could be formed at levels approaching 10% in the

presence of light. The IN-A5546 metabolite was also observed at significant levels in the

light exposed samples and both these metabolties have been included in the environmental

exposure assessment to take account of their possible formation in the presence of light. In

the Task Force study, the IN-V7160 metabolite formed at lower levels than observed in the

DuPont study. Additionally the IN-A5546 metabolite was not observed at all. The lower

formation of IN-V7160 may partially have been an artefact of the slower degradation that

was observed in the irradiated samples in the Task force study. The slower degradation was

plausibly attributed by the study author to lower moisture in the irradiated samples. The

study confirmed the conclusions from the original DAR that soil photolysis is not likely to be

a major route of dissipation under normal environmental conditions, when also considering

the rapid aerobic degradation of the parent molecule in the dark. Nevertheless the formation

of potential photometabolites IN-V7160 and IN-A5546 identified from the photolysis studies

by DuPont have been considered for relevance in the environmental exposure assessment.

The kinetic analysis of aerobic degradation rate and formation fractions for Thifensulfuron-

methyl and its major metabolites was relatively complex. This assessment considered in

detail the new route of degradation study from the Task Force supplemented by an extensive

set of metabolite dosed rate of degradation studies from both Applicants. The full details of

this assessment are included in Volume 3 Section B.8.1.4 and selected input parameters are

summarised in the list of endpoints section below.

DuPont submitted new field dissipation studies to supplement the information already

available in the original DAR. However the environmental exposure assessment is based on

degradation under laboratory conditions, utilising peak occurrence or formation fraction of

metabolites also under laboratory conditions. Degradation rates and metabolite formation

levels from the field are therefore not used in the assessment. The UK RMS concluded that

field dissipation studies were neither required nor used in the environmental exposure

assessment. It should also be noted that in accordance with the AIR2 Regulation

(Commission Regulation (EU) No 1141/2010) new data is required to reflect changes in

either the data requirements or changes in scientific knowledge since the first inclusion, or to

support specific representative uses. The UK RMS concluded that none of these aspects

warranted the submission of new field dissipation studies. From a review of the new data

provided, the information largely supported the conclusions of the laboratory route and rate

of degradation studies. Parent Thifensulfuron-methyl was observed to degrade rapidly at all

locations, with the major degradation products being essentially the same as observed under

laboratory conditions. Degradation products identified in field dissipation studies were IN-

L9225 (major), IN-L9226, IN-A4098 (major), IN-L9223, IN-A5546, and IN-W8268. Levels

of formation were lower than observed under laboratory conditions. This supported the use

of laboratory data in the environmental exposure assessment.

The following residue definition in soil has been proposed for further risk assessment, i.e all

metabolites which have been included in exposure assessments in soil and groundwater:

In soil and groundwater: parent, IN-L9225, IN-JZ789, IN-A4098, IN-L9223, 2-acid-3-triuret,

IN-W8268, IN-V7160, IN-L9226, IN-A5546 were the major components of the residue.


Route of degradation (aerobic) in soil (Annex IIA, point 7.1.1.1.1)

Mineralisation after 100 days

Non-extractable residues after 100 days

Metabolites requiring further consideration

-name and/or code, % of applied (range and

maximum)

Route of degradation in soil – Supplemental studies

Anaerobic degradation

Mineralisation after 100 days

Non-extractable residues after 100 days

Metabolites that may require further consideration for

risk assessment – name and/or code, % of applied (range

and maximum)

1.41 – 24.48% (N=4)*

*Simmons. M., 2012a (2 radiolabels per soil)

20.82 – 51.00% (N=4)*

*Simmonds, M2., 2012a (2 radiolabels per soil)

IN-L9225 (Thifensulfuron acid, 49.13- 93.52% at 14d;

max 94%)*

IN-JZ789 (O-Desmethyl thifensulfuron acid, 0.5-

9.73% at 61d; max 10%)*

2-Acid-3-triuret (IN No. Unknown, 3.13-16.95% at

61d; max 17%)*

IN-L9223 (2-Acid-3-sulfonamide, 0.15-19.3% at 29d;

max 19%)*

IN-A4098 (triazine amine, 2.47-17.97% at 29d; max

18%)*

IN-W8268 (Thiophene sulfonimide, max 29.6% at

4d)**

IN-A5546 (2-ester-3-sulfonamide, max 10.5% at 2d)**

IN-L9226 (O-demethyl-Thifensulfuron-methyl, max

18.5%)**

*Simmonds, M (2012a)

**Rapisarda, C (1984)

0.8% after 3+60d (latest sampling time)+

1.01% after 121 days (latest sampling time)-

+Hawkins, Elsom and Kane (1991). 3+60d = 3

days aerobic, 60 days anaerobic

-Simmonds, R (2011a)

N/A for Hawkins, Elsom and Kane (1991)

18.7% thiophene label, 23.0% triazine label for

Simmonds. R (2011a)

Not applicable


Soil photolysis

Metabolites that may require further consideration for

risk assessment – name and/or code, % of applied (range

and maximum).

Rate of degradation in soil

Laboratory studies

Thifensulfur

on-methyl

Aerobic conditions

Study

reference

Soil type pH t. oC / % MWHC

DT50 /DT90

(d)

DT50 (d)

20C

pF2/10kPa1

chi2

Method of

calculation


loamy sand

5.7 22oC / 40%

MWHC 1.7 / 5.7 2.0 3 SFO


loamy sand

7.0 22oC / 40%

MWHC 2.6 / 8.6 3.1 4 SFO

Simmonds,

2012a

Longwood;

sandy loam 7.5 20° / pF 2 -2.5

0.99 0.99 3.742 SFO

Simmonds,

2012a

Farditch;

loam 6.5 20° / pF 2 -2.5

1.12 1.12 6.782 SFO

Simmonds,

2012a

Lockington;

sandy clay 5.5 20° / pF 2 -2.5

1.23 1.23 10.02 SFO

Simmonds,

2012a

Kenslow;

loam 5.5 20° / pF 2 -2.5

0.85 0.85 5.662 SFO

Geometric mean - 1.39 - -

IN-A5546 (2-ester-3-sulfonamide, max 32.3% at

30d, triazine label)*

IN-V7160 (Triazine urea, 0% - 9.6% at 15d, from

photolysis study$; Max 9.6% )

*Ferguson, E.M. (1986); Photodegradation of

[thiophene-2-14

C]DPX-M6316 and [triazine-2-14

C]DPX M6316 on soil

$ McLaughlin, S.P. (2011); Photodegradation of

[14

C]DPX-M6316 on soil



Study

reference


MWHC DT50 /DT90

(d)

DT50 (d)

20C

pF2/10kPa

chi2

Method of

calculation

Manjanutha,

2000

Drummer, silty

clay loam

5.9 20°C / 40%

MWHC 42.5 / 141.2 34.9 11 SFO

Manjanutha,

2000

Glenville,

sandy loam

7.3 20°C / 40%

MWHC 20.6 / 68.5 17.2 9 SFO

Manjanutha,

2000

Gross-

Umstadt, silt

loam

7.5 20°C / 40%

MWHC 154.4 / 513 119.9 5 SFO

Simmonds,

M., 2012a

Longwoods

thiophene 7.3 20/ pF2 - 74.4 8.87 SFO

Simmonds,

M., 2012a

Longwoods

triazine 7.3 20/ pF2 - 85.1 8.21 SFO

Simmonds,

M., 2012a

Farditch

thiophene 5.9 20/ pF2 - 20.7 10.9 SFO

Simmonds,

M., 2012a

Farditch

triazine 5.9 20/ pF2 - 25.4 12.0 SFO

Simmonds,

M., 2012a

Lockington

thiophene 5.5 20/ pF2 - 17.5 11.2 SFO

Simmonds,

M., 2012a

Lockington

triazine 5.5 20/ pF2 - 20.3 1.0 SFO

Simmonds,

M., 2012a

Kenslow

thiophene 5.1 20/ pF2 - 14.4 13.5 SFO

Simmonds,

M., 2012a

Kenslow

triazine 5.1 20/ pF2 - 15.4 5.55 SFO

Geometric mean - - 32.3 - -



Study

reference


MWHC DT50 /DT90

(d)

DT50 (d)

20C

pF2/10kPa

chi2

Method of

calculation

Manjanutha,

2000

(DuPont)

Drummer, silty

clay loam

5.9 20°C / 40%

MWHC 2.0 1.6 5 SFO

Manjanutha,

2000

(DuPont)

Glenville,

sandy loam

7.3 20°C / 40%

MWHC 2.9 2.4 13 SFO

Manjanutha,

2000

(DuPont)

Gross-

Umstadt, silt

loam

7.5 20°C / 40%

MWHC 0.9 0.7 3 SFO

Knoch,

2012c

(Task Force)

LUFA 2.2;

loamy sand

5.5

(CaCl2) 20°C / 45%

MWHC 0.6 0.6 18.5 SFO

Knoch,

2012c

(Task Force)

LUFA 2.3;

sandy loam

6.8

(CaCl2) 20°C / 45%

MWHC 0.3 0.27 7.6 SFO

Knoch,

2012c

(Task Force)

LUFA 6S; clay

7.1

(CaCl2) 20°C / 45%

MWHC 3.3 1.63 12.5 SFO

Geometric mean 1.2 0.95 - -

IN-JZ789 Aerobic conditions

Study

reference


MWHC DT50 /DT90

(d)

DT50 (d)

20C

pF2/10kPa

chi2

Method of

calculation

Simmonds,

M., 2012a

Longwoods

thiophene 7.3 20/ pF2 - 362 49.8 SFO

Simmonds,

M., 2012a

Longwoods

triazine 7.3 20/ pF2 - 51.5 57.7 SFO

Simmonds,

M., 2012a

Farditch

thiophene 5.9 20/ pF2 - 128 37.0 SFO

Simmonds,

M., 2012a

Farditch

triazine 5.9 20/ pF2 - 1000 37.5 SFO

Simmonds,

M., 2012a

Lockington

thiophene 5.5 20/ pF2 - 39.5 47.3 SFO

Simmonds,

M., 2012a

Lockington

triazine 5.5 20/ pF2 - 8.06 73.8 SFO

Simmonds,

M., 2012a

Kenslow

thiophene 5.1 20/ pF2 - 1000 43.6 SFO

Simmonds,

M., 2012a

Kenslow

triazine 5.1 20/ pF2 - 1000 69.6 SFO

Geometric mean 60.0


2-Acid-3-

triuret

Aerobic conditions

Study

reference


MWHC DT50 /DT90

(d)

DT50 (d)

20C

pF2/10kPa

chi2

Method of

calculation

Simmonds,

M., 2012a

Longwoods

thiophene 7.3 20/ pF2 - 122 61.1 SFO

Simmonds,

M., 2012a

Longwoods

triazine 7.3 20/ pF2 - 57.9 57.7 SFO

Simmonds,

M., 2012a

Farditch

thiophene 5.9 20/ pF2 - 46.1 34.3 SFO

Simmonds,

M., 2012a

Farditch

triazine 5.9 20/ pF2 - 74.4 39.4 SFO

Simmonds,

M., 2012a

Lockington

thiophene 5.5 20/ pF2 - 38.4 35.8 SFO

Simmonds,

M., 2012a

Lockington

triazine 5.5 20/ pF2 - 115 36.3 SFO

Simmonds,

M., 2012a

Kenslow

thiophene 5.1 20/ pF2 - 57.0 48.1 SFO

Simmonds,

M., 2012a

Kenslow

triazine 5.1 20/ pF2 - 132 53.0 SFO

Geometric mean - - 73.0 - -


Study

reference


MWHC DT50 (d)

DT50 (d)

20C

pF2/10kPa

chi2

Method of

calculation

Simmonds,

M., 2012a

Longwoods

thiophene

(parent route

study)

7.3 20/ pF2

- >1000 39.2

SFO

Simmonds,

M., 2012a

Farditch

thiophene

(parent route

study)

5.9 20/ pF2

- 107 27.7

SFO

Simmonds,

M., 2012a

Lockington

thiophene

(parent route

study)

5.5 20/ pF2

- 194 29.1

SFO

Simmonds,

M., 2012a

Kenslow

thiophene

(parent route

study)

5.1 20/ pF2

- 272 23.9

SFO

Geometric mean (excluding “<1000d” values) - 178 - -



Study

reference


MWHC DT50 (d)

DT50 (d)

20C

pF2/10kPa

chi2

Method of

calculation

Rhodes,

1987a

(Dupont)

Keyport; silt

loam

4.3

25oC / 70% FC 208 254 6.2 SFO

Möndel,

2001

(Dupont)

Honville,

loamy silt

6.7

(H2O) 20°C / 40%

MWHC 260.1 201.6 3.0

HS (DT50

calculated

from slow

phase)

Jungmann,

Nicollier,

2006

(Dupont)

Gartenacker;

Loam,

6.9

(CaCl2) 20°C / pF2 102.2 102.2 3.5 SFO

Jungmann,

Nicollier,

2006

(Dupont)

18 Acres;

sandy clay

loam,

5.0

(CaCl2) 20°C / pF2 249.4 249.4 3.2 SFO

Jungmann,

Nicollier,

2006

(Dupont)

Krone; silt

loam,

4.9

(CaCl2) 20°C / pF2 190.8 190.8 3.7 SFO

Morlock

(2006a)

Task Force

Soil 2.2; loamy

sand

5.7

(H2O) 20°C / 45%

MWHC 67.3 67.3 5.68 SFO

Morlock

(2006a)

Task Force

Soil 3A; sandy

loam

7.3

(H2O) 20°C / 45%

MWHC 188.4 175.7 5.645 SFO

Morlock

(2006a)

Task Force

Soil 6S; clay

loam

7.1

(H2O) 20°C / 45%

MWHC 333.2 230.1 1.00 SFO

Scott

(2000)b

Arrow; sandy

loam 5.7

20°C / 50%

MWHC 44.7 22.5 14 HS

d

Wonders and

Melkebeke

(2002)c

Speyer 2.1;

sand 5.5 20°C / pF2 112.5 112.5 2.9 SFO

Wonders and

Melkebeke

(2002)c

Soil 115; clay

loam 8.6 20°C / pF2 175.2 175.2 3.1 SFO

Wonders and

Melkebeke

(2002)c

Soil 243;

sandy loam 5.6 20°C / pF2 96.4 96.4 6.2 SFO


146.1

169.4

132.4 - -

aKinetic fitting for the study of Rhodes (1987) was performed by the UK RMS using the FOCUS DEGKIN spreadsheet since this study was excluded by DuPont cAccepted in the RAR for metsulfuron methyl

dCalculated from slow phase rate constant (k1=0, fixed lag phase, k2 = 0.03082, tb = 22.25 d)



Study

reference


MWHC DT50 (d)

DT50 (d)

20C

pF2/10kPa

chi2

Method of

calculation

Bell, S., 2011 Sassafras 5.3

20/ pF2

<3 d - - -

Bell, S., 2011 Tama 6.1

20/pF2

<3 d - - -

Bell, S., 2011 Lleida 7.9

20/ pF2

<3 d - - -

Bell, S., 2011 Speyer 2.2 6.3

20/ pF2

<3 d - - -

Bell, S., 2011 Nambshiem 7.7

20/pF2

<3 d - - -

- 3.0* - - -

Comments A DT50 figure of 3d was used as a conservative figure for FOCUS

modeling. This was because the first sample point after 0 was 3 days,

and IN-A5546 was not observed at the 3d sampling time. aKinetic fitting for the study of Rhodes (1987) was performed by the UK RMS using the FOCUS DEGKIN spreadsheet since this study was excluded by DuPont

IN-V7160 Aerobic conditions

Study

reference

Soil type pH

(CaCl2)

t. oC / %

MWHC DT50 /DT90

(d)

DT50 (d)

20C

pF2/10kPaa

chi2

Method of

calculation

Tunink,

2009

(DuPont)

Mattapex,

sandy loam

4.35 20°C / 40 of 0

Bar 9.8 9.0 11 SFO

Tunink,

2009

(DuPont)

Lleida, silty

clay

7.50 20°C / 40 of 0

Bar 6.6 5.6 5 SFO

Tunink,

2009

(DuPont)

Nambsheim,

sandy loam

7.01 20°C / 40 of 0

Bar 3.3 3.3 2 SFO

Tunink,

2009

(DuPont) Goch, silt loam

5.13

20°C / 40 of 0

Bar

16.1/204.1

M0 = 95.3

K1 = 0.008

K2 = 0.175

g = 0.5

71.6

(based on

slow phase

rate constant)

3 DFOP

Tunink,

2009

(DuPont) Suchozebry,

sandy loam

5.04

20°C / 40 of 0

Bar

24.8/542.8

M0 = 94.2

K1 = 0.003

K2 = 0.097

g = 0.5

231

(based on

slow phase

rate constant)

2 DFOP

Geometric mean - - 19.4 - - amoisture correction was performed based on measured data for both study and reference conditions



Study

reference


MWHC DT50 /DT90

(d)

DT50 (d)

20C

pF2/10kPa

chi2

Method of

calculation

Fang, 2000

(DuPont)

Drummer, silty

clay loam

7.7 20°C / 40-50%

MWHC 59.0 59.0 2 SFO

Fang, 2000

(DuPont)

Glenville,

sandy loam

5.7 20°C / 40-50%

MWHC 64.2 61.1 4 SFO

Fang, 2000

(DuPont)

Gross-

Umstadt, silt

loam

7.8 20°C / 40-50%

MWHC 48.1 43.5 4 SFO

Knoch,

2012d

(Task Force)

LUFA 2.2;

loamy sand

5.5

(CaCl2) 20°C / 45%

MWHC 2.6 2.6 14 SFO

Knoch,

2012d

(Task Force)

LUFA 2.3;

sandy loam

6.8

(CaCl2) 20°C / 45%

MWHC 9.7 8.6 7.8 SFO

Knoch,

2012d

(Task Force)

LUFA 6S; clay

7.1

(CaCl2) 20°C / 45%

MWHC 24.5 12.1 8.9 SFO

Geometric mean - 22.0 18.7 - -

Field studies

No field studies were relied upon for the regulatory assessment.

Laboratory studies (anaerobic)

Study Thifensulfuron-

methyl

Anaerobic conditions

Hawkins, Elsom &

Kane., 1991

Soil type X2 pH t.

oC / % MWHC DT50 /DT90

(d)

X2 Method of

calculation

Simmonds, R.,

2011a

Keyport

Silt loam

7.2 25/75% of

MWCH

~5.0

Simmonds, R.,

2011a

Farditch thiophene

(complete dataset)

6.0 20/flooded 0.6/4.5 1.5 Hockey-stick

Simmonds, R.,

2011a

Farditch triazine

(complete dataset)

6.0 20/flooded 0.7/8.8 3.9 Hockey-stick

(slow phase)

Simmonds, R.,

2011a

Farditch thiophene

(anaerobic slow

phase HS)

6.0 20/ flooded 15.4 - -

Simmonds, R.,

2011a

Farditch triazine

(anaerobic slow

phase HS)

6.0 20/ flooded 4.7 - -

2 X This column is reserved for any other property that is considered to have a particular impact on the degradation rate.


B.8.2 Adsorption, desorption and mobility in soil (IIA 7.1.2, 7.1.3, IIIA 9.1.2)

B.8.2.1 Adsorption and desorption


Report: Priester, T.M. (1985); Batch equilibrium (adsorption/desorption) and

soil thin-layer chromatography studies with [thiophene-2-14

C] DPX-M6316



Test material: [14


Lot/Batch #: Not reported


Previous




DuPont submission this study has been supplemented by the study of

Bell (2011; DuPont-30563). However in the environmental exposure

assessment DuPont proposed retaining information on the Freundlich

Kfoc and 1/n values from the original study for modelling purposes as a

conservative approach. In the opinion of the UK RMS the fact that the

original study was not conducted to GLP does not automatically mean

that the study cannot be considered to meet current guidelines, because

the study was initiated before GLP was mandatory for environmental

safety studies (i.e. 1993). The original study evaluation from the 1996

DAR concluded that the study was conducted under US EPA guidelines

(US EPA 163-1) and was found to conform to OECD 106 and was

therefore considered acceptable.

The UK RMS has re-considered the validity of the original study. No

preliminary study appeared to have been performed. The adsorption

phase was conducted at 25°C at a 1:1 soil:solution ratio in 0.01N CaSO4

over a 24 hour equilibrium time. Significant degradation of parent

Thifensulfuron-methyl was reported. In the aqueous fraction parent

represented as little as 6% of recovered radioactivity at the end of the

desorption step. In the soil fraction parent represented as little as 15%

at the end of the desorption step. The main metabolite was

thifensulfuron acid (IN-L9925). The remaining metabolites were found

at levels up to 13%. Degradation was not accounted for in the

calculation of sorption coefficients. The sorption values presented may

therefore represent a combination of parent and metabolite sorption

potential. Although this approach might be conservative, overall the

UK RMS considered this to be uncertain and therefore concluded that

the original study should not be considered acceptable. It should be

further noted that in the new sorption studies provided by both DuPont

and the Task Force, the degradation of parent was accounted for by

utilising a combination of shorter equilibrium times (2 or 4 hours) and

reduced incubation temperatures (13°C). Therefore the sorption values


from the original study were not considered consistent with those

derived from the new studies and have been excluded from further

consideration.


DAR has been included below. This summary has been supplemented

by an additional table providing the full sorption results, which were

excluded from original DAR summary. Since this information is not

now relied on, it has been greyed out.

The study (AMR 286-84) was started in 1984 and reported by T.M. Priester



conform to OECD 106 guideline and was found acceptable.

Protocol - [thiophene-2-14

C]Thifensulfuron-methyl (radiochemical purity >98%)

in 0.01 M Ca SO4 solutions (0.2-6 ppm), was adsorbed by 4 soil types (20 ml + 20

g soil) for 1 day at 25°C then five consecutive desorptions were performed for the

highest initial concentration. Freundlich adsorption and desorption isotherms were

determined. Thifensulfuron-methyl degradation in solid and liquid phases was

checked after the last desorption. The soil characteristics are given in Table

B.8.190.


Soil

Country of Origin

Woodstown

U.S.A.

Cecil

U.S.A.

Flanagan

U.S.A.

Keyport

U.S.A.

% sand 60 61 2 12

% silt 33 21 81 83

% clay 7 18 17 5

pH 6.6 6.5 5.4 5.2

% organic carbon 0.64 1.22 2.5 4.4

% organic matter 1.1 2.1 4.3 7.5

CEC (mEq/100 g) 5.3 6.6 21.1 15.5

USDA textural class sandy loam sandy loam silt loam silt loam

CEC = Cation exchange capacity

Results - Thifensulfuron-methyl was weakly adsorbed to soil (Kd 0.081-1.38, Koc

< 55) in relation to soil organic matter content: the soils with the highest organic

matter had the highest adsorption values. Desorption constants were similar in

magnitude to adsorption constants (Koc < 67), except for soils with low organic

matter content. Thifensulfuron-methyl was highly degraded in some soils. Due to

degradation, values of sorption parameters are questionable but there is no need for

further information.


Table B.8.191 Adsorption constants of Thifensulfuron-methyl in 4 soils

STUDY SOIL % OC KF (ML/G) 1/N KFOC (ML/G)

PRIESTER, T.M.,

1985

(AMR 286-84)

WOODSTOWN 0.6 0.08 0.79 13.5

CECIL 1.2 0.19 1.0 15.8

FLANAGAN 2.5 1.38 0.87 55.2

KEYPORT 4.4 1.25 0.90 28.4

(Priester, 1985)

Report: Bell, S. (2011); Absorption/desorption of [14

C]-DPX-M6316 (Thifensulfuron-

methyl) via batch equilibrium method


Guidelines: OECD 106 (2000), OPPTS 835.1230 (2008), SETAC (1995) Deviations:

None



GLP: Yes


Previous





the regulatory assessment. Deviations or points to note are highlighted

below. For two of the soils tested the temperature and equilibrium

period were reduced to ensure acceptable stability of the test substance.

For these two soils (Lleida and Nambsheim) the definitive study was

performed at 13°C and a 4 hour equilibrium (the remaining three soils

were performed at 20°C and 24 hour equilibrium). The use of a shorter

equilibrium time is considered acceptable by the UK RMS. However

the use of low temperatures is considered non-standard and adds a

degree of uncertainty to the sorption values derived. Nevertheless, when

comparing the results from the two soils tested at the low temperature

(and shorter equilibrium) it is clear that measured sorption was lower

under these conditions. If these soils were excluded from the regulatory

data base due to the uncertainty over the use of the low temperature

incubations, the overal mean sorption values would be higher. For

example, the arithmetic mean Kfoc of all soils is 41.4 ml/g compared to

62.3 ml/g of the three soils tested at 20°C. The results from the low

temperature (and shorter equilibrium) soils were also noted to be

consistent with the results from the new study conducted by the Task

Force, where soils were tested at 20°C but with a shorter equilibrium

time only (2 hour adsorption equilibrium). Overall the UK RMS


concluded that the results from all 5 soils could be considered valid and

included in the overall regulatory database for determining exposure

assessment input parameters.

The detailed study summary from DuPont is provided below,

supplemented with additional information added by the UK RMS during

the evaluation.

Executive summary:

The adsorption and desorption properties of [14

C]-Thifensulfuron-methyl were investigated in

five soils (pH range of 4.8 to 7.6, organic carbon range of 0.8 to 3.0%) from USA, Germany,

Spain, and France.

One adsorption experiment was performed using the batch equilibration method on the soils

at five concentrations (ranging from nominal concentrations of 0.05–5.00 g/mL) of the test

substance in 0.01 M CaCl2. Two desorption cycles were performed on samples treated at the

highest test concentration. The test item was added to Sassafras, Drummer, and

Gross-Umstadt soils at a soil: solution ratio of 1:2 (5 g soil [oven dry weight]: 10 g

aqueous), and to Lleida and Nambsheim soils at a soil: solution ratio of 1:1 (10 g soil [oven

dry weight]: 10 g aqueous), to achieve five nominal rates of application (0.05, 0.10, 0.50,

1.00 and 5.00 g/mL).

The adsorption coefficients Kd, Kom, and Koc were calculated and reported for each soil at

each concentration of the test substance. Thifensulfuron-methyl can be classified according

to the ASTM International Classification scale as having “very high mobility or “high

mobility” in all soils tested, with a Koc range of 10–128 and an average Koc of 53. The test

substance was stable during the adsorption phase of the experiment.

Table B.8.192 Freundlich adsorption isotherm parameters

Thifensulfuron-methyl – at 20 2C for Sassafras, Drummer, and Gross-Umstadt soils, and a

temperature of 13 0.5C for the Lleida and Nambsheim soils.

Soil type OC% Soil pH

(CaCl2)

Kd

(g/g)

Koc

(mg/g)

Kf Kfoc 1/n R2

Loamy Sand

(Sassafras)

0.81 4.8 0.76 94 0.6660 82 0.9023 0.9959

Clay (Lleida) 1.74 7.6 0.17 10 0.1551 9 0.9826 0.9687

Clay Loam

(Drummer)

2.96 5.7 3.78 128 2.5468 86 0.8211 0.8211

Loam

(Gross-

Umstadt)

1.39 6.6 0.3 21 0.2679 19 0.9599 0.9599

Sandy Loam

(Nambsheim)

2.03 7.3 0.29 14 0.2164 11 0.8389 0.8389

Arithmetic mean 53.4 0.7705 41.4 0.901 -

pH dependence, yes or No No



A. MATERIALS

1. Test material: Thifensulfuron-methyl technical

Batch Number: M6316-186

Purity: 99.3%

Description: Powder

CAS Number 79277-27-3




Batch Number: [Triazine-2-14




Stability of test compound: Radiochemical purity tested prior to test system

application

Structure of DPX-M6316

The study was conducted with five different soil types (three European and two from the

U.S.A). Air-dried soils were stored at ambient temperature prior to experimentation. A

summary of the physical and chemical properties of the soils is provided in Table B.8.193.

The percent sand, silt, and clay are quoted on the basis of the USDA classification system.



Soil identity Sassafras Lleida Drummer

Gross-

Umstadt Nambsheim

Origin

Kent County,

Maryland,

USA

Lleida,

Catalunya,

Spain

Ogle County,

Illinois, USA

Gross-

Umstadt,

Darmstadt,

Germany

Nambsheim,

France

Soil texturea Loamy sand Clay Clay loam Loam Sandy loam

% Sand 80 20 26 45 62

% Silt 17 35 37 42 27

% Clay 3 45 37 13 11

pH (0.01 M CaCl2) 4.8 7.6 5.7 6.6 7.3

Organic carbon (%) 0.8 1.7 3.0 1.4 2.0

CEC (mEq/100 g) 5.4 15.0 27.0 9.8 11.7

Moisture content air dry

soil (%) 0.54 1.89 3.72 0.97 1.05

Bulk density (g/cm3) 1.29 0.99 1.10 1.16 1.09

a USDA soil classification system

B. STUDY DESIGN


The appropriate soil to solution ratio was determined in preliminary testing at 1:4

(w/w) with Sassafras and Drummer soils. Portions of test solution (20 g) were

shaken at 20 2C with samples of test soil (5 g) for a 24-hour equilibration period

in darkness. Due to instability of the test item at 20 2C with Lleida and

Nambsheim soils, the test was repeated at a soil to solution ratio of 1:1 (w/w) with

those two soils. Portions of test solution (10 g) were shaken at 12.6 0.3C with

samples of test soil (10 g) for a 6-hour equilibration period in darkness. Control

experiments were also performed to assess potential adsorption to test vessels.

Following centrifugation (3,000 g for 15 minutes), the supernatant was decanted and

triplicate aliquots prepared for liquid scintillation counting.

The definitive adsorption/desorption experiments were performed in duplicate at

five concentrations for each of the five test soils, at a temperature of 20 2C for

Sassafras, Drummer, and Gross-Umstadt soils, and a temperature of 13 0.5C for

the Lleida and Nambsheim soils. The temperature was reduced for the isotherm

experiment using Lleida and Nambsheim soils in attempts to maintain stability of

the test item for the duration of the test. Stock solutions of [14

C]-Thifensulfuron-

methyl in acetonitrile were prepared and aliquots added to portions of 0.01 M CaCl2

solution to give final test concentrations of 0.051, 0.10, 0.52, 1.07, and 4.59 g/mL

for Sassafras and Drummer soils, 0.0496, 0.10, 0.52, 1.07, and 4.59 g/mL for

Gross-Umstadt soils, and 0.044, 0.10, 0.46, 0.92, and 4.41 g/mL for Lleida and

Nambsheim soils. Portions of test solution (10 g for all soils) were shaken at

20 2C or 13 0.5C with samples of soil (5 g for Sassafras, Drummer, and

Gross-Umstadt soils, 10 g for Lleida and Nambsheim soils) for a 24-hour (Sassafras,

Drummer, and Gross-Umstadt soils), or a 4-hour (Lleida and Nambsheim soils)

equilibration period in darkness. A control experiment was also performed to assess

potential adsorption to test vessels. Following centrifugation (3,000 g for


15 minutes), the supernatant was decanted and triplicate aliquots prepared for liquid

scintillation counting.

Following the adsorption phase, fresh 0.01 M CaCl2, equivalent to that removed at

adsorption, was added to test vessels which had been treated at the highest dose

level. Samples were then equilibrated for 24 hours at 20 2C (Sassafras,

Drummer, and Gross-Umstadt soils) or 4 hours at 13 0.5C (Lleida and

Nambsheim soils), solutions and soils separated, quantified, and subject to a further

desorption phase. One replicate of adsorption supernatants from each test soil at

nominal concentrations of 5.0 and 1.0 g/mL were analysed by HPLC to confirm

test substance stability.


Radioactivity was determined by LSC. Aqueous adsorption supernatants from the

nominal 5.0 g/mL and 1.0 g/mL test concentrations obtained after equilibration

were analysed by reverse phase HPLC.


A. MASS BALANCE

Recovery of radioactivity was determined at the highest test concentration for all soils

and mean values ranged between 92.97% and 106.71% applied in the main isotherm

phase.

B. TRANSFORMATION OF PARENT COMPOUND

The [14

C]-Thifensulfuron-methyl was deemed stable in supernatants and extracts of

24-hour equilibration samples of Sassafras and Drummer soils, and in supernatants and

extracts of 4-hour equilibration samples of Lleida and Nambsheim soils.

C. FINDINGS

The sorption distribution coefficients Kd, Kom and Koc were calculated for each soil at

each concentration of the test substance using the following equations:

Kd = Cs/Cw

Kom = (Kd/om) 100 and Koc = (Kd/oc) 100

where Kd is the adsorption distribution coefficient and Kom and Koc are the adsorption

distribution coefficient normalised for organic matter and organic carbon, respectively.

The Kd values ranged from 0.11 in Lleida soil to 5.29 in Drummer soil. The Kom and Koc

values ranged from 4 and 6, respectively, in Lleida soil to 104 and 179, respectively, in

Drummer soil.

Adsorption isotherm data were analysed using the Freündlich equation:

log (Cs) = (1/n * log (Cw)) + log (Kf) (Table B.8.194).


Table B.8.194 Adsorption and desorption constants of Thifensulfuron-methyl in the soils

Soil

OC

%

pH (in

CaCl2)

Adsorption Desorption

KFa 1/n

b r

2 KFoc

c

D1

(%)d D2 (%)

e DT (%)

f

Sassafras 0.81 4.8 0.6660 0.9023 0.9959 82 55.90 22.53 78.43

Lleida 1.74 7.6 0.1551 0.9826 0.9687 9 6.65 29.92 36.56

Drummer 2.96 5.7 2.5468 0.8211 0.9942 86 26.81 17.16 43.96

Gross-Umstadt 1.39 6.6 0.2679 0.9599 0.9624 19 30.37 11.10 41.47

Nambsheim 2.03 7.3 0.2164 0.8389 0.9514 11 34.55 22.86 57.40

Average 0.7704 0.9010 - 41 - - - a Freundlich adsorption coefficients.

b Slope of Freundlich adsorption isotherms.

c Adsorption coefficient per organic carbon (K F/ organic carbon) 100.

d Mean percent of test item desorbed after first desorption interval.

e Mean percent of test item desorbed after second desorption interval.

f Mean total percent of test item desorbed after both desorption intervals.

Calculation of the Freundlich co-efficient 1/n values following the definitive adsorption

isotherm experiments (ca. 0.8) indicated that the Freundlich equation adequately

predicted the adsorption of Thifensulfuron-methyl to soils over the range of

concentrations tested. The Freundlich adsorption constants ranged from ca 0.15 to 2.55

for the five test soils. The % adsorbed Thifensulfuron-methyl at each concentration is

provided in Table B.8.195.

Table B.8.195 Concentration of Thifensulfuron-methyl in the solid and liquid phases

at the end of adsorption equilibration period

Test

concentration

(g a.s./mL)

Lleida Nambsheim

on soila

(g a.s./g)

in solution

(g a.s./mL)

%

adsorbedb

on soila

(g a.s./g)

in solution

(g a.s./mL)

%

adsorbedb

Control 0 0 0 0 0 0

0.044 0.005 0.039 11.14 0.011 0.033 25.00

0.10 0.020 0.080 19.55 0.026 0.073 26.16

0.46 0.050 0.412 10.80 0.121 0.342 26.13

0.92 0.131 0.789 14.16 0.141 0.779 15.33

4.41 0.616 3.782 13.93 0.683 3.734 15.47 a Calculated by difference (total applied – concentration in solution)

b b % adsorbed as the % of the applied.


Table B.8.195 Concentration of Thifensulfuron-methyl in the solid and liquid phases

at the end of adsorption equilibration period (continued)

Test concentration

(g a.s./mL)

Sassafras Drummer Gross-Umstadt

on soila

(g a.s./g)

in solution

(g a.s./mL) % adsorbedb

on soila

(g a.s./g)

in solution


on soila

(g a.s./g)

in solution


Control 0 0 0 0 0 0 0 0 0

0.051 0.032 0.035 30.99 0.074 0.014 72.45 0.018 0.041 18.15

0.10 0.061 0.071 30.00 0.140 0.031 69.26 0.020 0.091 9.65

0.52 0.276 0.381 26.56 0.679 0.179 65.39 0.103 0.466 9.95

1.07 0.581 0.783 27.05 1.311 0.409 61.03 0.244 0.949 11.33

4.59 2.017 3.574 21.96 4.619 2.276 50.31 1.289 3.934 14.04 a Calculated by difference (total applied – concentration in solution)

b % adsorbed as the % of the applied.


III. CONCLUSIONS

The adsorption/desorption of [14

C]-Thifensulfuron-methyl was examined on five different

soils designated Sassafras (loamy sand), Lleida (clay), Drummer (clay loam), Gross-Umstadt

(loam), and Nambsheim (sandy loam). The Kd values ranged from 0.11 in Lleida soil to 5.29

in Drummer soil. The Kom and Koc values ranged from 4 and 6, respectively, in Lleida soil to

104 and 179, respectively, in Drummer soil. The Freundlich adsorption isotherm coefficient

KF ranged from 0.155 to 2.547. The adsorption isotherm coefficient as a function of organic

carbon, KFoc, ranged from 9 to 86. Calculation of the Freundlich coefficient 1/n values (range

0.821–0.983) indicated that the Freundlich equation adequately predicted the adsorption of

Thifensulfuron-methyl to soils over the range of concentrations tested.

Using the ASTM International Classification scale to assess a chemical’s potential mobility

in soil (based on KOC), Thifensulfuron-methyl can be classified as having “very high

mobility” in Lleida (clay), Gross-Umstadt (loam), and Nambsheim (sandy loam) soils and

“high mobility” in Sassafras soil (loamy sand) and Drummer (clay loam) soils

(Bell, S., 2011)

Report: M. Simmonds, M. Burgess (2012) [14

C]-Thifensulfuron-methyl:

Adsorption to and desorption from four soil. Battelle UK Ltd.

[Cheminova A/S], Unpublished report No.: WB/10/007 [CHA Doc. No.

259 TIM]

Guidelines: OECD Guideline for the Testing of Chemicals, “Adsorption – Desorption

Using a Batch Equilibrium Method”, Method 106, January 2000

GLP: Yes. GLP practice statement and QA statement supplied. GLP certified

laboratory. GLP compliance claim excludes calculations using non-

validated higher tier functions in excel, collection and sterilisation of

soils, and physiochemical data related to the test substance.

Previous




reported and concluded that the study was acceptable for inclusion in the

overall regulatory database for determining exposure assessment input

parameters. As briefly noted above, the study used a short equilibrium

time (2 hours in all soils) in order to minimise parent degradation. The

detailed study summary from the Task Force is provided below,

supplemented with additional information added by the UK RMS during

the evaluation.


[Triazine-2-14


Specific radioactivity 5.18 MBq/mg-1



Lot/Batch: [Triazine-2-14

C]- Thifensulfuron-methyl 3783FDG003-2

Non-radiolabelled Thifensulfuron-methyl 984-LiN-38-3

Purity: [Triazine-2-14



Soils: The study was conducted with four different UK soil types. All soils

were air-dried, thoroughly mixed, 2 mm sieved and stored refrigerated

in the dark at room temperature (ca 4°C) prior to use. A summary of

physical and chemical properties of the soils is provided in Table

B.8.197. The percent sand, silt and clay are quoted on the basis of

USDA Particle size distribution classification.

Table B.8.197 Soil physiochemical properties

Soil Name Longwoods Farditch Kenslow Lockington

Origin UK UK UK UK

Textural class (USDA) Sandy loam Silt loam Loam Clay Loam

Sampling depth (cm) 5-20 10-20 10-20 0-20

% Sand 77 29 41 42

% Silt 8 54 44 21

% Clay 15 17 15 37

% Organic Carbon 1.3 3.5 3.9 2.8

CEC (mEq/100g) 12.4 12.5 10.8 24.8

pH (0.01M CaCl2) 7.3 5.9 5.1 5.5

% Moisture (pF 2.5) 8.4 27.7 25.4 23.4

In an adsorption / desorption study, 4 UK soils were used to assess the adsorption behaviour

of Thifensulfuron-methyl in soil.

UK RMS considers that the soils chosen exhibit sufficient variation in soil characteristics for

the purposes of the adsorption experiment. Specifically, UK RMS considers the variation

among the important soil characteristics for adsorption process (clay content and soil texture,

pH and % organic carbon) adequate.

Preliminary studies were carried out to check for adsorption to the tubes, to determine any

background radioactivity in the soil, to determine the soil: solution ratio to be used and to

determine the appropriate adsorption and desorption times to ensure that the test item remained

stable for the duration of the definitive test. A stock solution of Thifensulfuron-methyl in 0.01M

CaCl2 with a concentration of 0.01 mg L-1 was prepared. Aliquots of this treatment solution were

weighed for analysis by LSC.

Adsorption to the test vessels was found to be insignificant - A mean value of 100.5% of

applied substance was recovered after testing for adsorption to test vessels, as shown in the

Table below.


To determine an appropriate soil/solution ratio, a treatment solution was prepared to allow

treatment at a nominal concentration of 0.5 mg L-1. Soil (oven dried equivalent)/CaCl2 ratios of

approximately 1:3, 1:2 and 1:1 were set up and the tubes were shaken overnight to pre-equilibrate

(ca 16 hours) prior to treatment. Following pre-equilibration, 1 mL of the treatment solution was

added to each tube. The tubes were capped tightly, shaken by hand to suspend the soil and then

shaken for 24 hours. The tubes were then removed and centrifuged for 10 minutes.

Following the soil/solution ratio experiment the soils were extracted using three 60 mL portions

of methanol: water: formic acid (80:20:1 v/v/v). The tubes were placed on a wrist action shaker

for 30 minutes. The tubes were then removed, centrifuged for 10 minutes and the solvents

transferred to a pre-weighed plastic bottle. All extracts were combined, weighed and aliquots of

each supernatant were removed in order to determine the radioactivity by LSC. All supernatants

and combined solvent extracts were analysed by HPLC.

At the soil: solution ratio of 1:1 two of the four soils were within the acceptable range of 20 to

80% adsorption to soil, the exceptions were the Longwoods sandy loam and the Lockington clay

loam which only achieved 11.6 and 13.6% adsorption respectively (Table 7). A soil: solution

ratio of 1:1 was adopted for all soils in order to try to achieve the maximum adsorption possible.

Due to significant breakdown of the test item observed in the soil: solution ratio preliminary test,

subsequent tests were performed using soils that had been sterilised by gamma irradiation.

In order to assess the stability of the test item in the test medium, a single tube containing 0.01M

calcium chloride (ca 40 mL) without soil was prepared and treated with 1 mL of the stock

treatment solution (0.33 mg mL-1). This solution was then analysed periodically by HPLC.

Due to the instability of [14C]-Thifensulfuron-methyl observed after adsorption for 24 hours

during the soil/solution ratio determination, even whilst using sterile soils, the adsorption

equilibrium determination was conducted for a limited time period to ensure the stability of the

test item. Adsorption to the soil was therefore conducted for 1, 2 and 4 hours, followed by a 1

hour desorption time.

A treatment solution was prepared to allow treatment at a nominal concentration of 0.5 mg L-1.

Three 20 g ode replicates for each soil were weighed into numbered tubes, and mixed with CaCl2

0.01M solution for a 1:1 ratio. The mixture was shaken overnight to pre-equilibrate prior to

treatment. Following pre-equilibration, 1 mL of the treatment solution was added to each tube.

The tubes were shaken by hand to suspend the soil before being placed on an end-over-end

shaker. One tube from each soil type was removed after 1, 2, and 4 hours. At each time point, the

tubes were centrifuged for 10 minutes and the supernatants removed. Aliquots of the supernatant

were taken for analysis by LSC.


Following the adsorption phase a 1 hour desorption cycle was performed on each soil sample.

After 1 hour the tubes were removed and centrifuged for 10 minutes the supernatants were

removed. Weighed aliquots of the supernatant were taken for analysis by LSC.

Following the desorption phase of the 4 hour adsorption samples, the soils were extracted using

one 30 mL portion of methanol followed by two 30 mL portions of methanol: water: formic acid

(80:20:1 v/v/v). The tubes were placed on a wrist action shaker for 30 minutes. The tubes were

then removed, centrifuged for 10 minutes and the supernatants transferred to a pre-weighed

plastic bottle. All extracts were combined, weighed and aliquots of each supernatant were

removed in order to determine the radioactivity by LSC.

All adsorption and desorption supernatants and combined solvent extracts (for the 4 hour

adsorption samples) were analysed by HPLC.

Greater than 92% of the applied radioactivity was recovered in all soils; Longwoods sandy loam

98.1%, Farditch silt loam 94.1%, Kenslow loam 94.0% and Lockington clay loam 92.6%.

HPLC analysis of the above extracts indicated that the stability of the test item remained

acceptable after a 4 hour adsorption, a 1 hour desorption cycle and solvent extraction in three of

the four soils, with 90.9-96.4% of the total applied present as Thifensulfuron-methyl. The

exception was the Kenslow loam soil, where 88.2% of applied radioactivity was found to be

Thifensulfuron-methyl. No significant difference in adsorption was observed between 2 and 4

hours, therefore a 2 hour adsorption cycle was adopted for the definitive experiment to ensure

stability of Thifensulfuron-methyl in all four soils for the duration of the test.

The stability of Thifensulfuron-methyl proven beyond the duration of the definitive study for three of

the four soils. The stability was proven for the Kenslow soil during the definitive experiment.

For the definitive tests, all solutions were shaken in the dark at a temperature of 20 ± 2°C.

Uniquely labelled duplicate tubes were prepared for each soil (20 g dry weight, 2mm sieved) at

each of five concentrations. Following a 16 hour pre-equilibration with 0.01 M CaCl2, an

appropriate treatment solution volume and concentration was added to allow treatment at nominal

concentrations of 1.0, 0.33, 0.1, 0.03 and 0.01 mg L-1 [14C]-Thifensulfuron-methyl. The soil

solutions were mixed for approximately 2 hours on an end-over-end shaker.

The tubes were then weighed and centrifuged for 10 minutes. The supernatant solutions were

removed by decantation and the tubes containing the soil pellets were weighed. Aliquots of each

supernatant were weighed and the radioactivity determined by LSC.

Following removal of the adsorption supernatant an approximately equal volume of fresh calcium

chloride solution was added to each tube, which was capped and weighed. Each tube was shaken

by hand to re-suspend the soil and placed on an end-over-end shaker. After approximately 1 hour,

the tubes were removed, re-weighed and centrifuged for 10 minutes. The supernatant was

removed and the tubes were reweighed.

Aliquots of each supernatant were weighed and the radioactivity determined by LSC.

The recoveries of radioactivity were quantified, with all recoveries within the acceptable range of

90-110% of applied radioactivity. The overall material balance for individual samples was in the

range 98.2-102.7% for the Longwoods sandy loam (mean 100.5%), 98.4-102.2% for the Farditch

silt loam (mean 100.6%), 96.8-100.8% for the Kenslow loam (mean 98.4%) and 96.9-102.6% for

the Lockington clay loam (mean 100.2%).

The concentrations in the soil and water phases and the percent of applied radioactivity adsorbed

after the adsorption phase are given in Table B.8.198.


Table B.8.198 Concentrations in the soil and water phases and the percent of applied

radioactivity adsorbed after the adsorption phase

The calculated adsorption and desorption coefficients and constants are shown in Table B.8.199.

The Kf and 1/n values were validated by the UK RMS and were accepted.

For all soils the fit of log Cs1 vs. log Cw1 to a linear equation, was good with correlation

coefficients ranging from 0.998 to 1.000 depending upon soil. There was a linear relationship

between the soil and solution concentration for all soils tested, with 1/n values ranging from 0.95

in Kenslow loam to 1.01 in the Lockington clay loam.


The Kf values ranged from 0.08 mL g-1 in the Longwoods sandy loam to 0.33 mL g-1 in the

Kenslow loam soil. The corresponding values for Koc ranged from approximately 3 mL g-1 in the

Lockington clay loam to 8 mL g-1 in the Kenslow loam, with a mean value of 6 mL g-1.

Kdes values obtained ranged from 0.14 mL g-1 in the Longwoods sandy loam to 0.58 mL g-1 in the

Kenslow loam. The Kocdes values ranged from 11 mL g-1 in the Longwoods sandy loam and the

Lockington clay loam to 15 mL g-1 in the Farditch silt loam and Kenslow loam, with a mean of 13

mL g-1. These values were greater than the Koc for adsorption indicating that, once adsorbed,

Thifensulfuron-methyl was slightly less readily desorbed.

The values of 1/n for the desorption were similar to those obtained for the adsorption for each soil

and ranged from 0.96 in the Farditch silt loam to 1.04 in the Lockington clay loam.

The Freundlich exponents displayed linearity with 1/n values ranging from 0.95 to 1.01, thus

indicating little change between the amount adsorbed onto the soil and the amount in solution

through the concentration range tested.

Table B.8.199 Adsorption/desorption constants and correlation coefficients for Thifensulfuron-methyl in soil

Soil type OM

%

OC

% pH*


Kf

(mL/g)

Koc

(mL/g) 1/n R

2

Kf

(mL/g)

Kocdes

(mL/g) 1/n R

2

Long woods 2.2 1.3 7.3 0.08 6.0 0.967 0.999 0.14 10.7 1.002 0.999

Farditch 6.0 3.5 5.9 0.22 6.2 0.952 1.000 0.54 15.4 0.961 1.000

Kenslow 6.8 3.9 5.1 0.33 8.4 0.949 0.999 0.58 14.9 0.994 0.999

Lockington 4.8 2.8 5.5 0.09 3.1 1.012 0.998 0.29 10.5 1.039 0.997

Mean - - - 0.18 5.9 0.970 0.999 0.39 12.9 0.999 0.999

Kf = Freundlich coefficient

R2 = Correlation coefficient squared

Koc = Desorption coefficient for organic

carbon

* pH (0.01M CaCl2)

Kocdes = desorption coefficient for

organic carbon

(Simmonds and Burgess, 2012)

Combining the acceptable data from the new studies from both DuPont and the Task Force

resulted in data on sorption on 9 contrasting soils. The combined data set is summarised in

Table B.8.200 below.


Table B.8.200 Combined adorption data set for Thifensulfuron-methyl

Soil

OC

%

pH (in

CaCl2)

Adsorption

KF KFoc 1/n r2

Sassafras 0.81 4.8 0.6660 82 0.9023 0.9959

Lleida 1.74 7.6 0.1551 9 0.9826 0.9687

Drummer 2.96 5.7 2.5468 86 0.8211 0.9942

Gross-Umstadt 1.39 6.6 0.2679 19 0.9599 0.9624

Nambsheim 2.03 7.3 0.2164 11 0.8389 0.9514

Long woods 1.3 7.3 0.08 6.0 0.967 0.999

Farditch 3.5 5.9 0.22 6.2 0.952 1.000

Kenslow 3.9 5.1 0.33 8.4 0.949 0.999

Lockington 2.8 5.5 0.09 3.1 1.012 0.998

Median - - - 9 0.952 -

Arithmetic mean - - - 25.6 0.932 -

Considering the data set as a whole, there was no clear correlation between sorption (Kf) and

soil organic carbon content. However the UK RMS considered that some of the relationship

may have been masked by the fact that across the nine soil types and two studies, equilibrium

times varied from 2 to 24 hours and incubation temperatures varied from 13 to 20°C.

Considering the 4 soils tested by the Task Force, where both equilibrium time and

temperature were consistent, a clear correlation between sorption and organic carbon was

observed. On this basis the UK RMS considered it valid to normalise sorption for organic

carbon content and hence derive Kfoc values. No obvious correlation existed between soil

sorption and other soil properties such as soil pH, considering either the whole data set or the

same four soils where equilibrium conditions were consistent. Based on the generic FOCUS

groundwater guidance (2012), since data on 9 soils is available the use of a median Kfoc of 9

ml/g is considered appropriate for FOCUS modelling. In addition, based on the latest generic

FOCUS groundwater guidance, the use of an arithmetic mean 1/n of 0.932 is considered

appropriate for FOCUS modelling.

IN-A4098

Yeomans P. (1999)

Previous

evaluation:

In Addendum for original approval (2000).


partially meets current guideline OECD 106. When used in conjunction

with other data submitted by DuPont, it was considered acceptable to

aid understanding of the sorption behaviour of metabolite IN-A4098.

The UK RMS has briefly reviewed the study and notes that the original

DAR evaluation concluded that the results were unreliable due to low

adsorbed amounts.

The original text of the study summary from the 2000 DAR Addendum

has been included below. Since the study is not relied upon, it has been

shaded in grey.


Yeomans P. (1999), report 1805, GLP, in accordance with OECD guideline, acceptable but

unreliable results due to low adsorbed amounts (< 20 %)

2-14

C Triazine amine (purity > 96 %) at 0.1, 0.5, 1 and 5 mg/l in 25 ml 0.01 M CaCl2 was

adsorbed on 3 preconditioned soils (5 g equivalent dry soil) for 24 h at 20° C. Soil

characteristics are given in table below. Liquid phase was analysed by LSC and HPLC

(highest concentration only). After adsorption, 2 desorption steps (24 h each) were

performed. After desorption, the soils treated at the highest concentration were extracted

(acetonitrile/ammonium carbonate) and extracts were analysed by LSC. Extracted soils were

combusted for mass balance. For all soils, RA was fully recovered and no degradation

product was found in water phase after adsorption. Amounts of triazine amine adsorbed on

soils were low : < 5.4 % (Gross-Umstadt soil), < 13.5 % (Arrow soil) and < 9.5 % (Mattapex

soil). Kf was < 0.6 and Koc was < 26 but these values are not reliable due to the low adsorbed

amounts.

Soil characteristics


Soil texture Sandy loam Silt loam Silt loam

Sand % 71 20 34

Silt % 21 66 53

Clay % 8 14 13

pHw 5.7 7.7 6.4

OC % 2.3 1.2 2.6

CEC meq/100 g 12.3 21.9 11.7

(Yeomans, 1999)

Report: Yeomans, P., Swales, S. (2000); [14

C]IN-A4098: Adsorption/desorption in soil


Guidelines: OECD 106 (1981), U.S. EPA 163-1 (1982), EC Directive 95/36/EC, Active

Substances, Section 7.1.2 (1995) Deviations: None

Testing Facility: Covance Laboratories Europe (CLE), North Yorkshire, UK

Testing Facility Report No.: 550/80

GLP: Yes


Previous



The following study was evaluated by the UK RMS and considered


acceptable. The sorption endpoints from this study have been combined

with all acceptable data from other studies in order to derive an overall

average input parameter for the purposes of exposure modelling.

Executive summary:

The adsorption/desorption characteristics of 14

C-labeled IN-A4098 were studied in three soils

(pH range of 5.7 to 7.7, organic carbon range of 1.2 to 2.6%) from Germany, the U.K. and the

U.S at four different concentrations (0.05, 0.1, 0.5, and 1 μg/mL). The adsorption phase of

the study was carried out by equilibrating preconditioned soils with a 0.01 M CaCl2 solution

at 0.05, 0.1, 0.5 and 1 μg [14

C]IN-A4098/mL in the dark at 20C for 24 hr. The equilibrating

solution used was 0.01 M CaCl2, with a soil/solution ratio of 1:1. The desorption phase was

carried out by equilibrating the remaining soil with a solution of 0.01 M CaCl2 at 20C in the

dark. After 24 hr, the samples were centrifuged and the supernatants collected for analysis.

A second desorption phase was carried out in a like manner. The mass balance of the total

applied test item ranged from 90.8 to 97.9% of the applied radioactivity.

The adsorption KF values ranged from 0.225 to 0.682 mL/g. The adsorption KFOC values

ranged from 16.7 to 29.7 mL/g and the Kd values ranged from 0.2 to 0.9 (see Table B.8.201

for a summary).

Table B.8.201 Summary table of sorption parameters

IN-A4098 – assessment at 20ºC.


(water)

Kd

(ml/g)

Koc

(ml/g)

Kf (ml/g) Kfoc

(ml/g)

1/n

Gross-

Umstadt

(Silt loam)

1.2 7.7 0.2 17.1 0.2 18.8 1.05

Arrow

(Sandy

loam)

2.3 5.7 0.7-0.9 34.4 0.7 29.7 0.94

Mattapex

(Silt loam)

2.6 6.4 0.4-0.5 18.3 0.4 16.7 0.96


A. MATERIALS


C]IN-A4098technical metabolite

Lot/Batch #: Radiochemical file no. 160

Radiochemical purity: Approximately 99%


Description: Not reported

Stability of test compound: The test material stability was determined by HPLC.

Non-labelled test item with a chemical purity of 98.7% was provided by DuPont.


2. Soils:

The study was conducted with three different soil types (two European and one from

the U.S.). Air-dried soils were sieved through a 2-mm screen and mixed thoroughly

prior to use. A summary of the physical and chemical properties of the soils is

provided in Table B.8.202. The percent sand, silt, and clay are quoted on the basis

of the USDA classification.


Property Gross-Umstadt Arrow Mattapex

Origin Germany UK Maryland, USA

Soil texturea Silt Loam Sandy Loam Silt Loam

% Sand (2000-53 m) 20 71 34

% Silt (53-2 m) 66 21 53

% Clay (<2 m) 14 8 13

pH 7.7 5.7 6.4

Organic carbon (%)b

1.2 2.3 2.6

CEC (meq/100 g) 21.9 12.3 11.7

Moisture-Holding Capacity at

1/3 atm (pF 2.5) (%) 27.0 15.8 28.9


b Calculated values (% organic matter/1.724)

B. STUDY DESIGN


A preliminary experiment was conducted to determine the equilibration time and the

stability of IN-A4098 in soil/water suspension during the adsorption and desorption

equilibration. The results are reported in DuPont-1805 and support the selection of

24 hours as the equilibrium time for the adsorption and desorption phases of this

study.

Prior to testing, 10 g dry weight soil samples were preconditioned with 10 mL of

0.01 M CaCl2 for approximately 24 hours. The soil was centrifuged and the

supernatant liquids removed prior to use. The appropriate solution to soil ratio was

determined to be 1:1 after preliminary testing at 1:5. Stock solutions of 14

C-labeled

IN-A4098 in methanol were prepared and aliquots added to portions of 0.01 M

CaCl2 solution to give nominal concentrations of 0.05, 0.1, 0.5 and 1 g IN-

A4098/mL. Portions of test solution (10 mL) were shaken with samples of test soil

(10 g dry weight) for a 24-hour equilibration period in darkness at 20C. Following

centrifugation, the supernatant was collected, weighed and quantified by LSC.

Following the adsorption phase, fresh 0.01 M aqueous CaCl2 (10 mL) was added to

each test vessel, equilibrated for 24 hours at 20C in darkness, solutions and soils

separated, quantified by LSC and subject to a second desorption phase. The second

desorption phase was conducted in like manner.


Soil extracts from the highest concentration (1 μg/mL) tested after desorption cycle

2 were further extracted three times using 2 M ammonium carbonate 9:1 v/v (3


times, 20 mL) and the extracts used to assess the degree of degradation of IN-A4098

during equilibration. Treatment solutions at the highest concentrations (1 μg/mL)

and adsorption supernatants were analysed by HPLC for stability. The aqueous

phase of one replicate of the 0.1 and 1 μg/mL concentrations from each soil was

analysed by HPLC. The stability of IN-A4098 during the equilibration period was

confirmed by HPLC analysis of the supernatant phase.


A. MASS BALANCE

Recovery of radioactivity in aqueous supernatant and soil extracts on completion of

adsorption ranged from 90.1-97.9% of applied radioactivity.

B. FINDINGS

Soil extracts from the highest concentration (1 μg/mL) after desorption cycle 2 were

analysed for the degree of degradation of IN-A4098 during equilibration. Combustion

and trapping efficiencies were 99 3% and all reported data are therefore uncorrected.

Sorption isotherm data were analysed using the log form of the Freundlich equation:

log x/m = 1/n * log Ce + logKF and linear distribution coefficients (Kd) were calculated

from the mean ratios of x/m to Ce, where x/m and Ce represent the test substance

concentration in soil and in the aqueous phase at equilibrium, respectively (Table

B.8.203).

Table B.8.203 Adsorption and constants of IN-A4098 in the soils

Soil

OC

% pH

Adsorption

KFa 1/n r

2 KFOC

b

Gross-Umstadt 1.2 7.7 0.225 1.05 0.9985 18.8

Arrow 2.3 5.7 0.682 0.94 0.9991 29.7

Mattapex 2.6 6.4 0.433 0.96 0.9982 16.7 a Kf - Freundlich adsorption and desorption coefficients; 1/n - Slope of Freundlich adsorption/desorption isotherms

b Kfoc - Coefficient adsorption per organic carbon (Kf 100% organic carbon)

Adsorption of [14

C]IN-A4098 was observed in all three test soils and ranged from 11 to

14% in Gross-Umstadt, 22 to 26% in Mattapex and 32 to 38% in Arrow soil. Within

each soil type, the amount of adsorption was similar over all four test solution

concentration. Soil/water partitioning coefficients (Kd) and the Freundlich isotherms (Kf)

were in excellent agreement, ranging from 0.2-0.9 mL/g and 0.2-0.7 mL/g, respectively.

Freundlich adsorption constants related to organic contents (Kfoc) for Gross-Umstadt (silt

loam), Arrow (sandy loam) and Mattapex (silt loam) soils were 18.8, 29.7, and

16.7 mL/g, respectively. The Freundlich desorption constants were larger than those

obtained for adsorption, with desorption constants (Kf) in the range 0.529-0.980 mL/g

and 0.729-2.537 mL/g for desorption cycles 1 and 2, respectively. The proportion of

adsorbed [14

C] IN-A4098 not desorbed from soil during the two desorption processes

ranged from 23.21 to 72.73% for the Gross-Umstadt soil, in which only a limited amount


of adsorption occurred. For Arrow and Mattapex soil, the proportion of adsorbed [14

C]

IN-A4098 not desorbed from soil during the desorption processes ranged from 40.64 to

51.17% and 37.66 to 49.67%, respectively. The desorption Kfoc values are in the range

20.4 to 44.1 mL/g and 28.0 to 211.4 mL/g for desorption cycles 1 and 2, respectively,

indicating that once adsorbed, IN-A4098 is moderately to readily desorbed. The

% adsorbed and desorbed IN-A4098 at each concentration is provided in Table B.8.204

and Table B.8.205, respectively.


Table B.8.204

Concentration of IN-A4098 in the solid and liquid phases at the end of adsorption equilibration period (mean).

Concentration on

soil (g/mL)

Gross-Umstadt Arrow Mattapex

on soila

(g/g)

in solution

(g/mL) % adsorbedb

on soila

(g/g)

in solution

(g/mL) % adsorbedb

on soila

(g/g)

in solution

(g/mL) % adsorbedb

0.05 0.0057 0.0306 11.37 0.0185 0.0217 37.05 0.0124 0.0252 24.74

0.1 0.0120 0.0605 11.99 0.0370 0.0435 36.97 0.0252 0.0499 25.24

0.5 0.0685 0.3041 13.43 0.1753 0.2319 34.38 0.1239 0.2603 24.30

1 0.1261 0.6020 12.61 0.3247 0.4589 32.49 0.2244 0.5214 22.44 a The amount on soil residue is calculated by difference (total applied – concentration in solution).


Table B.8.205

Concentration of IN-A4098 in the solid and liquid phases at the end of desorption (total of all desorption phases).

Concentration

on soil

(g/mL)

Gross-Umstadt Arrow Mattapex

on soila

(g/g)

in solutiona

(g/mL)

% desorbed

as % of the

adsorbeda

on soila

(g/g)

in solutiona

(g/mL)

% desorbed

as % of the

adsorbeda

on soila

(g/g)

in solutiona

(g/mL)

% desorbed

as % of the

adsorbeda

0.05 0.0027 0.0013 0.0123 0.0052 52.82 23.51 0.0117 0.0083 0.0119 0.0065 37.09 18.38 0.0076 0.0056 0.0124 0.0062 38.80 16.21

0.1 0.0074 0.0066 0.0245 0.0099 38.35 7.38 0.0226 0.0151 0.0241 0.0136 38.79 20.45 0.0158 0.0117 0.0248 0.0124 37.19 16.21

0.5 0.0482 0.0421 0.1198 0.0491 29.47 12.41 0.1213 0.0890 0.1176 0.0654 30.80 18.44 0.0721 0.0509 0.1285 0.0623 41.80 17.13

1 0.0899 0.0905 0.2421 0.0959 28.73 1.77 0.2159 0.1532 0.2299 0.1249 33.50 19.32 0.1389 0.0975 0.2457 0.1200 38.02 18.45 a

Values listed for each soil type are for desorption cycle 1 and 2, respectively.


III. CONCLUSION

[14

C]IN-A4098 is weakly to moderately adsorbed to soil. The average linear adsorption

Freundlich Kfoc value was 21.7 mL/g. The average adsorption Freundlich 1/n value was 1.0.

Sorption was reversible and the adsorbed IN-A4098 was moderately to readily desorbed from

the test soils.

(Yeomans, P., Swales, S., 2000)

Report: Li,Y., McFetridge, R.D. (1996); Batch equilibrium (adsorption/desorption) study of

a metabolite, triazine amine (IN-A4098), of DPX-T6376 on soil


Guidelines: U.S. EPA 163-1 (1982) Deviations: None


Testing Facility Report No.: AMR 3656-95

GLP: Yes



Previous

evaluation: In Addendum for original approval (DAR Addendum 2000).


meets current guideline OECD 106. It was briefly reported in the 2000

Addendum, where it was stated that it had previously been submitted

under the evaluation of metsulfuron methyl. The UK RMS agreed that

the study was acceptable. Since the original study summary in the

Addendum was relatively brief, DuPont provided a full study summary

and this is provided below.

The sorption endpoints from this study have been combined with all

acceptable data from other studies in order to derive an overall average

input parameter for the purposes of exposure modelling.

Executive summary:

The adsorption/desorption characteristics of IN-A4098 was studied in four soils (pH range of

5.3 to 6.3, organic carbon range of 0.46 to 3.02%) in a batch equilibrium experiment. The

adsorption phase of the study was carried out by equilibrating air-dried/fresh soil with IN-

A4098 at 0.1, 0.5, 1.0 and 5.0 g IN-A4098/mL solution at 25C for 24 hours. The

equilibrating solution used was 0.01 M CaCl2, with a soil to solution ratio of 1 to 1. The

desorption phase of the study was conducted using only the highest concentration (5 g IN-

A4098/mL) with three successive desorption cycles. The mass balance at the end of all

desorption phases ranged from 97.4 to 99.9%.

A summary of the average sorption coefficients for each soil is presented in Table B.8.206.


Table B.8.206 Summary of the average sorption coefficients for IN-A4098 in each soil

Soil Kd (mL/g) Kom (mL/g)a Koc (mL/g)

Matapeake 2.06 108 187

Sassafras 0.46 58 99

Drummer 6.90 133 228

Myaka 0.22 22 38 a Kom = (Kd × 100)/%OM

The values for the Freundlich adsorption isothem parameters KF, KFom, KFoc, and 1/n were

derived from the linear form of the Freundlich equation for all soils. A summary of the

adsorption isotherm parameters for each soil is presented in Table B.8.207.

Table B.8.207 Summary of the adsorption isotherm parameters for IN-A4098 in each soil

Soil KF 1/n KFom (mL/g) KFoc (mL/g) R2

Matapeake 2.36 0,841 124 187 0.996

Sassafras 0.621 0.784 78 135 0.999

Drummer 6.80 0.841 131 225 0.995

Myaka 0.264 0.873 26 46 0.999 a KFom = (KF × 100)/%OM b KFoc = (KF × 100)/%OC

The percent IN-A4098 desorbed from the soils during the three desorption intervals (D1, D2

and D3) was calculated and tallied (DT) for all soils at the highest test solution concentration.

The DT values ranged from 4.2% in the Drummer soil to 109.3% in the Myaka soil. The

results are presented in Table B.8.208.

Table B.8.208 Summary of average percent desorption of IN-A4098 for each soil

Soil D1 (%) D2 (%) D3 (%) DT (%)

Matapeake 6.9 8.2 6.1 21.2

Sassafras 18.7 23.5 16.4 58.6

Drummer 0.12 2.0 2.1 4.2

Myaka 41.1 39.4 28.8 109.3

IN-A4098 is weakly adsorbed to sandy soil (Sassafras) and sandy loam soil (Myaka) and

moderately adsorbed to silty clay loam soil (Drummer) and silt loam soil (Matapeake). The

correlation coefficient of adsorption Freündlich constant (Kads) versus organic matter, clay,

cation exchange capacity, potassium, calcium and magnesium content in soil give a

significant indication of positive correlation. Soil organic matter and clay minerals are the

main factors affecting the adsorption process of IN-A4098.

The test substance adsorbed on sandy soil (Myaka) is relatively easily desorbed and on silty

clay loam (Drummer) soil is relatively strongly bound. The desorption ability is positively

correlated (easily desorbed) with sand content in soils and negatively correlated (not easily

desorbed) with clay content, organic carbon and organic matter in soils. IN-A4098 is in a

medium mobility class in Matapeake and Drummer soils and a high to very high mobility

class in Sassafras and Myaka soils, respectively.



A. MATERIALS

1. Radiolabelled test material: [2-14

C]IN-A4098 technical metabolite

Lot/Batch #: HOTC 160

Radiochemical purity: [2-14

C]IN-A4098: >99%

Specific activity: [2-14

C]IN-A4098: 18.3 Ci/mg



Chemical structure of IN-4098 showing position of label.

2. Soils:

The study was conducted with four different soil types. Sieved and air-dried soils

were stored in a plastic bag prior to experimentation. A summary of the physical

and chemical properties of the soils is provided in Table B.8.209. The percent sand,

silt, and clay are quoted on the basis of the USDA classification.

Table B.8.209 Soil characteristics (AMR 3656-95)

Property Matapeake Sassafras Drummer Myaka

Soil texturea Silt loam Sandy loam Silty clay loam Sand

% Sand 25.6 71.6 17.2 91.6

% Silt 61.6 21.6 52.0 4.0

% Clay 12.8 6.8 30.8 4.4

pH 5.3 6.3 5.7 6.2

Organic carbon (%) 1.10 0.46 3.02 0.58

CEC (meq/100 g) 7.7 3.9 34.5 3.8

Moisture holding

Capacity at 1/3 bar (%) 21.2 9.1 27.8 3.5

Bulk density (lb/ft3) 78 94 68 82

a USDA soil classification system.


B. STUDY DESIGN


A preliminary experiment was conducted to determine the test substance purity, the

equilibration time and container adsorption. One concentration, 5.0 g IN-

A4098/mL, was tested with four soil types, with a soil (20 g dry weight) to solution

(20 mL) ratio of 1 to 1. Test substance purity was assessed by HPLC equipped with

diode array and radiochemical detectors. Portions of test solution (20 mL) were

shaken at 25C with samples of test soil (20 g dry weight) for a 24-hour

equilibration period. Samples were analysed at 3, 20, and 24 hours by LSC. Test

substance stability was checked at the 24 hours sampling point by HPLC and LSC,

following supernatant samples being stored at 4C.

Stock solutions of 14

C-labeled IN-A4098 in methanol were prepared and aliquots

added to portions of 0.01 M CaCl2 solution to give a concentration nominal range of

0.1, 0.5, 1.0 and 5.0 g IN-A4098/mL. The appropriate solution to soil ratio was

determined in preliminary testing to be 1:1. Portions of test solution (20 mL) were

shaken at 25C with samples of test soil (20 g dry weight) for a 24-hour

equilibration period. Following centrifugation (2500 rpm for 10 minutes), the

supernatant was decanted and duplicate aliquots were prepared for radioassay. The

preliminary experiment indicated the test substance did not adsorb onto the test

container. Therefore, the controls were not included in the definitive experiment.

Following the adsorption phase, fresh 0.01 M aqueous CaCl2 (20 mL) was added to

each soil sample dosed at 5 g IN-A4098/mL. The samples were equilibrated for 24

hours at 25C, solutions and soils separated, quantified, and subject to further three

like desorption equilibration on successive days. After the third desorption, the soil

extracts were further extracted twice using 10 mL methanol and the extracts used to

assess the degree of degradation of IN-A4098 during equilibration. Following the

methanol extraction, soil samples were air-dried and aliquots combusted


Radioactivity was determined by LSC, and both the supernatant samples from the

adsorption and desorption studies and the methanol extracts from soil extraction step

were analysed by HPLC. Extracted soil samples were air-dried, combusted using an

oxidiser and the concentration of radioactivity determined by LSC.


A. MASS BALANCE

Recovery of radioactivity in aqueous supernatant and soil extracts on completion of

desorption (5 g IN-A4098/mL concentration) ranged from 97.4-99.9% of applied test

item.

B. STABILITY OF THE TEST SAMPLES

The results of the preliminary and definitive tests by HPLC with both UV and 14

C-

detectors indicate that no breakdown of IN-A4098 occurred.


C. FINDINGS

Sorption isotherm data were analysed using the log form of the Freündlich equation:

log x/m = 1/n * log Ce + logKf and the linear distribution coefficients (Kd) for the

adsorption experiment were calculated from the mean ratios of x/m to Ce (Table

B.8.210).

Table B.8.210 Adsorption constants of IN-A4098 in the soils

Soil

OC

% pH

Adsorption

Kf 1/n r2 KFoc

Matapeake 1.10 5.3 2.36 0.841 0.996 214.2

Sassafras 0.46 6.3 0.621 0.784 0.999 133.8

Drummer 3.02 5.7 6.80 0.841 0.995 225.5

Myaka 0.58 6.2 0.264 0.873 0.999 45.52

Kfoc Coefficient adsorption per organic carbon (KF 100/ % OC).

Kd Adsorption coefficient.

The Freündlich adsorption plot obtained showed no significant indication that adsorption

was affected by the increased concentrations based on the percent absorbed for each soil.

The Freündlich adsorption constants ranged from 0.264 to 6.80 for the four test soils

showing that IN-A4098 was weakly adsorbed to sandy and sandy loam soils (Sassafras

and Myaka) and moderately adsorbed to silty clay loam and sandy loam soils (Drummer

and Matapeake). Percent organic carbon and clay content are factors that dominantly

influence Kads. IN-A4098 is in a medium mobility class in Matapeake and Drummer

soils and a high to very high mobility class in Sassafras and Myaka soils, respectively.

The Freündlich desorption constants indicate that IN-A4098 adsorbed on sandy soil

(Myaka) is relatively easily desorbed and on silty clay loam soil (Drummer) is relatively

strongly bound. The % adsorbed and desorbed IN-A4098 at each concentration is

provided in Table B.8.211 and B.8.212, respectively.


Table B.8.211 Concentration of IN-A4098 in the solid and liquid phases at the end of adsorption equilibration period (mean s.d.)

Concentration

on soil (μg/mL)

Matapeake Sassafras Drummer Myaka

on soil

(g/g)a

in liquid

(g)a

%

adsorbedb

on soil

(g/g)a

in liquid

(g)a

%

adsorbedb

on soil

(g/g)a

in liquid

(g)a

%

adsorbedb

on soil

(g/g)a

in liquid

(g)a

%

adsorbedb

0.1 - 0.49 80 1.3 - 1.13 53 0.5 - 0.16 93 0.8 - 1.78 26 1.5

0.5 - 2.10 79 0.4 - 5.40 46 0.6 - 0.79 92 1.0 - 7.55 24 0.5

1.0 - 5.56 75 0.7 - 12.89 42 0.2 - 1.90 91 0.8 - 17.60 21 0.4

5.0 3.804 37.40 67 0.2 1.751 78.55 31 0.4 4.948 14.52 87 0.4 1.012 93.24 18 0.4 a Presented as the mean of 4 replicates as calculated by the reviewer.


Table B.8.212

Concentration of IN-A4098 in the solid phase at the end of desorption (total of all desorption phases).

Concentration on soil

(g/mL)

Matapeake Sassafras Drummer Myaka

on soil

(g/g)a

% desorbed as

% of the

adsorbed

on soil

(g/g)a

% desorbed as

% of the

adsorbed

on soil

(g a.s./g)a

% desorbed as

% of the

adsorbed

on soil

(g/g)a

% desorbed as

% of the

adsorbed

5.0 3.28 7.07 1.14 19.53 4.84 1.41 0.41 36.43 a Presented as the mean of the 1

st, 2

nd and 3

rd desorption cycles as calculated by the reviewer.


III. CONCLUSION

IN-A4098 is weakly adsorbed to sandy soil (Sassafras) and sandy loam soil (Myaka) and

moderately adsorbed to silty clay loam soil (Drummer) and silt loam soil (Matapeake). The

correlation coefficient of adsorption Freundlich constant (Kads) versus organic matter, clay,

cation exchange capacity, potassium, calcium and magnesium content in soil give a

significant indication of positive correlation. Soil organic matter and clay minerals are the

main factors affecting the adsorption process of this test substance.

The test substance adsorbed on sandy soil (Myaka) is relatively easily desorbed, and on silty

clay loam (Drummer) soil is relatively strongly bound. The desorption ability is positively

correlated (easily desorbed) with sand content in soils and negatively correlated (not easily

desorbed) with clay content, organic carbon and organic matter in soils.

IN-A4098 is in a medium mobility class in Matapeake and Drummer soils and a high to very

high mobility class in Sassafras and Myaka soils, respectively.

(Li, Y., McFetridge, R.D., 1996)

Report: Hein, W. (2001); Adsorption/desorption of AE F0594113-[2-

14C] on one soil

DuPont Report No.: AgrEvo OE98/111 (M-182936-02-1)

Guidelines: OECD 106 (1981) Deviations: None

Testing Facility: Staatliche Lehr- und Forschungsanstalt fur Landwirtschaft, Weinbau und

Gartenbau (SLFA), Neustadt/Weinstrasse, Germany

Testing Facility Report No.: OE98-111

GLP: Yes

Certifying Authority: Landesanstalt fur Pflanzenbau und Pflanzenschutz Rheinland-Pfalz

(Mainz, Germany)

Previous

evaluation:



The following study on the metabolite IN-A4098 was evaluated by the

UK RMS and considered acceptable. However given the age of this

study it is likely that it could have already been evaluated in the DAR of

other sulfonyl urea active substances. The sorption endpoints from this

study have been combined with all acceptable data from other studies in

order to derive an overall average input parameter for the purposes of

exposure modelling.

Executive summary:

For the test a soil/solution ratio of 1:1.67 corresponding to 12 g soil and 20 mL solution and a

shaking period of 24 hours was used. When applying the test substance at concentrations

corresponding to 4.76, 0.95, 0.19, and 0.04 mg/L CaCl2 solution, the proportion of AE

F05941 l-[2-14

C] being adsorbed ranged from 42 to 63%.

3 AE F059411 = IN-A4098


The chromatographic analysis of the clear centrifuged supernatant showed that more than

99% of the measured radioactivity could be assigned to the unchanged test substance. The

coefficients of the Freundlich Equation KF and 1/n, determined by means of the adsorption

isotherm, as well as the soil carbon-based sorption factor KOC, were calculated. The KF was

determined to be 1.57 mL/g and the Freundlich Exponent 1/n was 0.835. The corresponding

KOC for adsorption was calculated to be 172.

Desorption tests showed that between 34% and 45% of the adsorbed test substance was

desorbed again from the soils. For desorption, the KF was determined to be 2.50 mL/g and

1/n was 0.895. The corresponding KOC for desorption was calculated to be 274.



A. MATERIAL


C]BCS-CN85650

Report Name (free base): AE F059411



Sample ID: Z 2802 1-0

2. Soil: Sorption test were performed with one soil only.

The characteristics of the soil are summarised in

Table B.8.213.

Structure of radiolabelled compound

Table B.8.213 Characteristics of test soils

Designation

Batch ID

Units

Honville

25.08.1998

Origin

Chateaudun

(F)

Texture Loamy silt

Sand (0.050–2.000 mm) [%] n.a.

(0.063–2.000 mm) [%] 4.8

Silt (0.002–0.050 mm) [%] n.a.

(0.002–0.063 mm) [%] 79.8

Clay (<0.002 mm) [%] 15.4

pH 6.7

Organic carbon [%] 0.91

Cation exchange capacity [mval/100 g soil] 13


B. STUDY DESIGN


12-October-1998 to 05-November-1998


Samples of 12 g dry weight were weighed into the centrifuge tubes and filled up to a

total of 20 mL using different 0.01 M aqueous calcium chloride application

solutions. A soil to solution of 1.67 was established. Initial nominal concentrations

of the 14

C-test substance in the aqueous phase were 5, 1, 0.2, and 0.05 mg/L thus

covering two orders of magnitude.

Adsorption and desorption took place in the dark at 20 1

using an overhead shaker at approximately 20 rpm. One desorption cycle was

performed by adding fresh 0.01 M CaCl2 (20 mL) and renewed agitating for

24 hours.

For work-up the aqueous supernatant was separated from soil by decantation and

centrifugation. Radioactivity in water and soil extracts was determined by liquid

scintillation counting (LSC). Non-extractable radioactivity in soil was determined

by combustion followed by LSC to establish a full material balance.

Finally the adsorption parameters were calculated using the Freundlich adsorption

isotherm.


Radiolabelled AE F059411 was determined by liquid scintillation counting (LSC) in

the definitive test. HPLC analyses with 14

C Detector were used for the parental

mass balance.


A. MASS BALANCE AND STABILITY TESTS

After 24 hours of shaking, RA adsorbed to soil was 42.4–63.4%. No significant

degradation of AE F0059411 occurred (>99% remaining), and radioactive recoveries

were 95.5–97.1% AR in the total systems, suggesting appropriate stability of the test

substance.

B. FINDINGS

After 24 hours of shaking, RA adsorbed to soil was 42.4–63.4%. No significant

degradation of AE F0059411 occurred (>99% remaining), and radioactive recoveries

were 95.5–97.1% AR in the total systems, suggesting appropriate stability of the test

substance.

The Freundlich adsorption coefficients KF was calculated to be 1.57 mL/g, corresponding

to a KOC value of 172 mL/g. The Freundlich exponent (1/n) was 0.84. The desorption KF

value (2.50 mL/g) was higher than the adsorption KF value, indicating some hysteresis.

Correlation coefficients were 0.997 for the adsorption and desorption isotherms.


Table B.8.214 Definitive test: Concentration of AE F059411 in aqueous and soil phase of

soil Honville at the end of adsorption equilibrium (mean ± s.d.)

Initial concentration

of a.s. (g/20mL)

Soila

(g/12 g)

Solution

(g/20 mL)

Percentage

adsorbed

95.173 40.317 0.393 54.856 0.393 42.4 0.7

18.933 9.9821 0.2056 8.9508 0.2056 52.7 2.3

3.8338 2.4317 0.0110 1.4021 0.0110 63.4 0.8

0.74410 0.46437 0.02813 0.27973 0.02813 62.4 10.1 a The amount of test item adsorbed to the soil was calculated by subtracting the equilibrium concentration in the solution from the initial

concentration (applied concentration).

Table B.8.215 Definitive test: Concentration of AE F059411 in aqueous and soil phase at

the end of desorption equilibrium (mean ± s.d.)

Initially adsorbed concentration

of a.s. (g/12g)

Solution

(g/20mL) a

Percentage

desorbeda

40.317 0.393 22.071 0.596 45.3 1.5

9.9821 0.2056 6.1379 0.2088 38.5 2.1

2.4317 0.0110 1.5865 0.0283 34.8 1.2

0.46437 0.02813 0.30687 0.02227 33.9 4.8 a Reflects differences in AE F05941l -[2-

14C] in the aqueous solution before and after desorption.

Table B.8.216 Adsorption and desorption constants of AE F059411 in soil

Soil

type


KF

[mL/g] 1/n R²

KOC

[mL/g]

KF

[mL/g] 1/n R²

KOC

[mL/g]

Honville 1.57 0.8351 n.a. 172.0 2.50 0.8953 n.a. 274.3

KF: Freundlich coefficients of adsorption and desorption

1/n: Slope of the Freundlich adsorption/desorption isotherms

Koc: Adsorption coefficient per organic carbon (K x 100/% organic carbon)

n.a.: not available

III. CONCLUSION

The adsorption of AE F059411 was investigated in batch equilibrium studies with on soil.

Measured KOC value was 172.0 mL/g, with Freundlich exponent of 0.8953.

Using the Briggs classifications for the estimation of the mobility of crop protection agents in

soil based on KF and/or KOC-values, AE F059411 can be classified as low mobile for

adsorption and desorption.

(Hein, W., 2001)


Report: Kesterson, A. (1990); Soil adsorption/desorption of [14

C]CGA-1508294 by the batch

equilibrium method

DuPont Report No.: Ciba 470

Guidelines: U.S. EPA 163-1 (1982) Deviations: None

Testing Facility: PTRL, Lexington, Kentucky, USA


GLP: Yes



Previous

evaluation:



The following study on metabolite IN-A4098 was evaluated by the UK

RMS and considered acceptable. However given the age of this study it

is likely that it could have already been evaluated in the DAR of other

sulfonyl urea active substances. The sorption endpoints from this study

have been combined with all acceptable data from other studies in order

to derive an overall average input parameter for the purposes of

exposure modelling.

Executive summary:

The adsorption characteristics of 14

C-ring labelled CGA 150829 was investigated in 4

different soils: an agricultural sand, a sandy loam, a silt loam and a silty clay loam using a

standard batch equilibrium method. The soil adsorption coefficients Kd and KOC, together

with the Freundlich adsorption constants KF and KFOC, were determined for each soil.

The reversibility of the adsorption (desorption) was also determined.

The mass balance from all soils was between 94.3 and 105.2% of the applied radioactivity.

The mean adsorption KFOC from all soils was 143.4 mL/g and the mean slope (1/n) was

0.8904.

A summary of the key values is shown in Table B.8.217.

The desorption constants of CGA 150829 were higher than the adsorption constants thus

demonstrating that adsorption was not fully reversible.

4 CGA-150829 = IN-A4098


Table B.8.217 Soil adsorption constants for CGA 150829 in 4 soils

Parameter Agricultural sand Sandy loam Silt loam Silty clay loam

pH 7.9 7.8 6.5 6.9

%OM 0.6 1.7 3.0 1.2

%OC (a) 0.35 0.99 1.74 0.70

KF 0.2326 2.7760 0.9612 1.2010

KFOM 38.8 163.3 32.0 100.1

KFOC (a) 66.5 280.4 55.2 171.6

1/n 0.8702 1.0210 0.8474 0.8230

r2

0.9974 0.9955 0.9995 0.9980

KF (desorption) 1.0722 1.4111 1.8438 2.9561

KFOM (desorption) 178.7 83.0 61.5 246.3

KFOC (desorption)a 306.3 142.5 106.0 422.3

1/n 0.9689 0.8916 0.8810 0.9225

r2 0.9938 0.9954 0.9988 0.9991

a calculated as %OC = %OM / 1.724. It is highlighted that in the original report Kfoc was calculated considering that %OC = %OM / 2.

This has been updated in the current summary


A. MATERIALS

1. Test material: 14

C ring labelled CGA 150829

Lot/Batch #: CL-XIV-41

Specific activity: 6.383 MBq mg-1

Purity: 97.9%

2. Soils:

Four soils were used for the study (Table B.8.218)

Table B.8.218 Soil chracteristics.


Name Agricultural sand Sandy loam Silt loam Silty clay loam

Sampling location Fayette county,

Kentucky, USA

Fayette county,

Kentucky, USA

Fayette county,

Kentucky, USA

Fayette county,

Kentucky, USA

Particle size (% w/w):

Clay (<2 m) 1 10 17 34

Silt (50-2 m) 11 21 66 51

Sand (2000-50 m) 88 69 17 15

Texture (USDA) Sand Sandy loam Silt loam Silty clay loam

Taxonomy Not reported Not reported Not reported Not reported

pH 7.9 7.8 6.5 6.9

Organic matter (%) 0.6 1.7 3.0 1.2

CEC (meq/100 g soil) 3 10 16 30

B. STUDY DESIGN AND METHODS


The soil to water ratio and equilibration time were determined in preliminary testing

on all soils. The soil solution ratios for the definitive study were set of 1:1.2 for the

agricultural sand and sandy loam soils, and 1:2 for the silt loam and silty clay loam

soils. Equilibrium was reached for all soils after 24 hours. At equilibrium the

amount of test substance adsorbed ranged from 13.8 and 48.6%.

The mass balance was determined, after the desorption step, in triplicates on all soils

and at all concentrations.


Adsorption phase (Main Test)


Soil condition Air dried soil, passed through 2 mm sieve prior to use

Soil sample weight 25 g (dry weight) per replicate for the agricultural sand and

sandy loam soils, 15 g (dry weight) per replicate for the silt

loam and silty clay loam soils

Equilibration solution 0.01 M CaCl2 (10 mL for all soils)

Control conditions No control conditions

Number of replicates 2 (at each concentration)

Test apparatus 50 mL Teflon

centrifuge tubes

Test material

application

Identity of solvent Dosed in 0.01 M CaCl2

Volume of test

solution

used/treatment

-

Evaporation of

application solvent

No

Test material

concentration

Nominal application

rates (g ai/mL)

0.1

0.2

0.5

1.0

5.0

Actual application

rates (g ai/mL)

Not reported

Soil: Solution ratio 1:1.2 for the agricultural sand and sandy loam soils and

1:2 for the sandy loam and silty clay loam soils

Indication of test material adsorbing to walls of

test apparatus

No

Equilibration

conditions

Temperature (°C) 25

Time 24 hours

Continuous darkness

(Yes/No):

Yes

Shaking method Shaking water bath

Method of separation of supernatant Centrifugation

Centrifugation Speed 6000-15000 r.p.m.

Duration (min) 6-15

Method of separating

supernatant

Decanting


Desorption phase


Soil samples from adsorption phase used Yes

Number of desorption cycles 1

Equilibration solution 0.01M CaCl2 (volume added equivalent to volume of

adsorption decanted)

Control conditions Not done

Number of replicates 2

Test apparatus 50 mL Teflon

centrifuge tubes

Soil: Solution ratio 1:1.2 for the agricultural sand and sandy loam soils and

1:2 for the sandy loam and silty clay loam soils

Equilibration

conditions

Temperature (°C) 25

Time 24 hours

Continuous darkness

(Yes/No):

Yes

Shaking method Shaking water bath

Method of separation of supernatant Centrifugation

Centrifugation Speed (g) 6000–15000 r.p.m.

Duration (min) 6–15

Method of separating

supernatant

Decanting


All supernatants were radioassayed with LSC and the concentrations in each

aqueous phase were calculated. The concentrations adsorbed to the soil were

calculated by subtraction of the mass of the test compound recovered in the aqueous

phase from the mass applied.

After the desorption step, the soil samples were combusted with an oxidiser and

radioassayed by LSC. Mass balances were calculated by summation of the

percentages of applied radioactivity recovered in the aqueous phase and that

remaining in the soil after extraction (following sample oxidation/LSC).


The recovery of radioactivity was quantitative, with recoveries within the range of 94.3 and

105.2% of applied radioactivity.

The Freundlich coefficients are summarised below.


Table B.8.219 Summary of Freundlich coefficients

Soil % OM % Clay pH CEC 1/n r2

KF KFOC

(mL/g)

Adsorption Agricultural soil 0.6 1 7.9 3 0.8702 0.9974 0.2326 66.5

Desorption 0.9689 0.9938 1.0722 306.3

Adsorption Sandy loama 1.7 10 7.8 10

1.0210

0.9024

0.995

0.99

2.7760

0.57

280.4

58.2

Desorption 0.8916 0.9954 1.4111 142.5

Adsorption Silt loam 3.0 17 6.5 16 0.8474 0.9995 0.9612 55.2

Desorption 0.8810 0.9988 1.8438 106.0

Adsorption Silty clay loam 1.2 34 6.9 30 0.8230 0.9980 1.2010 171.6

Desorption 0.9225 0.9991 2.9561 422.3 aThe initial Kf of 2.7760 was incorrectly calculated in the original report. The corrected value, derived from the

peer reviewed RAR for triasulfuron and independently validated by the UK RMS has been added to the table.

The Kfoc and 1/n value have also been updated.

III. CONCLUSION

The adsorption/desorption behaviour of 14

C-CGA 150829 has been studied in four soils and

showed KFOC values between 55.2 and 171.6 280.4. Using the McCall Classification scale to

assess a chemical's potential mobility in soil (based on its KFOC), CGA 150829 can be

classified as having a "high" to “medium” potential mobility.

(Kesterson, A., 1990)

Report: Schmidt, E. (1998); Determination of the adsorption/desorption behaviour in the

system soil/water in three soil types according to OECD guideline #106

DuPont Report No.: AgrEvo CP98/014 (M-182945-01-1)

Guidelines: OECD 106 (1981) Deviations: None

Testing Facility: Hoechst Schering AgrEvo GmbH, Frankfurt am Main, Germany

Testing Facility Report No.: CP98-014

GLP: Yes

Certifying Authority: Not given

Previous




acceptable. However given the age of this study it is likely that it could

have already been evaluated in the DAR of other sulfonyl urea active

substances. The sorption endpoints from this study have been combined



Executive summary:

The adsorption/desorption characteristics of amino triazine (AE F059411) were determined

for three soils in a concentration range of two orders of magnitude (0.028 to 3.98 g/mL of


the test substance in 0.01 M CaCI2) at cons C) using a soil to

solution ratio of 1/1 (w/w). The mean mass balances showed recoveries from 97.8 to 99.3%

with standard deviations of 0.2 to 1.0%.

The calculated adsorption constants KF(ads) of the Freundlich isotherms for the three test

soils ranged from 0.30 to 0.44 mL/g. The Freundlich exponents 1/n were in the range of

0.840 to 0.909, indicating that the concentration of the test item affected the adsorption

behaviour in the examined concentration range.

No significant dependence was observed for the adsorption behaviour from pH or the texture

of investigated soils.

According to Briggs, AE F059411 can be classified as mobile for adsorption as well as for

desorption.


A. MATERIALS


C] AE F059411



Batch No.: Z 28021-0

2. Soils Sorption test were performed with three soils

covering a range of physico-chemical properties

(organic carbon 0.43-2.08%, pH 6.0-7.0, clay 9.5-

19.8%, cation exchange capacity (CEC) 3.7-32.6

meq/100 g). The characteristics of soils are


Structure of AE F059411


Table B.8.220 Characterisation of soils used to investigate adsorption/desorption of AE

F05941

Designation

Batch ID

(USDA)

SL S

#970708 B

LS 2.2

#970704 A

SL V

#1998/03/16

Origin

Hattersheim

(D)

Speyer

(D)

Frankfurt

(D)

Texture silt loam loamy sand sandy loam

Sand (0.050–2.000 mm) [%] 17.8 79.3 54.1

(0.063–2.000 mm) [%] 13.2 77.2 50.0

Silt (0.002–0.050 mm) [%] 62.4 11.2 33.7

(0.002–0.063 mm) [%] 67.0 13.4 37.7

Clay (<0.002 mm) [%] 19.8 9.5 12.2

pH 7.0 6.0 6.0

Organic carbon [%] 2.08 1.95 0.43

Cation exchange capacity [mval/100 g soil] 14.2 7.9 6.24

B. STUDY DESIGN


26-May-1998 to 24-July-1998


A soil to solution ratio of 1:1 was selected based on expected low adsorption.

Stability in the test system, absence of adsorption to the test vessel walls, and

adsorption equilibrium time were assayed as preliminary experiments, for selection

of an optimal set-up of the definitive test.

To establish Freundlich isotherms, the definitive experiments were conducted in

duplicates at five concentrations of AE F059411 ranging from 0.028 to 3.98 g/mL.

Samples of 25 g soil (dry weight basis) were pre-equilibrated with 25 mL 0.01 M

CaCl2 solution for a minimum of 24 hours, dosed with test substance (<1%

acetonitrile), and incubated under continuous agitation at 20 1C in the dark. For

convenience of scheduling a 24 h period was selected for the adsorption step and

periods between 22 and 24 hours for the desorption steps. After 24 hours

(adsorption period) the samples were centrifuged, decanted, and assayed by LSC and

exemplarily also by HPLC. Following the adsorption period, three consecutive

desorption cycles were performed by adding fresh 0.01 M CaCl2 (25 mL) and

renewed agitating for 22-24 hours. Finally, representative soil residues were air-

dried, homogenised, and combusted for mass balance.


isotherm.


Radiolabelled AE F059411 was determined by liquid scintillation counting (LSC).

HPLC analyses with 14

C-detector were conducted exemplarily to demonstrate the

stability of the test item in the supernatant. The limit of detection (LOD) of a 14

C-


labelled radiochemical by LSC is defined as twice the background value established

within each measurement for a given quench curve. For HPLC the LOD is the

visualisation of a single peak that is clearly above the background signal of the

instrument. In general, the limit of detection for LSC is about 100 dpm and the

LOD for HPLC is about 500 dpm.


A. STABILITY OF THE TEST ITEM AND MASS BALANCE:

The stability of [14

C]-AE F059411 in 0.01 M CaCI2 solution was confirmed by HPLC

analysis of the application control solutions. After the last desorption step a re-analysis

showed no significant decrease in the purity of the test compound.

The mean mass balances showed recoveries from 97.8 to 99.3% with standard deviations

of 0.2 to 1.0%.

B. FINDINGS

Based on the results of pre-tests for an adequate soil-to-solution ratio the definitive tests

were performed at ratios of 1:1 (w:w). A plateau concentration was reached within 10

hours of shaking. AE F059411 did not adhere to the test vessels. No degradation

occurred in the test system. The radioactive material balance was complete, with 97.8 to

99.3% recovery for the three soils.

Adsorption KF ranged from 0.30 to 0.44 mL/g and KOC ranged from 15.4 to 74.4 mL/g,

with Freundlich exponents (1/n) of 0.84 to 0.91. Desorption KF values increased each

desorption step, indicating some hysteresis. Correlation coefficients were 0.980 to 1.000

for all isotherms.

Organic carbon content appeared to have no direct influence on the adsorption of AE

F059411 and the variability of the observed KOC values would suggest that other soil

factors may have influenced the sorption processes. Cation exchange capacity, pH, clay-

content and water retention capacity were supposed also to influence the sorption of AE

F059411.


Table B.8.221 Concentration of AE F059411 in aqueous and soil phase at the end of

adsorption equilibrium (mean values of duplicates)

Description

Soil

(mg/kg)a

Solution

(mg/L)

Concentration

of a.s.

Soil SLS

Control N/A N/A

0.028 mg/L 0.0129 0.0194

0.184 mg/L 0.0808 0.1287

0.358 mg/L 0.1432 0.2605

0.726 mg/L 0.2697 0.5391

3.560 mg/L 1.0154 2.8579

Soil LS 2.2

Control N/A N/A

0.030 mg/L 0.0093 0.0233

0.195 mg/L 0.0562 0.1547

0.381 mg/L 0.1035 0.3054

0.756 mg/L 0.2014 0.6102

3.726 mg/L 0.7979 3.1481

Soil SLV

Control N/A N/A

0.032 mg/L 0.0124 0.0222

0.207 mg/L 0.0687 0.1543

0.404 mg/L 0.1183 0.3131

0.805 mg/L 0.2198 0.6357

3.977 mg/L 0.8382 3.3301 a The amount of test item adsorbed to the soil was calculated by subtracting the equilibrium concentration in the solution from the initial

concentration for each sample differences may occur due to the use of means.


Table B.8.222 Concentration of AE F059411 in aqueous and soil phase at the end of

desorption equilibrium (mean values of duplicates)

Description

Soil

(mg/kg)b

Solution

(mg/L)

Concentration

of a.s.a

Soil SLS

Control N/A N/A

0.028 mg/L 0.0078 0.0097

0.184 mg/L 0.0529 0.0602

0.358 mg/L 0.0876 0.1212

0.726 mg/L 0.1509 0.2490

3.560 mg/L 0.5297 1.2203

Soil LS 2.2

Control N/A N/A

0.030 mg/L 0.0049 0.0095

0.195 mg/L 0.0300 0.0613

0.381 mg/L 0.0526 0.1230

0.756 mg/L 0.1054 0.2376

3.726 mg/L 0.3863 1.1693

Soil SLV

Control N/A N/A

0.032 mg/L 0.0080 0.0085

0.207 mg/L 0.0373 0.0592

0.404 mg/L 0.0515 0.1238

0.805 mg/L 0.0838 0.2508

3.977 mg/L 0.2856 1.1923 a Initial applied concentrations were given

b The amount of test item adsorbed to the soil was calculated by subtracting the equilibrium concentration in the solution from the initial

concentration for each sample differences may occur due to the use of means.


Soil

type

Adsorption Desorption (first desorption step only)

KF

[mL/g] 1/n R²

KOC

[mL/g]

KF

[mL/g] 1/n R²

KOC

[mL/g]

SLS 0.44 0.873 0.9973 21.3 0.50 0.864 0.9919 24.0

LS2.2 0.30 0.909 0.9991 15.4 0.36 0.908 0.9983 18.5

SLV 0.32 0.840 0.9995 74.4 0.24 0.709 0.9954 55.8

KF Freundlich coefficients of adsorption (**) and after first desorption (***)

1/n Slope of the Freundlich adsorption/desorption isotherms

Koc Adsorption coefficient per organic carbon (K 100/% organic carbon)

R2 Regression coefficient of Freundlich equation

n.a. not available

Mean arithmetic


III. CONCLUSION

The adsorption of AE F059411 was investigated in batch equilibrium studies with a total of

three soils. Measured KfOC values ranged from 15.4 to 74.4 mL/g, with Freundlich exponents

between 0.840 and 0.909.

According to Briggs, AE F059411 can be classified as mobile for adsorption as well as for

desorption.

(Schmidt E, 1998)

Report: Stroech, K. (2010); [Triazine-2-14

C]BCS-CN85650 (AEF0594115):

Adsorption/desorption on five soils

DuPont Report No.: Bayer M1311857-6 (M-367103-01-1)

Guidelines: OECD 106 (2000), OPPTS 835.1230 (2008), Environmental Chemistry and

Fate Guidelines for Registration of Pesticides inCanada (1987) Deviations: None

Testing Facility: Bayer CropScience, Monheim am Rhein, Germany

Testing Facility Report No.: M1311857-6

GLP: Yes

Certifying Authority: Ministerium fur Arbeit, Gesundheit und Soziales des Landes

Nordrhein-Westfalen (Dusseldorf, Germany)

Previous

evaluation:



The following study on metabolite IN-A4098 was evaluated by the UK

RMS and considered acceptable. However given the age of this study it

is likely that it could have already been evaluated in the DAR of other

sulfonyl urea active substances. The sorption endpoints from this study

have been combined with all acceptable data from other studies in order

to derive an overall average input parameter for the purposes of

exposure modelling.

Executive summary:

The adsorption/desorption characteristics of amino triazine (AE F059411) were determined

for five soils: 3 from EU and 2 from US in a concentration range of two orders of magnitude.

The parental mass balance for all soils was in the range of 91.8 to 95.9% (mean: 93.7%) of

the applied radioactivity. In the definitive test the overall mean values of recoveries for all

concentrations were in the range of 93.3 to 97.6% (mean: 95.4%) and thus in an acceptable

range.

The calculated adsorption constants KF (ads) of the Freundlich isotherms for the five test soils

ranged from 0.481 to 3.147 mL/g (mean: 1.237 mL/g). The Freundlich exponents 1/n were

in the range of 0.9021 to 0.9755 (mean: 0.9325), indicating that the concentration of the test

item affected the adsorption behaviour in the examined concentration range.

5 AEF059411 = IN-A4098


The desorption KF(des) and the normalised KOC(des) values were significantly higher (2.3 to

8.0 times higher) than those obtained for the adsorption phase, indicating that the test item

once adsorbed to soil is not readily desorbed.

No significant dependence was observed for the adsorption behaviour from pH or the texture

of investigated soils.

According to Briggs, AE F059411 can be classified as low mobile to mobile for adsorption

and low mobile for desorption.


A. MATERIALS


C]BCS-CN85650

Report Name (free base): AE F059411

Specific radioactivity: 4.85 MBq/mg (131.09 µCi/mg)

Radiochemical purity: >98% (HPLC, radioactivity-detector)

Chemical purity: >98% (HPLC, UV-detector, 210 nm)

Sample ID: KATH 6353

Structure of compound


Table B.8.224 Characteristics of test soils

Parameter Results/Units c

Soil ID/

Batch ID

WW

20090227

HH

20090227

LC

20090212

GL

031109-S

SP

030909-S

Geographic location

(City / State /

Country)

Monheim/

North Rhine-

Westphalia/

Germany

Burscheid/

North Rhine-

Westphalia/

Germany

St. Etienné

Du Gres/

France

Guadalupe/

California/

USA

Springfield/

Nebraska/

USA

Soil series N/A N/A N/A Camarillo Marshall

Texture class a Loam Silt Loam Clay Loam Sandy Loam Silt Loam

Sand a

Silt a

Clay a

51%

28%

21%

27%

54%

19%

24%

45%

31%

56.0%

32.6%

11.4%

12.7%

60.8%

26.5%

pH (0.01 M CaCl2)

pH (Water, 1/1)

pH (Saturated paste)

pH (1 N KCl, 1/1)

5.3

5.5

5.5

4.9

6.6

6.8

6.9

6.3

7.6

8.0

7.8

7.4

6.7

6.8

6.5

N/A

6.6

7.2

6.9

N/A

Organic matter b

3.1% 4.1% 1.6% 1.2% 2.9%

Organic carbon 1.8% 2.4% 0.9% 0.7% 1.7%

Cation Exchange

Capacity (CEC)

10.8

meq/100 g

13.9

meq/100 g

11.4

meq/100 g

16.1

meq/100 g

16.1

meq/100 g

Water holding capacity

0.33 bar 15.7% 22.3% 20.5% 15.1% 27.2%

Maximum water

holding capacity 53.9 g/100 g 63.2 g/100 g 43.1 g/100 g 33.4 g/100 g 43.8 g/100 g

Bulk Density

Particle Density

1.19 g/cm3

N/A

1.05 g/cm3

N/A

1.14 g/cm3

N/A

1.17 g/cm3

N/A

0.98 g/cm3

N/A

Biomass N/A N/A N/A N/A N/A

Soil taxonomic

classification (USDA)

Loamy,

mixed, mesic,

Typic

Argudalfs

Loamy, mixed,

mesic, Typic

Argudalfs

N/A N/A

Fine-silty,

mixed,

superactive,

mesic Typic

Hapludolls

Soil mapping N 51° 04.9'

E 006° 55.3'

N 51 04.0'

E 007° 06.3'

N 43 48.2'

E 004 43.1'

N 35 01.1'

W 120 36.2'

N 41 03.7'

W 096 15.1'

a according to USDA classification

b % organic matter = % organic carbon 1.724

c Analyses performed at Agvise Laboratories, 604 Highway 15 West, Northwood, ND 58267, USA.

B. STUDY DESIGN


04-September-2009 to 16-February-2010


Samples of 20 g dry weight of soils Hoefchen Am Hohenseh 4a (Soil ID: HH), Les

Cayades (Soil ID: LC) and Guadalupe (Soil ID: GL) as well as 10 g (dry weight) of

soils Laacher Hof Wurmwiese (Soil ID: WW) and Springfield (Soil ID: SP) were


weighed into the centrifuge tubes to which a solution of 0.01 M aqueous calcium

chloride was added to result in a final volume of 18 mL. The slurry was

pre-equilibrated for at least one day followed by the addition of 2 mL of the

corresponding application solution to result in a final volume of 20 mL and a

soil/solution ratio of 1:2 and 1:4, respectively. As part of pre-tests control samples

containing no soil were prepared the same way for determination of stability of the

test item in calcium chloride solution and for testing of adsorption to the walls of the

test vessels. Initial nominal concentrations of the 14

C-test substance in the aqueous

phase were 1, 0.3, 0.1, 0.03, and 0.01 mg/L thus covering two orders of magnitude.

Adsorption and desorption took place in the dark at 20 1C for 24 hours each

using an overhead shaker at approximately 30 rpm.

For work-up the aqueous supernatant was separated from soil by decantation and

centrifugation (10 min, 4200 rpm). Radioactivity in water and soil extracts was

determined by liquid scintillation counting (LSC). Non-extractable radioactivity in

soil was determined by combustion followed by LSC to establish a full material

balance.


isotherm.


Radiolabelled AE F059411 was determined by liquid scintillation counting (LSC) in

the definitive test. HPLC analyses with 14

C Detector were used for the parental

mass balance in the pre tests. The limit of detection (LOD) was set to 0.3% of

applied radioactivity, the limit of quantification (LOQ) to three times the LOD, i.e.,

approximately 1% of the applied radioactivity. Values between LOD and LOQ are

used for calculation just as given.


A. MASS BALANCE AND RESULTS OF PRELIMINARY TESTS

Preliminary tests performed on solubility and stability of the test substance in aqueous

0.01 M calcium chloride solution confirmed stability under the conditions of the test only

one minor degradation product was detected in aqueous solution with <2% of the injected

radioactivity after 96 h of incubation. Pre-tests on adsorption to the walls of test vessels

by shaking an aqueous solution of the test substance in the absence of soil for up to 96

hours showed no adsorption as it is documented by a constant concentration during the

total testing period.

The parental mass balance for all soils was in the range of 91.8 to 95.9% (mean: 93.7%)

of the applied radioactivity.

The overall mass balances were determined by LSC of the adsorption and desorption

supernatants, and combustion of the remaining soils. The recovery of the applied

radioactivity for all concentrations and soils was in the range of 93.3 to 97.6% (mean:

95.4%).


B. FINDINGS

Based on the results of pre-tests for an adequate soil-to-solution ratio the definitive tests

were performed at ratios of 1:1 (soils Hoefchen Am Hohenseh 4a, Les Cayades and

Guadalupe) as well as 1:2 (soils Laacher Hof Wurmwiese and Springfield).

Within definitive tests, the portion of 14

C-AE F059411 adsorbed to soil after 24 hours

was found to be 38.4-50.2, 32.6–35.3, 35.6–45.1, 40.2–46.2, and 62.0–72.7% of the

applied radioactivity were adsorbed in soils Laacher Hof Wurmwiese, Hoefchen Am

Hohenseh 4a, Les Cayades, Guadalupe and Springfield, respectively (Table B.8.225).

At the end of the first desorption phase, 25.3–31.6, 18.4–20.1, 24.0–26.7, 23.3–27.3, and

13.5-19.6% of the initially adsorbed amounts were desorbed in soils Laacher Hof

Wurmwiese, Hoefchen Am Hohenseh 4a, Les Cayades, Guadalupe and Springfield,

respectively (Table B.8.226).

The adsorption behaviour of AE F059411 could be accurately described within a nominal

concentration range of 0.01 mg/L to 1.0 mg/L by the Freundlich equation for all soils

(Table B.8.227). The calculated adsorption constants KF(ads) of the Freundlich

isotherms for the five test soils ranged from 0.481 to 3.147 mL/g (mean: 1.237 mL/g).

The Freundlich exponents 1/n were in the range of 0.9021 to 0.9755 (mean: 0.9325),

indicating that the concentration of the test item affected the adsorption behaviour in the

examined concentration range. When being normalised for organic carbon content of soil

for AE F059411 the calculated KOC(ads) values varied between 20.0 and 185.1 mL/g

(mean: 87.5 mL/g).

The calculated desorption constants KF(des) of the Freundlich isotherms for the five test

soils ranged from 2.575 to 7.239 mL/g (mean: 4.318 mL/g), the exponents 1/n were in

the range of 0.9069 to 1.0069 (mean: 0.9667). The KOC(des) values of the soils ranged

from 160.2 to 425.8 mL/g (mean: 308.8 mL/g).

KOC(des) values were thus significant higher than the corresponding values of KOC(ads),

indicating a strengthening of binding of AE F059411 once adsorbed to soil particles.

Using the Briggs classifications for the estimation of the mobility of crop protection

agents in soil based on KF and/or KOC-values, AE F059411 can be classified as low

mobile to mobile for adsorption and low mobile for desorption.



the end of adsorption equilibrium (mean values of duplicates and mean s.d.)

Description

Soil

(mg/kg)

Solution

(mg/L)

Percentage

absorbed a

Concentration

of a.s.

Soil Laacher Hof Wurmwiese (Soil ID: WW)

Control N/A N/A

0.011 mg/L 0.010 0.006 47.8 0.5

0.033 mg/L 0.033 0.016 50.2 0.3

0.11 mg/L 0.098 0.058 45.7 1.8

0.32 mg/L 0.294 0.176 45.5 0.6

1.08 mg/L 0.831 0.665 38.4 1.3

Soil Hoefchen Am Hohenseh 4a (Soil ID: HH)

Control N/A N/A

0.011 mg/L 0.004 0.007 35.3 0.9

0.033 mg/L 0.011 0.021 34.3 0.3

0.11 mg/L 0.037 0.071 34.3 0.5

0.32 mg/L 0.105 0.217 32.6 0.2

1.08 mg/L 0.357 0.723 33.0 1.7

Soil Les Cayades (Soil ID: LC)

Control N/A N/A

0.011 mg/L 0.005 0.006 45.1 0.4

0.033 mg/L 0.014 0.018 44.3 0.1

0.11 mg/L 0.046 0.062 42.4 0.5

0.32 mg/L 0.128 0.194 39.8 0.1

1.08 mg/L 0.384 0.696 35.6 0.2

Soil Guadalupe (Soil ID: GL)

Control N/A N/A

0.011 mg/L 0.005 0.006 46.2 0.9

0.033 mg/L 0.015 0.018 45.2 0.7

0.11 mg/L 0.048 0.060 44.4 0.6

0.32 mg/L 0.138 0.184 42.9 0.2

1.08 mg/L 0.434 0.646 40.2 0.7

Soil Springfield (Soil ID: SP)

Control N/A N/A

0.011 mg/L 0.016 0.003 72.7 0.0

0.033 mg/L 0.047 0.009 71.3 0.1

0.11 mg/L 0.151 0.032 70.4 0.2

0.32 mg/L 0.430 0.107 66.7 0.1

1.08 mg/L 1.339 0.411 62.0 0.2 a The amount of test item adsorbed to the soil was calculated by subtracting the equilibrium concentration in the solution from the initial

concentration (applied concentration).



the end of desorption equilibrium (mean values of duplicates and mean s.d.)

Description

Soil

(mg/kg)

Solution

(mg/L)

Percentage

desorbed a

Concentration

of a.s.

Soil Laacher Hof Wurmwiese (Soil ID: WW)

Control N/A N/A

0.011 mg/L 0.008 0.001 27.6 0.7

0.033 mg/L 0.023 0.005 29.4 0.4

0.11 mg/L 0.071 0.014 27.7 1.3

0.32 mg/L 0.201 0.046 31.6 0.5

1.08 mg/L 0.620 0.106 25.3 3.1

Soil Hoefchen Am Hohenseh 4a (Soil ID: HH)

Control N/A N/A

0.011 mg/L 0.003 0.001 18.4 0.9

0.033 mg/L 0.009 0.002 19.3 1.9

0.11 mg/L 0.030 0.007 19.1 0.8

0.32 mg/L 0.085 0.020 18.8 1.1

1.08 mg/L 0.285 0.072 20.1 1.5

Soil Les Cayades (Soil ID: LC)

Control N/A N/A

0.011 mg/L 0.004 0.001 24.0 0.2

0.033 mg/L 0.011 0.004 24.9 0.7

0.11 mg/L 0.034 0.012 25.4 0.1

0.32 mg/L 0.094 0.034 26.7 0.3

1.08 mg/L 0.287 0.097 25.2 6.0

Soil Guadalupe (Soil ID: GL)

Control N/A N/A

0.011 mg/L 0.004 0.001 24.0 0.3

0.033 mg/L 0.011 0.003 23.3 2.3

0.11 mg/L 0.036 0.012 24.2 1.1

0.32 mg/L 0.104 0.034 24.5 0.3

1.08 mg/L 0.315 0.119 27.3 0.5

Soil Springfield (Soil ID: SP)

Control N/A N/A

0.011 mg/L 0.014 0.001 13.5 0.0

0.033 mg/L 0.040 0.003 13.7 0.6

0.11 mg/L 0.130 0.011 14.3 0.0

0.32 mg/L 0.359 0.035 16.5 0.0

1.08 mg/L 1.076 0.131 19.6 0.1 a Expressed as a percentage of the initially adsorbed material, one desorption step for all concentrations.



Soil

type


KF

[mL/g] 1/n R²

KOC

[mL/g]

KF

[mL/g] 1/n R²

KOC

[mL/g]

WW 1.321 0.9183 0.9965 73.4 5.239 1.0069 0.9927 291.0

HH 0.481 0.9755 0.9992 20.0 3.845 0.9805 0.9971 160.2

LC 0.561 0.9170 0.9994 62.3 2.692 0.9777 0.9905 299.1

GL 0.675 0.9498 0.9995 96.5 2.575 0.9613 0.9976 367.8

SP 3.147 0.9021 0.9991 185.1 7.239 0.9069 0.9984 425.8

KF Freundlich coefficients of adsorption (**) and after first desorption (***)

1/n Slope of the Freundlich adsorption/desorption isotherms

Koc Adsorption coefficient per organic carbon (K 100/% organic carbon)

R2 Regression coefficient of Freundlich equation

Mean Arithmetic

III. CONCLUSION

The adsorption of AE F059411 was investigated in batch equilibrium studies with a total of

five soils. Measured KOC values ranged from 20.0 to 185.1 mL/g, with Freundlich exponents

between 0.9021 and 0.9755.

Using the Briggs classifications for the estimation of the mobility of crop protection agents in

soil based on KF and/or KOC-values, AE F059411 can be classified as low mobile to mobile

for adsorption and low mobile for desorption.

(Stroech, K., 2010)

Report: G. Morlock (2006b) Determination of the adsorption/desorption

behaviour of 2-amino-4-methoxy-6-methyl-1,3,5-triazine (MM-TA)6 in

three different soils. GAB Biotechnologie GmbH & GAB Analytik

GmbH, [Cheminova A/S], Unpublished Report no. 20051104/01-PCAD

[CHA Doc. No. 212 MEM]


Using a Batch Equilibrium Method”, Method 106, January 2000; SETAC

1995

GLP: GLP practice statement and QA statement supplied. GLP certified




Previous





6 i.e. IN-A4098





Materials:

1. Test Material: IN-A4098 (MM-TA, Triazine amine)

Purity: 99.5%

2. Soils: Three soils were supplied by LUFA Speyer:

Table B.8.228 Soil physicochemical properties

Soil Name 2.2 3A 6S

Origin Germany Germany Germany

Textural class1 Silty Sand Sandy loam Clay loam

% Sand 87.7 42.9 24.6

% Silt 11.6 38.6 30.4

% Clay 0.7 18.5 45.0

% OC 1.97 2.42 1.84

CEC (mval/100g) 10.2 18.5 22.9

pH (H2O) 5.4 7.3 6.9

Water capacity (%) 42 51.1 43.7 1 DIN 4220

The adsorption properties of IN-A4098 (MM-TA, triazine amine) were studied in three soil

types (German Standard soils 2.2, 3A and 6S) following OECD 106 and SETAC

requirements. These soils were chosen to cover major differences in soil texture, cation

exchange capacity and pH. The soils were air dried at ambient temperature prior to the

experiments (preferably between 20 -25 ºC), sieved to a particle size ≤ 2 mm, and

homogenised. The moisture content of each soil was determined by heating three aliquots at

105 ºC until there was no significant change in weight (approx 12h).

All tests were performed at ambient temperature (between 20 and 25 ºC), and were protected

from light to avoid photochemical degradation. The test item was dissolved in a 0.01 M

solution of CaCl2 in distilled or de-ionised water. The stock solution of the test substance was

200 mg/L, was prepared just prior to application to soil samples.

Tier 1 preliminary testing was performed at a test substance concentration of 18.47 mg/L in

0.01 CaCl2 solution. All experiments including blanks and controls were performed in

duplicate. Tier 1 tests performed with soils 3A and 6S established that IN-A4098 is stable

within the test system and did not adhere to test vessels.


Tier 1 tests also established the appropriate soil/solution ratio (1:1) from the three ratios

suggested in OECD 106 (1:1, 1:5, 1:25), in two soils (3A and 6S). Air-dried soils samples

were equilibrated by shaking with a maximum 9/10 of the final volume of 0.01 M CaCl2 for

12 hours before the day of the experiment. Afterwards, an appropriate amount of stock

solution was added to achieve the correct ratio and test substance concentration. Agitation

was performed on a flat bed shaker at 100rpm to suspend the soil in the aqueous volume. At

0, 1, 2, 4, 6, 24 and 48 hours, samples were taken, centrifuged and 500 µl supernatant

samples taken for analysis. A blank run (1/1 soil/solution ratio with no test substance) and a

control run (test substance in CaCl2) were also tested for each soil. The pH of the aqueous

phase was measured before and after contact with the soil since it plays an important role in

the whole adsorption process, especially for ionisable substances.

The determination of the equilibrium time was performed within the experiment described

above. Small aliquots (500 µl of centrifuged supernatant) were mixed with 500 µl acetonitrile

for analysis for each sampling time.

Mass balance was carried out on the two soils and all ratios for tier 1. After the analysis of the

last samples (at 48 hours), the phases were separated by centrifugation. The aqueous phase

was recovered as completely as possible. Acetonitrile/ water 1:1 (v/v, including soil bound

water) was added to the soil to extract the test substance, and soil extracts analysed. Mass

balance and distribution coefficients were calculated. Low adsorption of IN-A4098 was

observed in the Tier 1 studies.

The tier 2 screening test was performed in soil 2.2 at a single concentration of 18.47 mg/L, a

soil/solution ratio of 1:1 and an equilibration time of 48 hours, based on the preliminary

results. Each experiment was performed in at least duplicate, and a blank (soil and 0.01 M

CaCl2, without test item) and control sample (test item in matrix solution) was included. The

soils samples were pre-equilibrated with 0.01 M CaCl2 for 12 hours. Stock solution of the test

item in 0.01 M CaCl2 was the added for a final concentration of 18.47 mg/L. Agitation was

performed on a flat bed shaker with a frequency of around 100 rpm to hold the soil dispersed

in the aqueous volume. The test was performed using the serial method: At defined intervals

mixtures were centrifuged and 500 µl aliquots of the aqueous phase were analysed for the test

item; then the experiment was continued with the original mixtures.

After 48 hours the phases were separated by centrifugation, the aqueous phase was recovered

as completely as possible. Acetonitrile/water 1:1 was added to the soil to extract the test item.

The amount of test item in the soil extracts was determined and the mass balance was

calculated. The distribution coefficients (Kd and KOC) were then calculated from the

measured concentrations in soil and water. Sorption to soil was low so adsorption coefficients

(KD) and organic carbon partition coefficients (KOC) were calculated based on analysis of

both the CaCl2 solution and soil from the mass balance samples. The results obtained after 48

hours in the Tier 1 & 2 studies are given in Table B.8.229. The results of the determination

of the Freundlich isotherms are given in Table B.8.230.


Table B.8.229 KOC and Kd values for IN-A4098

Soil 3A 6S 2.2

Adsorption [%] 18.0 29.9 16.6

KD [cm3g

-1] 0.21 0.40 0.19

KOC [cm3g

-1] 8.50 21.5 9.35

Log Koc (48h) 0.93 1.33 0.97

Recovery [%] 99.5 94.5 97.9

Tier 3 testing was performed in all three soils with five test item concentrations (10, 16, 26,

42 and 68 mg/L). The adsorption test was performed as in tier 2, but with only one analysis of

the aqueous phase at 48 hours (the time necessary to reach equilibrium).

After analysis, Freundlich adsorption isotherms were plotted and the Freundlich adsorption

coefficient (KF) and Freundlich constants (1/n) were determined. The organic carbon

normalised adsorption coefficient was also determined (KOC). A blank run per soil with the

1:1 soil/solution ratio and CaCl2 solution was subjected to the same test procedure. This acted

as a background control. A control sample with only the test item in matrix solution was also

tested in order to check the stability of the test item in CaCl2 solution and its possible

adsorption on the surfaces of test vessels.

The test was performed by the direct method (determination of the test item in water and in

soil). A 48 hour equilibrium time was used; with five test item concentrations (10, 16, 26, 42

and 68 mg/L). Freundlich adsorption coefficients (KF) and organic carbon partition

coefficients (KOC) were calculated based on the analysis of both the supernatant and soil and

KFs were 0.3728, 0.4350 and 0.0543 and KOCs were 18.92, 17.97 and 2.95 ml/g for soils 3A,

6S and 2.2 respectively. These figures are shown in the table below.

Table B.8.230 KOC and Kd values for IN-A4098

Soil type Soil 2.2 Soil 3A Soil 6S

Organic carbon % 1.97 2.42 1.84

Adsorption isotherms

1/n 0.640 0.759 1.422

Kads

F Ug1-1/1

(cm3)

1/ng

-1 0.3728 0.4350 0.0543

Kads

F OC Ug1-1/1

(cm3)

1/ng

-1 18.92 17.97 2.95

In the light of low levels of adsorption observed, desorption coefficients were not determined.

Recoveries during validation of the analytical method for soil are reported in the summary of

Morlock (2006c). The LOQ of the analytical method in soil was 0.665 µg/50g dry soil.

Recoveries during validation of the analytical method in the supernatant were 89.4 to 104.8%


(mean recoveries 93.4 to 101.9%). The LOQ of the analytical method in the supernatant was

0.8 mg/L.

(Morlock, 2006b)

In total 7 acceptable studies on the sorption potential of metabolite IN-A4098 were submitted

covering 23 contrasting soils. In addition data from an additional four soils were derived

from the peer reviewed RAR for triasulfuron. The UK RMS added these additional data to

the existing dataset in response to Open Point 4.6 in the Evaluation Table. This resulted in

data from 8 acceptable studies covering 27 contrasting soils. The combined data set is

summarised in the following Table B.8.231.

Table B.8.231 Summary of combined sorption data set for metabolite IN-A4098

Triazine amine a.k.a. 2-amino-4-methoxy-6-methyl-triazin a.k.a. 4-methoxy-6-methyl-1,3,5-triazin-2-amine

a.k.a. CGA 150829 (Syngenta) a.k.a. AE F059411 (Bayer Crop Science) a.k.a. IN-A4098 (Du Pont) a.k.a.

[Triazine-2-14

C] BCS-CN85650

Soil type OC

%

Soil

pH

Kd

(ml/g)

Koc

(ml/g)

Kf

(ml/g)

Kfoc

(ml/g)

1/n Temp

(ºC)

Report

author

Gross-

Umstadt (Silt

loam)

1.2 7.7 0.2 17.1 0.2 18.8 1.05 20 7.4.2-11

Yeomans and

Swale

Arrow

(Sandy loam)

2.3 5.7 0.7-

0.9

34.4 0.7 29.7 0.94 20 7.4.2-11

Yeomans and

Swale

Mattapex

(Silt loam)

2.6 6.4 0.4-

0.5

18.3 0.4 16.7 0.96 20 7.4.2-11

Yeomans and

Swale

Matapeake 1.1 5.3 2.06 187.3 2.36 214.2 0.841 25 7.4.2-07 – Li

and Mc

Fetridge

Sassafras 0.46 6.3 0.455 98.91 0.621 133.8 0.784 25 7.4.2-07 – Li

and Mc

Fetridge

Drummer 3.02 5.7 6.9 228.1 6.80 225.5 0.841 25 7.4.2-07 – Li

and Mc

Fetridge

Myaka 0.58 6.2 0.219 37.76 0.264 45.52 0.873 25 7.4.2-07 – Li

and Mc

Fetridge

Honville

(Chateadun)

0.91 6.7 - - 1.57 172 0.8351 20 7.4.2-05 Hein

Agriculutural

sand

0.35 7.9 - 77.53 0.2326 66.5 0.8702 25 7.4.2-06

Kesterson

Sandy loam 0.99 7.8 - 163.29 2.776

0.57

280.4

58.2

1.021

0.9024

25 7.4.2-06

Kesterson

Silt loam 1.74 6.5 - 64.08 0.9612 55.2 0.8474 25 7.4.2-06

Kesterson

Silty clay

loam

0.70 6.9 - 200.17 1.201 171.6 0.8230 25 7.4.2-06

Kesterson


Triazine amine a.k.a. 2-amino-4-methoxy-6-methyl-triazin a.k.a. 4-methoxy-6-methyl-1,3,5-triazin-2-amine

a.k.a. CGA 150829 (Syngenta) a.k.a. AE F059411 (Bayer Crop Science) a.k.a. IN-A4098 (Du Pont) a.k.a.

[Triazine-2-14

C] BCS-CN85650

Soil type OC

%

Soil

pH

Kd

(ml/g)

Koc

(ml/g)

Kf

(ml/g)

Kfoc

(ml/g)

1/n Temp

(ºC)

Report

author

SLS 2.08 7.0 - 0.44 21.3 0.873 20 7.4.2-08

Schmidt

LS2.2 1.95 6.0 - 0.30 15.4 0.909 20 7.4.2-08

Schmidt

SLV 0.43 6.0 - 0.32 74.4 0.840 20 7.4.2-08

Schmidt

Laacher Hof

Wurmwiese

(Loam)

1.8 5.3 - - 1.321 73.4 0.9183 20 7.4.2-09

Stroech

Hoefchen Am

Hohenseh 4a

(Silt laom)

2.4 6.6 - - 0.481 20.0 0.9755 20 7.4.2-09

Stroech

Les Cayades

(Clay loam)

0.9 7.6 - - 0.561 62.3 0.917 20 7.4.2-09

Stroech

Guadalupe

(Sandy

Loam)

0.7 6.7 - - 0.675 96.5 0.9498 20 7.4.2-09

Stroech

Springfield

(Silt loam)

1.7 6.6 - - 3.147 185.1 0.9021 20 7.4.2-09

Stroech

2.2

(silty sand)

1.97 5.4 0.3728 18.92 0.640 20 Morlock

3A

(sandy loam)

2.42 7.3 0.4350 17.97 0.759 20 Morlock

6S

(Clay loam)

1.84 6.9 0.0543 2.95 1.422 20 Morlock

Speyer 2.1 0.56 6.0 0.2025 36 0.92 Triasulfuron

RAR

Standard soil

no. 115

1.7 7.4 0.6255 37 0.89 Triasulfuron

RAR

Standard soil

no. 164

3.0 6.5 0.645 22 0.92 Triasulfuron

RAR

Standard soil

no. 243

1.1 4.3 0.337 31 0.91 Triasulfuron

RAR

Mediana 62.3

45.5

-

Arithmetic meana - 0.903

0.900

aNote these parameters are in agreement with those proposed in the peer reviewed RAR for

triasulfuron.

Considering the data set as a whole, there did not appear to be any strong correlation between

soil properties and sorption potential (for example between %OC and Kf, or between pH and

Kf or Kfoc). However sorption was noted to be highly variable (more than 2 orders of

magnitude between the highest and lowest sorption coefficients). If any correlation did exist,

it may have been masked by the fact that studies were performed under varying conditions

(temperature, soil:solution ratio, equilibrium time etc) over a period of nearly 20 years.

Based on the range of soils tested, the range of sorption parameters (n=27 23) and the

absence of any clear correlation, the UK RMS considered it appropriate to use a median Kfoc

of 45.5 62.3ml/g combined with an arithmetic mean 1/n of 0.900 0.903. This approach is in

line with the latest generic FOCUS groundwater guidance.


IN-A5546

Report: Bell, S. (2011); Adsorption/desorption of [14

C]-IN-A5546 via batch equilibrium

method



None



GLP: Yes


Previous

evaluation:



The following study was reviewed by the UK RMS and considered

acceptable. It should be noted that IN-A5546 is considered a transient

metabolite in soil. This study also confirms the rapid degradation of this

metabolite due to instability demonstrated during the preliminary phases

of the experiment. The detailed study summary from DuPont is

provided below.

Executive summary:


C]-IN-A5546 were investigated in five soils

(pH range of 4.8 to 7.7, organic carbon range of 0.8 to 3.0%) from USA, Germany, Spain,

and France.

Soils were pre-equilibrated with 0.01 M calcium chloride prior to addition of the test item.

[14

C]-IN-A5546 at final nominal concentrations of 0.05–5.00 g/mL in calcium chloride was

added to the soils and incubated in the dark at 20 2C. The soil to solution ratio was 1:2 or

1:1 (5 g or 10 g soil [oven dry weight]: 10 g aqueous).

The adsorption coefficients Kd, Kom, and Koc were calculated and reported for Sassafras,

Drummer, and Gross-Umstadt soils at each concentration of the test substance. IN-A5546

can be classified according to the ASTM International Classification scale as having “very

high mobility” in Sassafras and Gross-Umstadt soils, or “high mobility” in Drummer soil,

with a Koc range of 30–103 and an average Koc of 57. The test substance was stable during

the adsorption phase of the experiment in Sassafras, Drummer, and Gross-Umstadt soils. The

test substance was unstable in Lleida and Nambsheim soils and so data is not reported.



A. MATERIALS


C-IN-A5546 technical metabolite

Batch Number: [Thiophene-2-14

C]-IN-A5546: 3631068




with Sassafras, Drummer, and Gross-Umstadt soils.

2. Soils

The study was conducted with five different soil types (three European and two from

the U.S.A). Air-dried soils were stored at ambient temperature prior to

experimentation. A summary of the physical and chemical properties of the soils is


of the USDA classification system.


Soil Identity Sassafras Lleida Drummer

Gross-

Umstadt Nambsheim

Origin

Kent County,

Maryland,

USA

Lleida,

Catalunya,

Spain

Ogle County,

Illinois, USA

Gross-

Umstadt,

Darmstadt,

Germany

Nambsheim,

France

Soil texturea Loamy Sand Clay Clay Loam Loam Sandy Loam

% Sand 80 17 26 40 68

% Silt 17 35 37 46 21

% Clay 3 48 37 14 11

pH (0.01 M CaCl2) 4.8 7.7 5.7 6.8 7.4

Organic carbon (%) 0.81 2.09 2.96 1.28 1.68

CEC (mEq/100 g) 5.4 15.9 27.0 10.6 9.1

Moisture content air dry

soil (%) 0.60 1.74 4.14 0.95 0.85

Bulk density (g/cm3) 1.29 1.04 1.10 1.17 1.09


B. STUDY DESIGN


The appropriate soil to solution ratio was determined in preliminary testing at 1:4

(w/w) with Sassafras and Drummer soils. Portions of test solution (20 g) were

shaken at 20 2C with samples of test soil (5 g) for a 24-hour equilibration period

in darkness. Due to instability of the test item at 20 2C with Drummer soils, the

test was repeated at a soil to solution ratio of 1:2 (w/w) with that soil. Portions of

test solution (10 g) were shaken at 20 2C with samples of test soil (10 g) for a

4-hour equilibration period in darkness. Due to instability of the test item at

20 2C with Lleida and Nambsheim soils, the test was repeated at a soil to solution

ratio of 1:1 (w/w) with those two soils. Portions of test solution (10 g) were shaken

at 13.5 0.3C with samples of test soil (10 g) for a 6-hour equilibration period in


darkness. Control experiments were also performed to assess potential adsorption to

test vessels. Following centrifugation (3000 g for 15 minutes), the supernatant was

decanted and triplicate aliquots prepared for liquid scintillation counting.

The definitive adsorption/desorption experiments were performed in duplicate at

five concentrations for each of the test soils, at a temperature of 20 2C. Stock

solutions of [14

C]-IN-A5546 in acetonitrile were prepared and aliquots added to

portions of 0.01 M CaCl2 solution to give final test concentrations of 0.050, 0.107,

0.501, 1.018, and 5.192 g/mL. Portions of test solution (10 g) were shaken at

20 2C with samples of soil (5 g) for a 2-hour equilibration period in darkness. A

control experiment was also performed to assess potential adsorption to test vessels.

Following centrifugation (3,000 g for 15 minutes), the supernatant was decanted and

triplicate aliquots prepared for liquid scintillation counting.



level. Samples were then equilibrated for 2 hours at 20 2C, solutions and soils

separated, quantified, and subject to a further desorption phase. One replicate of

adsorption supernatants from each test soil at nominal concentrations of 5.0 and

1.0 g/mL were analysed by HPLC to confirm test substance stability.



nominal 5.0 g/mL and 1.0 g/mL test concentrations obtained after equilibration

were analysed by reverse phase HPLC.


A. MASS BALANCE

Recovery of radioactivity was determined at the highest test concentration for all soils

and mean values ranged between 100.08 and 100.75% applied in the main isotherm

phase.


The [14

C]-IN-A5546 was deemed stable in supernatants and extracts of 24-hour

equilibration samples of Sassafras soil (>90% characterised as IN-A5546 under test

conditions during the preliminary phase stability experiments), and in supernatants and

extracts of 2-hour equilibration samples of Drummer soil (also >90% characterised as IN-

A5546). The [14

C]-IN-A5546 was deemed unstable in the test system using Lleida an

Nambsheim soils and adsorption/desorption isotherm data is not reported for these two

soils as they are considered to be inaccurate.

C. FINDINGS

The sorption distribution coefficients Kd, Kom, and Koc were calculated for each soil at


Kd = Cs/Cw





The Kd values ranged from 0.32 in Sassafras soil to 3.04 in Drummer soil. The Kom and

Koc values ranged from 17 and 30, respectively, in Gross-Umstadt soil to 60 and 103,

respectively, in Drummer soil.

Adsorption isotherm data were analysed using the Freündlich equation:

log (Cs) = (1/n * log (Cw)) + log (Kf) (Table B.8.233).

Table B.8.233 Adsorption and desorption constants of IN-A5546 in the soils

Soil

OC

%

pH (in

CaCl2)


KFa 1/n

b r

2 KFoc

c

D1

(%)d D2 (%)

e DT (%)

f

Sassafras 0.81 4.8 0.2720 0.8767 0.9940 34 65.89 21.96 87.85

Drummer 2.96 5.7 2.5107 0.9004 0.9995 85 30.93 19.44 50.37

Gross-

Umstadt 1.28 6.8 0.3643 0.9521 0.9961 28 64.74 22.18 86.92

Arithmetic mean 0.910 - 49 - - - a Freundlich adsorption coefficients.


c Adsorption coefficient per organic carbon (KF/ organic carbon) 100.





isotherm experiments (0.87) indicated that the Freundlich equation adequately predicted

the adsorption of IN-A5546 to soils over the range of concentrations tested. The

Freundlich adsorption constants ranged from ca 0.27 to 2.51 for the three test soils. The

% adsorbed IN-A5546 at each concentration is provided in Table B.8.234.


Table B.8.234 Concentration of IN-A5546 in the solid and liquid phases at the end of adsorption equilibration period

Test concentration

(g/mL)

Sassafras Drummer Gross-Umstadt

on soila

(g/g)

in solution

(g/mL) % adsorbedb

on soila

(g/g)

in solution

(g/mL) % adsorbedb

on soila

(g/g)

in solution

(g/mL) % adsorbedb

Control 0 0 0 0 0 0 0 0 0

0.050 0.016c 0.042 15.67 0.064 0.018 63.87 0.016 0.042 15.77

0.107 0.039 0.087 18.06 0.138 0.038 64.73 0.042 0.086 19.37

0.501 0.116 0.442 11.56 0.597 0.203 59.38 0.149 0.425 14.87

1.018 0.244 0.891 12.01 1.176 0.426 57.95 0.317 0.857 15.56

5.192 1.091 4.633 10.51 5.499 2.434 53.07 1.514 4.418 14.58 a Calculated by difference (total applied – concentration in solution)


c Average of replicate samples.


III. CONCLUSIONS


C]-IN-A5546 was examined on five different soils designated

Sassafras (loamy sand), Lleida (clay), Drummer (clay loam), Gross-Umstadt (loam), and

Nambsheim (sandy loam). The test item was not stable in the presence of Lleida and

Nambsheim test soils and so the adsorption/desorption isotherms data are not reported as they

are considered to be inaccurate.


isotherm experiments (ca 0.87) indicated that the Freundlich equation adequately predicted

the adsorption of IN-A5546 to soils over the range of concentrations tested. Sorption

correlated with soil organic carbon content in the three soils where a Freundlich isotherm

could be established. The mean Kfoc was 49 ml/g with a mean 1/n of 0.910.

(Bell, S., 2011)

Report: R. Moseley (2011) Thifensulfonamid: Estimation of soil adsorption

coefficient (KOC) using high performance liquid chromatography

(HPLC). Covance Laboratories Ltd [Cheminova A/S], Unpublished

report No.: 8235716 [CHA Doc. No. 200 TIM]



Previous



The following study was only briefly reviewed by the UK RMS. It

should be noted that IN-A5546 is considered a transient metabolite. It

should alsobe noted that the Task Force have performed an OECD 121

(i.e. HPLC) study to determine sorption potential. It would have been

possible (as shown by the DuPont study above) to have performed an

OECD 106 study utilising shorter equilibrium times. This would also

have been consistent with the SCP opinion on how to conduct sorption

studies for rapidly degrading compounds. The test substance was also

noted to elute outside the range of the reference compounds which adds

further uncertainty to the estimated Koc values derived. For

completeness the detailed study summary from the Task Force is

provided below. However the groundwaterexposure assessment for IN-

A5546 has been based on the results of the batch sorption experiments

provided by DuPont above.

Executive Summary:

Because of the very short DT50 of IN-A5546 in soil (5 to 6.7 hours) the soil adsorption

coefficient was estimated using HPLC simulation technique in accordance with OECD

Guideline 121. The results showed that IN-A5546 eluted as a single component with a

retention time lower than that of the lowest standard (acetanilide). The log KOC value is


therefore estimated as <1.25 (KOC value <18). Extrapolation gave a log KOC value of 1.07

(KOC value 12).


Materials:

1. Test Material: IN-A5546 (Thifensulfonamid, 2-Ester-3-Sulfonamide)

Description: Solid

Lot/Batch #: 1265-JKV-84-3

Purity: 99.5%

CAS #: Not stated

Study Design:


HPLC Screen

The distribution coefficient was estimated by the HPLC simulation method using isocratic

elution. The procedures used conformed to those outlined in EC Directive 2001/59/EC

Method C19 and OECD Guideline 121. The table below shows the HPLC conditions.

Table B.8.235 Conditions for HPLC analysis

Instrument Waters 2695

Column Zorbax CN, 5µm, 250 x 4.6 mm

Column temperature 25 °C

Mobile phase Methanol : water, 55:45, v/v

Flow rate 1 mL/min

Injection volume 10 µL

Detection wavelenght 254 nm

Data collection time 25 minutes

A set of six appropriate reference substances were used to calibrate the chromatography

system. Two series of injections were made, each consisting of a single injection of the test

substance, duplicate injections of the reference substances and triplicate injections of

formamide (the void volume marker). Each material was prepared in methanol and analysed

using the HPLC conditions in the table above.


Table B.8.236 Reference substance data

Compound Purity

(%)

Literature value

(log Koc)

Mass injected

(µg)

Formamide > 99 N/A 1229.30

Acetanilide 97 1.25 1.40

Phenol > 99 1.32 10.91

Methyl benzoate 99 1.80 4.61

Monuron 99 1.99 2.29

Linuron 99.7 2.59 0.67

Phenanthrene 98 4.09 0.30

The capacity factor, K, of each component was calculated from TR (the mean retention time

for the component), and T0 (the system dead time, that is, the mean retention time of

formamide, the void volume marker), using the following equation:

K = TR-T0

T0

For the reference substances, the logarithm of the capacity factor was plotted against the

logarithm of the distribution coefficient to derive a calibration graph, fitted linearly.

Log K = slope x log Koc + constant

The estimated distribution coefficient for the test substance was calculated from the capacity

factor by derivation from the calibration graph equation.

log Koc = log K - constant

slope



Table B.8.237 Calibration data

Reference substance

First series Second series

Retention time

(min)

Capacity factor

(log K)

Retention time

(min)

Capacity factor

(log K)

Formamide 2.893 N/A 2.895 N/A

Acetanilide 3.984 -0.424 3.964 -0.433

Phenol 4.010 -0.413 3.900 -0.423

Methyl benzoate 5.052 -0.127 4.990 -0.141

Monuron 5.088 -0.120 5.046 -0.129

Linuron 8.045 0.251 7.885 0.236

Phenanthrene 14.920 0.619 14.613 0.607


Table B.8.238 Analytical data

IN-A5546 Retention time

(min)

Capacity factor

(log K) log Koc Lower 95 % Upper 95 %

First series 3.913 -0.453 1.06 0.57 1.39

Second series 3.899 -0.460 1.07 0.59 1.39

The test compound IN-A5546 eluted as a single peak with a retention time outside the range

of retention times of the calibration substances. It was therefore not possible to estimate the

Log KOC by interpolation and so the results of the estimation should be regarded as indicative

rather than absolute.

There were only minimal differences between the replicates of retention times for each of the

reference and test substances, and between the two injection sequences. The resultant

calculated values differed only to a small extent, and therefore the results may be considered

as acceptable for regulatory purposes.

The distribution coefficient of IN-A5546 was successfully evaluated using the HPLC

simulation technique. The test substance eluted as a single component with a retention time

lower than that of the lowest standard (acetanilide) giving an extrapolated log KOC value of

1.07 (KOC value 11.75). The log KOC value is therefore estimated as <1.25 (KOC value

<17.78).

Conclusions:

The distribution coefficient on soil (expressed as log KOC) of the test substance IN-A5546

was estimated using the HPLC simulation technique in accordance with OECD Guideline

121. The results show that the test substance eluted as a single component with a retention

time lower than that of the lowest standard (acetanilide) giving an extrapolated log KOC value

of 1.07 (KOC value 11.75). The log KOC value is therefore estimated as <1.25 (KOC value

<17.78).

(Moseley, 2011)


IN-L9223

Report: Cleland, H., Andrews, S. (2011); Adsorption/desorption of [14

C]-IN-L9223 via

batch equilibrium method


Guidelines: OPPTS 835.1230 (2008), OECD 106 (2000), SETAC Europe (1995)

Deviations: None



GLP: Yes


Previous

evaluation:




acceptable. Endpoints from this study have been used to determine

exposure modelling input parameters, when combined with data from

the other Applicant.

Executive summary:


C]-IN-L9223 were investigated in five soils

(pH range of 4.7 to 7.7, organic carbon range of 1.3 to 3.2%) from USA, Germany, Spain,

and France. The soils were sampled from a depth 20 cm. The adsorption properties were

investigated for all five soil types at a 1:1 (w/w) soil to solution ratio and a concentration of

4.630 g a.s./mL.

The definitive isotherm test was carried out on Drummer (pH 6.0 and organic carbon of

3.2%) soil type only due to low adsorption of IN-L9223 in the four other soil types from

preliminary soil to solution experiments.

Drummer soil was pre-equilibrated with 0.01 M calcium chloride prior to addition of the test

item. [14

C]IN-L9223 at final nominal concentrations of 5.1, 1.1, 0.5, 0.1, and 0.05 g a.s./mL

in 0.01 M calcium chloride was added to the soils and incubated in the dark at 20C for

24 hours. The soil to solution ratio was 1:1. The desorption phase of the study was carried

out on the highest treatment rate samples only. On removal of the adsorption supernatant, an

equivalent amount of fresh 0.01 M CaCl2 was added and the samples equilibrated for

24 hours. The supernatant was removed and a second desorption cycle performed in the

same manner. The mass balance following adsorption, two desorption cycles and combustion

of the soil pellet ranged from 100.32 to 101.80% of the applied radioactivity.

The adsorption coefficients Kd, Kom, and Koc, and the Freundlich adsorption isotherm

parameters KF, KFom, KFoc, and 1/n were calculated for Drummer soil only due to the low

adsorption in the other four soil types. KFoc was calculated as 8 in Drummer soil. At the end

of the desorption phase 44.15% of the adsorbed radioactivity was desorbed.



A. MATERIALS


C]-IN-L9223 technical metabolite

Batch Number: 3631069



Description: Powder

Stability of test compound Shown to be stable under the conditions of the test

Structure of IN L9223

3. Soils


the U.S.A) Although the efinitive test was only performed on one. Air-dried soils

were stored at ambient temperature prior to experimentation. A summary of the

physical and chemical properties of the soils is provided in Table B.8.239. The

percent sand, silt, and clay are quoted on the basis of the USDA classification

system.


Soil Identity Drummer

Gross-

Umstadt Lleida Nambsheim Sassafras

Origin Ogle, Illinois,

USA

Gross-

Umstadt,

Darmstadt,

Germany

Lleida,

Catalunya,

Spain

Nambsheim,

Alsace Region

France

Kent County,

Maryland,

USA

Soil texturea Silt loam Loam Silty clay Sandy loam Sand

% Sand 21 40 11 72 87

% Silt 52 46 42 19 12

% Clay 27 14 47 9 1

pH (in water) 6.4 7.2 7.9 7.7 5.3

Organic carbon (%) 3.2 1.3 1.8 2.2 1.4

CEC (mEq/100 g) 26.0 10.6 16.9 10.7 5.3

Moisture at 1/3 atm

(%) 33.8 16.7 31.7 18.9 9

Bulk density (g/cm3) 1.05 1.17 1.07 1.03 1.22



B. STUDY DESIGN


The appropriate soil to solution ratio was determined in preliminary testing as

1:1 (w/w). Portions of test solution (10 g) were shaken at 20C with samples of test

soil (10 g dry weight) for a 24-hour equilibration period in darkness. A control

experiment was also performed to assess potential adsorption to test vessels.

Following centrifugation (3000 g for 15 minutes) the supernatant was decanted and

triplicate aliquots prepared for radioassay.

The isotherms phase of the study was performed on Drummer soil only due to low

adsorption in other soil types. Stock solutions of [14

C]-IN-L9223 in 0.01 M CaCl2

were prepared and aliquots added to portions of 0.01 M CaCl2 solution to give final

test concentrations of 5.100, 1.100, 0.500, 0.100, and 0.050 g a.s./mL. Portions of

test solution (10 g) were shaken at 20C with samples of Drummer soil (10 g dry

weight) for a 24-hour equilibration period in darkness. A control experiment was

also performed to assess potential adsorption to test vessels. Following

centrifugation (3000 g for 15 minutes), the supernatant was decanted and triplicate

aliquots prepared for radioassay.



level. Samples were then equilibrated for 24 hours at 20C, solutions and soils

separated, quantified, and subject to a further desorption phase. Adsorption

supernatants from the 5.100 and 1.100 g/mL dose groups were used to assess the

degree of degradation of IN-L9223 during equilibration. Results demonstrated

compound stability under the test conditions.



5.100 and 1.100 g/mL test concentrations obtained after equilibration were

analysed by reverse phase HPLC. Soil pellet extracts of each soil type from 24-hour

1:1 (w/w) soil to solution ratio phase were combined, concentrated under a gentle

stream of N2 and analysed by reverse phase HPLC.


A. MASS BALANCE

Recovery of radioactivity was determined at the highest test concentration for Drummer

soil and ranged between 100.32 to 101.80% applied in the main isotherm phase.


During the 24-hour equilibration period, no significant degradation was detected.


C. FINDINGS

Adsorption isotherm data were analysed using the log form of the Freundlich equation:

log (Cs) = (1/n * log (Cw)) + log (KF) (Table B.8.240).

Table B.8.240 Adsorption and desorption constants of IN-L9223 in Drummer soil

Soil

OC

%

pH (in

water)


KFa 1/n

b r

2 KFoc

c D1 (%)

d D2 (%)

e DT (%)

f

Drummer 3.2 6.4 0.2595 0.9232 0.9991 8 26.24 17.91 44.15 a Freundlich adsorption coefficient.

b Slope of Freundlich adsorption isotherms (Freundlich Exponent).





The adsorption of [14

C]-IN-L9223 was examined on five different soils designated

Drummer (silt loam), Gross-Umstadt (loam), Lleida (silty clay), Nambsheim (sandy

loam), and Sassafras (sand). The sorption coefficient Kd values were 0.19, 0.00, 0.03,

0.00, 0.03 for the five soil types, respectively. The adsorption/desorption of

[14

C]-IN-L9223 was examined on Drummer (silt loam) soil only due to the low

adsorption of [14

C]-IN-L9223 on the Gross-Umstadt, Lleida , Nambsheim, and Sassafras

soils.

Calculation of the Freundlich co-efficient 1/n values, 0.9232, following the definitive

adsorption isotherm experiment indicated that the Freundlich equation adequately

predicted the adsorption of IN-L9223 to soil over the range of concentrations tested.

Using the McCall Classification scale to assess a chemical’s potential mobility in soil

(based on its Koc), IN-L9223 can be classified as being “very mobile” in Drummer (silt

loam), Gross-Umstadt (loam), Lleida (silty clay), Nambsheim (sandy loam), and

Sassafras (sand).


Table B.8.241 Determination of the adsorption coefficients for Drummer soil treated with

[14

C]-IN-L9223 at a 1:1 (w/w) soil to solution ratio

Adsorption

Test concentration

(g/mL) Rep Cw (g/mL) Cs (g/g) Kd (mL/g) Kom (mL/g) Koc (mL/g)

5.100 1 4.1942 0.907 0.22 4 7

5.100 2 4.4158 0.953 0.23 4 7

1.100 1 0.8711 0.230 0.26 5 8

1.100 2 0.8657 0.235 0.27 5 8

0.500 1 0.3881 0.112 0.29 5 9

0.500 2 0.3853 0.115 0.30 5 9

0.100 1 0.0750 0.025 0.33 6 10

0.100 2 0.0761 0.024 0.32 6 10

0.050 1 0.0383 0.012 0.31 6 10

0.050 2 0.0376 0.012 0.32 6 10

Mean 0.29 5 9

III. CONCLUSION

The adsorption of [14

C]-IN-L9223 was examined on five different soils designated Drummer

(silt loam), Gross-Umstadt (loam), Lleida (silty clay), Nambsheim (sandy loam), and

Sassafras (sand). The sorption coefficient (Kd) values were 0.19, 0.00, 0.03, 0.00, 0.03 for

the five soil types, respectively. The adsorption/desorption of [14

C]-IN-L9223 was examined

on Drummer (silt loam) soil only due to the low adsorption of [14

C]-IN-L9223 on the

Gross-Umstadt, Lleida , Nambsheim, and Sassafras soils.

Calculation of the Freundlich co-efficient 1/n values, 0.9232, following the definitive

adsorption isotherm experiment indicated that the Freundlich equation adequately predicted

the adsorption of IN-L9223 to soil over the range of concentrations tested.

Using the McCall Classification scale to assess a chemical’s potential mobility in soil (based

on its Koc), IN-L9223 can be classified as being “very mobile” in Drummer (silt loam),

Gross-Umstadt (loam), Lleida (silty clay), Nambsheim (sandy loam), and Sassafras (sand).

(Cleland, H., Andrews, S., 2011)


Report: A. Brice, J. Gilbert (2011c) 2-Acid-3-sulfonamide7: Adsorption/

desorption Study in three soils. Covance Laboratories Ltd [Cheminova

A/S], Unpublished report No.: 8235718 [CHA Doc. No. 202 TIM]







Previous



The following study on metabolite IN-L9223 was evaluated by the UK

RMS and considered acceptable. Endpoints from this study have been

used to determine exposure modelling input parameters, when combined

with data from the other Applicant.


Materials:

1. Test Material: IN-L9223 (2-acid-3-sulfonamide)

Purity: 97.7%

Stability: Stability in the test system was confirmed for at least 48 hours.

2. Soils: Three UK soils were supplied by the Land Research Associates.


Soil Name Longwoods Chelmorton Lockington

Origin UK UK UK

Textural class1 Sandy loam Clay loam Clay loam

% Sand 77 23 42

% Silt 9 57 24

% Clay 14 30 20 34

% OC 1.3 3.3 2.5

CEC (mEq/100g) 13.8 25.8 35.4

pH (H2O) 7.9 7.3 6.5

% Moisture (1/3 bar) pF

2.5 10.0 28.1 25.8

1 UK & BBA Textural class

7 i.e. IN-L9223


The adsorption characteristics of IN-L9223 (2-Acid-3-sulfonamide) were determined in three

soils. Soils were chosen for their variety in pH, clay, and organic carbon content. The soils

were air-dried, thoroughly mixed and passed through a 2mm sieve and sterilised with gamma

radiation. The soils were stored at room temperature in the dark prior to the experiments. The

moisture content of the soils was determined by drying samples at 105 ºC.

Soils were equilibrated by shaking with 0.01 M CaCl2 overnight the day prior to the

experiment initiation. All studies were performed at 20 ± 2 ºC in the dark.

During preliminary testing, test item adsorption to the chosen test containers (Teflon and

plastic vessels) was investigated. 10ml solutions of the test item at a concentration of

0.5µg/mL (lowest proposed test substance concentration) in 0.01 M CaCl2 were added to

duplicate Teflon and plastic test vessels and shaken for 24 hours. The recovery of the applied

2-acid-3-sulfonamide was:

Test vessel Recovery of 2-acid-3-sulfonamide (%)

Teflon 96.2

Teflon 97.3

Teflon (mean) 96.8

Plastic 96.8

Plastic 96.9

Plastic (mean) 96.9

Preliminary experiments were performed to determine the optimal experimental parameters.

The LOQ of the test item was determined as 0.025 μg/mL. To determine an appropriate

soil/solution ratio for the definitive test, a preliminary experiment was performed in all three

soils at a nominal test concentration of 50 µg/mL. Duplicate units were prepared for each soil

(dry weight equivalent) in the following soil/solution ratios:

1:1 (10g soil and 10ml of solution)

1:5 (5g soil and 25ml of solution)

The soils were equilibrated with 0.01 M CaCl2 (9ml for 1:1 w/v ratio and 22.5ml for 1:5 w/v

ratio) in Teflon vessels via shaking overnight before the experiment. An appropriate volume

of test item stock solution (500 µg/mL) was then added to produce a 50 µg/mL final solution

concentration (1ml for 1:1 w/v ratio and 2.5ml for 1:5 w/v ratio).


Following a 24 hour mixing period, the samples were centrifuged (40 minutes at ~3920 g),

and the 2-acid-3-sulfonamide concentration in the supernatant determined via UPLC-MS/MS

analysis.

Based on the results of the test, the 1:1 ratio was chosen for further study.

Using the 1:1 soil/solution ratio, the adsorption equilibrium time was determined. As above,

duplicate10 g dry weight equivalent was pre-equilibrated with 9ml 0.01 M CaCl2 via

overnight shaking prior to the experiment. 1ml of test item stock solution was added for a

nominal concentration of 50 µg/mL.

The soils were shaken for 3, 6, 24 and 48 hours. At each sampling time, duplicate samples

were removed, centrifuged (40 minutes at ~3920 g), and aliquots of supernatant analysed to

determine 2-acid-3-sulfonamide concentration via UPLC-MS/MS analysis. 24 hours was

chosen for the definitive test.

The recovery of 2-acid-3-sulfonamide in samples of each soil type, from the adsorption

equilibrium time determination test, was used to determine stability in the test system. At the

final (48 hour) time point the absorption supernatant from the soil replicates and extracts

from the soil were analysed via UPLC-MS/MS. Soil samples were extracted three times by

reciprocating shaking with 30 mL of acetonitrile: water: acetic acid (3:1:0.01 v/v/v), followed

by centrifugation. The extracts were pooled and made up to 100 mL. 10 mL aliquots were


evaporated to < 2 mL prior to making up to 100 mL with 0.01M calcium chloride. Further

dilutions were performed if necessary. The recovery was as follows:

All replicates were within the range of 95-99% of applied 2-acid-3-sulfonamide.

For the definitive test, 0.01 M CaCl2 solution was added to duplicate samples for all soils in

Teflon vessels. The soil solution ratio was 1:1. The vessels were pre-equilibrated by shaking

overnight before the day of the experiment. Aliquots (1 mL) of the appropriate application

solutions were added to the equilibrated units to achieve nominal initial concentrations in the

aqueous phase of 50, 10, 5, 1 and 0.5 μg/mL. All samples were shaken for 24 hours (the

adsorption equilibrium time) then centrifuged for ca 40 minutes at ca 3920 g. As much of the

adsorption supernatant as possible from each unit was decanted into separate vessels. An

aliquot of each supernatant was diluted with 0.01 M calcium chloride solution prior to

analysis by UPLC-MS/MS. Due to low adsorption (see table below), the desorption isotherms

test was not performed.


Freundlich adsorption coefficients related to organic carbon content (KOC) for the three soils

were in the range of ~2 to 3 L/kg (mean 3 L/kg). The range of 1/n values was 1.09 to 1.41

with a mean value of 1.23. The values were validated by the UK RMS and were accepted.

IN-L9223 was shown to be of “very high mobility” according to the McCall classification.

(Brice and Gilbert, 2011c)

Two acceptable studies on the sorption potential of metabolite IN-L9223 were submitted

covering 4 contrasting soils. The combined data set is summarised in the following Table

B.8.243.

Table B.8.243: Summary of the sorption values for metabolite IN-L9223 based on DuPont

and Task Force data


(CaCl2)

Kf (ml/g) Kfoc

(ml/g)

1/n

Drummer;

silt loam

(DuPont)

3.2 6.4

0.2595 8 0.9232

Longwood;

sandy loam

(Task Force)

1.3 7.9

(H2O) 0.03 2.03 1.4090

Chelmorton;

clay loam

(Task Force)

3.3 7.3

(H2O) 0.11 3.27 1.0931

Lockington;

clay loam

(Task Force)

2.5 6.5

(H2O) 0.07 2.97 1.204

Arithmetic mean - 4.07 1.157


Considering the data set as a whole, sorption was noted to be low in all soils. However

sorption was correlated to soil organic carbon. No correlation with soil pH was apparent,

however the range tested was noted to be relatively narrow and Kfoc values were low in all

soils. The UK RMS considered it appropriate to use an arithmetic mean Kfoc of 4.07ml/g

and arithmetic mean 1/n of 1.157.

IN-L9225

Yeomans P. (2000)

Previous

evaluation: In Addendum for original approval (2000).


fully meets current guideline OECD 106. The UK RMS also

considered the study valid. The sorption endpoints from this study have

been combined with all acceptable data from other studies in order to

derive an overall average input parameter for the purposes of exposure

modelling.


has been included below.

Yeomans P. (2000), report 1812, GLP, OECD guideline, acceptable

IN-L9225 (purity 98.8 %) at 0.05, 0.1, 0.5 and 1 mg/l in 10 ml 0.01 M CaCl2 was adsorbed

on 3 preconditioned soils (10 g equivalent dry soil) for 24 h at 20° C. Liquid phase was

analysed by HPLC-UV (LOQ 0.01 mg/l). After adsorption, 2 desorption steps (24 h each)

were performed. After desorption, the soils treated at the highest concentration were extracted

(acetonitrile/ammonium carbonate) and extracts were analysed by HPLC-UV. Controls

without the test substance were run. Recoveries were acceptable (89.5 - 95.9 %). No

degradation product was detected in water phase suggesting no degradation. Amounts of IN-

L9225 adsorbed on soils were > 20 % except for the Gross-Umstadt soil. IN-L9225 was

poorly adsorbed on soil with Kf in the range 0.08 - 0.35 and Koc in the range 6.9 - 13.5

(mean 11.2).


Table B.8.244 Soil characteristics and adsorption of IN-L9225



Sand % 71 20 34

Silt % 21 66 53

Clay % 8 14 13

pHw 5.7 7.7 6.4

OC % 2.3 1.2 2.6

CEC meq/100 g 12.3 21.9 11.7

Kf 0.30 0.083 0.35

1/n 0.74 0.62 0.76

Koc 13.1 6.9 13.5

Conclusion : The metabolite IN-L9225 (thifensulfuron acid) is poorly adsorbed on 3 soils

(OC 1.2 - 2.6 %, pH 5.7 - 7.7) with Kf in the range 0.08 - 0.35 and Koc in the range 6.9 - 13.5

(mean 11.2).

(Yeomans, 2000)

Report: E. Knoch (2012e) Adsorption of Thifensulfuron acid on Soils. SGS

Institut Fresenius GmbH [Cheminova A/S], Unpublished report No.: IF-

12/02135828 [CHA Doc. No. 305 TIM]







Previous







Executive Summary:

The adsorption characteristics of IN-L9225 (thifensulfuron acid) were determined in three

soil types (loamy sand, sandy loam and clay) with a pH range of 5.5 to 7.1. Adsorption

coefficients related to organic carbon content (KOC) for the three soils were in the range of 23


to 34 mL/g (mean 28.7 mL/g). IN-L9225 was shown to be of “very high mobility” according

to the McCall classification.


Materials:

1. Test Material: IN-L9225 (Thifensulfuron acid)

Description: White-beige Solid

Lot/Batch #: JKV-1265-11B-5

Purity: 96.2%

CAS #: 79277-67-1

Stability: Stability in the test system was confirmed for 1 month.

2. Soils: Three German soils were supplied by the LUFA Speyer.


Soil Name LUFA 2.2 LUFA 2.3 LUFA 6S


Textural class1 Loamy sand Sandy loam Clay

% Sand 80.6 63.7 22.2

% Silt 12.6 27.6 36.8

% Clay 6.8 8.7 41.0

% OC 1.87 0.94 1.64

CEC (mEq/100g) 9.9 10.7 23.7

pH (0.01M CaCl2) 5.5 6.8 7.1

WHC (g/100 g) 44.4 35.6 38.9 1 USDA Textural class

Study Design:


Following the equilibration of the three German soil systems (soil textures according to USDA

classification were: loamy sand for LUFA 2.2 soil, sandy loam for LUFA 2.3 soil, clay for

LUFA 6S soil) with 60 mL of 0.01 mol/L CaCl2, the test item was applied in methanol. The co-

solvent added to the aqueous solution by test item dosing did not exceed 0.1 vol. %.

The adsorption test was performed on two soil/solution ratios of 1:1 (60 mL of 0.01 mol/L CaCl2

and 60 g dry soil) and 5:1 (60 mL of 0.01 mol/L CaCl2 and 12 g dry soil) using one test

concentration of IN-L9225 (0.1 mg/L). Each test system was prepared in triplicate.


After agitation for 24 hours at 20±2 °C in the dark, the distribution of IN-L9225 between the

aqueous phase and the solid phase (soil) was assayed. LC-MS/MS was used for the analysis of

the equilibrium concentration in the aqueous phases. The adsorbed IN-L9225 in the solid phase

(soil) was calculated.


A time period of 24 hours maximum was assumed to be sufficient for reaching equilibrium.

After centrifugation (5000 rpm for 5 min) specimen portions of the supernatants were filtered

using a folded filter paper. Specimen aliquots of 0.1 mL, taken at the 24 hours time point,

were diluted with methanol/pure water/formic acid; 200:800:0.2; v/v/v and subjected to LC-

MS/MS analysis.

The amount of adsorbed IN-L9225 onto soil, the adsorption coefficient (K) and the adsorption

coefficient on basis of the soil organic carbon content (Koc) was calculated.


A. RECOVERIES

Mean recoveries of IN-L9225 in the aqueous soil extract solutions at time zero fortified at

0.01 and 0.1 mg/mL ranged from 90 to 96%. Results indicate the validity of the study. No

IN-L9225 was detected in the untreated soil extract solutions.

B. FINDINGS

The amount of test item adsorbed onto soil, the adsorption coefficient (K), the adsorption

coefficient on basis of soil organic carbon content (Koc) were calculated for each specimen

of the experimental setup. The respective adsorption coefficients on the basis of soil organic

carbon content (Koc) were calculated to be 23, 34 and 29 mL/g (ratio 1:1) for LUFA 2.2, 2.3

and 6S soils respectively. The Kocs derived from the 1:1 ratio experiments were more

conservative than those from the 5:1 ratio experiments. Additionally the 1:1 ratio experiments

featured higher overall adsorption (%).

Table B.8.246 Adsorption coefficients for IN-L9225 in soil (ratio 1:1)

Soil type OC % pH

0.01 M CaCl2

Adsorption (mL/g)a

K KOC 1/n

LUFA 2.2 (Loamy sand) 1.87 5.5 0.43476 23 NS

LUFA 2.3 (Sandy loam) 0.94 6.8 0.31791 34 NS

LUFA 6S (Clay) 1.64 7.1 0.48081 29 NS

a mean of 3 replicates

Conclusions:

The adsorption properties of IN-L9225 were studied in three German soils, namely LUFA 2.2

(Loamy sand), LUFA 2.3 (Sandy loam) and LUFA 6S (Clay). Adsorption coefficients

normalised for organic carbon (KOC) were in the range 23 to 34 mL/g with a mean value of

28.7 mL/g. IN-L9225 was shown to be of “very high mobility” according to the McCall

classification.


(Knoch, 2012e)



B.8.247.


and Task Force data


(H2O)

Kf (ml/g) Kfoc

(ml/g)

1/n

Arrow;

sandy loam 2.3 5.7

0.30 13.1 0.74

Gross-

Umstadt; silt

loam

1.2 7.7

0.083 6.9 0.62

Mattapex;

silt loam 2.6 6.4

0.35 13.5 0.76

LUFA 2.2;

loamy sand 1.87 5.5

(CaCl2) 0.435 23 -

LUFA 2.3;

sandy loam 0.94 6.8

(CaCl2) 0.318 34 -

LUFA 6S;

clay 1.64 7.1

(CaCl2) 0.481 29 -

Arithmetic mean - 19.9 0.85a

ain deriving an arithmetic mean, a default 1/n value of 1.0 was assumed for the three soils where no Freundlich

isotherm was determined because a single concentration had been tested.


sorption was weakly correlated to soil organic carbon. No clear correlation with soil pH was

apparent, even when soil pH was expressed in a similar medium (assuming pH in H2O is 0.7

units higher than a Cl medium as per FOCUS groundwater guidance). The UK RMS

considered it appropriate to use an arithmetic mean Kfoc of 19.9ml/g and arithmetic mean

1/n of 0.85.

IN-L9226

Yeomans P. (2000)

Previous

evaluation:




considered the study valid. It should be noted that IN-L9226 is

considered a transient non-major metabolite in soil. It has been

excluded from a full formal quantitative groundwater exposure

assessment due to its short half life. However the leaching risk of IN-

L9226 has been effectively addressed in the groundwater section based

on the assessment of IN-A5546 (see Section B.8.6 for further details).


As such the endpoints from this study are not used in the quantitative




Yeomans P. (2000), report 1813, GLP, in accordance with OECD guideline, acceptable

IN-L9226 (purity 95.1 %) at 0.1, 0.5, 1 and 5 mg/l in 25 ml 0.01 M CaCl2 was adsorbed on 3

preconditioned soils (5 g equivalent dry soil) for 24 h at 20° C. Soil characteristics are given

in table B.8.248 below. Liquid phase was analysed by HPLC-UV (LOQ 0.01 mg/l). After

adsorption, 2 desorption steps (24 h each) were performed. After desorption, the soils treated

at the highest concentration were extracted (acetonitrile/ammonium carbonate) and extracts

were analysed by HPLC-UV. Controls without the test substance were run. Recoveries were

acceptable (87.9-91.9 %). No degradation product was detected in water phase suggesting no

degradation. Amounts of IN-L9226 adsorbed on soils were > 20 % except for the Arrow soil.

IN-L9226 was moderately adsorbed on soil with Kf in the range 0.8-2.6 and Koc in the range

34-199 (mean 111).

Table B.8.248 Soil characteristics and adsorption of IN-L9226



Sand % 71 20 34

Silt % 21 66 53

Clay % 8 14 13

pHw 5.7 7.7 6.4

OC % 2.3 1.2 2.6

CEC meq/100 g 12.3 21.9 11.7

Kf 0.8 2.4 2.6

1/n 0.80 0.81 0.79

Koc 34 199 99

Conclusion : The metabolite IN-L9226 (O-desmethyl Thifensulfuron-methyl) is moderately

adsorbed on 3 soils (OC 1.2 - 2.6 %, pH 5.7 - 7.7) with Kf in the range 0.8 - 2.6 and Koc in

the range 34 - 199 (mean 111).

(Yeomans, 2000)


Report: E. Knoch (2012i) Adsorption of O-desmethyl Thifensulfuron-methyl on

soils. SGS Institut Fresenius GmbH [Cheminova A/S], Unpublished

report No.: IF-12/02132071 [CHA Doc. No. 303 TIM]



Previous




should be noted that IN-L9226 is considered a transient non-major

metabolite. It has been excluded from a full formal quantitative

groundwater exposure assessment due to its short half life. However the

leaching risk of IN-L9226 has been effectively addressed in the

groundwater section based on the assessment of IN-A5546 (see Section

B.8.6 for further details). As such the endpoints from this study are not

used in the quantitative exposure assessment. For completeness the


Executive Summary:

The adsorption characteristics of IN-L9226 (O-Desmethyl Thifensulfuron-methyl) were

determined in three soil types (loamy sand, sandy loam and clay) with a pH range of 5.5 to

7.1. Adsorption coefficients related to organic carbon content (KOC) for the three soils were

in the range of 86 to 201 mL/g (mean 140 mL/g).


Materials:

1. Test Material: IN-L9226 (O-Desmethyl Thifensulfuron-methyl)


Lot/Batch #: 957-PEJ-2

Purity: 93.1%

CAS #: 150258-68-7

Stability: Stable for at least 3 weeks.







% Sand 80.6 63.7 22.2

% Silt 12.6 27.6 36.8

% Clay 6.8 8.7 41.0

% OC 1.87 0.94 1.64

CEC (mEq/100g) 9.9 10.7 23.7

pH (0.01M CaCl2) 5.5 6.8 7.1


Study Design:








concentration of IN-L9226 (0.1 mg/L). Each test system was prepared in triplicate.

After agitation for 24 hours at 20±2 °C in the dark, the distribution of IN-L9226 between the


the equilibrium concentration in the aqueous phases. The adsorbed IN-L9226 in the solid phase







MS/MS analysis.

The amount of adsorbed IN-L9226 onto soil, the adsorption coefficient (K) and the

adsorption coefficient on basis of the soil organic carbon content (Koc) was calculated.


A. RECOVERIES


Mean recoveries of IN-L9226 in the aqueous soil extract solutions at time zero fortified at


IN-L9226 was detected in the untreated soil extract solutions.

B. FINDINGS





and 6S soils respectively.

Table B.8.250 Adsorption coefficients for IN-L9226 in soil (ratio 1:1)

Soil type OC % pH

0.01 M CaCl2

Adsorption (mL/g)a

K KOC 1/n



LUFA 6S (Clay) 1.64 7.1 2.19253 134 NS


Conclusions:

The adsorption properties of IN-L9226 were studied in three German soils, namely LUFA 2.2



140.3 mL/g. IN-L9226 was shown to be of “high mobility” according to the McCall

classification.

(Knoch, 2012i)


covering 6 contrasting soils. For completeness the combined data set is summarised in the

following Table B.8.251



and Task Force data


(H2O)

Kf (ml/g) Kfoc

(ml/g)

1/n

Arrow;

sandy loam 2.3 5.7

0.8 34 0.80

Gross-

Umstadt; silt

loam

1.2 7.7

2.4 199 0.81

Mattapex;

silt loam 2.6 6.4

2.6 99 0.79

LUFA 2.2;

loamy sand 1.87 5.5

(CaCl2) 1.605 86 -

LUFA 2.3;

sandy loam 0.94 6.8

(CaCl2) 1.886 201 -

LUFA 6S;

clay 1.64 7.1

(CaCl2) 2.193 134 -

Arithmetic mean 126 0.90 ain deriving an arithmetic mean, a default 1/n value of 1.0 was assumed for the three soils where no Freundlich


Considering the data set as a whole, there was no clear correlation between soil sorption and

either soil organic carbon or soil pH. As a transient metabolite, these sorption values will not

be used in a quantitative assessment. However for completeness the UK RMS considered it

appropriate to derive an arithmetic mean Kfoc of 126ml/g and arithmetic mean 1/n of 0.90.

IN-RDF00

Report: Anderson, C., Wardrope, L. (2011); Adsorption/desorption of [14

C]-IN-RDF00 via




None



GLP: Yes


Previous




should be noted that IN-RDF00 is not a major soil metabolite. It was

only found in major amounts in the sterile aqueous hydrolysis study at

pH 4. As such data on sorption is not strictly required. As such the

endpoints from this study are not used in the quantitative exposure

assessment. For completeness the detailed study summary from DuPont

is provided below. As the data from this study has not been relied it has

been highlighted in grey.


Executive summary:


C]-IN-RDF00 were investigated in five soils

(pH range of 5.1 to 7.7 in 0.01M CaCl2, organic carbon range of 0.9 to 3.2%) from USA,

Germany, Spain, and France in a batch equilibrium experiment.

Soils were pre-equilibrated with 0.01 M calcium chloride prior to addition of the test item.

[14

C]-IN-RDF00 at final nominal concentrations of 0.010–1.000 g a.s./mL in 0.01 M

calcium chloride was added to the soils and incubated in the dark at 12 2C for 24 hours.

The soil to solution ratio was 1:1 for the Gross-Umstadt, Nambsheim, Sassafras, and Lleida

soils and 1:4 for the Drummer soil. The desorption phase of the study was carried out on the

highest treatment rate samples only. On removal of the adsorption supernatant, an equivalent

amount of fresh 0.01 M CaCl2 was added and the samples equilibrated for 24 hours. The

desorption supernatant was removed and a second desorption cycle performed in the same

manner. The mass balance in Sassafras and Drummer soils, following adsorption, two

desorption cycles, and combustion of the soil pellet ranged from 99.18 to 101.90% of the

applied radioactivity for Sassafras and Drummer soils, respectively.

The adsorption coefficients Kd, KOM, and KOC were calculated and reported for Sassafras and

Drummer soils at each concentration of the test substance. Coefficients were calculated but

not reported for Gross-Umstadt, Nambsheim, and Lleida soils due to the instability of the test

item in the presence of those soils throughout the duration of the tests. The Freundlich

adsorption coefficient values for the Sassafras and Drummer soils were 0.18 and 3.17,

respectively. The organic carbon content normalised Freundlich coefficient values were 20

and 99 in the Sassafras and Drummer soils, respectively. At the end of the desorption phase,

46.22% (Drummer soil) and 60.69% (Sassafras soil) of the adsorbed radioactivity was

desorbed.

The Koc (organic carbon content normalised adsorption distribution coefficient) values were

23 and 130 in the Sassafras and Drummer soils, respectively, indicating that that IN-RDF00

is highly to very highly mobile (McCall classification).


A. MATERIALS


C]-IN-RDF00 technical metabolite

Batch Number: 3620295

Radiochemical purity: 98.17–99.21%


Description: Powder


in the Sassafras and Drummer soils.

2. Soils





of the USDA classification system.



Soil Identity Drummer

Gross-

Umstadt Lleida Nambsheim Sassafras

Origin Ogle, Illinois,

USA

Gross-

Umstadt,

Darmstadt,

Germany

Lleida,

Catalunya,

Spain

Nambsheim,

Alsace Region

France

Kent County,

Maryland,

USA

Soil texturea Silt loam Loam Clay Sandy loam Sandy loam

% Sand 21 40 17 68 57

% Silt 52 46 35 21 32

% Clay 27 14 48 11 11

pH (0.01M CaCl2) 6.0 6.8 7.7 7.4 5.1

Organic carbon (%) 3.2 1.3 2.1 1.7 0.9

CEC (mEq/100 g) 26.0 10.6 15.9 9.1 6.5

Moisture content air

dry soil (%) 4.15 1.03 1.89 0.90 0.82

Bulk density (g/cm3) 1.05 1.17 1.04 1.09 1.16

Soil taxonomic

classificationa

Unknown Udepts Cambids Fluvents

Fine-loamy,

siliceous,

semiactive,

mesic Typic

Hapludults a USDA soil classification system

B. STUDY DESIGN


The appropriate soil to solution ratio was determined in preliminary testing. For the

Gross-Umstadt and Drummer soils portions of test solution (20 g) were shaken at

20 2C with samples of test soil (5 g dry weight) for a 24-hour equilibration period

in darkness. A control experiment was also performed. Following centrifugation

(3,000 g for 15 minutes), the supernatant was decanted and triplicate aliquots

prepared for radioassay. The results of the preliminary testing indicated that the

most appropriate soil: solution ratios were 1:4 (w/w) for the Drummer soil and

1:1 (w/w) for the remaining soils.

The adsorption/desorption experiments were conducted concurrently. The

experiments were performed in duplicate at five concentrations for each of the five

test soils at a temperature of 12 2C. The temperature was reduced for the

isotherm experiment in attempts to maintain stability of the test item for the duration

of the test. Stock solutions of [14

C]-IN-RDF00 in acetonitrile were prepared and

aliquots added to portions of 0.01 M CaCl2 solution to give final test concentrations

of 0.991, 0.504, 0.101, 0.052, and 0.010 g/mL for Gross-Umstadt, Nambsheim,

Sassafras, and Lleida soils and 1.024, 0.507, 0.102, 0.051, and 0.010 g/mL for

Drummer soil. Portions of test solution (20 g for Drummer soil, 15 g for

Gross-Umstadt, Nambsheim, Sassafras, and Lleida soils) were shaken at 12 2C

with samples of soil (5 g dry weight for Drummer soil, 15 g dry weight for

Gross-Umstadt, Nambsheim, Sassafras, and Lleida soils) for a 2-hour equilibration

period in darkness. A control experiment was also performed to assess potential soil


matrix effects. Following centrifugation (3,000 g for 15 minutes), the supernatant

was decanted and triplicate aliquots prepared for radioassay.



level. Samples were then equilibrated for 2 hours at 12 2C, solutions and soils

separated, quantified, and subject to a further desorption phase. One replicate of

adsorption supernatant at concentrations of 0.991 and 0.504 g/mL (Gross-Umstadt,

Nambsheim, Sassafras, and Lleida soils) as well as 1.024 and 0.507 g/mL

(Drummer soil) were analysed by HPLC to confirm test substance stability.



two highest test concentrations obtained after equilibration were analysed by reverse

phase HPLC.


A. MASS BALANCE

Recovery of radioactivity was determined at the highest test concentration for Sassafras

and Drummer soils and ranged between 99.18 and 101.90% applied in the main isotherm

phase.


The test item was found to be stable in pure CaCl2 solution; however IN-RDF00 was

unstable in CaCl2 solution that had been exposed to soil. Analyses of adsorption

supernatants showed that [14

C]-IN-RDF00 was degraded to 79, 45, 92, 59, and 91% of

the applied amount in the Gross-Umstadt, Nambsheim, Sassafras, Lleida, and Drummer

soils, respectively, at nominal concentrations of 1 g/mL during the course of the

adsorption and desorption experiments. Therefore, valid adsorption coefficients and

isotherm data are reported for Sassafras and Drummer soils only, as test item stability in

these soils exceeded 90% and so met test guideline criteria. The adsorption coefficients

Kd, Kom, and Koc were calculated and reported for Sassafras and Drummer soils at each

concentration of the test item.

C. FINDINGS

The sorption distribution coefficients Kd, Kom, and Koc were calculated for each soil at


Kd = Cs/Cw




The Kd values were 0.21 in Sassafras soil and 4.14 in Drummer soil. The Kom and Koc

values were 13 and 23, respectively, in Sassafras soil and 75 and 130, respectively, in

Drummer soil.


Adsorption isotherm data were analysed using the log form of the Freündlich equation:

log (Cs) = (1/n * log (Cw)) + log (KF) (Table B.8.253).

Table B.8.253 Adsorption and desorption constants of IN-RDF00 in Sassafras and

Drummer soil

Soil

OC

%

pH (in

water)


KFa 1/n

b r

2 KFoc

c D1 (%)

d D2 (%)

e DT (%)

f

Drummer 3.2 6.4 3.1666 0.9091 0.9997 99 28.83 17.39 46.22

Sassafras 0.9 5.7 0.1769 0.9394 0.9998 20 37.23 23.46 60.69 a Freundlich adsorption coefficients.






Stability analyses determined that [14

C]-IN-RDF00 was very unstable (79% AR as

IN-RDF00) after only 2 hours equilibration in the Gross-Umstadt, Nambsheim, and

Lleida soils. The Gross-Umstadt, Nambsheim, and Lleida soils had pH values of 6.8, 7.4,

and 7.7, respectively (in 0.01 M CaCl2) while Sassafras and Drummer soils were more

acidic with pH values of 5.1 and 6.0, respectively. Coefficients were only reported for

the more acidic Sassafras and Drummer soils because of the extent of the test item’s

instability in the presence of the alkaline soils.


isotherm experiments (0.9) indicated that the Freundlich equation adequately predicted

the adsorption of IN-RDF00 to Sassafras and Drummer soils over the range of

concentrations tested.

Using the McCall classification scale to assess a chemical’s potential mobility in soil

(based on KOC), IN-RDF00’s potential mobility can be classified as being “very high” in

the Sassafras soil tested with KOC and KFOC values of 23 and 20, respectively.

IN-RDF00’s potential mobility in Drummer soil was classified as being “high” with KOC

and KFOC values of 130 and 99, respectively. The % adsorbed IN-RDF00 at each

concentration is provided in Table B.8.254.


Table B.8.254 Concentration of IN-RDF00 in the solid and liquid phases at the end of

adsorption equilibration period (mean s.d.)

Concentration on soil

(g a.s./mL)

Drummer

on soila

(g a.s./g)

in solution


Control 0 0 0

1.024 1.839 0.5663 44.85

0.507 0.961 0.2678 47.35

0.102 0.212 0.0498 51.67

0.051 0.109 0.0237 53.64

0.010 0.023 0.0046 55.12

0.991 0.149 0.8443 15.10

0.504 0.081 0.4253 16.01

0.101 0.018 0.0841 17.43

0.052 0.009 0.0427 17.40

0.010 0.002 0.0085 18.71 a Calculated by difference (total applied – concentration in solution)


III. CONCLUSION


C]-IN-RDF00 was examined on five different soils

designated Gross-Umstadt (loam), Nambsheim (sandy loam), Sassafras (sandy loam), Lleida

(clay), and Drummer (silt loam). The sorption coefficient (Kd) values were 0.21 and 4.14 in

Sassafras and Drummer soils, respectively. Coefficients were only reported for the more

acidic Sassafras and Drummer soils because of instability of the test item in the presence of

the neutral and alkaline soils.


isotherm experiments (0.9) indicated that the Freundlich equation adequately predicted the

adsorption of IN-RDF00 to Sassafras and Drummer soils over the range of concentrations

tested.

Using the McCall classification scale to assess a chemical’s potential mobility in soil (based

on Koc), IN-RDF00 can be classified as being “very highly mobile” in Sassafras soil and

“highly mobile” in Drummer soil.

(Anderson, C., Wardrope, L., 2011)


IN-V7160

Report: Elliott, T. (2009); 14

C-IN-V7160: Batch equilibrium (adsorption/desorption) in five

soils


Guidelines: OECD 106 (2000), U.S. EPA 163-1 (1982), OPPTS 835.1230 (2008)

Deviations: None

Testing Facility: ABC Laboratories, Inc. (Missouri), Columbia, Missouri, USA


GLP: Yes



Previous

evaluation:




acceptable. Data from this study has been used to derive input

parameters for the exposure assessment.

Executive summary:

The adsorption and desorption properties of 14

C-IN-V7160 (a metabolite associated with

chlorsulfuron) were investigated to assess its potential mobility in soils. The adsorption

coefficients Kd, Kom, and Koc, and the Freundlich adsorption isotherm parameters KF, KFom,

KFoc, and 1/n were calculated on three European and two North American soils.

The adsorption/desorption of 14

C-IN-V7160 was examined on five different soils: A silty

clay loam soil from Stark County, Illinois (USA) designated as Tama; a loamy sand soil from

Kent County, Maryland (USA) designated as Sassafras #16; a silty clay soil from Lleida,

Spain; a sandy loam soil from Nambsheim, France; and a sandy loam soil from Suchozebry,

Poland. The percent organic matter (Walkley-Black method) of the soils ranged from 1.3 to

5.3%, and the pH (1:1 soil:CaCl2) ranged from 5.0 to 7.5.


with five concentrations of the test substance in 0.01 M CaCl2. Two desorption cycles were

performed on the highest concentration of the test substance. A 1:1 soil to solution ratio was

used in the testing. Samples from the two alkaline soils (Lleida and Nambsheim) showed

some degradation, thus the samples prepared at 0.5 g/mL were extracted with a mixture of

aqueous and organic solvents. The percent of the radioactivity as 14

C-IN-V7160 was not

significantly different when the water phase was compared to the soil phase; therefore no

concentration correction was used.

The mass balance at the end of the study ranged from 92.4% to 106.3%. The mean

adsorption Kd or K values ranged from 1.12 to 8.16 mL/g. The mean adsorption Koc values

ranged from 71.5 to 265 mL/g. At the end of the second desorption phase, between 9.00%

and 42.9% of the adsorbed amount was desorbed.



A. MATERIALS


C-IN-V7160 technical metabolite

Lot/Batch #: [triazine-2-14

C]IN-V7160: 3612231

Radiochemical purity: [triazine-2-14

C]IN-V7160: 97%

14

C specific activity: [triazine-2-14

C]IN-V7160: 48.67 Ci/mg


Stability of test compound:

The test material was stable at the test conditions

for the duration of the study.

2. Soils:


the U.S.). The soils were stored refrigerated when not in use. The soils were sieved

(2-mm) and allowed to equilibrate to the test temperature overnight prior to dosing.

A summary of the physical and chemical properties of the soils is provided in Table

B.8.255. The percent sand, silt, and clay are quoted on the basis of the USDA

classification.


Property Tama Sassafras #16 Lleida Nambsheim Suchozebry

Origin

Stark County,

Illinois

(U.S.A.)

Kent County,

Maryland

(U.S.A.)

Lleida,

Spain

Nambsheim,

France

Suchozebry,

Poland

Soil texture

(USDA Classification) Silty clay loam Loamy sand Silty clay Sandy loam Sandy loam

% Sand 3 77 5 53 73

% Silt 62 16 43 29 18

% Clay 35 7 52 18 9

pH (in 0.01 M CaCl2 (aq)) 6.3 6.3 7.5 7.0 5.0

Organic carbon (%) 3.1 1.4 1.8 1.6 0.76

CEC (meq/100 g) 15.9 6.4 16.6 9.7 6.3

Moisture at 1/3 bar (%) 28.9 9.7 25.3 14.7 8.3

Bulk density (g/cm3) 1.00 1.21 1.05 1.08 1.22

B. STUDY DESIGN


Samples were prepared in duplicate for each concentration level to contain 15 g (dry

weight) of soil. A sufficient amount of 0.01 M CaCl2 was then added to bring the

moisture content to 13.5 mL (i.e., 90% of the total final volume of solution). The

samples were equilibrated overnight at the test temperature of 20C. Dose solutions

of IN-V7160 were prepared in 0.01 M CaCl2 at nominal concentrations of 0.01,

0.05, 0.1, 0.5, and 1.0 g/mL. A 1.5-mL aliquot of the corresponding dose solution

was added to the respective sample on the day of dosing, thus yielding a soil to

solution ratio of 1:1. The samples were shaken at 20C for a 24-hour equilibration


period. Preliminary testing of soil-less control samples and blank samples

containing no test substance were performed to assess potential adsorption to the test

vessels and any interference. Following centrifugation, the supernatant was

decanted, filtered through 0.2-m nylon filters, and aliquoted in triplicate for

radioassay. Representative supernatants from the 1.0 and 0.1 (0.05 for the Stark

County soil) g/mL concentrations were analysed by HPLC to assess the stability of

IN-V7160 during the adsorption equilibration period.

Following the adsorption phase, the samples from the highest concentration were

desorbed. Fresh 0.01 M CaCl2 was added to each of these test vessels to return the

total amount of solution to 15 g. The samples were equilibrated for 24 hours at

20C, and then solutions and soils were separated and quantified. The supernatants

were radioassayed. The soils were subjected to a second desorption.


Radioactivity in the supernatants was determined by LSC, and the adsorption

supernatants from the 1.0 and 0.1 (0.05 for the Stark County soil) g/mL

concentrations were analysed by reverse phase HPLC (Phenomenex, Luna C18, 250

mm 4.6 mm id, 5 m) with a gradient of 0.01 M ammonium acetate and

acetonitrile. The effluent was passed through an UV detector (254 nm) to detect the

reference standard and a radioactivity detector for peak shape comparison with UV,

followed by fraction collection to determine the quantities of radiolabelled

degradation products present. A detection limit of LSC analysis permitted detection

of radioactivity of <1% applied radioactivity (AR).

A non-radiolabelled reference substance solution and a 14

C-test substance solution

were analysed by HPLC on each analysis day to verify proper column and

instrument operation. The retention time of [14

C]IN-V7160 was determined to be

approximately 16 minutes.

After the second desorption experiment, the soils from the high concentration

samples were combusted, and 14

C levels were measured using LSC.


A. MASS BALANCE

The material balances ranged from 92.4 to 106.3% and are within the acceptable

guideline range of 90-110% of the applied radioactivity (Table B.8.248.


During the 24-hour equilibration period, no significant degradation was observed in three

of the soils. The two alkaline soils (Lleida and Nambsheim), however, showed some

degradation. The samples prepared at 0.5-g/mL were extracted with a mixture of

aqueous and organic solvents, but the recovered amount was not significantly different

when comparing the water and soil phases. No concentration correction was used.


C. FINDINGS

The mean Kd values ranged from 1.12 to 8.16 mL/g. The adsorption coefficients were

normalised to the organic matter and organic carbon contents for each test soil to

calculate the soil sorption coefficients Kom and Koc. The Kom values ranged from 41.6 to

154 mL/g, while the Koc values ranged from 71.5 to 265 mL/g (Table B.8.242).

The Freundlich adsorption coefficient (KF) and the exponential constant (1/n) were

determined from the linear regression of the Freundlich equation shown below.

))(C log(1/n x )(K log )(C log wFs

Plotting the linear form of the Freundlich equation with log (Cs) on the y-axis and log

(Cw) on the x-axis yielded a line with a slope of 1/n and a y-intercept of log (KF). The KF

values were used to calculate KFom and KFoc values.

100 x %om

KK F

Fom

100 x %oc

KK F

Foc

Linear isotherms were also constructed by plotting Cs (y-axis) and Cw (x-axis) for each

soil tested.

The percent adsorbed and desorbed IN-V7160 at each concentration is provided in Table

B.8.257and Table B.8.258, respectively.

The values for the Freundlich adsorption isotherm parameter, KF, were derived from the

linear form of the Freundlich equation (Table B.8.256). The values for the Freundlich

adsorption isotherm parameters, KF, ranged from 0.908 to 5.97. The organic matter and

organic carbon normalised Freundlich adsorption isotherm coefficients KFom and KFoc.

The KFom values ranged from 33.6 to 113), while the KFoc values ranged from 57.9 to

194. The values for 1/n ranged from 0.8686 to 0.9364 across all the test soils, and the

correlation coefficients (r2) for the analyses ranged from 0.9991 to 0.9998 for the

adsorption phase, indicating the Freundlich equation adequately predicts the adsorption

of the test substance over the concentration range studied. All results are presented in

Table B.8.256.


Table B.8.256 Sorption constants of IN-V7160 in the soils

Soil

%

Organic

carbon pH

Kd

(mL/g)

Kom

(mL/g)

Koc

(mL/g) KF KFom KFoc 1/n R2

Stark County

(Tama) 3.1 6.3 8.16 154 265 5.97 113 194 0.9297 0.9991

Kent County

(Sassafras #16) 1.4 6.3 1.31 54.7 94.2 0.969 40.4 69.4 0.9021 0.9993

Lleida 1.8 7.5 1.86 60.1 103 1.51 48.8 84.0 0.9364 0.9998

Nambsheim 1.6 7.0 1.12 41.6 71.5 0.908 33.6 57.9 0.9290 0.9998

Suchozebry 0.76 5.0 1.95 150 258 1.24 95.6 164 0.8686 0.9994

Arithmetic mean 113.9 0.913 -


Table B.8.257 Concentration of [14

C]IN-V7160 in the solid and liquid phases at the end of adsorption equilibration period

Nominal

dose

level

(g/mL)

Tama Sassafras #16 Lleida Nambsheim Suchozebry

On

soila

(g/g)

In

solution

(g/mL)

%

Adsorbb

On

soila

(g/g)

In

solution

(g/mL)

%

Adsorbb

On

soila

(g/g)

In

solution

(g/mL)

%

Adsorbb

On

soila

(g/g)

In

solution

(g/mL)

%

Adsorbb

On

soila

(g/g)

In

solution

(g/mL)

%

Adsorbb

0.01 0.00891 0.00103 89.7 0.00621 0.00379 62.3 0.00682 0.00318 68.3 0.00568 0.00431 56.9 0.00731 0.00266 73.3

0.01 0.00906 0.000934 90.7 0.00603 0.00390 60.8 0.00678 0.00319 68.0 0.00575 0.00423 57.6 0.00741 0.00261 73.9

0.05 0.0445 0.00489 90.1 0.0289 0.0201 58.8 0.0330 0.0162 67.1 0.0260 0.0233 52.8 0.0338 0.0153 68.9

0.05 0.0445 0.00495 90.0 0.0298 0.0192 60.9 0.0322 0.0166 66.0 0.0270 0.0221 55.0 0.0334 0.0160 67.6

0.1 0.0904 0.0102 89.8 0.0576 0.0425 57.6 0.0655 0.0346 65.4 0.0534 0.0467 53.4 0.0654 0.0349 65.2

0.1 0.0895 0.0104 89.6 0.0580 0.0420 58.0 0.0665 0.0339 66.3 0.0538 0.0461 53.9 0.0637 0.0362 63.8

0.5 0.432 0.0596 87.9 0.261 0.237 52.4 0.311 0.181 63.1 0.245 0.247 49.8 0.302 0.194 60.9

0.5 0.428 0.0609 87.6 0.256 0.236 52.1 0.309 0.184 62.7 0.247 0.245 50.2 0.301 0.193 60.9

1.0 0.880 0.130 87.1 0.519 0.496 51.1 0.611 0.392 61.0 0.492 0.520 48.6 0.590 0.416 58.7

1.0 0.878 0.132 86.9 0.504 0.506 50.0 0.615 0.388 61.3 0.493 0.516 48.7 0.595 0.414 59.0

Testing performed in duplicate at each concentration. Calculations performed using unrounded numbers. a Amount on soil is calculated by difference (total applied – concentration in solution).

b % adsorbed reported based on the % of the applied.


Table B.8.258 Desorption of IN-V7160 and mass balance

Soil-rep

% Desorbed

(Event 1)

% Desorbed

(Event 2)

% Desorbed

(Total)

Mass balance

(%)

Tama-1 4.75 4.73 9.48 92.4

Tama-2 4.58 4.42 9.00 98.0

Average 4.66 4.58 9.24 95.2

Sassafras #16-1 20.2 16.1 36.3 98.4

Sassafras #16-2 21.0 15.4 36.3 101.1

Average 20.6 15.7 36.3 99.7

Lleida-1 19.6 15.8 35.4 101.0

Lleida-2 19.3 15.9 35.2 106.3

Average 19.5 15.9 35.3 103.7

Nambsheim-1 22.1 18.2 40.4 99.9

Nambsheim-2 22.4 20.5 42.9 102.6

Average 22.3 19.3 41.6 101.3

Suchozebry-1 23.2 14.6 37.8 99.5

Suchozebry-2 23.6 14.2 37.8 97.6

Average 23.4 14.4 37.8 98.5

Calculations performed using unrounded values. An average was not calculated for the mass balance.

III. CONCLUSIONS

Koc values for IN-V7160 in five soils ranged from 71.5 to 265 mL/g. Considering the data set

as a whole, there was a clear correlation between soil sorption and soil organic carbon. No

other clear correlation with other soil properties was observed. The UK RMS considered it

appropriate to derive an arithmetic mean Kfoc of 113.9ml/g and arithmetic mean 1/n of 0.913

for the purposes of the environmental exposure assessment.

(Elliott, T., 2009)

IN-W8268

Yeomans P. (2000)

Previous

evaluation: In Addendum for original approval (2000).



considered the study valid, although it is noted that the original EU

evaluation concluded that the results may be unreliable due to low

adsorbed amounts (Kfoc in the range 2.6-4 ml/g). Irrespective of the

low sorption, data from this study has been used to derive input

parameters for the exposure assessment to ensure a conservative

groundwater leaching assessment has been performed.




Yeomans P. (2000), report 3172, GLP, OECD guideline, acceptable but results not reliable

due to low adsorbed amounts.

In preliminary experiment 14

C-thiophene sulfonimide (purity > 95 %) at 1 mg/l in 0.01 M

CaCl2 was adsorbed on 3 soils (same as above) at ratio of 1:5 and 1:1. Under both conditions,

the test substance was poorly adsorbed on soils. In definitive experiments, 14

C-thiophene

sulfonimide at 0.1, 0.5, 1 and 5 mg/l in 25 ml 0.01 M CaCl2 was adsorbed on the 3

preconditioned soils (5 g equivalent dry soil) for 24 h at 20° C. Liquid phase was analysed by

LSC and HPLC (highest concentration only). After adsorption, 2 desorption steps (24 h each)

were performed. After desorption, the soils treated at the highest concentration were extracted

(acetonitrile/ammonium carbonate) and extracts were analysed by LSC. Extracted soils were

combusted for mass balance. RA was fully recovered and analysis of water phase revealed no

significant degradation of the test substance. For all soils, amounts of adsorbed RA were < 3

% of applied. Kf was calculated to be about 0.1 and Koc was 2.6-4.

Conclusion : The metabolite IN-W8268 (thiophene sulfonimide) is poorly adsorbed on 3

soils (OC 1.2 - 2.6 %, pH 5.7 - 7.7) with Kf about 0.1 and Koc in the range 2.6 - 4. These

values are not reliable due to low adsorbed amounts but adsorption of IN-W8268 seems to be

negligible.

Report: E. Knoch (2012h) Adsorption of Thiophene Sulfonimide8 on soils. SGS


12/02132068 [CHA Doc. No. 301 TIM]







Previous

evaluation:



The following study on metabolite IN-W8268 was evaluated by the UK

RMS and considered acceptable. Data from this study has been used to

derive input parameters for the exposure assessment.

Executive Summary:

8 i.e. IN-W8268


The adsorption characteristics of IN-W8268 (thiophene sulfonimide) were determined in

three soil types (loamy sand, sandy loam and clay) with a pH range of 5.5 to 7.1. Adsorption

coefficients related to organic carbon content (KOC) for the three soils were in the range of 9

to 15 mL/g (mean 11.3 mL/g). IN-W8268 was shown to be of “very high mobility”

according to the McCall classification.


Materials:

1. Test Material: IN-W8268 (Thiophene sulfonimide)


Lot/Batch #: P1966-OSJ-TFM-03-D

Purity: 99.6%

CAS #: 59337-94-9

Stability: Stable within bounds of the experimental phase.





USDA Textural class Loamy sand Sandy loam Clay

% Sand 80.6 63.7 22.2

% Silt 12.6 27.6 36.8

% Clay 6.8 8.7 41.0

% OC 1.87 0.94 1.64

CEC (mEq/100g) 9.9 10.7 23.7

pH (0.01M CaCl2) 5.5 6.8 7.1


CRD considers that the soils chosen exhibit sufficient variation in soil characteristics for the

purposes of the adsorption experiment. Specifically, CRD considers the variation among the

important soil characteristics for adsorption process (clay content and soil texture, pH and %

organic carbon) adequate.

Study Design:









concentration of IN-W8268 (0.1 mg/L). Each test system was prepared in triplicate.

After agitation for 24 hours at 20±2 °C in the dark, the distribution of IN-W8268 between the


the equilibrium concentration in the aqueous phases. The adsorbed IN-W8268 in the solid phase







MS/MS analysis.

The amount of adsorbed IN-W8268 onto soil, the adsorption coefficient (K) and the



A. RECOVERIES

Mean recoveries of IN-W8268 in the aqueous soil extract solutions at time zero fortified at


IN-W8268 was detected in the untreated soil extract solutions.

B. FINDINGS




carbon content (Koc) were calculated to be 9, 10 and 15 mL/g (ratio 1:1) for LUFA 2.2, 2.3 and

6S soils respectively. The Koc values calculated from the 1:1 ratio experiments were more

conservative than those derived from the 5:1 ratio experiments. Additionally the 1:1 ratio

experiments featured higher overall adsorption (%).

Table B.8.260 Adsorption coefficients for IN-W8268 in soil (ratio 1:1)

Soil type OC % pH

0.01 M CaCl2

Adsorption (mL/g)a

K KOC 1/n



LUFA 6S (Clay) 1.64 7.1 0.25364 15 NS



Conclusions:

The adsorption properties of IN-W8268 were studied in three German soils, namely LUFA

2.2 (Loamy sand), LUFA 2.3 (Sandy loam) and LUFA 6S (Clay). Adsorption coefficients


11.3 mL/g. IN-W8268 was shown to be of “very high mobility” according to the McCall

classification.

(Knoch, 2012h)

Two acceptable studies on the sorption potential of metabolite IN-W8268 were submitted


B.8.261.

Table B.8.261: Summary of the sorption values for metabolite IN-W8268 based on DuPont

and Task Force data


(H2O)

Kf (ml/g) Kfoc

(ml/g)

1/n

Arrow;

sandy loam 2.3 5.7

0.10 3.6 1.10

Gross-

Umstadt; silt

loam

1.2 7.7

0.05 4.0 1.68

Mattapex;

silt loam 2.6 6.4

0.10 2.6 1.17

LUFA 2.2;

loamy sand 1.87 5.5

(CaCl2) 0.1652 9 -

LUFA 2.3;

sandy loam 0.94 6.8

(CaCl2) 0.0947 10 -

LUFA 6S;

clay 1.64 7.1

(CaCl2) 0.2536 15 -





sorption was weakly correlated to soil organic carbon. No clear correlation with soil pH was

apprarent, even when soil pH was expressed in a similar medium (assuming pH in H2O is 0.7

units higher than a Cl medium as per FOCUS groundwater guidance). The UK RMS

considered it appropriate to use an arithmetic mean Kfoc of 7.4ml/g and arithmetic mean 1/n

of 1.16.


IN-JZ789

Report: Suresh, G. (2012); Adsorption-desorption of IN-JZ789 via batch equilibrium in five

soils


Guidelines: OPPTS 835.1230 (2008), OECD Guideline 106 (2000) Deviations: None

Testing Facility: International Institute of Biotechnology and Toxicology (IIBAT), Tamil

Nadu, India


GLP: Yes

Certifying Authority: National GLP Compliance Monitoring Authority (India)

Previous

evaluation:






Executive summary:

The adsorption characteristics of IN-JZ789 were studied in five soils (pH range of 4.7 to 7.8,

organic carbon range of 1.2 to 3.3%) from USA, Germany, Spain, and France.


at a single concentration (10 g/mL) of the test substance in 0.01 M CaCl2.

The adsorption coefficients Kd, Kom, and Koc were calculated for Gross Umstadt, Lleida

Nambsheim and Sassafras soils. The average Kd was 0.39 (range 0.17–0.89) and the average

Koc was 18.6 (range 13.6–27.0).


A. MATERIALS

1. Test material: IN-JZ789 technical metabolite

Lot/Batch #: E97247-15

Purity: 97.4%, by analysis

Description: Solid, powder

CAS#: 171628-02-7


Structure of IN-JZ789


2. Soils




provided in Table B.8.262 The percent sand, silt, and clay are quoted on the basis of

the USDA classification system.


Property Drummer Gross-Umstadt Nambsheim Lleida Sassafras

Origin U.S.A. Germany France Spain U.S.A

Soil texturea Clay loam Loam Sandy loam Clay Sandy loam

% Sand (2000–50 m) 24 40 63 13 67

% Silt (50–2 m) 41 47 25 37 27

% Clay (2 m) 35 13 12 50 6

pH in 1:1 soil: water ratio 6.0 6.7 7.6 8.1 4.7

pH [0.01 M CaCl2 (1:2)] 5.9 6.4 7.2 7.8 4.7

Organic carbon (%) 3.3 1.2 1.3 2.0 1.6

CEC (meq/100 g) 31.4 14.1 22.1 31.8 9.0

Moisture at 1/3 atm (%) 28.7 14.8 12.6 31.5 14.2

Bulk density (g/cm3) 1.08 1.16 1.10 0.96 1.13


B. STUDY DESIGN


The stock solution of (100µg/ml) IN-JZ789 was prepared in 0.01 M CaCl2. The

appropriate soil to solution ratio was determined in preliminary testing using

10µg/ml IN-JZ789 and a soil ratio of at 1:4 at 20ºC. Samples were analysed at

2,4,6,18 and 24 hours.

Results showed that maximum absorptions were 23.08% and 4.20% adsorption for

Drummer and Gross-Umstadt soils, respectively, after 24-hours.

In the definitive tests a soil: solution ration of 1:2 was used for all soils except

Drummer which was tested at 1:4. Aliquots of stock solution were diluted in

0.01 M CaCl2 such that the final treatment solution concentration was 10 g/mL.

Soils were pre-equilibrated overnight at 20 2C with 36 mL (Drummer soil) or 18

mL (other soils) 0.01 M CaCl2. Aliquots of 4.0 mL treatment solution (100µg/ml)

were added to Drummer test soil, and aliquots of 2.0 mL treatment solution were

added to the remaining soils (10 g dry weight), and incubated 24 hours. Samples


were then centrifuged (10000 rpm for 15 minutes), the supernatant was decanted and

aliquots were prepared for HPLC analysis. An experiment without soil was also

performed to assess the potential adsorption to test vessels.


Aqueous supernatants were analysed by HPLC.


A. MASS BALANCE

The study was conducted with non-radiolabelled material and therefore mass balance

accounting was not performed.

The average recovery of IN JZ789 from the polypropylene tubes after 24 hours was

99.54% indicating that it was stable and it did not adsorb to the tube.


The test item was found stable during the 24-hour equilibration period.

C. FINDINGS

The sorption distribution coefficients Kd, Kom and Koc were calculated for each soil at


Kd = Cs/Cw




The Kd values ranged from 0.17 to 0.89 (Table B.8.263). The Kom values ranged from

7.7 to 15.6 and the Koc values ranged from 13.6 to 27.0.

Table B.8.263 Adsorption constants of IN-JZ789 in the soils

Soil

OC

(%)

pH

(0.01 M CaCl2)

Adsorption

Kda (mL/g) Kom

b (mL/g) Koc

c (mL/g)

Drummer 3.3 5.9 0.89 15.61 26.95

Gross-Umstadt 1.2 6.4 0.17 8.37 13.96

Nambsheim 1.3 7.2 0.18 7.69 13.61

Lleida 2.0 7.8 0.47 13.30 23.27

Sassafras 1.6 4.7 0.24 8.67 15.18

Average 0.39 10.73 18.59 a Adsorption coefficient

b Adsorption coefficient as a function of organic matter.

c Adsorption coefficient as a function of organic carbon.


The sorption concentrations (aqueous and soil) of IN-JZ789 are provided in Table

B.8.264.

Table B.8.264 Determination of adsorption coefficients for IN-JZ789

Soil Rep

C0

(g/mL)

Cw

(G/mL)

Cs

(g/g) Kd Kom Koc

Drummer 1 100.07 8.19 7.28 0.89 15.59 26.93

2 100.07 8.19 7.29 0.89 15.62 26.98

Gross-Umstadt 1 100.07 9.23 1.57 0.17 8.49 14.15

2 100.07 9.24 1.53 0.17 8.26 13.76

Lleida 1 100.07 8.11 3.79 0.47 13.36 23.38

2 100.07 8.13 3.77 0.46 13.23 23.15

Nambsheim 1 100.07 9.20 1.64 0.18 7.74 13.70

2 100.07 9.20 1.62 0.18 7.64 13.51

Sassafras 1 100.07 8.91 2.19 0.25 8.78 15.36

2 100.07 8.93 2.14 0.24 8.57 14.99

III. CONCLUSION

The adsorption of IN-JZ789 was examined on five different soils designated Sassafras (loamy

sand), Lleida (clay), Drummer (clay loam), Gross-Umstadt (loam) and Nambsheim (sandy

loam). For the five soils, the average Kd was 0.39 (range 0.17–0.89), the average Kom was

10.7 (range 7.7–15.6), and the average Koc was 18.6 (range 13.6–27.0).

(Suresh, G., 2012)

Report: E. Knoch (2012f) Adsorption of O-Desmethyl thifensulfuron acid on

soils. SGS Institut Fresenius GmbH [Cheminova A/S], Unpublished

report No.: IF-12/02132069 [CHA Doc. No. 302 TIM]







Previous



The following study on IN-JZ789 was evaluated by the UK RMS and

considered acceptable. Data from this study has been used to derive

input parameters for the exposure assessment.

Executive Summary:

The adsorption characteristics of IN-JZ789 (O-Desmethyl thifensulfuron acid) were

determined in three soil types (loamy sand, sandy loam and clay) with a pH range of 5.5 to


7.1. Adsorption coefficients related to organic carbon content (KOC) for the three soils were

in the range of 41 to 58 mL/g (mean 52 mL/g). IN-JZ789 was shown to be of “high

mobility” according to the McCall classification.


Materials:

1. Test Material: IN-JZ789 (O-Desmethyl thifensulfuron acid)

Description: White-beige Solid

Lot/Batch #: P1265-OSJ-THF-01-A

Purity: 94.2%

CAS #: 171628-02-7

Stability: Not stated.

2. Soils: Three German soils were supplied by the LUFA Speyer. Soils were chosen for

their variety in pH, clay, and organic carbon content





% Sand 80.6 63.7 22.2

% Silt 12.6 27.6 36.8

% Clay 6.8 8.7 41.0

% OC 1.87 0.94 1.64

CEC (mEq/100g) 9.9 10.7 23.7

pH (0.01M CaCl2) 5.5 6.8 7.1


Study Design:








concentration of IN-JZ789 (0.1 mg/L). Each test system was prepared in triplicate.


After agitation for 24 hours at 20±2 °C in the dark, the distribution of IN-JZ789 between the


the equilibrium concentration in the aqueous phases. The adsorbed IN-JZ789 in the solid phase







MS/MS analysis.

The amount of adsorbed IN-JZ789 onto soil, the adsorption coefficient (K) and the adsorption

coefficient on basis of the soil organic carbon content (Koc) was calculated.


A. RECOVERIES

Mean recoveries of IN-JZ789 in the aqueous soil extract solutions at time zero fortified at


IN-JZ789 was detected in the untreated soil extract solutions.

B. FINDINGS





and 6S soils respectively. The Koc values derived from the 1:1 ratio experiments are more

conservative than those derived from the 5:1 ratio experiments. Additionally the 1:1 ratio

experiments featured higher overall adsorption (%).

Table B.8.266 Adsorption coefficients for IN-JZ789 in soil (ratio 1:1)

Soil type OC % pH

0.01 M CaCl2

Adsorption (mL/g)a

K KOC 1/n



LUFA 6S (Clay) 1.64 7.1 0.90136 57 NS


Conclusions:

The adsorption properties of IN-JZ789 were studied in three German soils, namely LUFA 2.2




52 mL/g. IN-JZ789 was shown to be of “high mobility” according to the McCall

classification.

(Knoch, 2012f)

Two acceptable studies on the sorption potential of metabolite IN-JZ789 were submitted


B.8.267.

Table B.8.267: Summary of the sorption values for metabolite IN-JZ789 based on DuPont

and Task Force data


(CaCl2)

Kd (ml/g) Koc

(ml/g)

1/n

Drummer;

clay loam 3.3 5.9

0.89 26.95 -

Gross-

Umstadt;

loam

1.2 6.4

0.17 13.96

Nambsheim;

sandy loam 1.3 7.2

0.18 13.61

Lleida; clay 2.0 7.8 0.47 23.27 -

Sassafra;

sandy loam 1.6 4.7

0.24 15.18 -

LUFA 2.2;

loamy sand 1.87 5.5

0.759 41 -

LUFA 2.3;

sandy loam 0.94 6.8

0.546 58 -

LUFA 6S;

clay 1.64 7.1

0.901 57 -

Arithmetic mean 31.1 -


sorption was correlated to soil organic carbon. No clear correlation with soil pH was

apparent. The UK RMS considered it appropriate to use an arithmetic mean Koc of 31.1

ml/g and, since no attempt to measure the Freundlich isotherm was attempted, adefault 1/n of

1.0.

IN-B5528

Report: E. Knoch (2012g) Adsorption of O-desmethyl triazine amine on soils.

SGS Institut Fresenius GmbH [Cheminova A/S], Unpublished report

No.: IF-12/02132773 [CHA Doc. No. 304 TIM]



Previous



The following study was only briefly reviewed by the UK RMS.


Metabolite IN-B5528 was not a major soil metabolite and the data from

this study is therefore no used in the quantitative exposure assessment.

For completeness the detailed study summary from the Task Force is

provided below. As the data from this study is not relied it has been

highlighted in grey.

Executive Summary:

The adsorption characteristics of IN-B5528 (O-Desmethyl triazine amine) were determined in

three soil types (loamy sand, sandy loam and clay) with a pH range of 5.5 to 7.1. Adsorption

coefficients related to organic carbon content (KOC) for the three soils were in the range of

120 to 255 mL/g (mean 166 mL/g). IN-B5528 was shown to be of “medium mobility”

according to the McCall classification.


Materials:

1. Test Material: IN-B5528 (O-Desmethyl triazine amine)


Lot/Batch #: 194694

Purity: 97.3%

CAS #: 16352-06-0

Stability: Stable for at least 3 weeks.






% Sand 80.6 63.7 22.2

% Silt 12.6 27.6 36.8

% Clay 6.8 8.7 41.0

% OC 1.87 0.94 1.64

CEC (mEq/100g) 9.9 10.7 23.7

pH (0.01M CaCl2) 5.5 6.8 7.1


Study Design:









concentration of IN-B5528 (0.1 mg/L). Each test system was prepared in triplicate.

After agitation for 24 hours at 20±2 °C in the dark, the distribution of IN-B5528 between the


the equilibrium concentration in the aqueous phases. The adsorbed IN-B5528 in the solid phase






were diluted with 0.9 mL of pure water/methanol (95:5; v/v), containing 0.1 mol/L

ammonium carbonate and subjected to LC-MS/MS analysis.

The amount of adsorbed IN-B5528 onto soil, the adsorption coefficient (K) and the



A. RECOVERIES

Mean recoveries of IN-B5528 in the aqueous soil extract solutions at time zero fortified at


IN-B5528 was detected in the untreated soil extract solutions.

B. FINDINGS





and 6S soils respectively.

Table B.8.269 Adsorption coefficients for IN-B5528 in soil (ratio 1:1)

Soil type OC % pH

0.01 M CaCl2

Adsorption (mL/g)a

K KOC 1/n



LUFA 6S (Clay) 1.64 7.1 2.01227 123 NS



Conclusions:

The adsorption properties of IN-B5528 were studied in three German soils, namely LUFA

2.2 (Loamy sand), LUFA 2.3 (Sandy loam) and LUFA 6S (Clay). Adsorption coefficients


166 mL/g. IN-B5528 was shown to be of “medium mobility” according to the McCall

classification.

(Knoch, 2012g)

2-Acid-3-triuret

Report: E. Knoch (2012k) Adsorption of TIM 2-acid-3-triuret on soils. SGS


12/02251377 [CHA Doc. No.: TIM 316]







Previous






Executive Summary:

The adsorption characteristics of TIM 2-acid-3-triuret were determined in three soil types

(loamy sand, sandy loam and loam) with a pH range of 5.5 to 7.2. Adsorption coefficients

related to organic carbon content (KOC) for the three soils were in the range of 230-780 mL/g

(mean 524 mL/g). TIM 2-acid-3-triuret was shown to be of “low mobility” according to the

McCall classification.


Materials:

1. Test Material: TIM 2-acid-3-triuret

Description: Beige Solid

Lot/Batch #: P1265HRM-TFSM-17

Purity: 96.0%


CAS #: 171628-03-8

Stability: Expiration date April 03 2015.

2. Soils: Three German soils were supplied by the LUFA Speyer. Soils were chosen for

their variety in pH, clay, and organic carbon content


Soil Name LUFA 2.2 LUFA 2.3 LUFA 2.4


Textural class1 Loamy sand Sandy loam Loam

% Sand 78.9 63.1 33.6

% Silt 13.8 28.4 40.5

% Clay 7.3 8.5 25.9

% OC 1.77 0.94 2.26

CEC (mEq/100g) 10.1 10.9 31.4

pH (0.01M CaCl2) 5.5 6.8 7.2


Study Design:



classification were: loamy sand for LUFA 2.2 soil, sandy loam for LUFA 2.3 soil, loam for

LUFA 2.4 soil) with 60 mL of 0.01 mol/L CaCl2, the test item was applied in methanol. The co-




concentration of TIM 2-acid-3-triuret (0.1 mg/L Each test system was prepared in triplicate.

After agitation for 24 hours at 20±2 °C in the dark, the distribution of TIM 2-acid-3-triuret

between the aqueous phase and the solid phase (soil) was assayed. LC-MS/MS was used for the

analysis of the equilibrium concentration in the aqueous phases. The adsorbed TIM 2-acid-3

triuret in the solid phase (soil) was calculated.





were diluted with methanol Optigrade/ultra pure water (1:9; v/v) and subjected to LC-MS/MS

analysis.

The amount of adsorbed TIM 2-acid-3-triuret onto soil, the adsorption coefficient (K) and the




A. RECOVERIES

Mean recoveries of TIM 2-acid-3 triuret in the aqueous soil extract solutions at time zero

fortified at 0.01 and 0.1 mg/mL ranged from 83 to 99%. Results indicate the validity of the

study. No TIM 2-acid-3-triuret was detected in the untreated soil extract solutions.

B. FINDINGS





and 2.4 soils respectively. The Koc values derived from the 5:1 ratio experiments are more

conservative than those derived from the 5:1 ratio experiments.

Table B.8.271 Adsorption coefficients for TIM 2-acid-3-triuret in soil (ratio 5:1)

Soil type OC % pH

0.01 M CaCl2

Adsorption (mL/g)a

K KOC 1/n



LUFA 2.4 (Loam) 2.26 7.2 17.620 780 NS

Arithmetic mean 524 1.0 (default)


Conclusions:

The adsorption properties of TIM 2-acid-3-triuret were studied in three German soils, namely

LUFA 2.2 (Loamy sand), LUFA 2.3 (Sandy loam) and LUFA 2.4 (Loam). Adsorption

coefficients normalised for organic carbon (KOC) were in the range 230 to 780 mL/g with a

mean value of 524 mL/g. Although the correlation between sorption and organic carbon was

not consistent, strongest sorption was noted in the soil with the highest OC% (LUFA 2.4.

This soil also had the highest pH. When normalised for OC, the Koc appeared to correlate

with soil pH. However the number of soil is low (n=3) and exact relationship between

sorption, soil OC and pH is uncertain. Since the range of Koc values was relatively small, the

UK TRMS proposed the use of the mean Koc of 524ml/g in the environmental exposure

assessment. In the absence of a measured Freundlich isotherm, a default 1/n value of 1.0 was

assumed.

(Knoch, 2012k)


B.8.2.2 Column leaching

AMR 454-85

Previous



did partially meet current guidelines but was not conducted to GLP.

Since the sorption potential of Thifensulfuron-methyl and its major soil

metabolites have been adequately addressed via provision of batch

sorption studies, the information in this study is not critical.


DAR has been included below. Since this information is not now relied

on, it has been greyed out.

The study (AMR 454-85) was started in 05/1985 and reported by E.M. Ferguson

(1986). No GLP statement was included in the report. The US EPA, Pesticide Assessment

Guidelines: Environmental Fate 163-1 was used. The 6-day ageing period used was less than

recommended by the guideline but was compatible with the degradation rate of the

compound in soils. The study was found acceptable.

Protocol - [thiophene-2-14C]Thifensulfuron-methyl (radiochemical purity 98%) and

[triazine-2-14C]Thifensulfuron-methyl (radiochemical purity 99%) were applied (56-77 g

a.s./ha) to soil columns (5 cm diameter, 30 cm length) immediately or after ageing in soils (6

days, 25° C, 75% water holding concentration). Elution: 1000 ml water (500 mm), flow rate

50 ml/hour. Water did not contain CaCl2. Radioactivity in leachate was analysed (LSC,

HPLC, TLC) and distribution in soil column was determined. Soil characteristics and

treatment conditions are given in Table B.8.272.

Table B.8.272 Soil Characteristics and treatment conditions

Origin of

Soil

Soil Series

Name

Sand

(%)

Silt

(%)

Clay

(%)

OC

(%)

pH

CEC

(meq

100g-1)

Treatment

Cecil, Md. Cecil

Sandy Loam

61

21

18

1.2

6.5

6.

14C thiophene

Rochelle, Ill. Flanagan

Silt Loam

2

81

17

2.49

5.4

21.1

14C thiophene

or 14C triazine

aged or not

Newark, Del. Keyport

Silt Loam

12 83 5 4.34 5.2 15.5 14C thiophene

Penns Grove,

N.J.

Sassafras

Loamy Sand

75 20 5 0.46 6.9 3.4 14C thiophene


Results - Mass balance was in the range 87-116%. Thifensulfuron-methyl was very

mobile on unaged soil columns with 67-98 % (91-93% in Flanagan soil) of the applied

radioactivity appearing in the leachate. Radiolabel in column leachate was distributed among

Thifensulfuron-methyl (60 to 92%), Thifensulfuron acid (3 to 5%) and polar compounds (<1

to 14%).

In aged Flanagan soil study, 83% (14C-thiophene) and 60 % (14C triazine) of the

applied radioactivity was present in the leachate and 23 (14C-thiophene) and 19 % (14C

triazine) were retained in soil (mainly unextractable). With 14C-thiophene label aged soil

extracts contained predominantly Thifensulfuron-methyl (2%) and 2-ester-3-sulfonamide

(3%). THIFENSULFURON-METHYL (35%) and Thifensulfuron acid (29%) were the major

components in the leachate followed by lesser amounts of O-demethyl Thifensulfuron-methyl

(2%), 2-ester-3-sulfonamide, 2-acid-3-sulfonamide and polar compounds (2-5% each). With

14C triazine label aged soil extracts contained predominantly triazine amine (4%).

Thifensulfuron-methyl (24%) and Thifensulfuron acid (26%) were the only significant

components observed in the leachate.

In conclusion, Thifensulfuron was very mobile in soil column (67 to 98 % of the

applied radioactivity in the leachates) even after a 6 days ageing period (83 and 60% with

thiophene and triazine labels respectively). The mobility of Thifensulfuron-methyl was

inversely related to the organic content of the soils. THIFENSULFURON-METHYL was

partly degraded (24-35% of applied remaining in leachate) during the 6-day ageing period on

Flanagan silt loam soil. The major degradation product was Thifensulfuron acid (26-29% of

the applied radioactivity in the leachates).

(Ferguson, 1986)

B.8.2.3 Lysimeter studies

AMR 1481-89 B.P. Smyser and M.H. Russel (1994).

Previous



did meet current guidelines. Since the sorption potential of

Thifensulfuron-methyl and its major soil metabolites have been

adequately addressed via provision of batch sorption studies, the

information in this study is not critical. No additional metabolites

would be triggered for consideration in the environmental exposure

assessment on the basis of this study.





The study (AMR 1481-89) was started in 06/1989 and reported by B.P. Smyser and

M.H. Russel (1994). GLP statement was included in the report. No guideline existed when

experiment was conducted. The study does not comply with current guidelines in the

following ways:

- No crops were grown in the lysimeter.

- The study was terminated after one, rather than two years.

- Total radioactivity (calculated as Thifensulfuron-methyl equivalents) rather than

individual compounds were measured in the leachate.

Protocol - [thiophene-2-14C] and [triazine-2-14C]M6316 (radiochemical purity > 98

%) were applied (June 91) at 36 g a.s./ha (60% of the maximum label use rate) to undisturbed

soil cores (30 cm i.d., 0.5 or 1 m length, 3 soil types) placed outdoors at Newark, Delaware.

Leachates were collected bi-weekly for one year and analysed for radioactivity (LSC). Soil

cores were then divided into 8 segments and each was analysed for radioactivity

(combustion). Qualitative analysis was performed for the upper segments (HPLC, TLC).

Precipitations plus irrigation were 1288 mm over the year. Soil characteristics were given in

Table B.8.273.


Table B.8.273 Soil characteristics (15 cm top layer) Soil Sassafras Norfolk Naron

pH 5.6 5.9 5.7

OM (%) 1.5 1.8 1

Sand 80 84 64.4

Silt 16 12 27.6

Clay 4 4 8

Textural class loamy sand loamy sand sandy loam

CEC meq 100 g-1 3.29 3.57 5.99

MHC (33 kPa) 7.33 6.33 9.73

Moisture content (1500 kPa) 2.25 2.29 3.38

Results - Leachate volume was 9-37 % of precipitations plus irrigation. 20-70% of the

radioactivity was recovered, the remaining is believed to have been lost as 14CO2.

Radioactivity was in the top layer of soils (as triazine amine, polar metabolites and

unextractable) and it was < detection limit (0.9 ppb) below 30 cm. Maximum concentrations

(Thifensulfuron-methyl equivalent) and cumulated 14C in leachates of the 1 m lysimeters

were in the range < 0.135 (detection limit)-0.5 ppb and not detected- 0.5 % of applied

respectively.

In conclusion, despite high potential mobility, Thifensulfuron-methyl showed limited

movement in soils due to rapid degradation. At the applied doses, Thifensulfuron-methyl and

soil degradates have low potential for contaminating ground water.

(Smyser and M.H. Russel, 1994).

B.8.2.4 Summary & assessment – Soil sorption studies

Adsorption of thifensulfuron- methyl showed no clear correlation between sorption (Kf) and

soil organic carbon content when the entire data set was considered (n=9). However, the UK

RMS considered that some of the relationship may have been masked by the fact that across

the nine soil types and two studies, equilibrium times and incubation temperatures varied

widely. Considering the 4 soils tested by the Task Force, where both equilibrium time and

temperature were consistent, a clear correlation between sorption and organic carbon was

observed. On this basis the UK RMS considered it valid to normalise sorption for organic

carbon content and hence derive Kfoc values. No obvious correlation existed between soil

sorption and other soil properties such as soil pH. Considering either the whole data set or

the same four soils where equilibrium conditions were consistent. Based on the generic

FOCUS groundwater guidance (2012), since data on 9 soils is available the use of a median

Kfoc of 9 ml/g is considered appropriate for FOCUS modelling. In addition, based on the

latest generic FOCUS groundwater guidance, the use of an arithmetic mean 1/n of 0.932 is

considered appropriate for FOCUS modelling.

For each relevant metabolite the acceptable adsorption/desorption studies from the original

DAR together with those proposed by either Applicant were combined to generate full data

sets. Where a correlation between soil organic content and sorption was evident the Kfoc

was determined. In line with the latest generic FOCUS groundwater guidance the Median

Kfoc was determined where n ≥9, and the associated mean Kfoc was determined. No


metabolites displayed any clear correlation of sorption with soil pH. Therefore the use of

mean or median values in the environmental exposure assessment was consider appropriate

Despite the submission of adsorption/desorption studies; IN-RDF00 and IN-B5528 were not

major soil metabolites. Data from these studies were therefore not used in the quantitative


A summary of the Kfoc and freundlich component (1/n) for thifensulfuron and relevant

metabolites are provided in the table below. Full summary Tables are further below

Compound Kfoc (ml/g)

(Arithmetic

mean)

1/n

(Arithmetic

mean)

Thifensulfuron-methyl 9 0.932

IN-A4098 62.3

45.5 (Median)

0.903

0.900

IN-A5546 49 0.910

IN-JZ789 31.1* 1.0

IN-L9223 4.07 1.157

IN-L9225 19.9 0.85

IN-L9226 126 0.90

IN-V7160 113.9 0.913

IN-W8268 7.4 1.16

2-acid-3-triuret 524* 1.0

*Koc not Kfoc.


Soil type OC % pH (in

CaCl2) KF (ml/g)

KFoc

(ml/g) 1/n r2

Sassafras 0.81 4.8 0.6660 82 0.9023 0.9959

Lleida 1.74 7.6 0.1551 9 0.9826 0.9687

Drummer 2.96 5.7 2.5468 86 0.8211 0.9942

Gross-Umstadt 1.39 6.6 0.2679 19 0.9599 0.9624

Nambsheim 2.03 7.3 0.2164 11 0.8389 0.9514

Long woods 1.3 7.3 0.08 6.0 0.967 0.999

Farditch 3.5 5.9 0.22 6.2 0.952 1.000

Kenslow 3.9 5.1 0.33 8.4 0.949 0.999

Lockington 2.8 5.5 0.09 3.1 1.012 0.998

Arithmetic

median - - - 9 0.952 -

Arithmetic mean - - - 25.6 0.932 -


Triazine amine a.k.a. 2-amino-4-methoxy-6-methyl-triazin a.k.a. 4-methoxy-6-methyl-

1,3,5-triazin-2-amine a.k.a. CGA 150829 a.k.a. AE F059411 a.k.a. IN-A4098 a.k.a. BCS-

CN85650

Soil type OC% Soil pH Kf (ml/g) Kfoc (ml/g) 1/n

Gross-Umstadt (Silt loam) 1.2 7.7 0.2 18.8 1.05

Arrow (Sandy loam) 2.3 5.7 0.7 29.7 0.94

Mattapex (Silt loam) 2.6 6.4 0.4 16.7 0.96

Matapeake 1.1 5.3 2.36 214.2 0.841

Sassafras 0.46 6.3 0.621 133.8 0.784

Drummer 3.02 5.7 6.80 225.5 0.841

Myaka 0.58 6.2 0.264 45.52 0.873

Honville (Chateadun) 0.91 6.7 1.57 172 0.8351

Agriculutural sand 0.35 7.9 0.2326 66.5 0.8702

Sandy loam 0.99 7.8 2.776 280.4 1.021

Silt loam 1.74 6.5 0.9612 55.2 0.8474

Silty clay loam 0.70 6.9 1.201 171.6 0.8230

SLS 2.08 7.0 0.44 21.3 0.873

LS2.2 1.95 6.0 0.30 15.4 0.909

SLV 0.43 6.0 0.32 74.4 0.840

Laacher Hof Wurmwiese (Loam) 1.8 5.3 1.321 73.4 0.9183

Hoefchen Am Hohenseh 4a (Silt

loam)

2.4 6.6 0.481 20.0 0.9755

Les Cayades (Clay loam) 0.9 7.6 0.561 62.3 0.917

Guadalupe (Sandy Loam) 0.7 6.7 0.675 96.5 0.9498

Springfield (Silt loam) 1.7 6.6 3.147 185.1 0.9021

2.2 (silty sand) 1.97 5.4 0.3728 18.92 0.640

3A (sandy loam) 2.42 7.3 0.4350 17.97 0.759

6S (Clay loam) 1.84 6.9 0.0543 2.95 1.422 Speyer 2.1

a 0.56 6.0 0.2025 36 0.92

Standard soil no. 115 a 1.7 7.4 0.6255 37 0.89



Arthimetic median 62.3

45.5

-

Arithmetic mean - 0.903

0.900 aResults taken from the peer reviewed RAR for triasulfuron.

IN-L9223


(CaCl2)

Kf (ml/g) Kfoc

(ml/g)

1/n

Drummer; silt loam 3.2 6.4 0.2595 8 0.9232

Longwood; sandy loam 1.3 7.9 (H2O) 0.03 2.03 1.4090

Chelmorton; clay loam 3.3 7.3 (H2O) 0.11 3.27 1.0931

Lockington; clay loam 2.5 6.5 (H2O) 0.07 2.97 1.204

Arithmetic mean - 4.07 1.157


IN-L9225


(H2O)

Kf (ml/g) Kfoc

(ml/g)

1/n

Arrow; sandy loam 2.3 5.7 0.30 13.1 0.74

Gross-Umstadt; silt

loam

1.2 7.7 0.083 6.9 0.62

Mattapex; silt loam 2.6 6.4 0.35 13.5 0.76

LUFA 2.2; loamy sand 1.87 5.5 (CaCl2) 0.435 23 -

LUFA 2.3; sandy loam 0.94 6.8 (CaCl2) 0.318 34 -

LUFA 6S; clay 1.64 7.1 (CaCl2) 0.481 29 -




IN-L9226


(H2O)

Kf (ml/g) Kfoc

(ml/g)

1/n

Arrow; sandy loam 2.3 5.7 0.8 34 0.80

Gross-Umstadt; silt

loam

1.2 7.7 2.4 199 0.81

Mattapex; silt loam 2.6 6.4 2.6 99 0.79



LUFA 6S; clay 1.64 7.1 (CaCl2) 2.193 134 -

Arithmetic mean 126 0.90 ain deriving an arithmetic mean, a default 1/n value of 1.0 was assumed for the three soils where no Freundlich


IN-V7160

Soil OC% pH KF KFom KFoc 1/n R2

Stark County (Tama) 3.1 6.3 5.97 113 194 0.9297 0.9991

Kent County (Sassafras

#16) 1.4 6.3 0.969 40.4 69.4 0.9021 0.9993

Lleida 1.8 7.5 1.51 48.8 84.0 0.9364 0.9998

Nambsheim 1.6 7.0 0.908 33.6 57.9 0.9290 0.9998

Suchozebry 0.76 5.0 1.24 95.6 164 0.8686 0.9994

Arithmetic mean - - 114 0.913 0.999


IN-W8268

Soil type OC

%

Soil pH (H2O) Kf (ml/g) Kfoc

(ml/g)

1/n

Arrow; sandy loam 2.3 5.7 0.10 3.6 1.10

Gross-Umstadt; silt

loam

1.2 7.7 0.05 4.0 1.68

Mattapex; silt loam 2.6 6.4 0.10 2.6 1.17



LUFA 6S; clay 1.64 7.1 (CaCl2) 0.2536 15 -




IN-JZ789 a.k.a. O-Desmethyl thifensulfuron acid


(CaCl2)

Kd

(ml/g)

Koc

(ml/g)

1/n

Drummer; clay loam 3.3 5.9 0.89 26.95 -

Gross-Umstadt; loam 1.2 6.4 0.17 13.96

Nambsheim; sandy loam 1.3 7.2 0.18 13.61

Lleida; clay 2.0 7.8 0.47 23.27 -

Sassafra; sandy loam 1.6 4.7 0.24 15.18 -

LUFA 2.2; loamy sand 1.87 5.5 0.759 41 -

LUFA 2.3; sandy loam 0.94 6.8 0.546 58 -

LUFA 6S; clay 1.64 7.1 0.901 57 -

Arithmetic mean 31.1 1.0* * The UK RMS considered it appropriate since no attempt to measure the Freundlich isotherm was attempted, to

use a default 1/n of 1.0.

2-acid-3-triuret

Soil type OC % pH (CaCl2) Adsorption (mL/g)

a

K KOC 1/n

LUFA 2.2 (Loamy

sand) 1.77 5.5 4.130 230 -

LUFA 2.3 (Sandy

loam) 0.94 6.8 5.285 562 -

LUFA 2.4 (Loam) 2.26 7.2 17.620 780 -

Arithmetic mean 524 1.0* a mean of 3 replicates

* The UK RMS considered it appropriate since no attempt to measure the Freundlich isotherm was attempted, to

use a default 1/n of 1.0.


IN-A5546

Soil OC % pH (CaCl2)

Adsorption

KF 1/n r2 KFoc

Sassafras 0.81 4.8 0.2720 0.8767 0.9940 34

Drummer 2.96 5.7 2.5107 0.9004 0.9995 85

Gross-Umstadt 1.28 6.8 0.3643 0.9521 0.9961 28

Arithmetic mean 1.049 0.9097 0.997 49

B.8.3 Predicted environmental concentrations in soil (PECs) (IIIA 9.1)

Both Applicants submitted relatively extensive estimates of predicted environmental

concentrations soil. These assessments took into account the different GAPs and levels of

crop interception, as well as the peak occurrence or formation levels of the individual

metabolites from each Applicants data set. The UK RMS considered that due to the

relatively low toxicity to soil non-target organisms demonstrated by both thifensulfurion

methyl and the majority of metabolites, it would be possible to greatly simplify the soil

exposure assessment. Given the general complexity of this RAR, particularly the kinetic

assessment and groundwater and surface water exposure assessments, simplifying the soil

assessment seemed appropriate.

The UK RMS therefore chose to provide a very simple first tier soil PEC calculation that

could be used for parent and all metabolties in a first tier risk assessment. This first tier

PECsoil is based on the following assumptions:-

Single application of the maximum intended dose of 51 g a.s./ha (Task Force

application rate on spring cereals)

No crop interception (conservative assumption)

Even incorporation over 5cm soil layer with dry bulk density of 1.5 g cm-3

This resulted in a first tier PECsoil value of 0.068 mg a.s./kg. Since metabolites are all

formed at less than 100% parent and would not be expected to accumulate to levels greater

than applied parent, this value can also be used as a first tier value for the metabolite

exposure assessment. Based on the combined data sets and information in the original DAR,

the UK RMS considers the following metabolites should be included in the soil risk

assessment:-

Metabolites proposed for consideration in the soil exposure assessment

IN-L9225

IN-JZ789

IN-A4098

IN-L9223

2-acid-3-triuret

IN-W8268

IN-V7160

IN-L9226

IN-A5546


Based on a first tier consideration by UK RMS ecotox specialists, the only metabolite

requiring further refinement was IN-A4098. The first tier PECsoil value for this metabolite

has therefore been refined based on molecular weight differences (140.1/387.4) and a peak

occurrence of 18 32.3% AR (revised in response to Open Point 4.10). On this basis the first

tier PECsoil value of 0.068 mg/kg was reduced to 0.068 * 140.1/387.4 * 0.323 0.18 = 0.0079

0.0044 mg IN-A4098/kg.

Provided these PECsoil values result in acceptable ecotoxicological risk assessments, no

further information is required.

B.8.4 Fate and behaviour in water (IIA 7.2.1, IIIA 9.2.1, 9.2.3)

B.8.4.1 Aqueous hydrolysis

AMR 224-84 M.K. Koeppe and B.C. Rhodes (1984)

Previous

evaluation:





Wardrope (2011; DuPont-30225). In the Task Force submission this

study has been superseded by the study of Simmonds and Buntain

(2012).





the UK RMS has briefly reviewed this original hydrolysis study to


GLP status. The UK RMS noted that significant unidentified polar

compounds were reported (up to 35%). Since identification of major

metabolites was incomplete, the study was considered unacceptable.




The study (AMR 224-84) was started in 11/1983 and reported by M.K. Koeppe and

B.C. Rhodes (1984). No GLP statement was included in the report. The US EPA, Pesticide

Assessment Guidelines: Environmental Fate 161-1 was used. Experimental temperature was

25°C instead of 20°C. The study was found acceptable.

Protocol - Solutions of [thiophene-2-14C]Thifensulfuron-methyl (radiochemical purity

greater than 98%) or [triazine(U)-14C]Thifensulfuron-methyl (radiochemical purity greater

than 98%) were prepared at 0.5 and 5 ppm in sterile buffers at pH 5, 7 and 9 and kept in

darkness at 25°C. Additional 260 ppm solutions of each radiolabel in pH 5 buffer were made


for preparative isolation of metabolites. Analysis was performed by TLC, HPLC and MS for

30 days. Pseudo first-order reaction kinetics were assumed for the decline of Thifensulfuron-

methyl with time.

Results - Mass balance was in the range 80-114%. Half-live of Thifensulfuron-methyl

was 4-6 days (DT90 was 18 days) at pH 5 and less than 20 % were degraded at pH 7 (DT50

was about 180 days) and pH 9 (DT50 was about 90 days, buffer at pH 9 was not stable and

results were doubtful). Degradation occurred by cleavage of the sulphonyl urea bridge

yielding 2-ester-3-sulfonamide (up to 64%), triazine amine and two unidentified polar

compounds (up to 35%). The 30 days pH 5 buffer solutions also contained 2-ester-3-triuret, a

product of further hydrolysis of the triazine ring (figure B.8.33), at 8.4 and 32% and O-

demethyl Thifensulfuron-methyl at 4.4 and <0.1% (8.2% at 6 days), respectively. O-demethyl

triazine amine was also identified as a minor hydrolysis product of triazine amine.

Figure B.8.33

S

SO2(NHCO)4CH3

CO2CH3

2-ester-3-Triuret

In conclusion, the hydrolysis of Thifensulfuron-methyl was most rapid at pH 5 and

significantly slower at pH 7 and pH 9. Degradation at all three pH values occurred by

cleavage of the sulfonyl urea bridge yielding 2-ester-3-sulfonamide and triazine amine as

major hydrolysis products.

Report: Wardrope, L. (2011); Hydrolysis of [14

C]-DPX-M6316 (Thifensulfuron-methyl) as

a function of pH


Guidelines: U.S. EPA 161-1 (1982), OPPTS 835.2120 (2008), SETAC Europe (1995),

OECD 111 (2004) Deviations: None



GLP: Yes

Certifying Authority: Department of Health (UK)

Previous None: Submitted by DuPont for the purpose of renewal under


evaluation: Regulation 1141/2010.

The following study was submitted by DuPont to supersede the original

hydrolysis study from the DAR that was no longer considered

acceptable. The UK RMS has briefly evaluated this study and

considered it acceptable. The original study summary from DuPont is

provided below, supplemented with additional comments and

information provided as a result of the UK evaluation.

Executive summary:

The hydrolysis of [14

C]-Thifensulfuron-methyl in sterile aqueous buffered solutions at pH 4,

pH 7, and pH 9 and at 20, 30, and 50C was studied for up to 30 days. The test item

concentration was 5 g/mL with acetonitrile (0.13%) as a co-solvent. Total recovery of

radioactivity ranged from 95.13–104.11%.

The first-order DT50 values of Thifensulfuron-methyl were 6.3, 1.9, and 0.2 days in pH 4

buffer incubated at 20, 30, and 50C, respectively. The first-order DT50 values of

Thifensulfuron-methyl were 199.0, 65.0, and 4.0 days in pH 7 buffer incubated at 20, 30, and

50C, respectively. The first-order DT50 values of Thifensulfuron-methyl were 23.4, 6.5, and

0.6 days in pH 9 buffer incubated at 20, 30, and 50C, respectively.

At pH 4 at all temperatures, the major transformation products detected were a polar product,

IN-A5546, IN-A4098, IN-L9226, and IN-RDF00 at maximum concentrations of 56.36%

(50C), 93.73% (50C), 54.11% (50C), 11.86% (30C) and 31.85% AR (20C),

respectively. At pH 7 the major transformation products detected were IN-A5546, IN-L9223,

IN-A4098, and IN-L9225 at maximum concentrations (observed at 50oC) of 16.50%,

90.90%, 90.50%, and 6.71% AR, respectively. At pH 9 the major transformation products

detected were IN-L9223, IN-A4098, and IN-L9225 at maximum concentrations of 23.56%

(observed at 50C), 88.64% (50C), 74.61% (50C) and 70.05% AR (30C), respectively.

During the initial Completeness Check DuPont were asked to provide further information on

an unidentified polar metabolite. The polar metabolite (molecular weight 253.1) appeared to

be formed at levels significantly exceeding 10% in the hydrolysis study. DuPont were

therefore asked to provide robust argumentation to explain why this metabolite was not

further characterised or included in the surface water exposure assessment.

Du Pont’s response was that the peak only appeared at pH 4 at 20, 30 and 50ºC and pH 9 at

50ºC and that these conditions are not considered highly relevant to real-world environmental

conditions. The UK RMS did not fully accept this argument because it is possible that surface

water systems could have pH ranges covering those used in the experiments. In addition the

levels of formation of this metabolite at ambient temperatures between pH 4 and 7 cannot be

determined from the available information. In addition, DuPont did include the IN-RDF00

metabolite in their surface water assessment, even though it was only formed in significant

levels in the pH 4 buffer solutions. In response to Data Requirement 4.1 identified during the

EFSA peer review DuPont provided additional information on the identification of the

unknown polar metabolite (see Wardrope, 2014 below). This metabolite has now been

identified as IN-B5528.


DuPont have not further characterised the polar compound. They have surmised that as it is

only found with the triazine label, but is neither the triazine containing metabolite IN-V7160

nor IN-A4098. They also postulated that the mw of 253.1 may not be accurate. They

propose that the peak could be reasonably attributed to multiple polar fragments of the

triazine ring. For comparison, at the same conditions of pH 4, the Task Force found the same

metabolites as DuPont except the 253.1 mw peak (see Simmonds and Buntain, 2012).

However they also found a novel metabolite thiophene urea (which does not have a triazine

ring so cannot be the unidentified metabolite) and IN-F5475 which does have a triazine ring

and has a MW of approx 129. The UK RMS considers that it is possible that what the Task

Force identify as IN-F5475 could be part of the polar metabolite fraction identified by the

DuPont study, with the addition of some other peaks. The aquatic risk posed by the

unidentified metabolite in the DuPont study (or IN-F5475 in the Task Force study) has not

been addressed by either Applicant. Some further consideration is therefore required. The

UK RMS has performed a risk assessment of the IN-RDF00 metabolite that was also only

formed in the pH 4 samples. In the absence of metabolite specific effects data, the aquatic

risk assessment of IN-RDF00 was conservatively performed assuming the metabolite was 10

x more toxic than parent Thifensulfuron-methyl. Since these metabolites were only formed

in the water phase at levels comprable to IN-RDF00, and the assumption of 10 x increased

toxicity it likely to be highly conservative, the UK RMS considered that the quantitative risk

assessment of IN-RDF00 could be used as a surrogate for the assessment of either the polar

metabolite fraction (mw 253) or IN-F5475. Since the metabolites were only formed in the

pH 4 samples, and there is some uncertainty over whether the unknown metabolite in this

study is a single metabolite or multiple components, the UK RMS considered that this

approach was appropriate in this case. Neither metabolite has therefore been considered

further in the surface water exposure assessment as risks arising from these are covered by

the IN-RDF00 assessment.


A. MATERIALS

1. Radiolabelled test

material:

[14



C]Thifensulfuron-methyl, Lot # 3631034

[triazine-2-14

C]Thifensulfuron-methyl, Lot # 3587191


C]Thifensulfuron-methyl: 97.2%

[triazine-2-14

C]Thifensulfuron-methyl: 98.9%


C]Thifensulfuron-methyl: 10.7 µCi/mg

[triazine-2-14

C]Thifensulfuron-methyl: 33.9 µCi/mg

2. Buffers:

0.02M buffer solutions in Milli-Q grade water were prepared at pH 4, using

potassium hydrogen phthalate and sodium hydroxide, pH 7 using monopotassium

phosphate and NaOH and pH 9 using boric acid and NaOH. Buffers were filtered

(0.2 µm) to sterilise.


B. STUDY DESIGN


Hydrolysis of radiolabelled Thifensulfuron-methyl at 5.0 µg a.s./mL was studied in

the dark at 20, 30, or 50C in sterile aqueous buffered solutions at pH 4 (phthalate

buffer), pH 7 (phosphate buffer), and pH 9 (borate buffer) for up to 30 days. The

test solutions were placed in 20 mL capacity glass vessels and the headspace was

minimised. Acetonitrile (0.13%) was used as a co-solvent. Samples were analysed

at zero time and after 1 and 4 hours (pH 4) and 1, 2, 3, 6, 8, 10, 14, 21 and 30 days

by LSC and HPLC. Identification of parent and significant hydrolysis products was

by co-chromatography and the identifications confirmed using LC-MS analysis.

Significant hydrolysis products that were not identified by HPLC co-

chromatography were identified using LC-MS analysis. The limit of quantification

(LOQ) for both radiolabelled forms was <1% AR.


A. MASS BALANCE

The mass balance of radioactivity throughout the study for all test samples was within the

range of 95.13-104.11% AR.

B. FINDINGS

Hydrolysis of Thifensulfuron-methyl was pH and temperature dependant. At lower

temperatures the rate of hydrolysis was significantly less than at higher temperatures.

The pH dependency of the rate of hydrolysis was in the order pH 4 >pH 9 >> pH7. At

pH 4, the concentration of the parent compound decreased from 88.78% at Day 0 to

5.09% of the applied radioactivity (AR) after 30 days at 20C, from 89.61% (Day 0) to

0.33% AR (Day 30) at 30C and from 89.49% (Day 0) to 0.53% AR (Day 2) at 50C. At

pH 7, the concentration of the parent compound decreased from 95.92% at Day 0 to

86.86% AR after 30 days at 20C, from 96.53% to 69.06% AR at 30C and from 95.56%

to 0.87% AR at 50C at pH 7. At pH 9, the concentration of the parent compound

decreased from 93.75% at Day 0 to 42.42% AR after 30 days at 20C, from 94.66% (Day

0) to 4.70% AR (Day 30) at 30C and from 92.80% (Day 0) to 0.31% AR (Day 21) at

50C.

The first-order DT50 values of Thifensulfuron-methyl were 6.3, 1.9, and 0.2 days in pH 4

buffer incubated at 20, 30, and 50C, respectively. The first-order DT50 values of

Thifensulfuron-methyl were 199.0, 65.0, and 4.0 days in pH 7 buffer incubated at 20, 30,

and 50C, respectively. The first-order DT50 values of Thifensulfuron-methyl were 23.4,

6.5, and 0.6 days in pH 9 buffer incubated at 20, 30, and 50C, respectively. Half-life

data were calculated using ModelMaker 4.0 (Cherwell Scientific Ltd, Oxford, UK and

are summarised inTable B.8.274.


Table B.8.274 Hydrolytic DT50 and rate constants for Thifensulfuron-methyl

Analyte pH

Temperature

(C)

DT50

(days)

k

(day-1

) r2 Method of calculation

Thifensulfuron-

methyl

4

20 6.3 0.109 0.993 Simple first-order



7

20 199 0.003 0.603 Simple first-order

30 65 0.011 0.881 Simple first-order


9




At pH 4 at all temperatures, the major transformation products detected were a polar product

(molecular weight 253.1, triazine label; later identified as IN-B5528), IN-A5546 (thiophene

label), IN-A4098 (triazine label), IN-L9226 (thiophene and triazine labels) and IN-RDF00

(thiophene and triazine labels) at maximum concentrations of 56.36% (50C), 93.73%

(50C), 54.11% (50C), 11.86% (30C), and 31.85% AR (20C), respectively. Results are

presented in Table B.8.275 toTable B.8.277. At pH 7 the major transformation products

detected were IN-A5546 (only significant product detected at 20˚C, thiophene label), IN-

L9223 (thiophene label), IN-A4098 (triazine label) and IN-L9225 (thiophene and triazine

labels) at maximum concentrations of 16.50% (50C), 90.90% (50C), 90.50% (50C) and

6.71% AR (20C), respectively. Results are presented in Tbel B.9.278 toTable B.8.280. At

pH 9 the major transformation products detected were a significant polar product (molecular

weight 253.1, detected only at 50˚C, triazine label, later identified as IN-B5528), IN-L9223

(thiophene label), IN-A4098 (triazine label) and IN-L9225 (thiophene and triazine labels) at

maximum concentrations of 23.56% (50C), 88.64% (50C), 74.61% (50C) and 70.05% AR

(30C), respectively. Results are presented in Table B.8.281 to Table B.8.283. Other minor

components were detected throughout, which individually represented <5% of the applied

radioactivity.


Table B.8.275

Hydrolysis of Thifensulfuron-methyl at pH 4 and 20C (expressed as mean percentage of the applied radioactivity)

Compound

Radiolabel detected

under

Sampling times (days unless stated otherwise)

0 1 Hour 4 Hours 1 2 3 6 8 10 14 21 30

Thifensulfuron-

methyl Thiophene and Triazine 88.78 90.63 88.61 79.84 70.92 64.87 47.86 38.13 30.39 20.19 9.62 5.09

Polar MW 253.1

(IN-B5528) Triazine 0.55 0.00 0.47 1.21 2.31 2.80 6.42 9.84 12.10 16.00 23.06 25.28

IN-A4098 Triazine 0.59 1.97 2.19 5.13 8.32 7.36 11.62 16.36 18.07 22.97 26.53 29.57

IN-A5546 Thiophene 4.53 4.70 4.79 8.80 13.33 12.30 30.36 31.72 41.41 45.14 50.76 52.40

IN-L9226 Thiophene and Triazine 3.63 2.37 2.60 6.39 8.83 10.18 11.16 11.66 10.29 8.18 5.48 2.41 IN-RDF00 Thiophene and Triazine 0.00 0.00 0.45 1.24 2.54 3.58 8.58 13.12 16.52 21.20 27.98 31.85 Unidentified

radioactivitya

Thiophene and Triazine 4.96 3.87 4.61 4.80 6.18 9.96 7.07 7.68 6.78 7.90 6.34 6.25

a No individual unidentified component accounts for >5% AR.

Where the analyte was detectable with either radiolabel, the results presented are the mean of both labels


Table B.8.276


Compound

Radiolabel detected

under


0 1 Hour 4 Hours 1 2 3 6 8 10 14 21 30

Thifensulfuron-


Polar MW 253.1

(IN-B5528) Triazine 0.00 0.44 0.32 2.67 7.32 9.86 20.83 24.91 28.25 27.52 30.99 31.73

IN-A4098 Triazine 0.00 2.98 3.41 12.50 19.38 24.18 31.55 34.51 33.91 34.96 38.09 40.57

IN-A5546 Thiophene 6.10 5.97 7.41 23.23 37.03 45.80 60.68 68.50 64.93 69.55 72.93 71.22

IN-L9226 Thiophene and Triazine 4.08 2.93 3.90 11.20 11.86 10.03 5.66 3.47 2.39 1.09 0.52 0.00

IN-RDF00 Thiophene and Triazine 0.00 0.14 0.21 3.39 7.33 11.68 20.13 22.15 24.12 23.34 24.22 22.97 Unidentified

radioactivitya





Table B.8.277


Compound

Radiolabel detected

under


0 1 Hour 4 Hours 1 2 3 6 8 10 14 21 30

Thifensulfuron-


Polar MW 253.1

(IN-B5528) Triazine 0.00 0.53 1.29 18.51 24.40 25.58 26.00 28.89 35.84 41.83 51.07 56.36

IN-A4098 Triazine 0.89 7.93 19.23 54.14 54.41 53.20 45.15 46.43 44.14 39.73 34.57 29.84

IN-A5546 Thiophene 6.54 12.04 32.14 83.82 87.04 88.39 86.11 90.07 91.50 89.85 93.73 93.14

IN-L9226 Thiophene and Triazine 4.48 4.72 8.11 3.02 0.46 0.55 0.72 0.52 0.32 0.26 1.92 1.51

IN-RDF00 Thiophene and Triazine 0.00 0.40 1.70 9.59 9.97 10.03 8.81 8.08 6.66 5.75 3.52 2.28

Unidentified

radioactivitya




Table B.8.278


Compound

Radiolabel detected

under

Sampling times (days)

0 1 2 3 6 8 10 14 21 30

Thifensulfuron-methyl Thiophene and Triazine 95.92 94.54 93.84 92.40 91.98 92.80 91.20 89.12 88.46 86.86

IN-A5546 Thiophene 2.43 2.32 2.74 2.29 5.27 3.42 4.14 4.15 4.43 4.47

Unidentified

radioactivitya

Thiophene and Triazine 1.91 3.06 4.53 4.87 3.54 6.52 5.81 7.36 8.32 9.64




Table B.8.279


Compound

Radiolabel detected

under


0 1 2 3 6 8 10 14 21 30


IN-L9223 Thiophene 0.00 0.00 0.00 0.00 0.90 1.67 1.52 0.88 6.44 9.68

IN-A4098 Triazine 0.00 0.46 1.46 1.61 4.14 5.27 6.08 8.49 12.34 15.01

IN-A5546 Thiophene 2.11 2.87 4.28 4.54 5.93 7.19 6.84 10.34 11.78 14.14

IN-L9225 Thiophene and Triazine 0.00 0.21 0.32 0.43 1.53 1.71 2.00 2.45 4.27 5.19 Unidentified

radioactivitya




Table B.8.280


Compound

Radiolabel detected

under


0 1 2 3 6 8 10 14 21 30


IN-L9223 Thiophene 0.00 3.66 9.77 16.70 37.63 53.99 62.45 74.76 86.65 90.90

IN-A4098 Triazine 0.00 11.46 19.07 27.74 43.44 56.23 63.28 70.23 82.69 90.50

IN-A5546 Thiophene 2.74 12.03 15.87 16.32 16.50 11.06 9.17 4.76 1.59 0.00

IN-L9225 Thiophene and Triazine 0.00 2.29 4.10 5.13 6.71 5.83 5.24 3.70 1.84 0.28

Unidentified

radioactivitya





Table B.8.281


Compound

Radiolabel detected

under


0 1 2 3 6 8 10 14 21 30

Thifensulfuron-methyl Thiophene and Triazine 93.75 89.17 87.58 84.12 78.28 73.75 69.21 60.57 48.32 42.42 IN-L9225 Thiophene and Triazine 0.00 4.09 7.09 8.08 13.42 15.57 20.88 26.52 38.48 45.52 Unidentified

radioactivitya




Table B.8.282


Compound

Radiolabel detected

under


0 1 2 3 6 8 10 14 21 30


IN-L9223 Thiophene 0.00 2.20 2.62 4.33 6.37 6.59 7.87 11.51 13.53 19.51

IN-A4098 Triazine 0.00 0.70 2.03 2.21 4.41 6.05 7.00 10.09 13.99 4.42


Unidentified

radioactivitya





Table B.8.283


Compound

Radiolabel detected

under


0 1 2 3 6 8 10 14 21 30


Polar MW 253.1

(IN-B5528) Triazine 0.00 0.55 1.18 1.91 3.97 6.19 6.30 7.78 16.70 23.56

IN-L9223 Thiophene 0.00 13.84 23.73 31.05 48.35 60.39 67.06 74.79 85.71 88.64

IN-A4098 Triazine 0.00 12.06 21.07 28.15 41.67 52.84 55.27 60.78 68.92 74.61


Unidentified

radioactivitya





III. CONCLUSION

This study demonstrated that Thifensulfuron-methyl was hydrolytically unstable at pH 4 (most

significantly) and pH 9 and moderately susceptible to hydrolysis at pH 7. Hydrolysis occurred

more rapidly at higher temperatures for all pH values tested.

Based on the results of this study, hydrolysis would be a relavent dissipation route of

Thifensulfuron-methyl in the aquatic environment.

A proposed hydrolytic degradation pathway is outlined in Figure B.8.34. Note the unidentified

metabolite (mw 253) has been omitted from the Applicants degradation pathway).

Figure B.8.34 Proposed degradation pathway of Thifensulfuron-methyl under hydrolytic

conditions

DPX-M6316

(pH 4 only)

IN-L9225 IN-L9226

(pH 4 only)

IN-A5546 IN-A4098 IN-RDF00

CO2

IN-L9223

(Wardrope, L., 2011)


In response to Open Point 4.11 in the Evaluation Table the UK RMS has provided a revised

hydrolytic degradation scheme in Figure B.8.34 below.

Figure B.8.34 Proposed degradation pathway of Thifensulfuron-methyl under hydrolytic

conditions (taken from Reporting Table 4(17))

In response to Data Requirement 4.1 in the Evaluation Table DuPont have provided further

information on the identification of the unknown polar metabolite formed in the hydrolysis study

of Wardrope (2011). For information, the full text of the Data Requirement is provided below:-

Data requirement (DuPont) 4.1: Applicant to provide the position paper DuPont-30225,

Supplement 1 with the information of the unknown polar component formed in the

aqueous hydrolysis study. See also comment 4(92), 4(103) and data requirement in

comment 4(93). See reporting table 4(82).

Report: Wardrope, L. (2014); Hydrolysis of [14

C]-DPX-M6316 (thifensulfuron methyl) as a

function of pH- identification of unknown polar metabolite

DuPont Report No.: DuPont-30225, Supplement No. 1

Guidelines: U.S. EPA 161-1 (1982), OPPTS 835.2120 (2008), SETAC Europe (1995), OECD

111 (2004) Deviations: None



GLP: Yes



Executive summary

The hydrolysis of thifensulfuron methyl in sterile aqueous solutions buffered at pH 4, 7, and 9

was determined at 20, 30, and 50C under DuPont-30225. An unknown polar hydrolysis product

with a typical retention time of ca 4.0 minutes was detected in the triazine-radiolabelled pH 4

buffer samples at 20, 30, and 50ºC and the triazine-radiolabelled pH 9 buffer samples at 50ºC.

The polar hydrolysis product was assigned a molecular mass of m/z 253.1141 amu via LC-MS

analysis, however; further structural elucidation of this hydrolysis product was not reported in

DuPont-30225.

The LC-MS data associated with the unknown polar hydrolysis product from DuPont-30225 was

re-evaluated in this supplemental study and found to be consistent with IN-B5528, a known

metabolite of thifensulfuron methyl. A reference standard of IN-B5528 was analysed under LC-

MS conditions identical to those used in the original study, and results confirmed the

identification of the unknown polar hydrolysis product as IN-B5528.

A thifensulfuron methyl reference standard was also analysed in this supplemental study by using

the two HPLC methods described in DuPont-30225 to confirm that the performance of the two

HPLC methods remained unchanged. Under the HPLC and MS conditions used in this study,

IN-B5528 reference standard, although provided as a monomer, was subject to dimerisation in

the mass spectrometer. As a result, IN-B5528 molecular ion appeared as a dimer with an m/z

ratio of 253.1141 in the mass spectra.

Retention time (HPLC) data consistent with the monomeric form of IN-B5528, and spectral

(MS) data, consistent with the dimeric form of IN-B5528, matched data on the unknown

hydrolysis product generated in the original study. Therefore the unknown polar hydrolysis

product observed in the original study at pH 4 and pH 9 is confirmed as IN-B5528.

The proposed fragmentation is presented in the following diagram:


The UK RMS noted that there was a minor retention time shift of up to ca. 1.0 minute for the

previously unidentified peak between the two HPLC methods used in the original hydrolysis

study and used in the supplemental study of Wardrope (2014). However the UK RMS also

considered that the full scan ions and fragment ions were consistent for this peak observed in the

original hydrolysis study (DuPont-30225, Wardrope, 2011) and the IN-B5528 reference standard

studied in this supplemental study. For completeness, figures of the fragment ion scans are

provided below in Figures B.8.34a (for the IN-B5528 reference standard) and B.8.34b (for the

peak observed in the original hydrolysis study).

Overall the UK RMS was content that the additional analytical work provided good evidence that

the unknown polar metabolite was IN-B5528. No further information is considered necessary.

Figure B.8.34a MS-MS spectra from peak at 3.2 minutes in IN-B5528 reference standard


Figure B.8.34b Typical MS-MS spectra of peak at 4.2 minutes in analysis of concentrated

samples taken from original hydrolysis study (DuPont-30225)

(Wardrope, 2014)


Report: M. Simmonds, I. Buntain (2012) [14

C]-Thifensulfuron-methyl: Hydrolysis in

sterile buffer at pH 4, 7 and 9. Battelle UK Ltd. [Cheminova A/S],

Unpublished report No.: WB/10/008 [CHA Doc. No. 260 TIM]



Previous

evaluation:



The following study has briefly evaluated this study and considered it

acceptable. The original study summary from the Task Force is

provided below, supplemented with additional comments and

information provided as a result of the UK evaluation.

Executive Summary:

The hydrolysis of Thifensulfuron-methyl was studied in the dark in sterile aqueous buffered

solutions at pH 4 (sodium acetate), pH 7 (tris (hydroxymethyl) methylamine) and pH 9 (sodium

tetraborate) at a nominal concentration of 1 mg/L. To fully elucidate the pathway for hydrolytic

degradation two radiolabelled forms of the test item were employed; [thiophene-2-14

C]-

Thifensulfuron-methyl and [triazine-2-14

C]-Thifensulfuron-methyl.

A Tier 1 study was conducted at pH 4, 7 and 9 at 50°C. Duplicate samples for each pH value

were analysed at zero time and after 5 days incubation. The aqueous solutions were analysed

directly by liquid scintillation counting (LSC) and high performance liquid chromatography

(HPLC). The overall recovery of radioactivity was good, with all samples being within the range

98.3-105.5% of applied radioactivity (AR). Extensive degradation of Thifensulfuron-methyl was

observed at all pH and thus a Tier 2 study was triggered.

The Tier 2 study was conducted at pH 4, 7 and 9 at 25°C. Duplicate samples were analysed at

zero time and after 1, 2, 3, 7, 8, 14 and 30 days incubation (pH 4); zero time and after 1, 3, 9, 15,

21 and 30 days incubation (pH 7), and zero time and after 1, 2, 3, 7, 10, 21 and 30 days

incubation (pH 9). The aqueous solutions were again analysed directly by LSC and HPLC.

The overall recovery of radioactivity was good, with all samples being within the range of 94.3-

105.8% of applied radioactivity.

At pH 4 hydrolysis of Thifensulfuron-methyl was extensive with the levels of the parent

molecule dropping to ca 50% AR after only 2 days and to < 1% by 30 days. Six individual

degradates were detected at levels > 10% AR over the duration of the study; IN-L9226

(max 13.6% AR, day 3), IN-RDF00 (2-ester-3-triuret, max 34.0% AR, day 30), IN-A5546 (max

64.2% AR, day 30), Thiophene urea (IN No. unknown, max 9.9% AR, day 14), IN-A4098 (max

26.1% AR, day 14) and IN-F5475 (Methyl triazine diol, max 33.2% AR, day 30). Two additional

unidentified products were detected at maximum levels of 5-6% AR.

At pH 7 hydrolysis of Thifensulfuron-methyl was much less extensive than at pH 4 with the

parent molecule still representing ca 87% AR after 30 days. No individual degradates were

detected at levels > 10% AR although two were found at >5% AR; IN-A5546 (max 7.6% AR,

day 30) and IN-A4098 (max 5.9%, day 30).


At pH 9 hydrolysis of Thifensulfuron-methyl at pH 9 was again extensive with the levels of the

parent molecule dropping to ca 50% AR after 7 days and to < 3% by 30 days. Three individual

degradates were detected at levels > 10% AR over the duration of the study; IN-L9225 (max

79.8% AR, day 30), IN-L9223 (max 16.8% AR, day 30) and IN-A4098 (max 12.4% AR, day

30).

DT50 values for the degradation of Thifensulfuron-methyl at 25°C are 2.4 days, 137 days and 7.1

days for pH 4, 7 and 9 respectively.


1. Test Materials:

[Thiophene-2-14



[Triazine-2-14




Description: Off white powder (thiophene), Pale yellow powder (triazine)


C]-Thifensulfuron-methyl 3784FDG037-4

[Triazine-2-14

C]- Thifensulfuron-methyl 3783FDG003-2




[Triazine-2-14



CAS number: 79277-27-3

2. Buffers:

0.01 M buffer solutions in highly purified deionised water were prepared at pH4 using sodium

acetetate trihydrate and acetic acid, pH 7 using Tris aminomethane hydrochloride and NaOH and

pH 9 using di-Sodium tetraborate decahydrate.

Study Design:


The hydrolysis of [Thiophene-2-14


[Triazine-2-14

C]-Thifensulfuron-methyl was studied in the dark in sterile aqueous buffered

solutions at pH 4 (sodium acetate), pH 7 (tris (hydroxymethyl) methylamine) and pH 9 (sodium

tetraborate) at a nominal concentration of 1 mg/L. The test solutions (7.5 mL) were dispensed

into glass vials. The vials were covered with foil and sterilised by autoclaving. The vials were

capped in a laminar flow cabinet.

Tier 1

Samples were incubated at 50ºC in the dark. The final concentration of Thifensulfuron-methyl in

treated units was 0.99-1.03 mg/mL. Acetonitrile was included as a co-solvent but was only 0.5%


v/v in each test solution. Duplicate units were removed for analysis immediately after

application (zero-time) and at 5 days after application.

Tier 2

Samples were incubated at 25ºC in the dark. The final concentration of Thifensulfuron-methyl in

treated units was 0.99-1.08 mg/mL. Acetonitrile was included as a co-solvent but was only 0.5%

v/v in each test solution. Duplicate units were removed for analysis with the following sampling

intervals:

Table B.8.284 Sampling Intervals

pH Sampling interval (days)

4 0, 1, 2, 3, 7, 8, 14 and 30

7 0, 1, 3, 9, 15, 21 and 30

9 0, 1, 2, 3, 7, 10, 21 and 30

Quantitative measurement of radioactivity tier 1 and tier 2 tests were carried out using LSC.

HPLC (Kromasil C8 column; with UV (254 nm) and radio monitor detectors) was used for

identification and radiochemical purity of Thifensulfuron-methyl and hydrolysis products.

Confirmatory analysis was performed by LC-MS.


Mean recovery of applied radioactivity from samples for each pH was 99.5% to 105.3% at 50°C

and 97.3% to 104.4% at 25°C. The distribution of applied radioactivity in each of the test

systems is shown in the tables below.

The percent of applied radioactivity present as Thifensulfuron-methyl and the concentrations of

Thifensulfuron-methyl are summarised below:


Table B.8.285 Distribution of mean applied radioactivity for test 1 (50°C) buffer solutions


C]-thifensulfuron

Interval

(day)

% of Applied Radioactivity as compound

Th

ifen

sulf

uro

n-m

eth

yl

IN-L

92

23

IN-J

Z7

89

IN-A

55

46

IN-L

92

26

IN-L

92

25

IN-R

DF

00

Un

iden

tifi

ed

To

tal

pH 4

0 86.98 0.00 0.00 6.39 5.11 0.00 0.00 1.99 100.46

5 0.05 0.56 0.00 88.36 0.29 0.60 6.88 2.80 99.55

pH 7

0 100.60 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100.60

5 44.65 10.96 0.46 41.00 2.94 1.35 0.00 0.83 102.19

pH 9

0 98.48 0.00 0.00 0.00 0.00 1.93 0.00 0.00 100.41

5 0.05 42.74 7.43 0.00 0.00 48.87 0.60 0.05 99.70

Largest individual unidentified is 2.8% applied radioactivity.

Table B.8.286 Distribution of mean applied radioactivity for test 1 (50°C) buffer solutions

treated with [triazine-2-14

C]-thifensulfuron

Interval

(day)


Th

ifen

sulf

uro

n-m

eth

yl

IN-F

54

75

IN-A

40

98

IN-J

Z7

89

IN-L

92

26

IN-L

92

25

IN-R

DF

00

Un

iden

tifi

ed

To

tal

pH 4

0 88.10 0.60 3.55 0.00 6.59 0.00 0.00 2.52 101.36

5 0.03 39.89 36.50 0.00 0.00 0.87 10.94 14.55 102.79

pH 7

0 103.28 0.00 0.00 0.00 0.00 0.00 0.00 0.00 103.28

5 53.43 0.87 42.64 0.32 3.50 1.72 0.00 2.86 105.35

pH 9

0 98.04 0.00 0.00 0.00 0.00 3.18 0.00 0.00 101.23

5 0.01 4.12 33.10 8.27 0.00 55.76 0.27 0.00 101.53



Table B.8.287 Distribution of mean applied radioactivity for test 2 (25°C) in pH 4 buffer

solution treated with [thiophene-2-14

C]-thifensulfuron

Interval

(day)

% of Applied Radioactivity as compound T

hif

ensu

lfu

ron

-met

hy

l

Th

iop

hen

e u

rea

IN-A

55

46

IN-L

92

26

IN-L

92

25

IN-R

DF

00

Un

iden

tifi

ed

To

tal

0 96.81 0.00 1.36 1.00 0.00 0.00 0.00 99.17

1 68.39 4.70 15.61 8.30 0.36 1.95 0.00 99.31

2 51.69 6.30 24.86 10.72 0.52 5.45 0.00 99.54

3 38.91 7.81 32.54 10.57 0.70 9.23 0.00 99.75

7 12.48 9.22 50.92 5.49 0.72 20.78 0.00 99.62

8 9.71 9.33 52.97 4.23 0.94 22.17 0.00 99.35

14 1.74 9.88 59.11 1.46 1.05 25.91 0.60 99.74

30 0.04 8.81 64.22 1.03 0.92 24.32 0.65 99.98


Table B.8.288 Distribution of mean applied radioactivity for test 2 (25°C) in pH 4 buffer solution


C]-thifensulfuron

Interval

(day)


Th

ifen

sulf

uro

n-m

eth

yl

IN-F

54

75

IN-A

40

98

IN-L

92

26

IN-L

92

25

IN-R

DF

00

Un

iden

tifi

ed

To

tal

0 97.98 0.00 0.40 0.95 0.00 0.00 0.00 99.32

1 74.54 2.18 8.72 9.97 0.00 2.43 4.41 102.25

2 53.86 5.36 13.90 12.55 0.00 6.65 5.76 98.08

3 41.67 10.16 18.75 13.60 0.20 12.14 7.36 103.89

7 16.31 21.02 24.36 7.73 0.00 26.67 8.34 104.43

8 11.06 22.78 24.31 6.17 0.00 27.20 7.14 98.67

14 2.44 29.14 26.12 1.22 0.42 31.81 7.97 99.11

30 0.08 33.24 17.14 1.50 0.00 33.95 8.11 97.68

Largest individual unidentified is ≤5% applied radioactivity.




C]-thifensulfuron

Interval

(day)


Th

ifen

sulf

uro

n-m

eth

yl

IN-L

92

23

IN-A

55

46

IN-L

92

26

IN-L

92

25

Un

iden

tifi

ed

To

tal

0 99.96 0.00 0.00 0.00 0.00 0.00 99.96

1 99.96 0.00 0.00 0.00 0.00 0.00 99.96

3 98.81 0.00 1.02 0.00 0.00 0.00 99.83

9 96.32 0.00 2.37 0.33 0.64 0.00 99.66

15 94.16 0.00 4.37 0.54 0.95 0.00 100.02

21 90.27 0.51 5.52 0.95 1.65 0.00 98.80

30 86.72 1.41 7.58 1.08 2.27 0.58 99.65



C]-thifensulfuron

Interval (day) % of Applied Radioactivity as compound

Th

ifen

sulf

uro

n-m

eth

yl

IN-A

40

98

IN-L

92

26

IN-L

92

25

Un

iden

tifi

ed

To

tal

0 101.87 0.00 0.00 0.00 0.00 101.87

1 103.57 0.00 0.00 0.00 0.00 103.57

3 99.81 0.79 0.00 0.00 0.00 100.59

9 94.30 1.83 0.49 0.66 0.00 97.28

15 96.44 3.08 0.68 1.03 0.00 101.24

21 90.97 4.39 0.77 1.51 0.30 97.95

30 86.96 5.94 1.08 2.33 0.97 97.28



Table B.8.291 Distribution of mean applied radioactivity for test 2 (25°C) in pH 9 buffer

solution treated with [thiophene-2-14

C]-thifensulfuron

Interval

(day)


Th

ifen

sulf

uro

n-m

eth

yl

IN-L

92

23

IN-J

Z7

89

IN-A

55

46

IN-L

92

26

IN-L

92

25

To

tal

0 97.42 0.00 0.00 0.59 0.00 0.50 98.51

1 90.65 0.00 0.00 0.00 0.00 8.48 99.13

2 82.04 0.91 0.00 0.00 0.41 15.93 99.28

3 74.80 1.36 0.00 0.00 0.46 22.24 98.87

7 53.58 2.65 0.31 0.00 0.52 42.25 99.32

10 40.84 3.60 0.61 0.00 0.47 54.06 99.58

21 4.93 14.74 3.38 0.00 0.00 76.18 99.23

30 2.11 16.80 4.35 0.00 0.00 76.04 99.29



C]-thifensulfuron

Interval

(day)


Th

ifen

sulf

uro

n-m

eth

yl

IN-A

40

98

IN-J

Z7

89

IN-L

92

26

IN-L

92

25

Un

iden

tifi

ed

To

tal

0 97.26 0.56 0.00 0.40 0.76 0.00 98.98

1 89.10 0.84 0.00 0.00 9.55 0.00 99.49

2 81.07 0.98 0.00 0.30 16.73 0.00 99.08

3 75.39 1.13 0.00 0.45 23.23 0.00 100.19

7 53.89 2.02 0.43 0.61 42.18 0.00 99.14

10 40.46 2.61 0.64 0.55 55.19 0.00 99.44

21 4.93 11.14 3.68 0.25 78.92 0.46 99.38

30 2.32 12.41 4.51 0.00 79.83 0.40 99.47



Conclusions:

Thifensulfuron-methyl was found to be relatively resistant to hydrolysis at neutral pH (pH 7 DT50

137 days) but more labile under both acidic (pH 4 DT50 2.4 days) and alkaline conditions (pH 9

DT50 7.1 days). The following hydrolysis products were found to occur at > 10% applied

radioactivity during 30 days incubation at 25°C: IN-L9225 (pH 9), IN-L9226 (pH 4), IN-RDF00

(pH 4), IN-A5546 (pH 4), IN-L9223 (pH 9), thiophene urea (pH 4), IN-A4098 (pH 4 and 9) and

IN-F5475 diol (pH 4).

(Simmonds & Buntain, 2012)

B.8.4.2 Aqueous photolysis

AMR 511-86 D.L. Ryan (1986)

Previous



does partially meet current guidelines, with the only deviation being that

it was not conducted to GLP. In the DuPont submission this study has

also been supported by the study of Lenz (2001; DuPont-6047) and

Umstaetter (2006; DuPont-20549). In the Task Force submission this

study has been superseded by the study of Oddy (2012).





the UK RMS has briefly reviewed this original photolysis study and

considered that it was acceptable. For completeness the original text of

the study summary from the 1996 DAR has been included below.

The study (AMR 511-86) was started in 07/1985 and reported by D.L. Ryan (1986). No

GLP statement was included in the report. The US EPA, Pesticide Assessment Guidelines:

Environmental Fate 161-2 was used. The study was found acceptable.

Protocol - [thiophene-2-14C]Thifensulfuron-methyl or [triazine(U)-14C]Thifensulfuron-

methyl (radiochemical purity greater than 98%) and [thiophene-2-13C]Thifensulfuron-methyl

(purity 97%) were dissolved at 10 ppm in sterile buffers at pH 5, 7 or 9 (acetonitrile was < 0.5%)

and kept at 25°C in darkness or exposed to summer sunlight (285-2800 nm) (Thifensulfuron-

methyl does not absorb after 310 nm) at Wilmington, USA. Large amounts of photo products for

spectral identification were generated by irradiating a 320 ppm solution of Thifensulfuron-methyl

six inches under a bank of six fluorescent sun lamps for 42 hours. 14CO2 was trapped and


analysis of degradation products were performed by TLC, HPLC, MS and NMR for 14 days.

First-order reaction kinetics were assumed for the decline of Thifensulfuron-methyl with time.

Results - Mass balance was in the range 93-114 % and pH values were stable. In darkness,

Thifensulfuron-methyl was significantly degraded at pH 5 and 9. In light, degradation was

enhanced at every pH (table 7.2.1). When corrected for hydrolysis, the photolysis rate was

independent of pH in the pH range 5-9 (117-129 hours). Major degradation products were

triazine amine (14%), triazine urea (11%) and methyl-3-(4-methoxy-6-methyl-1,3,5,-triazin-2-yl-

amino)-2-thiophene carboxylate (7%, figure 7.2.2). A large number of minor compounds were

detected, each < 4% (Thifensulfuron acid, O-demethyl-Thifensulfuron-methyl, and 2-ester-3-

sulfonamide...). Detection of 14 CO2 indicated extensive breakdown of the thiophene ring.

Table B.8.293 - Photo degradation kinetics Linear DT50 (hours)

pH 5 pH 7 pH 9

Darkness 608 4400 381

Sunlight 98 125 97

Figure B.8.35 - Proposed photo product: methyl-3-(4-methoxy-6-methyl-1,3,5,-triazin-2-yl-amino)-2-

thiophene carboxylate

S

CO2CH3

N

N

N

OCH3

CH3

HN


Report: Lentz, N.R. (2001); Photodegradation of Thifensulfuron-methyl in natural water by

simulated sunlight


Guidelines: Japanese Guideline 12 Noshan No. 8147 Deviations: None

Testing Facility: Ricerca, LLC, Concord, Ohio, USA

Testing Facility Report No.: 013515-1

GLP: Yes

Certifying Authority: Laboratories in the USA are not certified by any governmental agency,

but are subject to regular inspections by the U.S. EPA.

Report: Umstaetter, S. (2006); Assessment of the identity of the photolysis degradation

products of Thifensulfuron-methyl (DPX-M6316) observed in sterile buffers and natural waters

(DuPont-6047)


Guidelines: Not provided Deviations: None

Testing Facility: DuPont Stine-Haskell Research Center, Newark, Delaware, USA


GLP: No

Certifying Authority: Not applicable - position paper

Previous

evaluation:



The following studies were submitted by DuPont to support the original

photolysis study from the DAR. The UK RMS has briefly evaluated

these studies and considered them acceptable. The original study


Executive summary:

A photolysis study (AMR-511-86) was performed to determine the degradation rate of

Thifensulfuron-methyl in sterile, buffered, aqueous solutions at pH 5, 7, and 9 under midsummer

sunlight conditions. Specifically, the purpose of this study was to determine the photolytic rate

constants and half lives of Thifensulfuron-methyl in sterile pH 5, 7, and 9 aqueous buffers and to

identify structures of photoproducts formed in excess of 10%AR. A subsequent aqueous

photolysis study (DuPont-6047) was performed to determine the degradation rate and quantum

yield of Thifensulfuron-methyl in natural water and pH 7 buffer under constant irradiation. In

this study, several known metabolites were identified by co-chromatography with known

standards, including IN-V7160, IN-A5546, IN-L9225, and IN-L9226. However, since the

purpose of DuPont-6047 was not to determine the degradation products, these were not reported.

Therefore, the purpose of the additional position paper was to assess the degradation products of

Thifensulfuron-methyl observed in DuPont-6047.

The aqueous phototransformation of [14

C]-Thifensulfuron-methyl was studied in sterile natural

water and sterile buffer at pH 7 and 25 1C for 15 days. The initial test item concentration was

4.67–4.90 g/L and the study was conducted under artificial irradiation (Suntest XLS+,

Enhanced Model benchtop xenon exposure system, 290 nm cut-off). Samples were analysed

directly by high-performance liquid chromatography with radiochemical flow detection

(HPLC-RAD) to determine the distribution of radioactivity. The quantum yield of


Thifensulfuron-methyl was calculated to be = 0.037 using chemical actinometry. Assuming

first order kinetics, the DT50 value in both irradiated solutions (natural water and in pH 7 buffer)

was calculated to be 0.5 days. The mass balance of radioactivity for [thiophene-2-14

C]-

Thifensulfuron-methyl in sterile natural water and sterile pH 7 buffer ranged from 97.1 to

102.3% and 96.6 to 103.6%, respectively. The mass balance ranged from 100.0 to 106.5% and

99.1 to 105.6% for [triazine-2-14

C] Thifensulfuron-methyl in sterile natural water and sterile

pH 7 buffer, respectively.

Aqueous photolysis is expected to contribute significantly to the degradation of Thifensulfuron-

methyl in natural water systems.


A. MATERIALS


C Thifensulfuron-methyl technical


C] Thifensulfuron-methyl: DuPont

CPC Isotope Inventory No. 206

[triazine-2-14

C] Thifensulfuron-methyl: DuPont

CPC Isotope Inventory No. 227


C] Thifensulfuron-methyl: 95%

[triazine-2-14

C] Thifensulfuron-methyl: 95%


C] Thifensulfuron-methyl: 23.0

Ci/mg

[triazine-2-14

C] Thifensulfuron-methyl: 33.9

Ci/mg


Stability of test compound: Not reported

B. STUDY DESIGN


Natural water was collected from Lums Pond (New Castle County, Delaware) and stored

at 4C for up to 3 months. A buffer concentration of 0.01 M was used to minimise

possible catalytic effects. Immediately prior to sample preparation, the natural water and

buffer solutions were filter sterilised through a 0.2-m filter.

The aqueous phototransformation of radiolabelled Thifensulfuron-methyl was studied at

25 1C in natural water and pH 7 buffer at an initial concentration of 4.67–

4.90 g a.s./L under artificial irradiation (Suntest XLS+, Enhanced Model benchtop

xenon exposure system, 290 nm cut-off) for 15 days (equivalent to at least 30 days of

natural sunlight at midday, Painesville Ohio, USA). The concentration of acetonitrile as

co-solvent was 0.5%. Additional samples were used as dark controls in pH 7 sterile

buffer maintained at 25 1C. Volatiles traps consisting of 100 mL ethylene glycol

followed by two solutions of approximately 100 mL of 1N NaOH were connected to each

of the irradiated test samples.


A p-nitroacetophenone (PNAP)/pyridine (PYR) actinometer was used to determine the

irradiation intensity entering the test solution by the xenon arc lamp. An aliquot of each


sample was removed and a portion of it analysed by HPLC at time 0, 0.5, 1, 2, 3, and

5 days.

For the purposes of determining the quantum yield of the test substance, the molar

absorptivity of Thifensulfuron-methyl was measured. A 10–4

M solution of

Thifensulfuron-methyl in 0.01 M pH 7 buffer was prepared and the absorbance measure

between 290 and 800 nm using a UV-Visible spectrometer.

Samples were analysed immediately after the addition of the test substance and at 0.5, 1,

2, 3, 5, 7, and 15 days after treatment. The solutions were analysed for total radioactivity

by LSC and by HPLC by co-chromatography with authentic reference standards. The

limit of detection (LOD) for Thifensulfuron-methyl was 0.002 g/mL for LSC

determination and 0.005 g/g for HPLC determination.


A. MASS BALANCE

The material balance of radioactivity ranged from 97.1 to 102.3% and 96.6 to 103.6% for

[thiophene-2-14

C] Thifensulfuron-methyl in natural water and buffer solutions, respectively.

The material balance of radioactivity ranged from 100.0 to 106.5% and 99.1 to 105.6% for

[triazine-2-14

C] Thifensulfuron-methyl in natural water and sterile pH 7 buffer solutions,

respectively.

B. FINDINGS

Results are presented in Tables B.8.293a to 293d (taken from the position paper of

Umstaetter, 2006). Assuming first order kinetics, the DT50 value in both irradiated solutions

(natural water and pH 7 buffer) was calculated to be 0.5 days. In the dark controls samples

Thifensulfuron-methyl degraded with a DT50 value of 126 days.

[Thiophene-2-14

C] Thifensulfuron-methyl photodegraded rapidly to the degradation products

IN-A5546 and polar compounds in natural water and in pH 7 buffer within 2 days. After

7 days of irradiation no single degradation product could be identified and most of applied

radioactivity consisted of the polar fraction. [Triazine-2-14

C] Thifensulfuron-methyl

photodegraded rapidly to the degradation products IN-V7160 and polar compounds in

natural water and in pH 7 buffer within 2 and 7 days, respectively. In addition, one

unidentified transient metabolite with a HPLC retention time of approximately 40 minutes

exceeded 10% AR in the natural water samples with both labels. The study author proposed

that this was more than likely the same photoproduct identified in AMR-511-86 (Ryan,

1996) as methyl-2-(4-methoxy-6-methyl-1,3,5-triazin-2-yl-amino)-3-thiophene-carboxylate

(IN-D8856 IN-D88589). The two studies used similar HPLC conditions and the retention

time of the unknown peak was similar to the photoproduct identified in AMR-511-86. The

structure of the photoproduct in AMR-511-86 was confirmed by NMR and MS. Due to the

very slow degradation of [thiophene-2-14

C] and [triazine-2-14

C] Thifensulfuron-methyl in the

dark control samples, low amounts of the degradation products IN-A5546 and IN-L9225

were identified in the Day 15 sample.

9 During the EFSA peer review it became apparent that some of the original reports written by DuPont had misquouted the code

number of IN-D8858 as IN-D8856. Further analytical work was conducted to confirm the structure as IN-D8858 and the

correct code has been used throughout the updated RAR.


The quantum yield of Thifensulfuron-methyl was calculated to be = 0.037. Validation of

the quantum yield calculation was achieved using the reference system p-nitroacetophenone

(PNAP)/pyridine (PYR).

Table B.8.293a: Distribution of radioactivity in the natural water samples treated with

triazine-2-14


Day

Thifensulf

uron-

methyl

IN-V7160 IN-

L9226

IN-

L9225

Unknown

40 minute

peak*

Other

non-

polar**

Other

polar**

Total

%AR in

aqueous

phase

0 96 0.8 2.3 nd nd 0.9 0.0 100.0

0.5 47.5 11.3 nd 3.8 6.7 31.1 0.0 100.4

1 25.6 18.2 nd 6.8 12.4 33.3 4.1 100.4

2 7.1 24.2 nd nd 14.0 47.7 8.4 101.4

3 nd 20.9 nd nd 10.9 59.1 9.5 100.4

5 nd 24.6 nd nd 5.9 59.7 11.0 101.2

7 nd 25.8 nd nd 2.4 58.1 18.2 104.5

15 nd 21.8 nd nd 1.5 52.1 26.2 101.6

*based on comparison of HPLC retention times, this degradation product was proposed to be IN-D8858 6

idenified in AMR-511-86 (Ryan, 1986) as methyl-2-(4-methoxy-6-methyl-1,3,5-triazin-2-yl-amino)-3-

thiophene-carboxylate

**consists of multiple components, none of which exceeded 10% AR.

Table B.8.293b: Distribution of radioactivity in the natural water samples treated with

thiophene-2-14


Day

Thifensulfu

ron-methyl IN-A5546

IN-

L9226

IN-

L9225

Unknown

40 minute

peak*

Other

non-

polar**

Other

polar**

Total

%AR in

aqueous

phase

0 96.9 0.7 1.5 1.0 nd 0 0.0 100.0

0.5 64.3 3.7 2.6 3.7 8.7 14.0 5.3 102.3

1 32.9 8 nd 4.3 10.2 29.2 15.9 100.5

2 7.2 6.6 nd nd 15.3 40.6 27.6 97.3

3 nd 4.9 nd nd 13.3 46.9 32.2 97.3

5 nd 1.9 nd nd 10.3 44.0 37.8 94.0

7 nd nd nd nd 7.6 44.4 43.8 95.8

15 nd nd nd nd 1.9 39.3 48.2 89.4






Table B.8.293c: Distribution of radioactivity in the irradiated pH 7 buffer samples treated

with triazine-2-14


Day

Thifensulfu

ron-methyl IN-V7160

IN-

L9226

IN-

L9225

Unknown

40 minute

peak*

Other

non-

polar**

Other

polar**

Total

%AR in

aqueous

phase

0 96.0 0.6 1.7 0.9 nd 0.8 0.0 100.0

0.5 41.7 13.4 nd 5.2 4.4 34.4 0.0 99.1

1 16.9 19.3 nd 8.3 7.8 39.4 7.8 99.5

2 3.7 22.6 nd nd 8.6 57.8 9.7 102.4

3 nd 20.5 nd nd 7.4 63.2 11.7 102.8

5 nd 20.1 nd nd 5.5 62.1 14.3 102.0

7 nd 23.8 nd nd 5.4 59.8 14.8 103.8

15 nd 22.2 nd nd 2.0 61.4 18.3 103.9





Table B.8.293d: Distribution of radioactivity in the irradiated pH 7 buffer samples treated

with thiophene-2-14


Day

Thifensulfu

ron-methyl IN-A5546

IN-

L9226

IN-

L9225

Unknown

40 minute

peak*

Other

non-

polar**

Other

polar**

Total

%AR in

aqueous

phase

0 96.6 0.6 1.3 0.8 nd 0.7 0 100.0

0.5 66.7 5.3 3.1 3.8 4.4 13.6 4.4 101.3

1 58.7 7.4 nd 3.8 3.8 19.7 8.3 101.7

2 10.2 10.3 nd nd 9.3 49.4 23.5*** 102.7

3 nd 7.5 nd nd 8.5 50.3 32.6*** 98.9

5 nd 7.5 nd nd 7.6 45.1 36.2*** 96.4

7 nd nd nd nd 4.7 47.9 42.2*** 94.8

15 nd nd nd nd 2.3 44.5 45.3*** 92.1

*based on comparison of HPLC retention times, this degradation product was proposed to be IN-D8858 6 idenified

in AMR-511-86 (Ryan, 1986) as methyl-2-(4-methoxy-6-methyl-1,3,5-triazin-2-yl-amino)-3-thiophene-carboxylate


***consists of regions of radioactivity eluting at or near the solvent front that are >10% AR. However the study

author proposed that these regions consist of multiple components, none of which exceeded 10% AR.

III. CONCLUSION

Thifensulfuron-methyl degraded rapidly in natural water and in pH 7 buffer under artificial

sunlight. Under continuous irradiation the DT50 value of Thifensulfuron-methyl was calculated

to be 0.5 days in both test systems. Besides a very polar fraction, the degradation products

IN-A5546, IN-V7160, and IN-L9225 were detected. CO2 accounted for up to 9.8% of applied

radioactivity at the end of the study. Slow hydrolytic degradation of Thifensulfuron-methyl was

observed in the dark control samples incubated at pH 7 and 25C. The quantum efficiency of

Thifensulfuron-methyl was calculated to be 0.037. Based on the results of this study, photolysis

will be a major route of elimination of Thifensulfuron-methyl from the environment.

(Lentz, N.R., 2001)

(Umstaetter, S., 2006)


Report: A. Oddy (2012) [14

C]-Thifensulfuron-methyl: Aqueous Photolysis and

Quantum Yield Determination in Sterile Buffer Solution. Battelle UK Ltd

[Cheminova A/S], Unpublished report No.: WB/10/009 [CHA Doc. No.284

TIM]

Guidelines: OECD Guideline 316: Phototransformation of Chemicals in Water – Direct

Photolysis (October 2008)

GLP: GLP compliance statement and quality assurance statement supplied.

Previous

evaluation:



The following study was submitted by the Task Force and has been

briefly evaluated by the UK RMS and considered acceptable. The

original study summary from the Task Force is provided below.

Test material:

[Thiophene-2-14

C]-Thifensulfuron-methyl Specific radioactivity 5.17 MBq/mg

[Triazine-2-14

C]-Thifensulfuron-methyl Specific radioactivity 5.18 MBq/mg




[Triazine-2-14



Radiopurity [Thiophene-2-14


[Triazine-2-14


Buffer Tier 1: pH 4 0.01M acetate buffer, pH 7 0.01M Phosphate buffer and pH 9

0.01M borate buffer.

Tier 2: sterile 0.01 M phosphate buffer at pH 7 (adjusted to pH with 0.1M

sodium hydroxide solution.

Buffers were sterilised by a 0.22 µm Millipore Steritop sterile filter.

The photolysis of Thifensulfuron-methyl in an aqueous environment was investigated in

accordance with the two tiered approach described in OECD guideline 316. A Tier 1 theoretical

screen was first performed to estimate the maximum possible direct photolysis rate constant and

corresponding DT50 value, for Thifensulfuron-methyl under varying pH buffers (4, 7 and 9).

10ml, 0.1087 g L-1 stock solutions of Thifensulfuron-methyl was produced by diluting a 1ml,

1.087 g L-1 solution of the substance in acetone with the appropriate buffer. The buffers were

sterilised by filtration through a 0.22 μm Millipore Steritop filter. The UV absorbance of the

Thifensulfuron-methyl in each of the buffer solutions was measured between 295 and 380 nm

using a Thermo Electron Evolution 300 spectrophotometer. The spectral data were used to


estimate the maximum photolysis rate constant for Thifensulfuron-methyl, at 40° latitude for the

summer season, at each pH using the methods described in the OECD guideline.

The test substance was found to have a molar decadic absorption coefficient >10 in a range of

wavelengths ≥290 nm (297.5- 320.0 nm) across a number of pH values (4, 7, 9). The DT50

values for three pHs (4, 7, and 9) were estimated using the equation below:

Where is the molar adsorption coefficient

is the solar irradiance (average daily solar photon irradiance at 40º latitude)

is the quantum yield (set at 1.0 or tier 1 screen)

Tier 1 results pH 4 pH 7 pH 9

Sum of molar

adsorption

coefficient * sum of

solar irradiance

1.19E+01 7.18E+00 7.87E+00

T ½ [d] (DT50) 0.06 0.10 0.09

From this screening test it was determined that Thifensulfuron-methyl would be predicted to

undergo direct photolysis and that a full experimental study was therefore required.

In the Tier 2 study, the photolysis of [thiophene-2-14

C]-Thifensulfuron-methyl and [triazine-2-14

C]-Thifensulfuron-methyl in aqueous buffer solution (0.01 M phosphate, pH 7) was

investigated. The study was conducted under sterile conditions (using autoclaved glassware and

methanol sterilised pipettes) at 25 ± 2ºC, with continuous irradiation under artificial sunlight

provided by a xenon arc lamp with filters to cut off any radiation below 290 nm.

The study was conducted using a Heraeus Sun Test (CPS+). The experiment was performed in a

water jacketed steel tray under the suntest apparatus. 18ml aliquots of the buffer solution were

placed into quartz photolysis vessels and sealed. A quartz vessel was used as a temperature probe

(in 18ml water) and another used for the actinometer solution to measure the spectral photon

irradiance of the light source.

Aliquots (18 mL) of the buffer solution were also placed into glass measuring cylinders and

sealed. These cylinders were left in the dark at 25°C. Duplicate zero time samples, to be used for

both irradiated and non-irradiated data sets, were also prepared in this manner.

The light intensity of the irradiated experiment was found to be 65.22 Wm-2

at 300-400 nm,

calculated from measurements taken before and after the study using a Bentham CMc150-MDE

Integrated Double Spectroradiometer at the level of the liquid in the photolysis vessels.

Measurements were made at eight positions and the average value used to calculate the

equivalent days of natural sunlight.


Irradiation was continued for a period of 168 hours (7 days; equivalent to 18.2 days natural

sunlight at 30-50°N) by which time > 90% of the applied Thifensulfuron-methyl had degraded

and the formation and decline of major transformation products had been established.

The initial nominal concentration of Thifensulfuron-methyl was 1.0 mg L-1

, with ca 0.5%

acetonitrile present as co-solvent. Duplicate samples were taken at 0, 1, 2, 6, 24, 72 and 168

hours for the thiophene label and 0, 1, 3, 6, 24, 72 and 168 hours for the triazine label.

Irradiated test vessels were removed from the suntest and placed in an ice bath for ca 2 minutes

before opening to cool the samples and thus minimise any potential losses of activity. The non-

irradiated test vessels were removed from the temperature controlled room at the same time and

treated in the same manner. To maintain sterility the samples were transferred to a laminar flow

cabinet for processing.

The contents of the test vessels were transferred to a suitable storage vessel and the test vessels

were each rinsed with 5 x 1 mL aliquots of acetonitrile. The total weight of the rinses was

recorded and duplicate aliquots (by weight) were assayed for radioactivity by LSC. The samples

and vessel rinses were combined prior to HPLC analysis and selected LC-MS analysis. The

samples were stored at ca 5°C and a portion in HPLC vials at < -15ºC. After the initial HPLC

analysis the sample vials were stored at < -15ºC. Recovery of applied radioactivity was

determined by LSC (LOQ 0.00032 μg mL-1 /0.03% AR), with subsequent identification and

quantification of Thifensulfuron-methyl and individual transformation products performed by

HPLC (LOQ 0.41% region of interest). Secondary confirmation of identity was performed using

LC-MS techniques.

For the irradiated samples the overall mean recoveries were 96.1% AR (mean range 88.2 (at 168

hours) to 100.5% AR) for the thiophene label and 99.1% AR (mean range 94.5 to 101.9% AR)

for the triazine label. The corresponding figures for the non-irradiated samples were 98.6% AR

(mean range 97.0 to 101.1% AR) for the thiophene label and 99.7% AR (mean range 98.0 to

101.0% AR) for the triazine label.

Table B.8.294 Mean distribution and Recovery of Radioactivity, thiophene label, irradiated samples

Test Point Actual

Hours* Suntest Days

EU Sunlight

days

% Applied Radioactivity in:

Sample Vessel Rinse Total

recovered

0 hrs 0.0 0.0 0.0 100.53 NA 100.53

1 hour 1.0 0.04 0.1 96.76 1.15 97.91

2 hours 2.0 0.08 0.2 98.03 1.71 99.74

6 hours 6.0 0.25 0.6 94.78 1.56 96.34

24 hours 24.0 1.0 2.6 94.56 1.15 95.72

72 hours 71.9 3.0 7.8 93.12 1.23 94.35

168 hours 167.9 7.0 18.2 86.73 1.43 88.16

* Actual irradiation time under suntest; EU sunlight days = suntest days x 2.6


Table B.8.295 Mean distribution and Recovery of Radioactivity, thiophene label, non-irradiated samples

Test Point Actual Hours* % Applied Radioactivity in:

Sample Vessel Rinse Total recovered

1 hour** 1.0 98.96 1.18 100.14

2 hours 2.0 96.27 1.22 97.49

6 hours 6.0 98.08 2.04 100.12

24 hours 24.0 96.28 0.68 96.95

72 hours 72 98.01 0.68 98.70

168 hours 168 97.87 0.56 98.43

* Actual time in temperature controlled room; Zero time data shared with irradiated dataset.

Table B.8.296 Mean distribution and Recovery of Radioactivity, triazine label, irradiated samples

Test Point Actual

Hours* Suntest Days

EU Sunlight

days

% Applied Radioactivity in:

Sample Vessel Rinse Total

recovered

0 hrs 0.0 0.0 0.0 101.50 0.43 101.93

1 hour 1.0 0.04 0.1 99.04 1.32 100.36

3 hours 3.0 0.13 0.2 98.89 1.47 100.36

6 hours 6.0 0.25 0.6 97.43 1.50 98.93

24 hours 23.5 1.0 2.5 97.24 1.31 98.55

72 hours 71.7 3.0 7.8 97.26 1.56 98.83

168 hours 167.5 7.0 18.1 93.08 1.42 94.50

* Actual irradiation time under suntest; EU sunlight days = suntest days x 2.6

Table B.8.297 Mean distribution and Recovery of Radioactivity, triazine label, non-irradiated samples

Test Point Actual Hours* % Applied Radioactivity in:

Sample Vessel Rinse Total recovered

1 hour** 1.0 100.47 0.47 100.95

3 hours 2.0 97.80 0.80 98.60

6 hours 6.0 99.98 0.55 100.53

24 hours 24.0 97.47 0.53 98.00

72 hours 72 99.31 0.71 100.02

168 hours 168 99.11 0.79 99.89

* Actual time in temperature controlled room; Zero time data shared with irradiated dataset.


In the thiophene labelled samples the parent compound decreased rapidly from > 97% AR at time

zero to < 5% AR after 72 hours, reaching <1% AR by the end of the irradiation period (168

hours). Concurrently there was an increase in two major areas of radioactivity and up to 30 minor

regions. Due to the large number of discrete regions full tabulation of results has been omitted.

However the significant regions have been tabulated below. The two major areas were a polar

region and a non-polar degradate. The polar region (RRT 0.12-0.16) appeared to consist of a

number of components which together accounted for ca 50% AR by the end of the study. HPLC

analysis of this polar fraction, following isolation, under a second set of HPLC conditions,

confirmed that it consisted of a multitude of individual degradates, each at < 5.2% AR.

The non-polar degradate (RRT 1.07), which was observed in both the thiophene and triazine

labelled experiments, increased from 3.9% AR at 2 hours up to a maximum of 12.2% AR at 6

hours, and then declined to < 1% AR by the end of the study. This degradate has been tentatively

identified by LC-MS to be thiophenyl triazinyl amine (IN-No. unknown). Several minor

degradates (each at < 5.8% AR) were also detected, some of which corresponded to the available

reference standards. IN-W8268 increased to 3.4% AR by 24 hours then declined to 1.1% AR by

the end of the study at 168 hours, IN-A5546 increased to 3.6% AR by 72 hours then declined to

1.7% AR at 168 hours, IN-L9226 increased to 5.1% AR by 6 hours then declined to 0.3% AR at

168 hours and IN-L9225 increased to 5.8% AR by 6 hours then declined to 1.0% AR at time 168

hours. IN-L9223 increased to 3.6% AR by 72 hours then declined to 1.7% AR at 168 hours.

These metabolites were not confirmed by LC-MS due to their low concentrations in the sample.

In the triazine labelled samples the parent compound decreased rapidly from > 98% AR at time

zero to < 5% AR after 72 hours, reaching ca 1% AR by the end of the irradiation period (168

hours). Concurrently there was an increase in three major degradates (each > 10% AR), namely

IN-A4098, IN-V7160 and thiophenyl triazinyl amine.

IN-A4098 (RRT 0.35) was found to increase to a maximum of 16.8% AR by the end of the

irradiation period and was confirmed by LC-MS. IN-V7160 (RRT 0.68), also confirmed by LC-

MS, reached a maximum of 19.4% AR at 72 hours and then declined slightly to 17.5% AR by the

end of the study. Thiophenyl triazinyl amine (RRT 1.07) increased to a maximum of 14.3% AR

by 24 hours then declined to < 1% AR by the end of the study. Several minor degradates (each at

< 7.8% AR) were also detected, some of which corresponded to available reference standards.

IN-L9226 increased to 4.9% AR by 6 hours then declined to 1.9% AR at 168 hours. IN-L9225

increased to 4.8% AR after 3 hours then declined to < 1% AR by the end of the study.

Significant metabolites (Irradiated thiophene label)

Major areas

of

radioactivity

RRT 0.21 –

0.24

RRT 0.53 – 0.77

(2-acid-3-

sulfonamide)

RRT 0.97 –

1.0

RRT 1.07

(Thiophenyl

triazinyl amine)

% AR

(sample time)

8.05

(167.9 hrs)

5.18

(167.9 hrs)

5.00

(2hrs),

6.08

(6 hours)

12.23 (6 hrs), 12.16

(24 hrs), 7.08 (71.9

hrs)


Significant metabolites (Irradiated triazine label)

Major areas of

radioactivity

RRT 0.14 RRT 0.15 RRT 0.35 (IN-

A4098))

RRT 0.39 RRT 0.68

(IN-V7160)

RRT 1.07

(Thiophenyl

triazinyl amine)

% AR (sample

time)

7.03

(167.9

hrs)

7.83 (71,9

hrs), 7.59

(167.9 hrs)

6.59 (3 hrs)

9.77 (6 hrs)

10.34 (24 hrs)

16.82 (71.9 hrs)

16.81 (167.9

hrs)

5.70

(167.9 hrs)

11.95 (3 hrs) 13.84

(6 hrs) 16.9 (24

hrs)

19.39 (71.9 hrs)

17.47 (17.9 hrs)

11.79 (3 hrs),

13.08 (6 hrs),

14.27 (24 hrs),

7.27 (71.9 hrs)

In the non- irradiated samples, no significant degradation of the parent compound was seen for

either label over the duration of the experiment with limited (< 3% AR) formation of other

metabolites.

The quantum yield was determined using a pyridine/PNAP actinometer which was irradiated

simultaneously with the triazine labelled Thifensulfuron-methyl samples. The initial PNAP

concentration for the experiment was 1.89E-06 M and the pyridine concentration was 0.1998 M.

The quantum yield for Thifensulfuron-methyl in aqueous solution at pH 7 was found to be 0.044.

The HPLC LOQ for PNAP was <2.7% nominal application rate.

DT50 and DT90 figures for the decline of Thifensulfuron-methyl were determined according to the

FOCUS guidance document on degradation kinetics using KinGUI version 1.1 and assuming first

order kinetics. The DT50 in natural sunlight was calculated to be between 0.32 and 0.67 days

(7.7-16.2 hours) and the DT90 was calculated as 1.07-2.24 days.

Table B.8.298 Degradation rate of Thifensulfuron-methyl using Single First Order Kinetics for irradiated

samples

System Model T-test

Chi2 error

In suntest Natural sunlight*

DT50 DT90 DT50 DT90

Irradiated –

thiophene

label

SFO - 3.6615 6.2 hours

(0.26 days)

20.7 hours

(0.86

days)

16.2 hours

(0.67

days)

53.83

hours

(2.24

days)

Irradiated –

Triazine label SFO - 9.9058

3.0 hours

(0.12 days)

9.8 hours

(0.41

days)

7.7 hours

(0.32

days)

25.6 hours

(1.07

days)

*corrected for 1 suntest day equivalent to 2.6 days natural sunlight at 30-50ºN


Figure B.8.36 Photolytic degradation pathway of Thifensulfuron-methyl

S

S

HN

HN

N N

N OCH3

CH3

OO O

OCH3

O

H2N

N N

N OCH3

CH3Triazine amineIN-A4098


S

HN

N N

N OCH3

CH3

OCH3O

Thiophenyl triazinyl amine

H2NHN

N N

N OCH3

CH3

O

Triazine ureaIN-V7160

(Oddy, 2012)

Identification of proposed photoproducts

The results of the existing aqueous photolysis study of Ryan (1986) and the new study from

DuPont (Lentz, 2001 and Umstaetter, 2006) propose a slightly different photoproduct to that

tentatively identified in the new study from the Task Force (Oddy, 2012). The structures are

shown below in Figure B.8.36a. As can be seen in the figure below, the difference arises from a

possible rearrangement of the thiophene ring in the IN-D8858 6 metabolite proposed by the

DuPont submission. However the structures are isomers, and the UK RMS considered the

possibility that one of these structures may have arisen incorrectly as a result of mis-

identification.

Considering the work done by DuPont in the original study of Ryan (1986) the proposal for the

structure of IN-D8858 6 seems plausible in the opinion of the UK RMS. In that study, Mass

Spectral evidence was used to initially propose the structure as thiophenyl triazinyl amine (as

proposed by the Task Force). This proposed structure was subsequently synthesised as a

standard for use in further analytical work. Chromatographic retention times of this synthetic

standard and the photoproduct obtained in the sunlight exposed samples were shown to be the

same. However whilst the Chemical Ionisation mass spectra of the two compounds was very

similar (i.e. showing the same mass ions and major fragments) the Electron Ionisation spectra

differed in the relative intensities of several of the fragment ions. These results indicated that the

synthetic compound and the photoproducts were closely related, but not identical. Additional

NMR analysis suggested that the photoproduct was an isomer of the synthetic standard and the

structure IN-D8858 6 was proposed. In addition, a literature reference was cited that

demonstrated photoisomeration of thiophene containing compounds can occur. In re-evaluating

the work in Ryan (1986), the UK RMS considered that DuPont had provided strong evidence that

the photoproduct in that study was not thiophenyl triazinyl amine. However without a reference

standard being prepared for the IN-D8858 6 structure the UK RMS considered that the MS data

could not be used to a make an absolutely conclusive judgement on the structure. The UK RMS


does not have sufficient experience of the NMR techniques used to be able to rely on the NMR

data to confirm the identification. However based on our limited experience the information was

at least supportive and consistent with the findings of the MS work. Importantly in this work the

use of a reference standard was available to demonstrate that the photoproduct was not

thiophenyl triazinyl amine.

The identification work performed by the Task Force was much more limited and resulted in

only a tentative identification of the photoproduct as the thiophenyl triazinyl amine structure.

Although MS was undertaken, no standards were used for comparison. Effectively the structure

was proposed based on the molecular weights of fragments. In addition it should be noted that

the degree of fragmentation in the Task Force analysis was quite different to that obtained in the

DuPont study. The degree of fragmentation in the Task Force study suggested that a much softer

method of splitting had been used relative to the method in the DuPont study. As demonstrated

in the work of Ryan (1986) with softer Chemical Ionisation, it was not possible to distinguish the

photoproduct with the synthetic standard. The difference in structures was only apparent under

harsher Electron Ionisation fragmentation.

Finally the UK RMS considered whether the two unknowns could in fact be the same metabolite.

The formation of a relatively stable ion at 249/251 in both cases from the loss of OCH3

suggested that they could be the same structure. However the rest of the spectra from the two

studies are quite different. Also it should be noted that the conditions used to produce the ions

and the subsequent fragmentation were quite different. In addition the equipment used to

perform these analyses were quite different, with the analytical work being undertaken 26 years

apart. These differences may have artefactually led to a difference in fragmentation patterns and

the differences may not necessarily be due to different starting structures of the photoproducts.

Overall the evidence for the structure of the photoproduct being that represented by IN-D8858 6

as proposed by DuPont appears to be more comprehensive (two forms of MS plus NMR with at

least one reference standard in DuPont package compared to a single MS analysis with no

standards in the Task Force submission). However based on the existing data, the UK RMS was

unable to definitively conclude on the actual structures proposed. Since the aquatic risk

assessment of this metabolite has not been fully resolved, the UK RMS proposes that further

work be performed to definitively identify this photoproduct or photoproducts before any further

ecotoxicological testing is performed.


Figure B.8.36a: Proposed structures of photoproducts in DuPont and Task Force datasets

Thiophenyl triazinyl amine (Task Force)

S

O

CH3

O

N

NN

CH3

O

CH3

HN

IN-D8858 6 (DuPont)

Methyl-2-(4-methoxy-6-methyl-1, 3, 5-triazin-

2-yl-amino)-3-thiophene-carboxylate

S

CO2CH

3

N

N

N

CH3

NH

O CH3

In response to Data Requirement 4.2 in the Evaluation Table DuPont have provided further

information on the identification of the photoproduct coded IN-D8858 in the original aqueous

photolysis studies. For information, the full text of the Data Requirement is provided below:-

Data requirement (DuPont) 4.2: Applicant to provide the report DuPont-41912 with

further information on the identity of the aqueous photolysis metabolite identified as IN-

D8856. See also comment 4(86), 4(103) and 4(104). See reporting table 4(87).

Report: Sharma, A.K. (2014); Photodegradation of [14

C]-DPX-M6316 in buffer, confirmation

of structure of degradate IN-D8858


Guidelines: OECD Draft Guideline “Phototransformation of Chemicals in Water – Direct and

Indirect Photolysis” (August 2000) Deviations: None

Testing Facility: DuPont Stine-Haskell Research Center, Newark, Delaware, USA


GLP: No



Executive summary

In the course of conducting an aqueous photolysis study of thifensulfuron methyl in buffer

systems and in natural water [Ryan 1986 (AMR 511-86), and Umstatter, 2006 (DuPont-20549),

one of the degradation products formed was proposed as IN-D8858. This product results from

partial degradation of the sulphonamide bridge of the parent compound accompanied by


rearrangement of the thiophene ring. Other workers [Cheminova A/S Report No.: 284 TIM

Oddy, 2012] conducting similar photo-degradation studies have identified this product as

thiophenyl triazinyl amine (coded IN-N8016 here). During the ongoing EU review of these

studies, the UK RMS noted this difference regarding the identity of this metabolite as follows:

The results of the existing aqueous photolysis study of Ryan (1986) and the new study from

DuPont (Lentz, 2001 and Umstatter, 2006) propose a slightly different photoproduct to that

tentatively identified in the new study from the Task Force (Oddy, 2012). The structures are

shown below. As can be seen in the figure below, the difference arises from a possible

rearrangement of the thiophene ring in the IN-D8858 metabolite proposed by the DuPont

submission. However, the structures are isomers and the UK RMS considered the possibility that

one of these structures may have arisen incorrectly as a result of misidentification.

N

N

N

S OMe

O

N

CH3

OMe

N

N

NS

OMe

O

NH

CH3

OMe

IN-N8016 IN-D8858

This position paper offers additional work conducted at DuPont and further evidence that the

product generated from photochemical degradation of thifensulfuron methyl is indeed IN-D8858.

Strategy for Identification of IN-D8858 in Aqueous Photolysis

Strategies used for the identification of this photo-product were as follows:

1. Repeat the photolysis experiment using conditions similar to those used in the GLP

studies submitted for registration.

2. If the photolysis in the current experiment proceeds essentially equivalent to those

submitted previously in both the rate of degradation of thifensulfuron methyl, and the

photoproducts generated are also the same, then it can be assumed that the “amine”

generated is the same product whose identity is in question

3. Identification of the amine generated can then be addressed to conclusively state that

the amine formed in all photolysis degradations was indeed the one defined as IN-

D8858, provided all spectral and chromatographic properties have been

demonstrated to match this reference standard.

Results and Discussion

Since the focus of this investigation was to identify whether the amine-photoproduct was IN-

D8858 or IN-N8016, reference standards of both compounds were prepared so that it could be

conclusively stated not only which isomer was formed, but which isomer was not generated

during aqueous photolysis. The identities of the two synthesised standards were confirmed using

LC-MS, 1H-NMR, and

13C-NMR, and a 1,1-ADEQUATE NMR experiment.

The two isomers in question are positional isomers in which the triazine moiety is attached to

either the 2- or 3-postion of the thiophene ring, while the other position carries the methyl ester.

The mass spectra and the fragmentation pattern verified the structures of the two isomeric

amines; however, both isomers displayed insufficient differences in the mass spectrum


fragmentation to enable a differentiation of the two structures. Since the UV maxima around 225

to 245 nm were clearly different for the two isomers, the UV spectra coupled with HPLC

retention times allowed for an unequivocal determination of the isomer formed in the

photodegradation.

An HPLC method was developed which clearly separated the two amines [IN-N8016 and IN-

D8858] in question. The retention time of the photodegradation product matched that of IN-

D8858 but not IN-N8016. A comparison of the UV spectra of the reference standard of IN-

D8858 with the photodegradation product suggested that the photodegradation product was IN-

D8858, not IN-N8016, due to a nearly perfect matching of the UV spectra as shown in Figure

B.8.36b. For completeness the UV spectra of the IN-N8016 reference standard is provided in

Figire B.8.36c.

Figure B.8.36b Overlaid UV spectra of reference standard IN-D8858 and the amine photoproduct

Figure B.8.36c UV spectra of reference standard IN-N8016


Conclusion

The UK RMS notes that this work was not conducted in accordance with GLP. The position

paper stated that some of the specialised equipment needed for the investigation work were not

located in a GLP certified laboratory and no claim for GLP compliance was therefore made.

Stirctly this work should have been conducted to GLP. However based on the previous

analytical work that was conducted as part of the original photolysis studies, the UK RMS

considered that DuPont had provided strong evidence that the photometabolite was not

thiophenyl triazinyl amine (IN-N8016). The main reason for the UK RMS not being able to

conclude definitively that the structure was IN-D8858 on the basis of the previous work was the

absence of a reference standard. In the new information presented in the position paper,

reference standards for both possible structures were provided and identities confirmed via NMR

and chromatographic retention times. Futher evidence to support the earlier identification work

came in the form of HPLC retention times for the metabolite in question compared with the

reference standards as well as comparision of UV spectra (as shown in Figures B.8.36b and 36c).

Overall the UK RMS is content to conclude that the photodegradation product of thifensulfuron

methyl in question has been identified as IN-D8858 and not IN-N8016 by using a combination of

chromatographic separation and spectra analysis. These results provide further support to the

earlier identification work that used NMR and Electron Ionisation spectra to propose the

structure as IN-D8858. No further work is considered necessary.

(Sharma, 2014)

B.8.4.3 Ready biodegradation

Report: Barnes, S.P. (2000); DPX-M6316 assessment of ready biodegradability by modified

Sturm test


Guidelines: EEC Method C.4-C. (1992), OECD 301 B (1992) Deviations: None

Testing Facility: Huntingdon Life Sciences Ltd., Huntingdon, Cambridgeshire, UK

Testing Facility Report No.: DPT 533/003580

GLP: Yes


Previous

evaluation:



The following ready biodegradability study was submitted by DuPont to

meet the current data requirements. The UK RMS has only briefly

evaluated this study and considered it acceptable. The original study


Executive summary:

The present study was conducted to determine the ready biodegradability of Thifensulfuron-

methyl. The ready biodegradability was tested using the CO2 Evolution Test (Modified Sturm

Test). The test item was added to two test vessels at the concentration of 30 mg/L of mineral

medium (equivalent to 10 mg Carbon [C]/L). Two control treatments containing only the

inoculum, one positive control treatment containing inoculum plus reference standard (sodium


benzoate, 10 mgC/L), and one toxicity control treatment containing the inoculum plus test item

and reference standard were also tested. All the treatments were prepared with inoculum from a

secondary effluent treatment plant receiving predominantly domestic sewage.

Test, control, and reference mixtures were aerated for 29 days with carbon dioxide (CO2) free air.

The CO2 released by each treatment mixture was trapped in a series of Dreschel bottles

containing barium hydroxide, which were connected to the outlet of each test vessel. The

residual barium hydroxide was measured on the 1, 3, 5, 7, 9, 12, 19, 28, and 29 days after the

initiation of the test by titration. The pH of the treatment mixtures was measured at the start of

the test and on Day 28.

Sodium benzoate had biodegraded by 64% at Day 7 and 86% by Day 29 in the absence of

Thifensulfuron-methyl meeting the validity criteria of the test. Test mixture containing sodium

benzoate and Thifensulfuron-methyl had biodegraded by 66% at Day 7 showing that

Thifensulfuron-methyl was not inhibitory at this concentration.

The cumulative CO2 production by mixtures containing only Thifensulfuron-methyl was

negligible and had achieved, at most, 1% of the theoretical value (TCO2, 110.1 mg CO2) by the

end of the test on Day 29. Based on the pass levels (60% bio-degradation in the 10-day window

period), the test item cannot be considered as readily biodegradable since a 1% degradation was

achieved during the test period of 29 days.


A. MATERIALS

1. Test material name Thifensulfuron-methyl technical


Purity: 99.7%


CAS#: 79227-27-3

Stability of test compound: Not reported

2. Reference item: Sodium benzoate

Lot/Batch #: Not reported

Manufactured by: Fisher Scientific (United Kingdom)

3. Inoculum

Secondary effluent collected from a treatment plant receiving predominantly domestic

sewage was used as the inoculum. Oakley, Eye, Suffolk, United Kingdom sewage

treatment works.

Aliquots of a homogenised sample (25 mL) were filtered and the resulting samples were

dried for at least 1 hour at approximately 105C, allowed to cool, and weighed. The solid

level in the sludge was determined and then an appropriate volume used to inoculate

control and test vessels to give a final suspended solids concentration of 30 mg/L.

B. METHODS


The test was conducted using a test concentration of 30 mg/L of test medium.


Test systems were prepared by adding the stock solutions as described in Table B.8.299

to each of six numbered 5-L flasks. These flasks were aerated with CO2-free air at 40 to

80 mL/minute, overnight to purge the system of carbon dioxide.

Table B.8.299 Experimental design of ready biodegradation test

The vessels were treated with Thifensulfuron-

methyl and the reference standard, sodium

benzoate as follows: flask no. Contents

1 & 2 Controls - mineral salts medium, and inoculum (30 mg

solids/L), 200 mL ultrapure water (total volume 3000 mL)

3 Reference - inoculated mineral salts medium plus sodium

benzoate (10 mgC/L) (total volume 3000 mL)

4 & 5 Test substance - 10 mg C/L plus inoculated mineral salts

medium (total volume 3000 mL)

6 Sodium benzoate - 10 mg C/L plus inoculated mineral salts

medium (total volume 3000 mL)

Vessel contents were stirred continuously for 29 days with treated air. The air outlet for

each vessel was connected to three Dreschel bottles in a series, each containing 0.025 N,

nominal barium hydroxide (100 mL).

The residual concentrations of barium hydroxide in the bottles nearest to the test vessels

were determined at intervals by duplicate titration of 20-mL samples with 0.05 N HCL,

using phenolphthalein indicator.

On Day 28, titrations were undertaken and samples (approximately 100 mL) removed

from the vessel for pH determination. Concentrated HCl (1 mL) was added to each

vessel to dissolve inorganic carbon. The contents of the vessels were then aerated

overnight and the final titrations performed on Day 29.


Cumulative CO2 production in the controls was 68.8 and 67.1 mg CO2/3 L that was typical for

this type of test and inoculum source and were within the acceptable range for this assay system.

The degradation of sodium benzoate was rapid and had achieved 64% of its TCO2 after 7 days,

86% after 29 days.

The degradation of sodium benzoate was also rapid in the presence of Thifensulfuron-methyl and

had achieved 66% of its TCO2 after 7 days. These results show that Thifensulfuron-methyl did

not cause any inhibitory effect on the test system at this concentration.

Mean cumulative CO2

production by the mixtures containing Thifensulfuron-methyl was

negligible and had achieved, at most, 1% of its TCO2 by the end of the test of Day 29.

The pH of each test and control mixture was between 7.4 and 7.5 at the start of the test and 7.3 to

7.6 at the end of the test. The rate of air-flow during the test ranged from 40 to 80 mL/minute.

The temperature of the test area ranged from 19.8 to 22.9C over the test period.


III. CONCLUSIONS

Mean cumulative CO2

production by the mixtures containing Thifensulfuron-methyl was

negligible and had achieved, at most, 1% of its TCO2 by the end of the test of Day 29.

Substances are considered to be readily biodegradable in this test if CO2 production is equal to or

greater than 60% of the theoretical value within 10 days of achieving the 10% level. Since at a

maximum, 1% degradation was achieved during the test period of 29 days, Thifensulfuron-

methyl is considered to be not readily biodegradable.

(Barnes, S.P., 2000)


B.8.4.4 Water/sediment studies

AMR 540-86 W. Lewis and L.G. Carter

Previous



does not meet current guidelines, but has been superceded by the study

of Spare (2000). The UK RMS agreed that the study was not acceptable

since it was conducted under anaerobic conditions, and notes that the

study was only considered as supplemental information in the original

DAR. For completeness the original text of the study summary from the

1996 DAR has been included below. Since this information is no longer

relied upon, it has been shaded in grey.

A supplementary study (AMR 540-86) was reported by W. Lewis and L.G. Carter and

conducted according to US-EPA Pesticide assessment guidelines, Environmental Fate 161-2. An

anaerobic pond water/sediment study with [thiophene-2-14C] Thifensulfuron-methyl was

conducted on systems from North Carolina, Illinois, and Pennsylvania for 1 year. The half-life of

Thifensulfuron-methyl was approximately 2.5 to 3 weeks in the non-sterile systems and the

metabolic pathway was also nearly the same as in the former studies (Table B.8.300). The major

metabolic difference was the formation of 2-acid-3-sulfonic acid ((3-sulfonic acid)-2-

thiophenecarboxylic acid) (Figure B.8.377) and only minor amounts of Thifensulfuron acid.

Table B.8.300 - Quantities of radioactive components in combined water and sediment after

application of [thiophene-2-14C]Thifensulfuron-methyl at a nominal rate of 0.05 µg/ml.

(Results are expressed as % applied radioactivity)

N. CAROLINA Time after Application in Days

Radioactive component 0 7 14 28 64 112 196

Thifensulfuron-methyl 93 72 41 37 17 0 0

Thifensulfuron acid. 0 1 2 0 2 0 0

2-ester-3-sulfonamide 0 14 28 34 27 40 20

2-acid-3-sulfonamide 0 0 3 4 14 26 37

2-acid-3-sulfonic acid. 0 0 7 4 11 22 24

ILLINOIS Time after Application in Days






2-acid-3-sulfonic acid 0 0 0 0 8 16 16

PENNSYLVANIA Time after Application in Days







2-acid-3-sulfonic acid 0 1 3 2 22 16 2

Figure B.8.37 2-acid-3-sulfonic acid

S

SO3H

CO2H

In conclusion, one new metabolite, 2-acid-3-sulfonic acid (>10% of applied after 2 months)

was reported on water/sediment systems from US. Maximum concentration after one year of

incubation under anaerobic conditions was 24% of applied. This metabolite was not found in any

of the previously summarised aerobic/anaerobic soil or aquatic studies, presumably because of

the shorter study times (<3 months) or the partial aerobic conditions. 2-acid-3-sulfonic acid may

accumulate long-term (>2 months) in the anaerobic sediment/aquatic environment.

TNO R91/256 Y.A. Matla, P.I. Muttzall and J.W. Vonk (1991)

TNO R91/255 P.I. Muttzall and J.W. Vonk (1992)

Previous

evaluation:



does not meet current guidelines, but has been superceded by the study

of Spare (2000). The UK RMS agreed that the study was not acceptable,

and notes that the study was conducted in the presence of light. For

completeness the original text of the study summary from the 1996 DAR

has been included below. Since this information is no longer relied

upon, it has been shaded in grey.

The study (TNO R91/256) was started in 08/1991 and reported by Y.A. Matla, P.I.

Muttzall and J.W. Vonk (1991) and the study (TNO R91/255) was started in 08/1991 and

reported by P.I. Muttzall and J.W. Vonk (1992). No GLP statement was included in the reports.

The BBA guideline IV, 5-1 was used. Studies were not conducted in darkness as recommended

in SETAC method.

Protocol - Two sediment-water systems (gently shaken) from Netherlands (Table B.8.301)

gives sediment characteristics) were pre incubated 15-23 days at 20°C and 12 hour photo period

and then supplemented with [thiophene-2-14C]Thifensulfuron-methyl (radiochemical purity =

98%) or [triazine-2-14C]Thifensulfuron-methyl (radiochemical purity = 96%) at 1 ppm in water.

Measurements of pH, O2 concentration and ATP were performed for 13 weeks. Radioactive


compounds were analysed in water and sediments (TLC, HPLC) and 14CO2 was trapped in

NaOH. Pseudo first-order reaction kinetics were assumed for the decline of Thifensulfuron-

methyl in the total system and in the aqueous phase.

Table B.8.301 Sediment characteristics

14C label Sediment Series Sand

(%)

Silt

(%)

Clay

(%)

OC

(%)

OM

(%)

CEC

(meq/100 g)

pH

thiophene Kromme Rijn

Sandy Loam

94.3 1.2 2.7 0.41 0.7 3.0 7.5

TNO

Silty Clay Loam

61.5 15.2 13.0 3.41 5.8 19.8 7.2

triazine Kromme Rijn

Sandy Loam

68.2 12.3 11.7 1.6 2.8 11.1 7.4

TNO

Silty Clay Loam

23.0 33.0 23.8 6.5 11.1 35.8 7.1

Results - pH and O2 were in the range 8-9 and 1.5-8.9 mg/l. Mass balance was in the range

96-112%. 14CO2 was < 2.7%. Radioactivity distribution in water, sediments and bound residues

after 13 weeks was in the range 71-86%, 12-21% and < 8% for thiophene-14C and 54-64%, 30-

38% and 7-11% for triazine-14C. Thifensulfuron-methyl was degraded in both water and

sediment (DT50=2-2.3 weeks and DT90=6.5-7.7 weeks in the entire system). The major

metabolite in both water/sediment systems was Thifensulfuron acid (total final amounts 38-44

and 50-81%, according to soil and label). Other metabolites detected were 2-ester-3-sulfonamide,

2-acid-3-sulfonamide, triazine amine, and triazine urea (Table B.8.302).

Table B.8.302 Quantities of radioactive components in water and sediment from TNO after

application of [thiophene-2-14C]Thifensulfuron-methyl at a nominal rate of 1.0 µg/ml.

(Results are expressed as % applied radioactivity)

WATER REPLICATE 1 REPLICATE 2

Radioactive Time after application in weeks

Component 0 2 4 8 13 0 2 4 8 13

Thifensulfuron-methyl 94 60 24 11 <1 95 n.d 26 5 2

Thifensulfuron acid. 6 25 48 27 50 5 15 45 25 48

2-ester-3-sulfonamide <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

2-acid-3-sulfonamide 1 2 <1 32 12 1 2 <1 42 20

14CO2 0 0.4 0.7 1.4 2.1 0 0.4 0.8 1.2 1.6

SEDIMENT REPLICATE 1 REPLICATE 2

Radioactive Time After Application in Weeks

Component 0 2 4 8 13 0 2 4 8 13

Thifensulfuron-methyl 2 14 7 3 <1 3 12 8 2 1

Thifensulfuron acid. 1 6 12 12 11 <1 5 11 11 12

2-ester-3-sulfonamide <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

2-acid-3-sulfonamide <1 1 1 4 5 <1 2 1 4 4

Not extracted <1 3 4 6 8 <1 3 4 6 8


In conclusion, Thifensulfuron-methyl was degraded in both the water and the sediment phases,

exhibiting first-order degradation kinetics. Averaged DT50 and DT90 values for Thifensulfuron-

methyl in the complete water/sediment systems were 2.2 and 7.1 weeks for the Kromme Rijn

sediment and 2.3 and 7.6 weeks for the TNO sediment. The major metabolite in both

water/sediment systems was Thifensulfuron acid.

Spare W.C. (2000), report 1206, GLP, SETAC guideline, acceptable

Previous

evaluation:



fully meets current guidelines. The UK RMS has briefly reviewed the

study and agrees that the study is valid.


has been included below. Since the kinetics have been fully revised in

line with FOCUS guidelines, this aspect of the original study summary

has been deleted using strikethrough text.

Methods : [Thiophene-2-14

C] and [Triazine-2-14

C] Thifensulfuron-methyl were applied at 1 mg/l

to 2 water sediment systems (50 g sediment + 200 ml water). Characteristics of the water

sediment systems are given in table below. Incubation was at 20° C for 182 d. Volatiles were

trapped. Water and sediment phases were analysed separately. Sediment was extracted, extracts

were concentrated (evaporation, freeze dried) and analysed by HPLC and TLC. Unextracted RA

was determined by combustion. Water phase was directly analysed by HPLC and TLC.

Table B.8.303 Characteristics of water sediment systems

Middletown, MD, Red Oak

Sream

Middletown, MD, Town Park

Pond

Sediment Texture Loamy sand Loam

sand % 83 43

silt % 16 46

clay % 1 11

OM % 1.1 2.6

pH 7.1 7.2

Water pH 7.6 7.8

Results : RA was fully recovered. Mineralization was low : < 4 % for the thiophene moiety and <

9 % for the triazine moiety after 182 d. Bound residues were < 18 % for both moieties.

Extractable RA in sediment was < 15 % and no compound exceeded 10 % (< 8 % each). Most of

the applied RA was found in water. The major metabolites derived from the thiophene moiety

were IN-L9225 (thifensulfuron acid) max. 54 % after 70-100 d, IN-JZ789 (O-desmethyl

thifensulfuron acid) max. 18 % after 70 d and IN-L9223 (2-acid-3-sulfonamide) max. 39 % after


182 d. The major metabolites derived from the triazine moiety were IN-L9225 max. 55 % after

100 d, IN-JZ789 max. 10 % after 84 d, IN-V7160 (triazine urea) max. 25 % after 182 d) and IN-

A4098 (triazine amine) max. 19 % after 182 d. The metabolites IN-L9226 (O demethyl

Thifensulfuron-methyl) and IN-W8268 (thiophene sulfonimide) were detected in small amounts.

For Thifensulfuron-methyl, DT50 and DT90 values were calculated to be respectively 21 - 27 d

and 70 - 89 d in water, and 21 - 27 d and 71 - 91 d in whole system using first order kinetics.


Table B.8.304 Degradation of Thiophene-14

C Thifensulfuron-methyl in the Pond system

DAT % of applied RA

Water Sediment CO2 Rec.

Thif L9225 JZ789 L9223 Ext.* Bound

0 101 - 0.5 - - - - 101

1 93 1.2 1.4 - - 4 - 100

7 72 15 2 1.2 5 4 - 100

14 53 24 4 2 9 4 - 98

28 35 32 10 4 10 6 - 99

42 18 38 12 9 12 7 - 98

56 10 35 14 13 11 9 - 97

70 6 31 18 19 12 11 - 98

84 5 31 15 19 11 12 0.6 98

100 3 26 16 21 12 15 1.6 98

125 1.1 23 16 27 12 14 1.3 96

154 0.6 18 15 32 11 16 1.8 98

182 0.3 13 14 39 12 14 3 100

*no major compound (<5% AR each of IN-L9225, JZ789, L9223, W8268)

Minor unidentified fractions in aqueous phase, e.g. IN-L9226, IN-W8268 and polar material (all <5%AR) excluded

from the Table

Table B.8.305 Degradation of Thiophene-14

C Thifensulfuron-methyl in the Stream system

DAT % of applied RA


Thif L9225 JZ789 L9223 Ext.* Bound

0 99 0.3 0.5 - - - - 100

1 93 1.4 1.3 - - 4 - 100

7 77 12 1.1 0.9 7 2 - 101

14 62 23 1.5 2 8 3 - 100

28 41 37 4 4 10 2 - 100

42 31 43 6 6 9 1.5 - 100

56 21 51 7 7 9 3 0.5 99

70 14 54 6 10 9 4 0.7 98

84 12 48 8 15 10 4 1.0 99

100 6 54 7 15 9 5 1.4 99

125 3 49 6 21 10 7 2 98

154 4 44 7 21 7 6 3 98

182 0.9 39 4 26 10 8 4 95

* no major compound (<5% AR each of IN-L9225, JZ789, L9223, W8268)

Minor unidentified fractions in aqueous phase e.g. IN-L9226, and polar material (all <5%AR) excluded from the

Table


Table B.8.306 Degradation of Triazine-14

C Thifensulfuron-methyl in the Pond system

DAT % for applied RA


Thif L9225 JZ789 V7160 A4098 Ext.* Bound

0 98 0.1 - - 1.2 - - - 100

1 90 1.5 - - 1.3 - 4 - 98

7 69 14 1.5 - 1.5 5 4 - 97

14 52 23 4 1.5 2 10 4 - 97

28 31 33 8 1.5 4 12 6 - 97

42 20 36 11 3 4 13 7 - 96

56 13 37 15 5 4 12 8 0.7 97

70 9 34 15 9 5 12 11 0.6 96

84 5 28 19 10 5 12 13 1.3 95

100 4 28 16 14 5 13 13 1.6 96

125 1.1 20 21 13 6 13 14 3 94

154 0.4 15 17 19 6 11 18 4 95

182 0.3 11 15 25 5 13 15 4 92

* no major compound (<5% AR each of IN-L9225, JZ789, V7160, A4098, L9226, B5528)

Minor unidentified fractions in aqueous phase e.g. IN-L9226, IN-B5528 and polar material (all <5%AR) excluded

from the Table

Table B.8.307 Degradation of Triazine-14

C Thifensulfuron-methyl in the Stream system

DAT % of applied RA


Thif L9225 JZ789 V7160 A4098 Ext.* Bound

0 99 0.2 0.5 - - - - - 100

1 89 1.5 0.2 - 1.7 - 4 - 98

7 75 12 0.5 0.4 1.4 7 1.7 - 100

14 62 21 1.1 1.1 2 7 3 - 98

28 41 35 4 1.1 4 9 1.3 - 97

42 32 42 5 0.3 5 10 1.5 - 99

56 20 41 8 1.1 9 11 3 - 98

70 18 48 7 2 8 11 3 0.4 99

84 8 40 10 2 14 12 5 3 97

100 8 55 9 3 9 11 4 0.9 99

125 4 52 7 5 11 12 5 1.5 98

154 1.4 15 15 5 16 13 7 9 86

182 0.5 20 8 8 19 15 7 8 90

* no major compound (<5% AR each of IN-L9225, JZ789, V7160, A4098, L9226, B5528)

Minor unidentified fractions in aqueous phase e.g. IN-L9226, IN-B5528 and polar material (all <5%AR) excluded

from the Table.

The rates of degradation of thifensulfuron-methyl and its metabolites were recalculated using

ModelManager version 1.0 (Singles S.K. , 2000, report 1206, supplement No. 1). Results are

shown in table below (R2 was > 0.97).


DT50 (d) of thifensulfuron-methyl and its major metabolites in aqueous phase

Thiophene label Triazine label

Pond Stream Pond Stream

Thifensulfuron-

methyl

18 26 18 26

IN-L9225 66 109 72 109

IN-JZ789 51 27 - -

IN-A4098 - - 49 71

Conclusions : Thifensulfuron-methyl is significantly degraded in water sediment systems.

Degradation occurs by hydrolysis to the acid derivative IN-L9225 (max. 55 % after 70-100 d)

further degraded to IN-JZ789 (max. 21 % after 125 d) by O-demethylation. Cleavage of the

sulfonylurea bridge leads to IN-L9223 (2-acid-3-sulfonamide, max. 39 % after 182 d) and IN-

V7160 (triazine urea, max. 25 % after 182 d) and IN-A4098 (triazine amine, max. 19 % after 182

d). No major compounds were found in sediment. Thifensulfuron-methyl was poorly mineralised

(< 4 % for the thiophene moiety and < 9 % for the triazine moiety after 182 d) and bound

residues were < 18 % for both moieties. For thifensulfuron-methyl, DT50 and DT90 values were

calculated to be respectively 18 - 26 d (mean 22 d) and 60 - 86 d in water, and 21 - 27 d and 71 -

91 d in whole system using first order kinetics. For IN-L9225, IN-JZ789 and IN-A4098, DT50

were calculated to be 66 - 109 d (mean 89 d), 27 - 51 d (mean 39 d) and 49 - 71 d (mean 60 d),

respectively.


Report: van Beinum, W., Beulke, S. (2006); Calculation of degradation endpoints from water-

sediment studies for Thifensulfuron-methyl (DPX-M6316) and its metabolites


Guidelines: FOCUS (2005) Deviations: None

Testing Facility: Central Science Laboratory, Sand Hutton, York, UK


GLP: No

Certifying Authority: Not applicable

Previous


Regulation 1141/2010. The following study provided a modern FOCUS

kinetic assessment of the above acceptable water sediment study.



the regulatory assessment. The detailed study summary from DuPont is

provided below, supplemented with additional information added by the

UK RMS during the evaluation. Endpoints from this study are

combined with acceptable information from the Task Force submission

and used to determine appropriate surface water input parameters.

The analysis presented in this report were based on the data derived by Spare (2000) on the rate

and route of degradation of Thifensulfuron-methyl (DPX-M6316) and its major metabolites in

two aerobic water-sediment systems.

Degradation endpoints from two water-sediment systems (Town Park Pond and Red Oak Stream)

with [14

C]-Thifensulfuron-methyl (thiophene label and triazine label) were derived for the parent

compound and its major metabolites IN-L9225, IN-JZ789, IN-L9223, IN-V7160, and IN-A4098

in accordance with FOCUS guidance. Persistence endpoints for comparison with regulatory

triggers for further work and endpoints for use as model input were calculated. A maximum of

four kinetic models were fitted to the concentrations of the parent compound or the metabolite in

the water phase, the sediment phase and the whole system from maximum accumulation

onwards. A model that considers parent degradation in the water and sediment and exchange

between the two compartments was fitted to water and sediment data simultaneously (Level P-

II). Degradation endpoints were derived for IN-L9225 and IN-V7160 in the total water-sediment

system using a model that considers degradation of the parent and formation and degradation of

the metabolite.

Persistence DT50 values for Thifensulfuron-methyl in the Town Park water-sediment system

were 16.5 days in the water column, 10.6 days in the sediment, and 16.8 days in the total system.

Dissipation was somewhat slower in the Red Oak water-sediment system, with DT50 values of

23.5 days in the water column, 25.3 days in the sediment phase, and 23.4 days in the total

system.


Table B.8.308 Summary of persistence endpoints for Thifensulfuron-methyl

System DT50 (days) DT90 (days) Chi2 error % Kinetic Model

Water Town Park 16.5 63.1 3.1 FOMC

Red Oak 23.5 89.7 3.2 FOMC

Sediment Town Park 10.6 87.7 5.9 HS

Red Oak 25.3 97.4 5.9 FOMC

Total System Town Park 16.8 63.8 1.5 DFOP

Red Oak 23.4 90.4 1.9 HS

Persistence DT50 values for IN-L9225 were 93.9 days, 103.6 days, and 94.7 days for the water

phase, sediment phase and the total system of the Town Park water-sediment system,

respectively. Default DT50 values of 1000 days were assigned to IN-L9225 in the Red Oak

water-sediment system. A robust fitting of kinetic models was not possible for this system

because of scattering in the data.

Default values of 1000 days were also assigned to the remaining metabolites (IN-JZ789 and IN-

V7160, data not tabulated) because a robust fitting was not possible (the number of datapoints in

the decline phase was too small or there was no clear decline in concentrations by the end of the

study period).

Table B.8.309 Summary of persistence endpoints for IN-L9225

System DissT50 (days) DissT90 (days) Kinetic Model

Water Town Park 93.9 312.0 SFO

Red Oak 1000 1000 n/a

Sediment Town Park 103.6 344.2 SFO

Red Oak 1000 1000 n/a

Total system Town Park 94.7 314.6 SFO

Red Oak 1000 1000 n/a

Modelling system DegT50 values for Thifensulfuron-methyl for modelling using FOCUS surface

water Step 1, 2 and 3 were 18.2 days for the Town Park water-sediment system (chi2 error % =

3.9) and 26.1 days for the Red Oak water-sediment system (chi2 error % = 3.2) (see Table

B.8.310 and Figure B.8.37a). The choice of modelling input parameters was appropriate in light

of the generic guidance on FOCUSsw (2012).


Table B.8.310 Summary of modelling endpoints for Thifensulfuron-methyl used in FOCUSsw

Steps 1, 2 and 3

System Step 1 Step 2 Step 3

DegT50 Kinetics DegT50 Kinetics DegT50 Kinetics

Town park 18.2

(system) P-I, SFO

18.2

(P-I system value

used for water)

P-I, SFO,

used as

default

18.2

(P-I system

value used for

water)

P-I, SFO, used

as default

1000 (default value

used for sediment) default

1000

(default value

used for

sediment)

default

Red oak 26.1

(system) P-I, SFO

26.1

(P-I system value

used for water)

P-I, SFO,

used as

default

26.1

(P-I system

value used for

sediment)

P-I, SFO, used

as default

1000

(default used for

sediment)

default

1000

(default used

for water)

default


Figure B.8.37a: Graphical fitting of the whole system SFO DT50 values for the Town Park

(left hand image) and Red Oak (right hand image)


Modelling system degradation endpoints were derived for IN-L9225 and IN-V7160. The DegT50

values for IN-L9225 were 66.6 days in the Town Park system and 109.3 in the Red Oak water-

sediment system. The DegT50 values for IN-V7160 were set to the default value of 1000 days

because the fitted degradation rate constant for the metabolite was zero for both water-sediment

systems. All other metabolites had the degradation DT50 set to the default value of 1000days for

both compartments.

(van Beinum, W., Beulke, S., 2006)

Report: M. Simmonds (2012b) [14

C]-Thifensulfuron-methyl: Degradation and

retention in two water-sediment systems. Battelle UK Ltd [Cheminova A/S],

Unpublished report No.: WB/10/010 [CHA Doc. No. 285 TIM]



Previous





the regualtory assessment. The detailed study summary from the Task

Force is provided below, supplemented with additional information

added by the UK RMS during the evaluation. Kinetic endpoints from

this study are used to derive overall mean kinetic input parameters for

FOCUS surface water modelling for parent Thifensulfuron-methyl.

Executive Summary:

The route and rate of degradation of [thiophene-2-14

C]-Thifensulfuron-methyl and [triazine-2-14

C]-Thifensulfuron-methyl has been investigated in two water-sediment systems: Swiss Lake

water-sediment system, pH (H2O) 7.4 and Calwich Abbey Lake system, pH (H2O) 8.3, for 104

days at 20°C in darkness. Thifensulfuron-methyl was applied to the water surface at an

approximate application rate of 250 g ai ha-1

, equivalent to an initial water concentration of 0.08

mg/L. The overall recoveries were good for all systems with mean values for each system

ranging from 98.3 to 100.1% of applied radioactivity (AR). Individual recoveries were all within

the range of 90 to 110% AR, namely, 93.2% to 103.7% AR.

In the total system, Thifensulfuron-methyl steadily degraded in both systems, declining to levels

of between 2.8% and 11.6% AR over the course of the study. The dissipation of Thifensulfuron-

methyl from the water phase and degradation in the total system was evaluated according to the

FOCUS guidance document on degradation kinetics using the most appropriate model for the

best fit to the data set. The results are calculated from the thiophene and triazine labels combined

as replicates and are presented in the table below. In addition, kinetic evaluations were carried

out on the metabolite IN-L9225 in the total system. In the opinion of the Applicant, the Swiss

Lake dataset indicated a single inconsistency in the levels of IN-L9225 observed at 104 days with

the remaining data. Due to the uncertainty over whether this value is really an outlier, this


evaluation has been conducted including and excluding this outlier. It should be noted that for all

metabolites, a very simple conservative surface water exposure assessment has been performed

which assumed a default 1000 d DT50 in water/sediment systems. Therefore the metabolite

specific DT50 values are not actually used in the final exposure assessment.

Table B.8.311 Summary of DT50 and DT90 values for Thifensulfuron-methyl and IN-L9225 in

water sediment systems.

Water-sediment System Thifensulfuron-methyl IN-L9225

Model DT50 (days) DT90 (days) DT50 (days) DT90 (days)

Swiss Lake (water) SFO 32.0 106.5 NA NA

Swiss Lake (total system) SFO 32.3 107.3 162 (109)* 537 (362)*

Calwich Abbey (water) SFO 17.3 57.3 NA NA

Calwich Abbey (total system) SFO 17.6 58.5 142 473

* Values calculated with outlier removed. Neither value used in actual environmental exposure assessment.

The maximum degree of volatile formation was low in both systems, ranging from 1.8% to 2.6%

AR in both labels and both systems at the end of the study.

In the thiophene-labelled systems, the major metabolites observed were IN-L9225 (max. 52.7%

AR), IN-L9223 (max 24.3% AR) and IN-JZ789 (max. 15.5% AR). The metabolite IN-L9226

was also observed to a lesser degree, achieving a maximum level of 7.2% AR. Other minor

metabolites were formed, none of which achieved >5% AR at any timepoint.

In the triazine-labelled systems, the major metabolites observed were IN-L9225 (max. 49.6%

AR), IN-A4098 (max. 20.0% AR) and IN-JZ789 (max. 13.1% AR). The metabolite IN-L9226

was also observed to a lesser degree, achieving a maximum level 7.8% AR. Other minor

metabolites were formed, none of which achieved >5% AR at any timepoint.


Materials:

1.Test Material

[Thiophen-2-14

C]-Thifensulfuron-methyl Specific activity 5.17 MBq/mg

[Triazine-2-14

C]-Thifensulfuron-methyl Specific activity 5.18 MBq/mg


Description: Off-White solid

Lot/Batch #: [Thiophen-2-14


[Triazine-2-14



Purity: [Thiophen-2-14


[Triazine-2-14




CAS #: 79277-27-3


2. Water/Sediment Two freshly collected water / sediment systems were used, one from Swiss

Lake, Chatsworth, Derbyshire, and one from Calwich Abbey Lake,

Calwich, Ashbourne, Derbyshire. Prior to use the water was passed

through a 0.2 mm sieve and the sediment sieved through a 2.0 mm sieve.

Table B.8.312 Physicochemical parameter of the water / sediment systems

System Swiss Lake Calwich Abbey Lake

Before Start At End Before Start At End

Flask number 86825 86826 86825 86826 86833 86834 86833 86834

Water phase

Total OC (µg/L) 8.0 - - - 3.9 - - -

pH 7.6 7.3 6.5 6.75 8.25 8.35 7.31 7.09

Oxygen content (mg/L) 7.2 7.1 6.2 6.1 7.4 6.9 5.9 6.3

Redox potential (mV) 80 51 419 283 80 50 391 104

Sediment

Redox potential (mV) -168 -566 -373 -454 -512 -406 -589 -512

C.E.C (meq/100g) 3.3 10.1

pH 6.0 7.4

OC (%) 0.95 - - - 5.0 - - -

Microbial biomass (µgC/g dry

sediment) 161 136 838 786

% Clay 4 - - - 8 - - -

% Silt 7 - - - 59 - - -

% Sand 89 - - - 33 - - -

UK Classification Sand Silt loam

Study Design:


The sediment and associated water were added to specially adapted individual glass incubation

flasks with a screw top and straight sides of approximately 600 mL capacity (6.0 cm diameter).

Approximately 133 g oven-dried equivalent (ode) of Swiss Lake sediment or 74 g ode of

Calwich Abbey Lake sediment (each sieved to 2 mm) along with ca 337 mL of the associated

water, was dispensed into glass flasks. The samples were allowed to acclimatise under study

conditions for approximately 10 days prior to application of the test item. Ratios of

approximately 1:4 (based upon soil: water depth) were obtained for all samples of both systems.

A layer of ca 3 cm depth was established and then water was added to give a column of about 12

cm above the sediment. Each flask was connected to a series of three traps, the first containing

ethylene glycol, and the second and third containing 2M potassium hydroxide. The test systems

were maintained at 20 ± 2°C for the experimental period.


Radiolabelled Thifensulfuron-methyl was applied to the surface of the test system at a

concentration of 27.8-28.7 µg per unit. The study was conducted over 104 days in dark

conditions.

2. Sampling

Duplicate units and their associated traps were removed for analysis immediately after test

substance application. Further duplicate incubation units and their associated traps were

removed at intervals of 3, 7, 14, 31, 59 and 104 days after application.

Biomass units were removed for analysis immediately after dosing (Day 0) and at the end of the

incubation (104 days).


The water was decanted from the sediment directly into a pre-weighed bottle containing 30 mL

of methanol, taking care not to disturb the sediment. The total volume was determined by weight

and the radioactive content determined by taking appropriate aliquots, by weight, for liquid

scintillation counting (LSC).

Sediment samples were extracted by shaking and centrifugation three times with

methanol:water:formic acid (80:20:1 v/v/v). The supernatants were pooled and quantified by

LSC. The sediment was then subjected to a further extraction regime by shaking and

centrifugation three times with acetonitrile:water (50/50 v/v). The supernatants were pooled and

quantified by LSC. Sample extracts were concentrated to 1-2 mL by turbovap evaporation and

reconstituted in water and acetonitrile with the aid of sonication. The extract was then quantified

by LSC. The sediment residues were air dried prior to quantification by combustion.

Sub-samples of selected residues were further extracted via fractionation into humin, humic acids

and fulvic acids using AIBS methods. Radioactivity in the fulvic acid and reconstituted humic

acid fractions was determined by LSC. Radioactivity in the humin fraction was determined by

combustion followed by LSC.

The surface water and sediment extracts were co-chromatographed with the test substance and

appropriate potential degradation product reference standards by HPLC in duplicate. Selected

extracts were chromatographed using LC-MS to confirm the identification of Thifensulfuron-

methyl and metabolites. With the exception of the zero time samples, trap solutions were

removed for analysis at each sampling time. The volume of each trap solution was measured by

weight, recorded and the radioactivity present was determined by LSC.



Table B.8.313 Mean percentage recovery of applied radioactivity for Swiss Lake

Sampling Interval

(Days)

Surface

Water

Sediment

Extract 1

Sediment

Extract 2

Unextracted Total

Volatiles

Mass

Balance

[Thiophene-2-14


0 99.28 2.45 NA 0.13 NA 101.86

3 98.60 1.39 NA 0.12 0.08 100.18

7 94.15 2.37 NA 1.12 0.33 97.96

14 91.39 1.82 0.11 0.16 0.22 93.69

31 83.59 14.51 1.12 1.26 1.10 101.58

59 81.26 13.75 1.51 1.87 1.03 99.41

104 80.71 15.71 1.51 2.14 1.94 101.99

[Triazine-2-14


0 99.42 2.49 NA 0.09 NA 101.99

3 98.56 2.44 NA 0.12 0.02 101.13

7 94.57 4.75 NA 0.48 0.07 99.86

14 89.42 5.18 0.23 0.20 0.06 95.08

31 83.88 16.46 1.40 0.99 0.17 102.89

59 76.13 18.33 2.50 2.52 0.60 100.07

104 74.45 17.41 2.35 3.40 2.17 99.76

Table B.8.314 Mean percentage recovery of applied radioactivity for Calwich Abbey Lake

Sampling Interval

(Days)

Surface

Water

Sediment

Extract 1

Sediment

Extract 2

Unextracted Total

Volatiles

Mass

Balance

[Thiophene-2-14


0 98.31 1.92 NA 0.16 NA 100.39

3 93.08 5.46 NA 1.52 0.09 100.14

7 85.92 9.32 NA 2.55 0.25 98.04

14 81.41 9.92 0.93 1.25 0.52 94.02

31 73.94 19.31 2.77 3.58 1.06 100.65

59 65.93 20.21 4.07 6.64 1.26 98.10

104 64.78 18.32 3.47 7.70 2.55 96.81

[Triazine-2-14


0 98.62 1.67 NA 0.13 NA 100.41

3 94.17 4.56 NA 0.81 0.02 99.55

7 97.42 1.81 NA 0.30 0.05 99.58

14 75.88 14.50 2.04 2.38 0.06 94.85

31 77.53 19.01 3.14 3.69 0.22 103.58

59 67.44 21.71 4.49 6.37 0.37 100.38

104 60.44 22.95 4.40 9.89 1.78 99.45


Table B.8.315 Characterisation of non-extractable residues in Calwich Abbey Lake sediment by

organic matter fractionation

Label Timepoint (days) Unit As % Applied

Fulvic Acid Humic Acid Humin Total

Thiophene 104 10055 3.68 2.07 2.46 8.21

Triazine 104 10099 4.62 2.37 2.39 9.37

As % of Non-Extractable Residue

Thiophene 104 10055 44.83 25.22 29.95 100.00

Triazine 104 10099 49.22 25.30 25.48 100.00

Table B.8.316 Mean percentage recovery of applied radioactivity present as Thifensulfuron-

methyl and metabolites for Swiss Lake following [Thiophene-2-14


application

Incubation Time (days)

0 3 7 14 31 59 104

Water

% AR 99.28 98.60 94.15 91.39 83.59 81.91 81.26


IN-L9223 0.00 0.00 0.00 0.00 3.08 6.26 18.37

IN-JZ789 0.00 0.00 0.91 1.10 2.39 3.88 9.75

IN-L9226 0.29 0.27 0.80 0.84 0.92 0.60 1.10

IN-L9225 0.00 0.36 2.04 3.30 28.46 39.98 40.60

Sediment

% AR 2.45 1.39 2.37 1.82 15.63 15.26 17.21


IN-L9223 0.00 0.00 0.26 0.00 4.72 4.05 6.25

IN-JZ789 0.07 0.00 0.21 0.00 3.44 3.04 2.97

IN-A5546 0.72 0.00 0.79 0.00 1.78 1.12 0.67

IN-L9226 0.04 0.00 0.14 0.00 2.29 2.55 3.49

IN-L9225 0.14 0.00 0.25 0.00 2.45 3.52 3.12

Total

% AR 101.73 99.99 96.52 93.21 99.22 96.52 97.92


IN-L9223 0.00 0.00 0.26 0.00 7.80 10.25 24.33

IN-JZ789 0.07 0.00 1.12 1.10 5.83 6.89 12.60

IN-A5546 0.72 0.00 0.79 0.00 1.78 1.12 0.67

IN-L9226 0.33 0.27 0.94 0.84 3.21 3.13 4.55

IN-L9225 0.14 0.36 2.29 3.30 30.91 43.26 43.65



0 3 7 14 31 59 104

Total Unknowns 0.00 0.00 0.16 0.00 0.18 0.20 0.44


methyl and metabolites for Swiss Lake following [Triazine-2-14


application


0 3 7 14 31 59 104

Water

% AR 99.42 98.56 94.57 89.42 83.88 78.52 76.13


IN-A4098 0.00 0.00 2.04 1.78 3.55 8.16 16.79

IN-JZ789 0.00 0.00 0.00 0.00 1.43 6.75 11.84

IN-L9226 0.32 0.00 0.28 0.47 0.55 1.03 1.26

IN-L9225 0.00 0.18 3.44 5.86 28.46 38.35 27.33

Sediment

% AR 2.49 2.44 4.75 5.18 17.85 20.82 19.75


IN-B5528* 0.49 1.17 1.56 0.66 2.46 3.55 4.34

IN-A4098 0.55 0.27 1.43 0.71 3.36 2.88 3.20

IN-JZ789 0.00 0.07 0.01 0.17 1.46 2.23 1.28

IN-L9226 0.09 0.05 0.17 0.79 2.34 3.40 3.48

IN-L9225 0.00 0.39 0.16 0.67 2.88 3.90 2.59

Total

% AR 101.90 101.00 99.31 94.60 101.73 96.95 94.20


IN-B5528* 0.49 1.17 1.56 0.66 2.46 3.55 4.34

IN-A4098 0.55 0.27 3.47 2.50 6.90 11.03 19.98

IN-JZ789 0.00 0.07 0.01 0.17 2.89 8.98 13.12

IN-L9226 0.41 0.05 0.45 1.26 2.90 4.44 4.74

IN-L9225 0.00 0.57 3.60 6.53 31.34 42.25 29.91

Total Unknowns** 0.06 0.04 0.15 0.48 3.77 4.05 11.39

* IN-B5528 not confirmed by LC/MS;

** All unknown metabolites < 4.2% AR.



methyl and metabolites for Calwich Abbey Lake following [Thiophene-2-14

C]-Thifensulfuron-

methyl application


0 3 7 14 31 59 104

Water

% AR 98.31 93.08 85.92 81.41 73.94 65.93 64.78


IN-L9223 0.00 0.00 0.00 0.00 2.94 4.36 9.91

IN-JZ789 0.00 0.00 0.16 0.40 3.95 7.65 13.00

IN-L9225 1.02 6.94 10.86 18.20 45.71 42.38 39.14

Sediment

% AR 1.92 5.46 9.32 9.92 22.08 24.28 21.79


IN-L9223 0.00 0.28 0.92 0.61 3.04 3.45 7.66

IN-JZ789 0.00 0.23 0.49 0.95 2.90 2.70 2.53

IN-L9226 0.00 0.73 2.35 3.61 4.94 6.67 7.21

IN-L9225 0.00 1.81 1.98 1.98 6.95 6.50 3.69

Total

% AR 100.23 98.53 95.24 91.33 96.02 90.21 86.56


IN-L9223 0.00 0.28 0.92 0.61 5.98 7.81 17.57

IN-JZ789 0.00 0.23 0.65 1.35 6.85 10.35 15.53

IN-L9226 0.21 0.73 3.03 4.29 4.94 7.02 7.21

IN-L9225 1.02 8.74 12.83 20.18 52.66 48.88 42.83

Total Unknowns 0.00 0.04 0.17 1.32 0.29 0.38 0.57



methyl and metabolites for Calwich Abbey Lake following [Triazine-2-14

C]-Thifensulfuron-

methyl application


0 3 7 14 31 59 104

Water

% AR 98.62 94.17 97.42 75.88 77.53 67.44 60.44


IN-A4098 0.00 0.00 1.25 1.76 2.85 4.21 5.06

IN-JZ789 0.00 0.00 0.00 1.34 3.98 7.02 9.70

IN-L9225 1.82 4.61 10.87 20.08 43.82 43.29 39.62

Sediment

% AR 1.67 4.56 1.81 14.50 22.15 26.20 27.35


IN-B5528 0.00 0.71 0.00 2.64 2.39 3.14 4.02

IN-A4098 0.00 0.77 0.00 1.51 2.89 2.80 2.95

IN-JZ789 0.00 0.07 0.00 0.40 2.02 1.78 1.99

IN-L9226 0.00 0.68 0.00 5.08 4.85 7.78 7.40

IN-L9225 0.00 0.47 0.00 2.63 5.78 5.93 5.64

Total

% AR 100.28 98.73 99.23 90.38 99.68 93.64 87.79


IN-B5528 0.00 0.71 0.00 2.64 2.39 3.14 4.02

IN-A4098 0.00 0.77 1.25 3.27 5.73 7.01 8.01

IN-JZ789 0.00 0.07 0.00 1.74 6.00 8.80 11.69

IN-L9226 0.00 0.68 0.00 5.41 4.85 7.78 7.40

IN-L9225 1.82 5.09 10.87 22.71 49.60 49.22 45.26

Total Unknowns** 0.00 0.09 0.00 0.43 2.54 2.89 5.37

* IN-B5528 not confirmed by LC/MS;

** All unknown metabolites < 3.7% AR

Table B.8.320 DT50 and DT90 values for Thifensulfuron-methyl

Water-sediment System Thifensulfuron-methyl

Model DT50 (days) DT90 (days) Chi2 (%) t-test

Swiss Lake (water) SFO 32.0 106.5 4.3 3.5E-18

Swiss Lake (total system) SFO 32.3 107.3 4.3 1.6E-18

Calwich Abbey (water) SFO 17.3 57.3 4.6 7.8E-16

Calwich Abbey (total system) SFO 17.6 58.5 4.5 5.2E-16


The DT50 value for the degradation of the most significant metabolite, IN-L9225, in the total

water/sediment systems was 162 days (109 days with outlier removed) in the Swiss Lake total

system and 142 days in the Calwich Abbey Lake total system. Corresponding DT90 values were

537 days (362 days with outlier removed) and 473 days respectively.

Table B.8.321 DT50 and DT90 values for IN-L9225

Total System IN-L9225

DT50 (days) DT90 (days) ffm (-) Chi2 (%) t-test

Swiss Lake

(outlier removed)

162

(109)

537

(362)

0.58

(0.60)

27.0

(32.1)

0.0308

(0.0063)

Calwich Abbey Lake 142 473 0.67 14.0 2.9E-04

Conclusions:

[14

C]-Thifensulfuron-methyl was found to steadily degrade in natural water sediment systems

incubated under aerobic conditions at 20 ºC with total system DT50 values of 32.3 days and 17.6

days for the Swiss Lake and Calwich Abbey systems investigated (DT90 values of 107.3 and 58.5

days respectively).

Following application to the overlying water, the compound dissipated from the water phase with

a DT50 value of 32.0 days for the Swiss Lake system and 17.3 days for the Calwich Abbey

system, with corresponding DT90 values of 106.5 days and 57.3 days for each system

respectively.

The applied radioactivity dissipated gradually from the water phase to the sediment to form

bound residues (≤10% AR) and minor amounts of carbon dioxide (<3% AR).

Calculation of half-lives for modelling purposes

The DT50 values determined in the above study are best fit trigger DT50 values. However,

because the best fit model in all cases was SFO, these values are also considered suitable for

deriving half-lives for modelling purposes. For Thifensulfuron-methyl, both total system fits

were acceptable visually and statistically, giving DT50 values of 32.3 and 17.6 days (mean

25 days). Degradation was predominately in the water phase. For IN-L9225, both total system

fits were acceptable visually, but the Chi2 error was relatively high in one system. Degradation

was predominately in the water phase.


Figure B.8.38 Proposed metabolite pathway for Thifensulfuron-methyl in water-sediments

systems

S

S

HN

HN

N N

N OCH3

CH3

OO O

OCH3

O

S

S

HN

HN

N N

N OH

CH3

OO O

OH

O

S

S

HN

HN

N N

N OCH3

CH3

OO O

OH

O

S

S

NH2

O O

OH

O

H2N

N N

N OCH3

CH3

H2N

N N

N OH

CH3

CO2 and Non-extractable residues

O-desmethyl triazine amineIN-B5528

Triazine amineIN-A4098

2-Aicd-3-sulfonamideIN-L9223

O-desmethyl thifensulfuron acidIN-JZ789

Thifensulfuron acidIN-L9225


S

S

HN

HN

N N

N OH

CH3

OO O

OCH3

O

O-desmethyl thifensulfuron-methylIN-L9226

(Simmonds, 2012b)

Combining the acceptable water sediment study data from the two Applicants resulted in 4

contrasting systems being tested. For the purposes of FOCUSsw modelling, both of the


Applicants proposed the use of the whole system values for the water phase (where the majority

of degradation was expected to occur) and a default 1000 d for the sediment phase. The UK

RMS accepted this simple approach as it is in line with the FOCUS kinetics guidance. The

geometric mean of the four acceptable whole system values (i.e. 18.2, 26.1, 32.3 and 17.6 d) was

calculated to be 22.8 d and this value has been used in the UK RMS FOCUSsw exposure

assessment.

B.8.4.5 Aquatic dissipation in the field

No data submitted.

B.8.4.6 Summary & assessment – fate and behaviour in water

In the original hydrolysis study present in the DAR, Thifensulfuron-methyl was shown to

degrade rapidly via hydrolysis at pH 5 (DT50 4 to 6 d) but slower at pH 7 and 9. Degradation

occurred by cleavage of the sulphonyl urea bridge yielding the major metabolites IN-A5546 and

IN-A4098 and two unidentified polar compounds (up to 35%). In a new study submitted by

DuPont, rapid degradation was also seen at pH 4. The major transformation products detected

were an unidentified polar product (up to 25.3% at pH 4 and 20°C), IN-A5546, IN-A4098, IN-

L9226, and IN-RDF00. Similar results were seen in a new study from the Task Force, with the

exception that additional major metabolites was IN-F5475 at pH 4 (33.2%).

DuPont were asked to provide further information on the unidentified polar metabolite in their

new hydrolysis study. Du Pont’s response was that the peak only appeared at pH 4 at 20, 30 and

50ºC and pH 9 at 50ºC and that these conditions are not considered highly relevant to real-world

environmental conditions. The UK RMS did not fully accept this argument because it is possible

that surface water systems could have pH ranges covering those used in the experiments. In

addition the levels of formation of this metabolite at ambient temperatures between pH 4 and 9

cannot be determined from the available information. In addition, DuPont did include the IN-

RDF00 metabolite in their surface water exposure assessment, even though it was only formed in

significant levels in the pH 4 buffer solutions. The approach to handling the unknown metabolite

was therefore inconsistent. In response to Data Requirement 4.1 identified during the EFSA peer

review DuPont provided additional information on the identification of the unknown polar

metabolite from the hydrolysis study. This metabolite has now been identified as IN-B5528.

Due to the close structural similarity between IN-B5528, IN-F5475 and IN-A4098 it is proposed

that the aquatic risk assessment of the IN-A4098 can be used as a suitable surrogate for the

assessments of the IN-B5528 and IN-F5475 metabolites. Neither metabolite has therefore been

considered quantitatively in the surface water exposure assessment as risks arising from these are

considered covered by the IN-A4098 assessment. For completeness the structures are presented

below:-

N

N

N

NH2

O

CH3

CH3

IN-A4098 N

N

N

NH2

O

CH3

H

IN-B5528

N

N

N

OH

O

CH3

H

IN-F5475


DuPont have not further characterised the polar compound. They have surmised that as it is only

found with the triazine label, but is neither the triazine containing metabolite IN-V7160 nor IN-

A4098. They also postulated that the mw of 253.1 may not be accurate. They propose that the

peak could be reasonably attributed to multiple polar fragments of the triazine ring. For

comparison, at the same conditions of pH 4, the Task Force found the same metabolites as

DuPont except the 253.1 mw peak (see Simmonds and Buntain, 2012). However they also found

a novel metabolite thiophene urea in minor amounts <10% (which does not have a triazine ring

so cannot be the unidentified metabolite) and IN-F5475 which does have a triazine ring and has a

MW of approximately 129. The UK RMS considers that it is possible that what the Task Force

identify as IN-F5475 could be part of the polar metabolite fraction identified by the DuPont

study, with the addition of some other peaks. The aquatic risk posed by the unidentified

metabolite in the DuPont study (or IN-F5475 in the Task Force study) has not been addressed by

either Applicant. Some further consideration is therefore required. The UK RMS has performed

a risk assessment of the IN-RDF00 metabolite that was also only formed in the pH 4 samples. In

the absence of metabolite specific effects data, the aquatic risk assessment of IN-RDF00 was

conservatively performed assuming the metabolite was 10 x more toxic than parent

Thifensulfuron-methyl. Since these metabolites were only formed in the water phase at levels

comparable to IN-RDF00, and the assumption of 10 x increased toxicity it likely to be highly

conservative, the UK RMS considered that the quantitative risk assessment of IN-RDF00 could

be used as a surrogate for the assessment of either the polar metabolite fraction (mw 253) or IN-

F5475. Since the metabolites were only formed in the pH 4 samples, and there is some

uncertainty over whether the unknown metabolite in this study is a single metabolite or multiple

components, the UK RMS considered that this approach was appropriate in this case. Neither

metabolite has therefore been considered further in the surface water exposure assessment as

risks arising from these are covered by the IN-RDF00 assessment.

Three studies were conducted in sterile buffer or sterile water at 25ºC to evaluate photolytic

degradation in the aqueous environment. The original study generated a DT50 of 97 – 125h

(equivalent to 4.04 -5.2 d). Two subsequent studies generated DT50s of 0.5d and 0.32-0.68d. All

studies showed that Thifensulfuron-methyl degrades rapidly in water due to photolysis. The

major degradation products identified in the original study were IN-A4098, IN-V7160 and a

metabolite identified as IN-D8858 6 based on MS and NMR analysis. Similar results were

obtained in a new study submitted by DuPont, with an unknown peak tentatively identified as the

same metabolite IN-D8858 6 based on HPLC retention time only. In addition the IN-A5546

metabolite was detected. However in the new study by the Task Force a slightly different

structure was proposed for the IN-D8858 6. The Task Force proposed that this metabolite was

thiophenyl triazinyl amine. The structures are shown below in Figure B.8.38a. As can be seen in

the figure below, the difference arises from a possible rearrangement of the thiophene ring in the

IN-D8858 6 metabolite proposed by the DuPont submission. However the structures are

isomers, and the UK RMS considered the possibility that one of these structures may have arisen

incorrectly as a result of mis-identification.

Considering the work done by DuPont in the original study of Ryan (1986) the proposal for the

structure of IN-D8858 6 seems plausible in the opinion of the UK RMS. In that study, Mass

Spectral evidence was used to initially propose the structure as thiophenyl triazinyl amine (as

proposed by the Task Force). This proposed structure was subsequently synthesised as a

standard for use in further analytical work. Chromatographic retention times of this synthetic

standard and the photoproduct obtained in the sunlight exposed samples were shown to be the

same. However whilst the Chemical Ionisation mass spectra of the two compounds was very


similar (i.e. showing the same mass ions and major fragments) the Electron Ionisation spectra

differed in the relative intensities of several of the fragment ions. These results indicated that the

synthetic compound and the photoproducts were closely related, but not identical. Additional

NMR analysis suggested that the photoproduct was an isomer of the synthetic standard and the

structure IN-D8858 6 was proposed. In addition, a literature reference was cited that

demonstrated photoisomeration of thiophene containing compounds can occur. In re-evaluating

the work in Ryan (1986), the UK RMS considered that DuPont had provided strong evidence that

the photoproduct in that study was not thiophenyl triazinyl amine. However without a reference

standard being prepared for the IN-D8858 6 structure the UK RMS considered that the MS data

could not be used to a make an absolutely conclusive judgement on the structure. The UK RMS

does not have sufficient experience of the NMR techniques used to be able to rely on the NMR

data to confirm the identification. However based on our limited experience the information was

at least supportive and consistent with the findings of the MS work. Importantly in this work the

use of a reference standard was available to demonstrate that the photoproduct was not

thiophenyl triazinyl amine.

The identification work performed by the Task Force was much more limited and resulted in

only a tentative identification of the photoproduct as the thiophenyl triazinyl amine structure.

Although MS was undertaken, no standards were used for comparison. Effectively the structure

was proposed based on the molecular weights of fragments. In addition it should be noted that

the degree of fragmentation in the Task Force analysis was quite different to that obtained in the

DuPont study. The degree of fragmentation in the Task Force study suggested that a much softer

method of splitting had been used relative to the method in the DuPont study. As demonstrated

in the work of Ryan (1986) with softer Chemical Ionisation, it was not possible to distinguish the

photoproduct with the synthetic standard. The difference in structures was only apparent under

harsher Electon Ionisation fragmentation.

Finally the UK RMS considered whether the two unknowns could in fact be the same metabolite.

The formation of a relatively stable ion at 249/251 in both cases from the loss of OCH3

suggested that they could be the same structure. However the rest of the spectra from the two

studies are quite different. Also it should be noted that the conditions used to produce the ions

and the subsequent fragmentation were quite different. In addition the equipment used to

perform these analyses were quite different, with the analytical work being undertaken 26 years

apart. These differences may have artefactually led to a difference in fragmentation patterns and

the differences may not necessarily be due to different starting structures of the photoproducts.

Overall the evidence for the structure of the photoproduct being that represented by IN-D8858 6

as proposed by DuPont appears to be more comprehensive (two forms of MS plus NMR with at

least one reference standard in DuPont package compared to a single MS analysis with no

standards in the Task Force submission). However based on the existing data, the UK RMS was

unable to definitively conclude on the actual structures proposed. Since the aquatic risk

assessment of this metabolite has not been fully resolved, the UK RMS proposes that further

work be performed to definitively identify this photoproduct or photoproducts before any further

ecotoxicological testing is performed.

In response to Data Requirement 4.2 in the Evaluation Table DuPont provided further

information on the identification of the photoproduct coded IN-D8858 in the original aqueous

photolysis studies. In the new information presented, reference standards for both possible

structures were provided and identities confirmed via NMR and chromatographic retention times.

Futher evidence to support the earlier identification work came in the form of HPLC retention

times for the metabolite in question compared with the reference standards as well as


comparision of UV spectra. Overall the UK RMS is content to conclude that the

photodegradation product of thifensulfuron methyl in question has been identified as IN-D8858

and not the thiophenyl triazinyl amine structure IN-N8016 by using a combination of

chromatographic separation and spectra analysis. These results provide further support to the

earlier identification work that used NMR and Electron Ionisation spectra to propose the

structure as IN-D8858. No further work is considered necessary.


Figure B.8.38a: Proposed structures of photoproducts in DuPont and Task Force datasets

Thiophenyl triazinyl amine (Task Force)

S

O

CH3

O

N

NN

CH3

O

CH3

HN

IN-D8858 6 (DuPont)

Methyl-2-(4-methoxy-6-methyl-1, 3, 5-triazin-

2-yl-amino)-3-thiophene-carboxylate

S

CO2CH

3

N

N

N

CH3

NH

O CH3

Thifensulfuron-methyl is not readily biodegradable.

With regards fate and behaviour in water sediment system, DuPont referenced the acceptable

data already available in the DAR. The Task Force submitted a new study. The data from the

two studies was largely consistent, with the major metabolites listed below. Note that the IN-

V7160 metabolite was not identified in the new study supplied by the Task Force. In water

sediment studies very little Thifensulfuron-methyl (max 1.08%) was found in sediment. No

major metabolites (>10%) occurred in sediment either. Degradation of parent thifensulfuron in

the whole system (with residues largely occurring in the water phase) was relatively rapid with a

geomean DT50 of 22.8 days across the 4 systems.

The main metabolites observed in water sediment studies were as shown in the table below:

Metabolite Max occurrence in

water (% AR)

Max occurrence in

sediment (%AR)

IN-L9225 55% 7%

IN-L9226 7.8% 7.2%

IN-JZ789 21 % 4%

IN-L9223 39 % 8%

IN-V7160 25 % 6%

IN-A4098 20.0% 7%


Hydrolytic degradation of the active

substance and metabolites > 10 % ‡

Thifensulfuron – Methyl at pH4

pH 4: DT50 6.3d at 20 °C (1st order, r

2=0.993)

pH 4: DT50 2.4d at 25 °C (1st order)

pH 4: DT50 1.9d at 30 °C (1st order, r

2=0.997)

Metabolites at pH 4:

IN-A4098: 26.1% AR (25ºC) (14d)

IN-A5546: 64.2% AR (25ºC) (30d)

IN-F5475: 33.2% AR (25ºC) (30d)

IN-L9226: 13.6% AR (25ºC) (3d)

IN-RDF00: 31.85% AR (20C) (30d)

IN-B5528 Polar compound (mw 253.1): 25.3%

AR (20C) (30d)

Thifensulfuron – Methyl at pH7

pH 7: DT50 199d at 20°C (1st order, r

2=0.603)

pH 7: DT50 137d at 25°C (1st order)

pH 7: DT50 65d at 30°C (1st order, r

2=0.881)

pH 7: DT50 4.0d at 50°C (1st order, r

2=0.992)

Metabolites at pH 7:

IN-A4098: 5.9% AR (25ºC) (30d).

IN-A5546: 7.6% AR (25ºC) (30d)

Thifensulfuron – Methyl at pH 9


2=0.973)

pH 9: DT50 7.1 d at 25 °C (1st order)


2=0.997)

Metabolites at pH9:

IN-A4098: 12.4% AR (25ºC) (30d)

IN-L9223: 16.8% AR (25ºC) (30d)

IN-L9225: 70.05% AR (30C) (30d)

IN-L9225: 79.8% AR (25ºC) (30d)


Photolytic degradation of active substance

and metabolites above 10 % ‡

Thifensulfuron-methyl:

1. Study with Thifensulfuron-methyl in sterile

buffers. Exposed to 42 hours of artificial light,

equivalent to summer sunlight at Wilmington,

USA.

DT50: 98h pH5, 125h pH 7, 97h pH9 (25ºC)

Metabolites:

IN-A4098: 14% AR

IN-V7160: 11% AR

IN-D8858 6 (Methyl-3-(4-methoxy-6-methyl-

1,3,5,-triazin-2-yl-amino)-2-thiophene

carboxylate): 7% AR


buffers pH 7 and in sterile natural water.

Exposed to 15 days of artificial light equivalent

to at least 30 days of natural sunlight at

midday, Painesville Ohio, USA.

DT50: 0.5d in both pH7 buffer and sterile

natural water, (25ºC) (continuous light)

Metabolites:

polar fraction:

IN-A5546: 10.3% AR

IN-V7160: 25.8 % AR

IN-D8858 6: 15.3% AR


buffer. Exposed to 7 days of artificial light

equivalent to 18.2 days natural sunlight at 30-

50°N.

DT50: 0.32 – 0.68 d (pH 7) (25ºC) (corrected

for 1 suntest day equivalent to 2.6 days natural

sunlight at 30-50ºN)

Metabolites:

IN-A4098: 16.8% AR (168h)

IN-V7160: 19.4%AR (72h)

Thiophenyl triazinyl amine (likely to be IN-

D8858): 14.3% AR (24h)


Quantum yield of direct

phototransformation in water at > 290

nm

Study with Thifensulfuron-methyl in sterile

buffers pH 7 and in sterile natural water.

Exposed to 15 days of artificial light equivalent

to at least 30 days of natural sunlight at

midday, Painesville Ohio, USA. The quantum

yield of Thifensulfuron-methyl was calculated

to be = 0.037


buffer. Exposed to 7 days of artificial light

equivalent to 18.2 days natural sunlight at 30-

50°N.The quantum yield for Thifensulfuron-

methyl in aqueous solution at pH 7 was found

to be 0.044

Readily biodegradable ‡

(yes/no)

No

Degradation in water / sediment

Thifensulfuro

n-methyl

Distribution Max in water >99% at 0 d, Max sed 1.08% at 31d

Water /

sediment

system

pH

water

phase

pH

sed

t. oC DT50

whole

sys.

St.

Chi2

DT50

water

St.

Chi2

DT50

sed

St.

Method

of

calculatio

n

Town park

pond

7.8 7.2 20 18.2d nr 18.2d nr 1000d - SFO

Red Oak

stream

7.6 7.1 20 26.1d nr 26.1d nr 1000d - SFO

Swiss lake 5.4 - 20 32.3d 4.3 32.0d 4.3 1000d - SFO

Calwich Abbey

Lake

7.3 - 20 17.6d 4.5 17.3d 4.6 1000d - SFO

Geometric mean 22.8d -* 1000d -

nr: not reported

*For FOCUSsw modelling the whole system geomean DT50 (22.8 day) was used for the water

phase.

Metabolite DT50 whole

system/ water /

sediment

Maximum

occurrence in water

(%AR)

Maximum

occurrence in

sediment (%AR)

IN-L9226 1000d 7.8% 7.2%

IN-JZ789 1000d 21 % after 125 d 4%

IN-L9223 (2-acid-3- 1000d 39 % after 182 d 8%


sulfonamide)

IN-V7160 (triazine urea) 1000d 25 % after 182 d 6%

IN-A4098 (triazine amine) 1000d 20.0% 7%

IN-L9225 1000d 55% 7.0%

Mineralization and non extractable residues

Water /

sediment

system

pH

water

phase

pH

sed

Mineralization

x % after n d.

(end of the

study).

Non-extractable

residues in sed.

Max x % after n d

Non-extractable

residues in sed. Max x

% after x d (end of the

study)

Town park

pond

7.8 7.2 4% at 154-182 d 18% at 154 d 15% at 182d

Red Oak

Stream

7.6 7.1 7% at 154-182 d 8% at 182d 8% at 182 d

Swiss lake 7.4 nr 2.17% at 104 d 3.40% at 104 d 3.40% at 104 d

Calwich

Abbey Lake

8.3 nr 2.55% at 104 d 9.89% at 104 d 9.89% at 104 d

nr: not reported

B.8.5 Impact on water treatment procedures (Annex IIIA 9.2.2)

Not submitted and not required for the representative use of Thifensulfuron-methyl.

For potential effects on sewage sludge, see section B.9.10.

B.8.6 Predicted environmental concentrations in surface water and groundwater

(PECsw and PECgw) (IIIA 9.2.1, 9.2.3)

Surface Water & Sediment

Previous

evaluation:

Both Applicants provided assessments of potential surface water

exposure utilising input parameters from their own data sets. In general

both submissions were acceptable and used the standard FOCUS surface

water methodology and guidance. However to ensure the surface water

exposure assessment fully considered all acceptable data from both

Applicants, the UK RMS was unable to accept either report in its

entirety. Instead the UK RMS performed an independent surface water

exposure assessment, utilising combined endpoints from both

Applicants. However many elements of the Applicant approaches were

relied upon (for example application rates and timings assumed in the

FOCUSsw modelling). For simplicity the UK RMS has produced a

combined summary based on the Applicants modelling reports, but using

UK RMS selected endpoints and UK RMS derived PECsw values.

Predicted environmental concentrations in surface water (PECsw) for the active substance

Thifensulfuron-methyl were determined using a tiered approach. The transport of


Thifensulfuron-methyl into surface water bodies was assessed by means of modelling tools and

scenarios developed by FOCUS Surface Water Working Group (FOCUS, 2001). The assessment

started with the assumption of a worst-case loading in Step 1 and was subsequently refined in

Steps 2 and 3. Risk mitigation measures were applied at Step 4.

For the purposes of the aquatic risk assessment, concentrations in surface water only were

required and no assessment of risk to sediment dwellers was necessary. To simplify the

assessment the UK RMS has only presented results of the surface water concentrations as these

are the only values relied upon in the aquatic risk assessment.

The combined residue definition for the environmental exposure assessment in surface water

from both Applicants encompassed the following 11 13 metabolites:-

IN-L9223, IN-L9225, IN-L9226, IN-A5546, IN-V7160, IN-W8268, IN-A4098, IN-JZ789, IN-

RDF00, IN-B5528, IN-F5475, 2-acid-3-triuret and IN-D8858 thiopenyl triazinyl amine.

All of these metabolites were detected in significant amounts in both soil and water, with the

exception of IN-RDF00, IN-F5475 and IN-D8858 thiopenyl triazinyl amine (which were major

in water only).

The combined GAPs from both Applicants comprised of up to 8 different crop, application rate

or application timing combinations to consider. Considering the need to assess exposure of

metabolites at Step 1 and Step 2 (including NEU and SEU scenarios) this could have resulted in

the generation of over 170 separate results tables. The surface water exposure assessment

summary from DuPont alone contained 105 separate results tables for the Step 1 and 2

FOCUSsw assessments. The UK RMS did not consider this to be practical and therefore

developed a much simplified assessment scheme for the metabolites. Rather than running

metabolite specific assessments using individual endpoints and peak occurrence levels, the UK

RMS performed a simple conservative first tier assessment that was intended to be protective of

all metabolites. This assessment assumed a default worst-case DT50 of 1000 d in soil and water

sediment systems, a default Koc of zero to maximise surface water concentrations and a default

worst-case 100% formation level in soil and water. These inputs were selected to be highly

protective of all metabolites. Due to the close structural similarity between IN-B5528, IN-F5475

and IN-A4098 it is proposed that the aquatic risk assessment of the IN-A4098 can be used as a

suitable surrogate for the assessments of the IN-B5528 and IN-F5475 metabolites. Where this

simple assessment resulted in unacceptable TER values following consideration by ecotox,

further refined assessments were performed. The only metabolite requiring further consideration

was the IN-RDF00 metabolite (where in the absence of ecotox effects data the metabolite was

conservatively assumed to be 10 x more toxic than Thifensulfuron-methyl). Overall this

approach is considered by the UK RMS to be a pragmatic approach to assessing the risks posed

by the metabolites, which in general present a much lower risk to aquatic non-target organisms

relative to the active substance.

The formulated products of Thifensulfuron-methyl are applied to a number of crops such as

winter and spring cereals, maize and soybeans for the control of a wide range of broad-leaf

weeds in the EU. The following application scenarios were selected for PECsw calculations in

the present modelling study:

Spring application to spring cereals at annual application rate of 30.0 g a.s./ha occurring

10 days after crop emergence [DuPont GAP].


Spring application to spring cereals at annual application rate of 40.8 g a.s./ha occurring

10 days after crop emergence [Task Force GAP].

Autumn application to winter cereals at annual application rate of 30.0 g a.s./ha occurring

10 days after crop emergence [DuPont GAP].

Winter application to winter cereals at 37.5 g a.s./ha occurring either between January 1st

to March 31st (Northern Europe) or between December 1st to February 28th (Southern

and Central Europe) [DuPont GAP].

Spring application to winter cereals at 37.5 g a.s./ha occurring either between April 1st to

June 30th (Northern Europe) or between March 1st to May 31st (Southern and Central

Europe) [DuPont GAP].

Spring application to winter cereals at 51 g a.s./ha occurring either between April 1st to

June 30th (Northern Europe) or between March 1st to May 31st (Southern and Central

Europe) [Task Force GAP].

Spring application to maize at annual application rate of 11.25 g a.s./ha occurring 10 days

after crop emergence [DuPont GAP].

Spring application to soybeans at annual application rate of 7.5 g a.s./ha occurring 10

days after crop emergence [DuPont GAP].

All physico-chemical input parameters (e.g., DT50, Kfoc, 1/n) for Thifensulfuron-methyl were

selected according to EU FOCUS guidance.

The simple worst-case Step 1 and 2 PECsw for all metabolites (except IN-RDF00) met the

pertinent TERa values in all application scenarios. Therefore, Step 3 PECsw calculations for the

metabolites were not considered necessary, except for metabolite IN–RDF00 which was refined

at Step 3.

The predicted exposure concentrations of Thifensulfuron-methyl exceeded the pertinent

threshold concentrations in the ecological risk assessment in Steps 1 and 2. Therefore, Step 3

simulations were conducted for Thifensulfuron-methyl. Risk mitigation measures in the form of

no spray buffer zones and vegetated filter strips to mitigate runoff were applied at Step 4. In

performing this exposure assessment the UK RMS utilised a Regulatory Acceptable

Concentration (RAC) of 0.0866 μg Thifensulfuron-methyl/l. This RAC was derived from the

lowest a.s. endpoint (toxicity to the aquatic plant Lemna gibba at 0.866 μg/l divided by the

Annex VI trigger of 10). This RAC has been used to determine the level of mitigation necessary

at Step 4 in order to achieve acceptable aquatic risk assessments for each scenario where

possible. As a result of the PRAPeR expert meeting 128 (March 2015) an acceptable toxicity

study with Lemna is no longer considered to be available for use in the risk assessment and

therefore a data gap has been set which should be addressed at a product level. Aquatic

macrophytes are considered to be the most sensitive aquatic group as a result of exposure to

Thifensulfuron-methyl. Although an RAC for the standard aquatic plant species (Lemna) is not

available, an RAC derived from a study with the aquatic macrophyte Vallisneria americana

(RAC 0.023 µg/l) has been used in the Ecotox section to give an illustration of the toxicity of

Thifensulfuron-methyl to aquatic plants. Due to the reduction in the RAC, the levels of risk


mitigation presented below may no longer be sufficient to demonstrate acceptable risks to aquatic

life.

Input parameters

All physico-chemical input parameters were selected in compliance with the recommendations of

FOCUS guidance. Degradation parameters (DegT50) were derived in general agreement with

FOCUS kinetics guidance (FOCUS, 2006). Degradation of the active substance in soil was

simulated with the respective laboratory values which were normalised to a reference

temperature of 20C and soil moisture content at 10 kPa (pF2). The PECsw calculations were

based on the geo-mean DegT50 value for Thifensulfuron-methyl.

The geometric mean whole system DT50 of 22.8 days from the combined data set of 4 contrasting

water sediment systems was selected in the Step 1 PECsw simulations for Thifensulfuron-methyl.

This value was assigned to water phase and a default worst-case DT50 of 1000 days was assigned

to the sediment phase in Step 2, 3 and 4 PECsw simulations for Thifensulfuron-methyl. The

default worst-case DT50 of 1000 days was selected to describe degradation in total system, water,

and sediment compartment for all metabolites.

A plant uptake factor of 0.0 was assumed for Thifensulfuron-methyl and metabolites in all

simulation runs.

Key input parameters for Thifensulfuron-methyl and its significant soil and aquatic degradation

products are summarised in Table B.8.322 and B.8.323.

Table B.8.322 Key input parameters used in PECsw simulations for Thifensulfuron-methyl

Parameter Value Units Notes

Water solubility (pH 7.0): Thifensulfuron-methyl

2240 mg/L Previous Annex I agreed endpoint and

higher than new GLP figure

Vapour pressure (20C): Thifensulfuron-methyl

5.2E-9 Pa Lowest value from new GLP study

Molecular weight: Thifensulfuron-methyl

387.4 g/mole

Half life in soil (lab): Thifensulfuron-methyl

1.39 d Combined geomean of 6 soils

Freundlich Kfoc (1/n) Thifensulfuron-methyl

9 (0.932) mL/g Combined median of 9 values (arithmetic

mean 1/n)

Half life in total system (Step 1): Thifensulfuron-methyl

22.8 d Combined geomean of 4 systems

Half life in water (Step 2,3 and 4): Thifensulfuron-methyl

22.8 d Combined geomean of 4 systems

Half life in sediment (Step 2,3 and 4): Thifensulfuron-methyl

1000 d FOCUS default

Plant uptake factor 0 - default


Table B.8.323 Key input parameters used in PECsw simulations for metabolites

Parameter Value Units Notes

Water solubility (pH 7.0): 1000 mg/L Conservative default

Molecular weight: 387.4 g/mole Parent value used as default

Half life in soil (lab): 1000 d FOCUS default

Freundlich Kfoc 0 mL/g Default to maximise PECsw values

Half life in total system 1000 d FOCUS default

Half life in water 1000 d FOCUS default

Half life in sediment 1000 d FOCUS default

Maximum occurrence in soil 100 % Conservative worst-case

Maximum occurrence in water/sediment 100 % Conservative worst-case

Simulation of the PECsw for Thifensulfuron-methyl and its metabolites followed a tiered

approach. The models used for the PECsw calculations were ‘FOCUS Surface Water Tool for

Exposure Predictions – STEPS 1 and 2’ version 2.1, and ‘FOCUS SWASH’ version 3.1 for

STEP 3 calculations. MACRO version 4.4.2 and PRZM version 3.1.1 was used for drainflow

and run off simulations respectively. FOCUS TOXSWA version 3.3.1 was used to estimate

surface water PEC values. All software tools corresponded to the most recent version of the

models at the time when the assessment was conducted.

Step-3 simulations were carried out for Thifensulfuron-methyl and IN-RDF00. In Step-3 runs all

crop scenarios were parameterised in accordance to the recommendations of FOCUS (2001) and

simulated with application rates shown in Table B.8.324. Tables B.8.325 to B.8.330 give an

overview of selected application windows for Thifensulfuron-methyl application scenarios.

Table B.8.324 Application scenarios for Thifensulfuron-methyl

Crop Application period Annual Application rate

(g a.s.ha-1

)

Crop growth

Stage

First possible day of

application

Spring cereals Spring application 1 30.0 BBCH 12-39

10 days after emergence 1 x 40.8 BBCH 13-39

Winter cereals

Autumn application 1 30.0 BBCH 12-39 10 days after emergence

Winter application 1 37.5 BBCH 21 01-Jana / 01-Dec

b

Spring application 1 37.5 BBCH 30 01-Apr

a/ 01-Mar

b

1 x 51 BBCH 13-39 01-Apra/ 01-Mar

b

Maize Spring application 1 11.25 BBCH 10-16 10 days after emergence

Soybeans Spring application 1 7.5 BBCH 10-14 10 days after emergence a First possible day of application for North European scenarios.

b First possible day of application for Central and South European scenarios.


Table B.8.325 Application window used in Step-3 simulations for spring cereals: Spring

application at 30.0 g a.s./ha or 40.8 g a.s./ha

Crop Scenario

Date of

emergence

Application

Windowa

Julian

Days

Application

Dates Found by

PAT

Spring

cereals

D1 5-May 15-May to 14-June 135-165 15-May

D3 1-Apr 11-Apr to 11-May 101-131 10-Aprb

D4 26-Apr 6-May to 5-June 126-156 30-May

D5 15-Mar 25-Mar to 24-Apr 84-114 8-Apr

R4 15-Mar 25-Mar to 24-Apr 84-114 25-Mar a A 30 day window was defined in SWASH considering the first possible day of application 10 days after emergence.

b In the leap year (e.g., 1992) the Julian day 101 represents 10 April instead of 11 April (in a normal year).

Table B.8.326 Application window used in Step-3 simulations for winter cereals: Autumn

application at 30.0 g a.s./ha

Crop Scenario

Date of

emergence

Application

Windowa

Julian

Days

Application

Dates Found by

PAT

Winter

cereals

D1 25-Sep 5-Oct to 4-Nov 278-308 5-Oct

D2 25-Oct 4-Nov to 4-Dec 308-338 4-Nov

D3 21-Nov 1-Dec to 31-Dec 335-365 10-Dec

D4 22-Sep 2-Oct to 1-Nov 275-305 2-Oct

D5 10-Nov 20-Nov to 20-Dec 324-354 27-Nov

D6 30-Nov 10-Dec to 9-Jan 344-9 10-Dec

R1 12-Nov 22-Nov to 22-dec 326-356 27-Nov

R3 1-Dec 11-Dec to 10-Jan 345-10 11-Dec

R4 10-Nov 20-Nov to 20-dec 324-354 10-Dec a A 30 day window was defined in SWASH considering the first possible day of application 10 days after emergence.

Table B.8.327 Application window used in Step-3 simulations for winter cereals: Winter


Crop Scenario

Date of

emergence

Application

Windowa

Julian

Days

Application

Dates Found by

PAT

Winter

cereals

D1 25-Sep 1-Jan to 31-March 1-90 16-Jan

D2 25-Oct 1-Dec to 28-Feb 335-59 1-Dec

D3 21-Nov 1-Dec to 28-Feb 335-59 10-Dec

D4 22-Sep 1-Jan to 31-March 1-90 16-Jan

D5 10-Nov 1-Dec to 28-Feb 335-59 18-Dec

D6 30-Nov 10-Dec to 9-Jan 344-9 10-Dec

R1 12-Nov 1-Dec to 28-Feb 335-59 1-Dec

R3 1-Dec 11-Dec to 10-Jan 345-10 11-Dec

R4 10-Nov 1-Dec to 28-Feb 335-59 10-Dec a The application window was defined in SWASH considering the first possible day of application 1

st January for North

European scenarios and 1st December for Central and South European scenarios. The last day of application was defined

as 31st March for North European scenarios and 28

th February for Central and South European scenarios. For D6 and R3

the UK RMS considered these dates too early based on emergence dates. Therefore slightly later dates were selected as

reported above (consistent with the Autumn application pattern).


Table B.8.328 Application window used in Step-3 simulations for winter cereals: Spring

application at 37.5 g a.s./ha or 51 g a.s./ha

Crop Scenario

Date of

emergence

Application

Windowa

Julian

Days

Application

Dates Found by

PAT

Winter

cereals

D1 25-Sep 1-Apr to 30-June 91-181 1-Apr

D2 25-Oct 1-Mar to 31-May 60-151 12-Mar

D3 21-Nov 1-Mar to 31-May 60-151 29-Feb

D4 22-Sep 1-Apr to 30-June 91-181 18-Apr

D5 10-Nov 1-Mar to 31-May 60-151 7-Mar

D6 30-Nov 1-Mar to 31-May 60-151 5-Mar

R1 12-Nov 1-Mar to 31-May 60-151 17-Mar

R3 1-Dec 1-Mar to 31-May 60-151 1-Mar

R4 10-Nov 1-Mar to 31-May 60-151 5-Mar a The application window was defined in SWASH considering the first possible day of application 1

st April for North

European scenarios and 1st March for Central and South European scenarios. The last day of application was defined as

30th

June for North European scenarios and 31st May for Central and South European scenarios.

Table B.8.329 Application window used in Step-3 simulations for maize: Spring application

at 11.25 g a.s./ha

Crop Scenario

Date of

emergence

Application

Windowa

Julian

Days

Application

Dates Found by

PAT

Maize




D6 20-Apr 30-Apr to 30-May 120-150 3-May

R1 3-May 13-May to 12-June 133-163 15-May



R4 10-Apr 20-Apr to 20-May 110-140 20-Apr a A 30 day window was defined in SWASH considering the first possible day of application 10 days after emergence.

Table B.8.330 Application window used in Step-3 simulations for soybeans: Spring


Crop Scenario

Date of

emergence

Application

Windowa

Julian

Days

Application

Dates Found by

PAT

Soybeans R3 10-May 20-May to 19-June 140-170 01-June

R4 10-Mar 20-Mar to 19-Apr 79-109 21-Mar a A 30 day window was defined in SWASH considering the first possible day of application 10 days after emergence.


Results

Step 1 and 2

Table B.8.331 provides a summary of the maximum PECsw (and PECsed) values for

thifensulfuron at Step 1 and 2.

Table B.8.331 Summary of maximum FOCUS Step 1 and 2 PECsw and PECsed values for


Crop Application

period

(Step 2

timing)

Application

rate

(g a.s./ha)

Growth

stage

(Step 2

interception)

Step 1 Maximum PEC

values

Step 2 Maximum

PEC values

PECsw

(μg/l)

PECsed

(μg/kg)

PECsw

(μg/l)

PECsed

(μg/kg)

Spring

cereals

Spring

(Mar. – May)

1 x 30 BBCH 12-39

(minimal

cover)

10.16

0.89

0.65

(SEU)

0.06

(SEU)

1 x 40.8 13.81

1.21

0.88

(SEU)

0.08

(SEU)

Winter

cereals

Autumn

(Oct. – Feb.) 1 x 30

BBCH 12-39

(minimal

cover)

10.16

0.89

0.75

(NEU)

0.07

(NEU)

Winter

(Oct. – Feb.) 1 x 37.5

12.70

1.11

0.93

(NEU)

0.08

(NEU)

Spring

(Mar. – May)

1 x 37.5 BBCH 12-39

(minimal

cover)

12.70

1.11

0.81

(SEU)

0.07

(SEU)

1 x 51 17.27 1.51 1.10

(SEU)

0.10

(SEU)

Maize Spring

(Mar. – May) 1 x 11.25

BBCH 10-16

(minimal

cover)

3.81 0.33 0.24

(SEU)

0.02

(SEU)

Soybeans Spring

(Mar. – May) 1 x 7.5

BBCH 10-14

(minimal

cover)

2.54 0.22 0.17

(SEU)

0.02

(SEU)

It should be noted that for winter cereals (all timings and rates) the FOCUSsw simulations gave

some higher PECsw values at Step 3. Therefore Step 3 values need to be considered, even if

Step 1 or 2 exposure levels resulted in acceptable aquatic risk assessment for some species.

Spring cereals, maize and soybeans all gave lower PECsw at all Step 3 scenarios

The following Table B.8.332 provides a very simple first tier FOCUS Step 1 and 2 exposure

estimate designed to be protective of all metabolites. This exposure assessment has been

produced based on very conservative input parameters (worst-case GAP, no degradation in soil

or water, 100% formation from parent, no partitioning to sediment to maximise PECsw etc).

Given the low toxicity of the metabolites relative to the active substance, this approach is

considered appropriate to simplify the aquatic assessment of these substances. These PECsw

values are appropriate for use in the aquatic risk assessment of all major soil and water

metabolites.


Table B.8.332 Simple first tier FOCUS Step 1 and 2 exposure assessment for all metabolites

Crop Application

period

(Step 2

timing)

Application

rate

(g a.s./ha)

Growth

stage

(Step 2

interception)

Step 1 Maximum

PECsw

(μg/l)

Step 2 Maximum

PECsw

(μg/l)

Winter

cereals

Spring

(Mar. – May) 1 x 51

BBCH 12-39

(minimal

cover)

17.47 5.55

(SEU)

Step 3

Table B.8.333 to B.8.340 provide summary results of maximum and 7 d TWA PECsw values for

Thifensulfuron-methyl at Step 3 for each crop, timing and application rate combination.

Table B.8.333: Summary of maximum Step 3 PECSW and 7 d TWA PECSw for Thifensulfuron-methyl

after application of 1 × 30 g a.s./ha to winter cereals in the autumn at BBCH 12 – 39

Scenario Date of

Application

Maximum PECSW 7 d TWA PECSw Main route

of entry Date of

maximum µg/L

Date of 7 d

TWA µg/L

D1 Ditch 5-Oct 13-Feb 0.639 18-Feb 0.602 Drainage

D1 Stream 5-Oct 13-Feb 0.403 18-Feb 0.372 Drainage

D2 Ditch 4-Nov 9-Nov 2.916 16-Nov 1.275 Drainage

D2 Stream 4-Nov 9-Nov 1.875 16-Nov 0.635 Drainage

D3 Ditch 10-Dec 10-Dec 0.189 17-Dec 0.0198 Drift

D4 Pond 2-Oct 2-Oct 0.00656 9-Oct 0.00617 Drift

D4 Stream 2-Oct 2-Oct 0.164 9-Oct 0.00694 Drift

D5 Pond 27-Nov 27-Nov 0.00657 4-Dec 0.00623 Drift

D5 Stream 27-Nov 27-Nov 0.177 4-Dec 0.00993 Drift

D6 Ditch 10-Dec 17-Dec 0.301 18-Dec 0.145 Drainage

R1 Pond 27-Nov 27-Nov 0.00656 4-Dec 0.00619 Drift

R1 Stream 27-Nov 9-Dec 0.223 4-Dec 0.00323 Runoff

R3 Stream 11-Dec 16-Dec 2.350 18-Dec 0.180 Runoff




after application of 1 × 37.5 g a.s./ha to winter cereals in the winter at BBCH 12 – 39

Scenario Date of

Application


of entry Date of

maximum µg/L

Date of 7 d

TWA µg/L

D1 Ditch 16-Jan 3-Mar 2.676 9-Mar 2.270 Drainage

D1 Stream 16-Jan 3-Mar 1.677 9-Mar 1.404 Drainage

D2 Ditch 1-Dec 22-Jan 2.349 26-Jan 1.080 Drainage

D2 Stream 1-Dec 22-Jan 1.635 26-Jan 0.605 Drainage


D4 Pond 16-Jan 11-Feb 0.147 15-Feb 0.146 Drainage

D4 Stream 16-Jan 2-Feb 0.569 8-Feb 0.377 Drainage

D5 Pond 18-Dec 9-Feb 0.0317 12-Feb 0.0315 Drainage

D5 Stream 18-Dec 18-Dec 0.222 9-Jan 0.0517 Drift

D6 Ditch 10-Dec 17-Dec 0.376 18-Dec 0.181 Drainage

R1 Pond 1-Dec 1-Dec 0.00820 8-Dec 0.00770 Drift





after application of 1 × 37.5 g a.s./ha to winter cereals in the spring at BBCH 12 – 39

Scenario Date of

Application


of entry Date of

maximum µg/L

Date of 7 d

TWA µg/L

D1 Ditch 1-Apr 9-Apr 3.000 15-Apr 2.464 Drainage

D1 Stream 1-Apr 9-Apr 1.874 15-Apr 1.513 Drainage

D2 Ditch 12-Mar 23-Mar 3.160 29-Mar 1.322 Drainage

D2 Stream 12-Mar 23-Mar 1.996 29-Mar 0.733 Drainage

D3 Ditch 29-Feb 29-Feb 0.237 7-Mar 0.0267 Drift

D4 Pond 18-Apr 18-Apr 0.00820 25-Apr 0.00778 Drift

D4 Stream 18-Apr 18-Apr 0.189 25-Apr 0.00183 Drift

D5 Pond 7-Mar 7-Mar 0.00820 14-Mar 0.00767 Drift

D5 Stream 7-Mar 7-Mar 0.187 14-Mar 0.00101 Drift

D6 Ditch 5-Mar 5-Mar 0.244 10-Mar 0.0433 Drift

R1 Pond 17-Mar 1-Apr 0.0146 8-Apr 0.0137 Runoff

R1 Stream 17-Mar 1-Apr 0.364 8-Apr 0.0265 Runoff

R3 Stream 1-Mar 8-Mar 0.999 15-Mar 0.0879 Runoff

R4 Stream 5-Mar 5-Mar 0.157 12-Mar 0.00425 Drift



after application of 1 × 51 g a.s./ha to winter cereals in the spring at BBCH 13 – 39

Scenario Date of

Application


of entry Date of

maximum µg/L

Date of 7 d

TWA µg/L

D1 Ditch 1-Apr 9-Apr 4.088 15-Apr 3.357 Drainage

D1 Stream 1-Apr 9-Apr 2.554 15-Apr 2.061 Drainage

D2 Ditch 12-Mar 23-Mar 4.308 29-Mar 1.809 Drainage

D2 Stream 12-Mar 23-Mar 2.721 29-Mar 1.004 Drainage




D5 Pond 7-Mar 7-Mar 0.0111 14-Mar 0.0104 Drift



R1 Pond 17-Mar 1-Apr 0.0198 8-Apr 0.0187 Runoff





after application of 1 × 30 g a.s./ha to spring cereals in the spring at BBCH 12 – 39

Scenario Date of

Application


of entry Date of

maximum µg/L

Date of 7 d

TWA µg/L

D1 Ditch 15-May 26-May 0.251 1-Jun 0.243 Drainage

D1 Stream 15-May 24-May 0.160 31-May 0.151 Drainage

D3 Ditch 10-Apr 10-Apr 0.190 17-Apr 0.0269 Drift

D4 Pond 30-May 30-May 0.00656 6-Jun 0.00607 Drift

D4 Stream 30-May 30-May 0.158 6-Jun 0.00255 Drift



R4 Stream 25-Mar 25-Mar 0.125 1-Apr 0.00330 Drift


Table B.8.338: Summary of maximum Step 3 PECSW and 7 d TWA PECSw for Thifensulfuron-

methyl after application of 1 × 40.8 g a.s./ha to spring cereals in the spring at BBCH

13 – 39

Scenario Date of

Application


of entry Date of

maximum µg/L

Date of 7 d

TWA µg/L

D1 Ditch 15-May 26-May 0.348 1-Jun 0.337 Drainage









after application of 1 × 11.25g a.s./ha to Maize in the spring at BBCH 10-16

Scenario Date of

Application


of entry Date of

maximum µg/L

Date of 7 d

TWA µg/L

D3 Ditch 14- May 14-May 0.0587 21-May 0.00878 Drift





D6 Ditch 03-May 03-May 0.0587 10-May 0.0118 Drift

R1 Pond 15-May 20-May 0.00768 27-May 0.00713 Runoff

R1 Stream 15-May 20-May 0.139 22-May 0.0108 Runoff

R2 Stream 20-May 20-May 0.055 27-May 0.000841 Drift

R3 Stream 20-May 20-May 0.0545 27-May 0.000833 Drift

R4 Stream 20-Apr 27-Apr 0.158 04-May 0.0170 Runoff


after application of 1 × 7.5g a.s./ha to Soybeans in the spring at BBCH 10-16

Scenario Date of

Application


of entry Date of

maximum µg/L

Date of 7 d

TWA µg/L

R3 Stream 01-Jun 01-Jun 0.0385 08-Jun 0.00209 Drift



Full graphical oputputs of the exposure profiles from the winter applications to winter cereals (at

37.5 g a.s./ha) and from the spring application to winter cereals (at 51 g a.s./ha) are presented in

Appendix 1 of this RAR section. These graphical outputs are intended to be used to support and

inform the detailed aquatic risk assessment in Section B.9.2.5.

The Applicant (DuPont) proposed the use of dormancy of non-target aquatic species as a

refinement to their aquatic risk assessment (see Section B.9.2.5). This approach utilised different

Regulatory Acceptable Concentrations depending in the temperature of the FOCUS surface water

scenario water bodies, with higher endpoints being used during the Applicant defined cold

period. The standard approach to selecting conservative application windows above had

generally tried to select earliest application timings, when drainflow may be most significant and

crop interception reduced. However this approach may not necessarily be appropriate when

combined with the Applicants proposed refined assessment (since exposures occurring in the

warmer periods would need to be assessed against a lower regulatory acceptable concentration).

Further discussion of the Applicants approach is presented in Section B.9.2.5. However in order

to provide additional conservative FOCUSsw Step 3 exposure estimates for use against the

Applicants proposed refined effect endpoints, the UK RMS ran additional FOCUSsw Step 3

simulations with applications being made at the end of the Applicant defined cold period. This

ensured exposures occurred within the warm period (and thus needing to be compared against the

lower effect endpoint). Results are presented below in Table B.8.341. Interestingly the later

applications actually resulted in higher concentrations for the D2, D6 and R4 scenarios.


after application of 1 × 37.5 g a.s./ha to winter cereals in the spring at BBCH 12 – 39:

APPLICATIONS MADE AT END OF COLD PERIOD

Scenario Date of

Application


of entry Date of

maximum µg/L

Date of 7 d

TWA µg/L

D1 Ditch 16-May 16-May 0.271 23-May 0.251 Drift

D1 Stream 16-May 16-May 0.210 18-Feb 0.0382 Drift

D2 Ditch 7-May 14-May 5.353 21-May 1.871 Drainage







D6 Ditch 20-Jan 27-Jan 0.312 3-Feb 0.114 Drainage

R1 Pond 26-Apr 26-Apr 0.00820 3-May 0.00766 Drift

R1 Stream 26-Apr 7-May 0.178 14-May 0.0105 Runoff




Step 4:

The SWAN tool (v3.0.0) was used for the Step 4 simulations considering mitigation via

increased no spray buffer zones (NSBZ) and/or vegetated filter strips (VFS) to mitigate runoff as

appropriate for each crop/rate and timing combination (Table B.8.342 to B.8.348). The

mitigation parameters for runoff were as outlined in the EU FOCUS Landscape and Mitigation

guidance document for VFS of 10-12 or 18-20m.

Table B.8.342: Summary of Step 4 maximum PECSW and 7 d TWA PECSw for Thifensulfuron-

methyl after application of 1 × 30 g a.s./ha to winter cereals in the autumn at BBCH 12

– 39; 5 m no spray buffer zone plus 10-12 m or 18-20m VFS for runoff mitigation

Note the D4, D5 and R1 pond scenarios excluded from Step 4 tables as these scenarios gave

PECsw values below the RAC** at Step 3.

Scenario Date of Application

Maximum PECSW 7 d TWA PECSw Main

route of

entry Date of

maximum µg/L

Date of 7 d

TWA µg/L

5m NSBZ

D1 Ditch 5-Oct 13-Feb 0.639* 18-Feb 0.602* Drainage

D1 Stream 5-Oct 13-Feb 0.403* 18-Feb 0.372* Drainage

D2 Ditch 4-Nov 9-Nov 2.915* 16-Nov 1.274* Drainage

D2 Stream 4-Nov 9-Nov 1.875* 16-Nov 0.635* Drainage


D4 Stream 2-Oct 2-Oct 0.0601 9-Oct 0.00253 Drift

D5 Stream 27-Nov 27-Nov 0.0648 4-Dec 0.00362 Drift

D6 Ditch 10-Dec 17-Dec 0.301* 24-Dec 0.0907 Drainage

5m NSBZ and 10-12m VFS

R1 Stream 27-Nov 9-Dec 0.0900 4-Dec 0.00118 Runoff




R1 Stream 27-Nov 27-Nov 0.0457 4-Dec 0.00118 Drift


*since the peak PECsw values in these scenarios were as a result of drainflow, the Step 4 PECsw values are identical to the Step 3 values (i.e. no mitigation as a result of spray drift/VFS).

**Note that the RAC was changed as a result of PRAPeR Meeting 128 and the levels of risk

mitigation may no longer be sufficient to demonstrate an acceptable risk to aquatic life.



after application of 1 × 37.5 g a.s./ha to winter cereals in the winter at BBCH 12 – 39; 5 m no

spray buffer zone plus 10-12 m or 18-20m VFS for runoff mitigation

Note the D5 and R1 pond scenarios excluded from Step 4 tables as these scenarios gave PECsw values

below the RAC** at Step 3.

Scenario Date of

Application


of entry Date of

maximum µg/L

Date of 7 d

TWA µg/L

5m NSBZ

D1 Ditch 16-Jan 3-Mar 2.676* 9-Mar 2.270* Drainage

D1 Stream 16-Jan 3-Mar 1.677* 9-Mar 1.404* Drainage

D2 Ditch 1-Dec 22-Jan 2.349* 26-Jan 1.080* Drainage

D2 Stream 1-Dec 22-Jan 1.635* 26-Jan 0.605* Drainage


D4 Pond 16-Jan 11-Feb 0.146* 15-Feb 0.145* Drainage

D4 Stream 16-Jan 2-Feb 0.569* 8-Feb 0.377* Drainage

D5 Stream 18-Dec 18-Dec 0.0810 9-Jan 0.0517 Drift

D6 Ditch 10-Dec 17-Dec 0.375* 24-Dec 0.113 Drainage












Table B.8.344: Summary of maximum Step 4 PECSW and 7 d TWA PECSw for Thifensulfuron-

methyl after application of 1 × 37.5 g a.s./ha to winter cereals in the spring at BBCH

12 – 39; 5 m no spray buffer zone plus 10-12 m or 18-20m VFS for runoff mitigation

Note the D4, D5 and R1 pond scenarios excluded from Step 4 tables as these scenarios gave PECsw

values below the RAC** at Step 3.

Scenario Date of

Application


of entry Date of

maximum µg/L

Date of 7 d

TWA µg/L

5m NSBZ

D1 Ditch 1-Apr 9-Apr 3.000* 15-Apr 2.464* Drainage

D1 Stream 1-Apr 9-Apr 1.874* 15-Apr 1.513* Drainage

D2 Ditch 12-Mar 23-Mar 3.160* 29-Mar 1.322* Drainage

D2 Stream 12-Mar 23-Mar 1.996* 29-Mar 0.733* Drainage












*since the peak PECsw values in these scenarios were as a result of drainflow, the Step 4 PECsw values are identical to the Step 3 values (i.e. no

mitigation as a result of spray drift/VFS).





after application of 1 × 51 g a.s./ha to winter cereals in the spring at BBCH 12 – 39; 10 m no


Note the D4, D5 and R1 pond scenarios excluded from Step 4 tables as these scenarios gave PECsw

values below the RAC** at Step 3.

Scenario Date of

Application


of entry Date of

maximum µg/L

Date of 7 d

TWA µg/L

10m NSBZ

D1 Ditch 1-Apr 9-Apr 4.088* 15-Apr 3.357* Drainage

D1 Stream 1-Apr 9-Apr 2.554* 15-Apr 2.061* Drainage

D2 Ditch 12-Mar 23-Mar 4.308* 29-Mar 1.809* Drainage

D2 Stream 12-Mar 23-Mar 2.721* 29-Mar 1.004* Drainage


















after application of 1 × 30 g a.s./ha to spring cereals in the spring at BBCH 12 – 39; 5 m no


Note the D4 and D5 pond scenarios excluded from Step 4 tables as these scenarios gave PECsw values


Scenario Date of

Application


of entry Date of

maximum µg/L

Date of 7 d

TWA µg/L

5m NSBZ

D1 Ditch 15-May 26-May 0.251* 1-Jun 0.243* Drainage

D1 Stream 15-May 24-May 0.160* 31-May 0.151* Drainage










after application of 1 × 40.8 g a.s./ha to spring cereals in the spring at BBCH 12 – 39; 5 m no


Note the D4 and D5 pond scenarios excluded from Step 4 tables as these scenarios gave PECsw values


Scenario Date of

Application


of entry Date of

maximum µg/L

Date of 7 d

TWA µg/L

5m NSBZ

D1 Ditch 15-May 26-May 0.348* 1-Jun 0.337* Drainage

D1 Stream 15-May 24-May 0.221* 31-May 0.209* Drainage











Table B.8.348: Summary of Step 4 maximum PECSW and 7 d TWA PECSw for Thifensulfuron-methyl

after application of 1 × 11.25 g a.s./ha to Maize in the spring at BBCH 10-16: 10 m VFS for

run-off mitigation only

Note the D scenarios excluded from Step 4 tables as these scenarios gave PECsw values below

the RAC** at Step 3.

Scenario Date of

Application


of entry Date of

maximum µg/L

Date of 7 d

TWA µg/L

R1 Stream 15-May 20-May 0.0629 22-May 0.00531 Runoff

R4 Stream 20-Apr 27-Apr 0.0717 04-May 0.00775 Runoff



Refined Step 3 estimates for the IN-RDF00 metabolite

IN-RDF00 was the only metabolite that failed the aquatic risk assessment on the basis of the

simple first tier Step 1 and 2 PECsw estimates. A refined approach using Step 3 was therefore

performed.

The maximum amount of metabolite IN-RDF00 in aquatic systems was reported solely from the

hydrolysis study (31.9%, sterile pH 4 samples only). Since IN-RDF00 was not reported in the

water-sediment study nor in any other environmental fate study, it is assumed that the metabolite

would occur primarily in the water layer. The peak concentration of IN-RDF00 was reported at

day 30 (and not above 10% until after day 8). Therefore, it was assumed that the maximum

formation of IN-RDF00 would occur 30 days after Thifensulfuron-methyl reached its global

maximum concentration in the water body.

According to the FOCUS SW guidance (2011), the following criterion is used to determine the

water-body (ditch, stream. or pond) that is suitable for simulating the formation of metabolites.

This requires comparing the time for peak formation of metabolite (Tform) in water-sediment or

hydrolysis studies with the average hydraulic residence time of the FOCUS surface water bodies

(). The average hydraulic residence time for a stream, ditch, and pond is defined as 0.1, 5, and

150 day, respectively, in the FOCUS SW framework. If Tform >, the formation of metabolite in

the FOCUS surface water body is considered negligible (nearly all substance has flowed out

before considerable metabolite mass has been formed).

Following the above criteria it is clear that the time required for peak IN-RDF00 formation (30

days) is much longer than the average residence time in ditch and stream water bodies.

Therefore, the formation of IN-RDF00 is expected to be negligible in FOCUS ditch and stream

scenarios. However, the average residence time in the FOCUS pond scenario (150 days) is much

longer than the time for peak IN-RDF00 formation (30 days). Therefore, the formation of IN-

RDF00 is only simulated in the FOCUS pond scenarios following the FOCUS recommendation.

Since the IN-RDF00 metabolite was only formed in significant quantities in the sterile pH 4

buffer samples, a simplified approach was used to derive refined Step 3 PECsw values for this

metabolite. The UK RMS therefore determined the peak PECsw values for parent


Thifensulfuron-methyl in the pond scenarios for each GAP at Step 3. The IN-RDF00

concentrations were then estimated assuming it was formed at a peak of 31.9% and corrected for

molecular weight differences (where the molecular weight of IN-RDF00 is 392.4 and the

molecular weight of parent thifensulfuron is 387.4). Values are provided in Table B.8.349

below:-

Table B.8.349: Estimated Step 3 PECsw values for IN-RDF00 metabolite in the FOCUSsw pond

scenarios

Crop Application period

Application

rate

(g a.s./ha)

Growth stage

(Step 2

interception)

Peak Step 3 PECsw values in

pond scenarios

Thifensulfuron

PECsw

(μg/l)

IN-RDF00

PECswa

(μg/1)

Spring cereals Spring

1 x 30 BBCH 12-39

(minimal cover)

0.00656

(D4 pond) 0.00212

1 x 40.8 0.00893

(D4 pond) 0.00288

Winter cereals

Autumn 1 x 30 BBCH 12-39

(minimal cover)

0.00657

(D5 pond) 0.00212

Winter 1 x 37.5 0.147

(D4 Pond) 0.0475

Spring

1 x 37.5 BBCH 12-39

(minimal cover)

0.0146

(R1 pond) 0.00472

1 x 51 0.0198

(R1 pond) 0.00640

Maize Spring 1 x 11.25 BBCH 10-16

(minimal cover)

0.00768

(R1 pond) 0.00248

Soybeans Spring 1 x 7.5 BBCH 10-14

(minimal cover) No pond scenarios

aestimated from parent PECsw values assuming a peak occurrence of 31.9% and molecular weight correction factor of

392.4/387.4 (1.013)

Surface water exposure estimates for the formulated products

In order to assess the risks arising from the formulated product, the UK RMS produced separate

spray drift only PECsw values. These values were derived using the separate drift calculator

within the SWASH tool. In determining the appropriate spray drift buffer zones, the UK RMS

has utilised the following Regulatory Acceptable Concentrations (RACs) for the three

formulations:-

Dupont Formulation (Thifensulfuron-methyl 50SG)

RAC- 0.141 ug/l

Cheminova formulation (CHA-8730)

RAC-0.0681 ug/L

Rotam formulation (FH-009)

RAC- 0.0444 ug/l


Table B.8.350 Maximum initial PECsw values for the formulations based on spray drift only;

Single application of 75 g product per ha to winter cereals (covers represents the maximum

application rate of all three products: Thifensulfuron-methyl 50SG, CHA-8730 and FH-009 on

winter cereals)

Buffer distance (m)

FOCUS water body type

Ditch Pond Streamb

PECsw (μg/l)

FOCUS defaulta 0.4818 0.0164 0.4291

5m 0.1306 - 0.1567

6m 0.1108 - 0.1330

10m 0.0693 - 0.0832

12m 0.0584 - 0.0701

14m 0.0505 - 0.0606

18m 0.0398 - 0.0478

20m - - 0.0432

A 1m for ditch, 3.5 m for pond, 1.5 m for stream bincludes contribution from 20% treated upstream catchment

Calculated using the simple drift calculator within SWASH.


Single application of 60 g product per ha to spring cereals (covers represents the maximum

application rate of all three products: Thifensulfuron-methyl 50SG, CHA-8730 and FH-009 on

spring cereals)

Buffer distance (m)


Ditch Pond Streamb

PECsw (μg/l)

FOCUS defaulta 0.3855 0.0131 0.3433

4m 0.1273 - 0.1528

5m 0.1045 - 0.1254

8m 0.0682 - 0.08184

9m 0.0611 - 0.0733

10m 0.0554 - 0.0668

12m 0.0467 - 0.0560

14m 0.0404 - 0.0485

16m - - 0.0427

A 1m for ditch, 3.5 m for pond, 1.5 m for stream bincludes contribution from 20% treated upstream catchment



Single application of 22.5 g product per ha to maize (Thifensulfuron-methyl 50SG)

Buffer distance (m)


Ditch Pond Streamb

PECsw (μg/l)

FOCUS defaulta 0.1195 0.0043 0.112

3m 0.0612 0.0734

4m 0.0477 0.0572

5m 0.0392 0.0470

6m - 0.0400

A 1.3m for ditch, 3.8 m for pond, 1.8 m for stream bincludes contribution from 20% treated upstream catchment




Single application of 15 g product per ha to soybeans (Thifensulfuron-methyl 50SG)

Buffer distance (m)


Ditch Pond Streamb

PECsw (μg/l)

FOCUS defaulta 0.0797 0.0032 0.0745

2m 0.0571 0.0685

3m 0.0408 0.0490

4m 0.0382

A 1.3m for ditch, 3.8 m for pond, 1.8 m for stream bincludes contribution from 20% treated upstream catchment


Groundwater

Previous

evaluation: Both Applicants provided assessments of potential ground water

exposure utilising input parameters from their respective data sets.

The UK RMS has remodelled the groundwater exposure using combined

endpoints derived from the data of both applicants.

For simplicity, the UK RMS has produced a combined summary based

on the Applicants modelling reports (PECgw values resulting from the

proposed GAP tables of both applicants are reported), but using UK

RMS selected endpoints and UK RMS derived PECgw values.

New information, combined endpoints and PECgw values calculated by

the UK RMS are detailed below. The groundwater assessment was

updated post PRAPeR meeting 126 to reflect revised input parameters

for the IN-A4098 metabolite.

The formulated products of Thifensulfuron-methyl are applied to a number of crops such as

winter and spring cereals, maize and soybeans for the control of a wide range of broad-leaf

weeds in the EU.

The combined GAPs from both Applicants comprised of up to 8 different crop, application rate

or application timing combinations to consider. Due to the varying crops, application rates and

timings of the proposed uses, it was not possible to identify a critical GAP suitable for risk

enveloping all other uses. In addition multiple metabolites exceeded the 0.1μg/l limit for the

worst-case uses. FOCUS groundwater modelling for all proposed uses was therefore performed,

and results are summarised in separate tables below.

Groundwater modelling for Thifensulfuron-methyl and its major soil metabolites IN-L9225, IN-

JZ789, 2-Acid-3-triuret, IN-L9223, IN-A4098, IN-V716010

and IN-W826811

was conducted

using all relevant GAPs and FOCUS groundwater scenarios with the PELMO model (v.4.4.3),

using the proposed uses in Table B.8.354, and the metabolites schemes detailed in Figure B.8.39

10 triggered by occurrence in one of the soil photolysis studies 11 triggered by occurrence in the existing route of degradation in soil study


and Figure B.8.40 below. PEARL (v4.4.4) modelling was also performed, using the formation

fractions from Table B.8.357 to model metabolite formation.

Two PELMO metabolite pathways were modelled as the metabolism of Thifensulfuron-methyl

involves cleavage of the molecule into thiophene containing metabolites and triazine containing

metabolites. Components containing both thiophene and triazine portions of the molecule are

simulated in both schemes (identical PECgw values were obtained for the metabolites).

The parent and metabolite physiochemical properties in Table B.8.356 and Table B.8.357 were

used for modelling purposes. The parent water solubility and vapour pressure values (2240 mg/L

and 5.2E-9 Pa, respectively) were used for all metabolites.

All physico-chemical input parameters were selected in compliance with the recommendations of

FOCUS guidance. Degradation parameters (DegT50) were derived in general agreement with

FOCUS kinetics guidance (FOCUS, 2006). Degradation of the active substance in soil was

simulated with the respective laboratory values which were normalised to a reference

temperature of 20C and soil moisture content at 10 kPa (pF2).

Additionally, the metabolites IN-V7160 and IN-W8268 were each applied as a parent compound

in separate PEARL 4.4.4 and PELMO 4.4.3 modelling. Normally the UK RMS would always

prefer to model metabolites as part of the degradation scheme, utilising appropriate formation

fractions from the precursors. The major soil metabolites IN-L9225, IN-JZ789, 2-Acid-3-triuret,

IN-L9223 and IN-A4098 have been triggered by occurrence in the Task Force route of

degradation study, where formation fractions have been derived. These metabolites have all been

modelled as being formed by parent thifensulfuron and or their precursor metabolites as per

FOCUS guidance. IN-V7160 was triggered due to occurrence at close to 10% (9.6% after 15 d)

in the DuPont soil photolysis study. IN-W8268 was included by the UK RMS because it formed

in significant amounts in the existing route of degradation study available in the original DAR

(peaking at 29.6% after 1 week). However no detailed kinetic evaluation of these studies was

available and no formation fractions available. To enable these to be included in the groundwater

exposure assessment in a simplistic manner, modelling them as parent substances was considered

appropriate by the UK RMS. In this case, because both metabolites formed at peak levels

relatively quickly in the respective studies, any underestimation of formation by modelling them

as parent substances is likely to be relatively minor. In addition, it should be noted that based on

this methodology, IN-V7160 was always <0.001μg/l and IN-W8268 was frequently >0.1μg/l and

peaked at 0.907μg/l and therefore triggered a drinking water risk assessment as part of the

consideration of its relevance. Therefore any error introduced into the modelling by taking this

approach is unlikely to have a significant effect on the overall regulatory conclusions based on

this modelling. For these metabolites the application rate of Thifensulfuron-methyl was adjusted

according to relative molecular weight and the maximum % observed in the soil (9.6% and

29.6%, respectively). See Table B.8.355 for the net soil deposits assumed for each

metabolite/crop combination, which also takes into account molecular weight differences.

The crop uptake factor was set at the worst-case default value of 0 for both parent and all

metabolites to ensure a conservative approach. All GAPs assumed annual applications.

Following the evaluation of the combined Annex II data from both Applicants, the UK RMS

considered that no formal quantitative groundwater assessment was necessary for metabolites


IN–A5546 or IN-L9226. This conclusion was based on their short half lives in soil and

uncertainty over the reliability of the studies in which they were detected in major amounts (e.g.

for IN-L9226 detected in the existing and new aerobic route of degradation in soil studies which

were subsequently considered unreliable by the UK RMS). However for completeness the UK

RMS chose to perform a very simple first tier FOCUSgw modelling assessment of the IN-A5546

metabolite. This was performed to confirm that these metabolites represented no risk of

groundwater leaching due to their short half-lives. This metabolite can be considered to

represent the greater leaching risk relative to IN-L9226, due to its combination of longer DT50

(e.g. 3 d versus 0.95 d) and greater mobility (Kfoc of 49 ml/g and 1/n of 0.910 versus Kfoc of 126

ml/g and 1/n of 0.9 for IN-L9226). Modelling was performed applying IN-A5546 as parent,

using the same maximum soil loadings as per Thifensulfuron-methyl for winter cereals (winter

and spring application) in Table B.8.354 (i.e. assuming 100% formation from parent with no

correction for molecular weight differences or peak occurrence). This approach was considered a

simple worst-case approach. All scenarios resulted in PECgw values <0.000001μg/l and due to

the large margin of safety these assessments were considered sufficiently protective of all other

uses.

Table B.8.354 Application scenarios for Thifensulfuron-methyl

Crop

Application

period

Annual

Application

rate

(g a.s.ha-1

)

Crop growth

stage

Interception

(%)

Net soil

deposit

(g a.s. ha-1)

Application

timing

Applicant

Spring

cereals

Spring

application

1 30.0 BBCH 12-39 25 22.50 10 days after

emergence

DuPont

1 x 40.8 BBCH13-39 25 30.6 TSM Task

Force

Winter

cereals

Autumn

application 1 30.0 BBCH 12-39 25 22.50

10 days after

emergence

DuPont

Winter

application 1 37.5 BBCH 21 25 28.13 15-Dec

DuPont

Spring

application

1 37.5 BBCH 12-39 25 28.13

15-March

DuPont

1 x 51 BBCH 13-39 25 38.25 TSM Task

Force

Maize Spring


10 days after

emergence

DuPont

Soybeans Spring


10 days after

emergence

DuPont


Table B.8.355 Application scenarios for metabolites IN-V7160 and IN-W8268

Crop

Application

period

Annual

Application

rate

(g a.s.ha-1

)

Crop

growth

stage

Interception

(%)

IN-V7160

Net soil

deposit

(g a.s. ha-1)

IN-W8268

Net soil

deposit

(g a.s. ha-1)

Application

timing

Applicant

Spring

cereals

Spring

application

1 30.0 BBCH

12-39 25 1.021

3.253

10 days after

emergence

DuPont

1 x 40.8 BBCH13-

39 25 1.385

4.409 TSM Task

Force

Winter

cereals

Autumn

application 1 30.0

BBCH

12-39 25 1.021

3.253 10 days after

emergence

DuPont

Winter

application 1 37.5 BBCH 21 25 1.277

4.067 15-Dec

DuPont

Spring

application

1 37.5 BBCH

12-39 25 1.277

4.067

15-March

DuPont

1 x 51 BBCH

13-39 25 1.736

5.529 TSM Task

Force

Maize Spring

application 1 11.25

BBCH

10-16 25 0.381

1.214 10 days after

emergence

DuPont

Soybeans Spring

application 1 7.5

BBCH

10-14 35 0.222

0.708 10 days after

emergence

DuPont

Mol. wt of thifensulfuron = 387.4; mol. wt of IN-V7160 = 183.2; mol. wt of IN-W8268 = 189.2


Table B.8.356 Input parameters for Thifensulfuron-methyl

Parameter Thifensulfuron-methyl Reference

Molecular Wt 387.4 LoEP

(SANCO/7577/VI/97-final 2001)

Water Solubility (mg/l) 2240 (pH 7) LoEP

(SANCO/7577/VI/97-final 2001)

KOC (l/kg) 9 Median of 9

KOM 5.2 Calculated KOC / 1.724

1/n (mean) 0.932 Arithmetic mean

Vapour Pressure (pa) 5.2 x 10-9

(20ºC) New GLP value

Soil DT50 (days) 1.39 Geomean of 6 soils

Plant uptake coefficient 0.0 FOCUS default

Table B.8.357 Input parameters for soil metabolites

Parameter IN-L9225 IN-JZ789 2-Acid-3-

triuret IN-L9223 IN-A4098 IN-V7160

IN-

W8268

Molecular Wt 373.4 359.3 378.3 207.2 140.1 183.2 189.2

KOC (l/kg) 19.9 31.1 524 4.07 62.3

(45.5*)

113.9 7.4

Kom (l/kg) 11.5 18.0 304 2.4

36.1

(26.4*) 66.1 4.3

1/n (mean) 0.85 1.0 1.0 1.157 0.903

(0.900*)

0.913 1.16

Soil DT50

(days) 32.3 60 73 178

169.4

(132.4*)

(167.9*)

19.4 18.7

Fraction

Formation

0.95 (from

Thifensulfu

ron-methyl)

0.26 (from

IN-L9225)

0.22 (from

IN-L9225)

and 1.0

(from IN-

JZ789)

0.30 (from

IN-L9225)

0.05 (from

Thifensulfur

on-methyl)

and 0.30

(and 0.14*)

(from IN-

L9225)

Stand

alone

parent

assuming

peak of

9.6%

Stand

alone

assuming

peak of

29.6%

Parent physiochemical properties (vapour pressure, water solubility) used for metabolites, to provide minimal

partitioning to air. Plant uptake was set to zero. *As a result of the EFSA peer review the degradation and sorption dataset for IN-A4098 was updated to reflect

additional data available in other peer reviewed RARs. The values in brackets reflect the modelling endpoints from

the revised combined dataset. For degradation and formation fraction, the modelling endpoints for IN-A4098 have

been further updated following expert discussion at PRAPeR 126.

The results of the PELMO 4.4.3 and PEARL 4.4.4 groundwater modelling are displayed in the

following tables below.


Spring cereals at 30 g a.s./ha – Tables B.8.358 to 361

Spring cereals at 40.8 g a.s./ha – Tables B.8.362 to 365

Winter cereals at 30 g a.s./ha autumn application – Tables B.8.366 to 369

Winter cereals at 37.5 g a.s./ha winter application – Tables B.8.370 to 373

Winter cereals at 37.5 g a.s./ha spring application – Tables B.8.374 to 377

Winter cereals at 51 g a.s./ha spring application – Tables B.8.378 to 381

Maize at 11.25 g a.s./ha spring application – Tables B.8.382 to 385

Soybeans at 7.5 g a.s./ha spring application – Tables B.8.386 to 389

As highlighted in Table B.8.357 the endpoints for the IN-A4098 metabolite were revised as a

result of the EFSA peer review to include data from other peer reviewed RARs. This led to a

decrease in the modelling DT50 for this metabolite (to 132.4 d from 169.4 d used in the original

modelling). Subsequent expert discussion at PRAPeR 126 led to this value increasing back up to

167.9 d (from the combined data set of metabolite and parent dosed studies, n = 16). The expert

meeting discussions also led to a decrease in formation fraction for the IN-A4098 metabolite

forming from IN-L9225 (reduced to 0.14 from 0.30 used in original modelling). It also led to a

decrease in the sorption parameters, with Kfoc reducing to 45.5ml/g from 62.3 ml/g and 1/n

reducing to 0.900 from 0.903 used in the original modelling. In order to investigate the impact of

these changes on this metabolite, the UK RMS re-ran a subset of the original modelling. The UK

RMS selected the worst case scenarios that previously gave the highest PECgw values for this

metabolite. These were also selected to cover both winter and spring applications to cereals with

both FOCUS PEARL v4.4.4 and FOCUS PELMO v 4.4.3. The results of the groundwater

modelling using the updated endpoints are included along side the original values in the tables

below (this update includes the final agreed endpoints post PRAPeR 126 meeting). Overall the

change in modelling parameters had only a minor the effect of reducing the PECgw values for

IN-A4098. For some scenarios the PECgw values were reduced and for others there was a slight

increase. In this case it appears that the impact of the increased mobility is offset by the reduced

DT50 formation fraction from IN-L9225 (which represents the main route of formation of IN-

A4098). As part of the re-modelling exercise the UK RMS identified that the previous peak

PECgw value of 0.772μg/l was actually a typographical error (the PECgw value for this scenario

was actually 0.3772μg/l – see Table B.8.364). With the addition of the re-modelled scenarios,

the peak PECgw value for IN-A4098 was reduced to 0.662μg/l (this value being based on the

original and now more conservative endpoints – see Table B.8.378 – with the post-PRAPeR

agreed endpoints the actual peak PECgw is reduced to 0.394μg/l for the worst case scenario).

Since the IN-A4098 metabolite is a terminal metabolite, the changes to these endpoints has no

effect on the PECgw estimates of the other metabolites.

A final summary table of peak PECgw values is provided in Table B.8.390.


Figure B.8.39 Metabolite scheme for PELMO 4.4.3, thiophene radiolabel groundwater

simulation.

Figure B.8.40 Metabolite scheme for PELMO 4.4.3, triazine radiolabel groundwater simulation.


Summary of PECgw (80th

percentile annual average concentration at 1m)

Focus Crop Spring cereals

Application rate 30 g a.s/ha

Application date 10 days after emergence

Interception 25%

Amount reaching soil 22.5 g a.s/ha

Table B.8.358 PELMO 4.4.3 - Thiophene label Scenario Thifensulfuron-

methyl

IN-L9225 IN-JZ789 IN-L9223 2-acid-3-

triuret

Châteaudun <0.001 0.029 0.287 1.180 0.081

Hamburg <0.001 0.215 0.654 1.310 0.151

Jokioinen <0.001 0.149 0.574 1.694 0.083

Kremsmünster <0.001 0.234 0.520 1.032 0.143

Okehampton <0.001 0.259 0.443 0.754 0.108

Porto <0.001 0.127 0.312 0.714 0.037

PELMO 4.4.3 - Triazine label Scenario Thifensulfuron-

methyl

IN-L9225 IN-JZ789 IN-A4098 2-acid-3-

triuret

Châteaudun <0.001 0.029 0.287 0.173 0.081

Hamburg <0.001 0.215 0.654 0.299 0.151

Jokioinen <0.001 0.149 0.574 0.214 0.083

Kremsmünster <0.001 0.234 0.520 0.255 0.143

Okehampton <0.001 0.259 0.443 0.240 0.108

Porto <0.001 0.127 0.312 0.145 0.037

Table B.8.359 PELMO 4.4.3 - Metabolites applied as parent Scenario IN-V7160 IN-W8268

Châteaudun <0.001 0.020

Hamburg <0.001 0.084

Jokioinen <0.001 0.191

Kremsmünster <0.001 0.100

Okehampton <0.001 0.093

Porto <0.001 0.027

Table B.8.360 PEARL 4.4.4 – Thifensulfuron-methyl and associated metabolites Scenario Thifensulfuron-

methyl

IN-L9225 IN-JZ789 2-acid-3-

triuret

IN-L9223 IN-A4098

Châteaudun <0.001 0.0464 0.326 0.090 1.407 0.195

Hamburg <0.001 0.316 0.895 0.215 1.990 0.379

Jokioinen <0.001 0.157 0.615 0.097 2.130 0.229

Kremsmünster <0.001 0.238 0.520 0.163 0.948 0.265

Okehampton <0.001 0.278 0.467 0.119 0.828 0.248

Porto <0.001 0.071 0.280 0.039 0.769 0.141

Table B.8.361 PEARL 4.4.4 – Metabolites applied as parent Scenario IN-V7160 IN-W8268


Hamburg <0.001 0.088




Porto <0.001 0.008




Focus Crop Spring cereals

Application rate 40.8 g a.s/ha

Application date 10 days after

emergence

Interception 25%



methyl

IN-L9225 IN-JZ789 IN-L9223 2-acid-3-

triuret

Châteaudun <0.001 0.046 0.396 1.606 0.112

Hamburg <0.001 0.326 0.894 1.774 0.208

Jokioinen <0.001 0.233 0.786 2.303 0.114

Kremsmünster <0.001 0.357 0.713 1.401 0.198

Okehampton <0.001 0.389 0.603 1.023 0.148

Porto <0.001 0.187 0.425 0.970 0.051


methyl

IN-L9225 IN-JZ789 IN-A4098 2-acid-3-

triuret

Châteaudun <0.001 0.046 0.396 0.245 0.112

Hamburg <0.001 0.326 0.894 0.421 0.208

Jokioinen <0.001 0.233 0.786 0.309 0.114

Kremsmünster <0.001 0.357 0.713 0.361 0.198

Okehampton <0.001 0.389 0.603 0.334 0.148

Porto <0.001 0.187 0.425 0.203 0.051



Hamburg <0.001 0.104




Porto <0.001 0.034


methyl

IN-

L9225

IN-

JZ789

2-acid-3-

triuret

IN-L9223 IN-A4098 IN-A4098 (DT50 = 167.9

132.4 d; Kfoc =

45.5 ml/g; formation fraction

from IN-L9225 =

0.14)

Châteaudun <0.001 0.073 0.450 0.124 1.913 0.207 0.281* 0.275 0.190

Hamburg <0.001 0.471 1.228 0.296 2.701 0.533 0.539 0.344

Jokioinen <0.001 0.242 0.843 0.133 2.896 0.328 0.344 0.227

Kremsmünster <0.001 0.359 0.714 0.225 1.288 0.772 0.377* 0.384 0.245

Okehampton <0.001 0.412 0.636 0.164 1.122 0.344 0.336 0.209

Porto <0.001 0.108 0.383 0.053 1.045 0.197 0.197 0.128 *The values reported for these two scenarios were identified as being typos during the re-modelling conducted by the UK RMS



Hamburg <0.001 0.242





Porto <0.001 0.024



Focus Crop Winter cereals



(autumn application)

Interception 25%



methyl

IN-L9225 IN-JZ789 IN-L9223 2-acid-3-

triuret

Châteaudun <0.001 0.155 0.561 1.778 0.165

Hamburg 0.012 1.023 0.9 1.403 0.279

Jokioinen 0.010 0.608 0.889 2.096 0.136

Kremsmünster 0.002 0.549 0.664 1.042 0.218

Okehampton 0.003 0.806 0.605 0.756 0.202

Piacenza 0.008 0.505 0.527 1.418 0.213

Porto 0.012 0.652 0.452 0.783 0.107

Sevilla <0.001 0.005 0.131 0.875 0.022

Thiva <0.001 0.066 0.366 1.474 0.096


methyl

IN-L9225 IN-JZ789 IN-A4098 2-acid-3-

triuret

Châteaudun <0.001 0.155 0.561 0.315 0.165

Hamburg 0.012 1.023 0.900 0.419 0.279

Jokioinen 0.010 0.608 0.889 0.326 0.136

Kremsmünster 0.002 0.549 0.664 0.352 0.218

Okehampton 0.003 0.806 0.605 0.303 0.202

Piacenza 0.008 0.505 0.527 0.307 0.213

Porto 0.012 0.652 0.452 0.217 0.107

Sevilla <0.001 0.005 0.131 0.062 0.022

Thiva <0.001 0.066 0.366 0.242 0.096



Hamburg <0.001 0.586




Piacenza <0.001 0.267

Porto <0.001 0.331

Sevilla <0.001 0.032

Thiva <0.001 0.051



percentile annual average concentration at 1m) (continued)




(autumn application)

Interception 25%



methyl


triuret

IN-L9223 IN-A4098

Châteaudun <0.001 0.195 0.544 0.162 1.908 0.295

Hamburg 0.004 0.854 0.849 0.284 1.449 0.404

Jokioinen <0.001 0.444 0.855 0.135 2.445 0.311

Kremsmünster <0.001 0.422 0.573 0.198 0.860 0.298

Okehampton <0.001 0.666 0.570 0.199 0.763 0.284

Piacenza <0.001 0.314 0.403 0.188 1.145 0.257

Porto 0.001 0.442 0.450 0.109 0.713 0.212

Sevilla <0.001 <0.001 0.079 0.010 1.003 0.022

Thiva <0.001 0.077 0.472 0.144 2.214 0.359



Hamburg <0.001 0.733




Piacenza <0.001 0.334

Porto <0.001 0.414

Sevilla <0.001 0.040

Thiva <0.001 0.064






Application date 15th

December

(winter application)

Interception 25%



methyl

IN-L9225 IN-JZ789 IN-L9223 2-acid-3-

triuret

Châteaudun <0.001 0.199 0.658 2.164 0.195

Hamburg 0.02 1.044 1.071 1.781 0.334

Jokioinen 0.088 1.163 1.192 2.539 0.207

Kremsmünster 0.004 0.756 0.800 1.287 0.275

Okehampton 0.004 0.945 0.725 0.958 0.237

Piacenza 0.014 0.672 0.675 1.784 0.273

Porto 0.025 0.927 0.545 0.984 0.136

Sevilla 0.001 0.009 0.172 1.087 0.029

Thiva <0.001 0.095 0.474 1.848 0.122


methyl

IN-L9225 IN-JZ789 IN-A4098 IN-A4098 (DT50 = 167.9 132.4

d; Kfoc = 45.5 ml/g;

formation fraction from IN-L9225 =

0.14)

2-acid-3-

triuret

Châteaudun <0.001 0.199 0.658 0.406 0.384 0.252 0.195

Hamburg 0.020 1.044 1.071 0.439 0.544 0.332 0.334

Jokioinen 0.088 1.163 1.192 0.499 0.510 0.326 0.207

Kremsmünster 0.004 0.756 0.8 0.437 0.433 0.266 0.275

Okehampton 0.004 0.945 0.725 0.376 0.379 0.225 0.237

Piacenza 0.014 0.672 0.675 0.4 0.390 0.257 0.273

Porto 0.025 0.927 0.545 0.274 0.279 0.167 0.136

Sevilla 0.001 0.009 0.172 0.085 0.090 0.074 0.029

Thiva <0.001 0.095 0.474 0.316 0.297 0.213 0.122



Hamburg <0.001 0.611




Piacenza <0.001 0.337

Porto <0.001 0.410

Sevilla <0.001 0.039

Thiva <0.001 0.063







December

(winter application)

Interception 25%



methyl

IN-

L9225

IN-

JZ789

2-acid-3-

triuret

IN-

L9223

IN-

A4098

IN-A4098 (DT50 = 167.9 132.4 d; Kfoc =

45.5 ml/g;

formation fraction from IN-L9225 =

0.14)

Châteaudun <0.001 0.222 0.653 0.189 2.320 0.366 0.354 0.235

Hamburg 0.003 0.904 0.996 0.305 1.819 0.483 0.493 0.303

Jokioinen 0.003 0.763 1.172 0.186 3.049 0.438 0.465 0.293

Kremsmünster <0.001 0.538 0.665 0.235 1.071 0.355 0.342 0.216

Okehampton 0.001 0.769 0.684 0.229 0.980 0.347 0.349 0.211

Piacenza 0.001 0.442 0.506 0.239 1.436 0.323 0.303 0.195

Porto 0.002 0.611 0.558 0.137 0.908 0.273 0.260 0.165

Sevilla <0.001 <0.001 0.107 0.012 1.245 0.030 0.026 0.025

Thiva <0.001 0.111 0.606 0.183 2.766 0.475 0.435 0.318



Hamburg <0.001 0.424




Piacenza <0.001 0.163

Porto <0.001 0.269

Sevilla <0.001 <0.001

Thiva <0.001 0.043







March

(Spring application)

Interception 25%



methyl

IN-L9225 IN-JZ789 IN-L9223 2-acid-3-

triuret

Châteaudun <0.001 0.089 0.476 2.025 0.140

Hamburg <0.001 0.410 0.916 1.762 0.218

Jokioinen <0.001 0.305 0.958 2.573 0.130

Kremsmünster <0.001 0.389 0.713 1.269 0.209

Okehampton <0.001 0.518 0.636 0.996 0.175

Piacenza <0.001 0.243 0.587 1.572 0.197

Porto <0.001 0.185 0.396 0.937 0.056

Sevilla <0.001 0.002 0.129 0.942 0.020

Thiva <0.001 0.005 0.190 1.594 0.053


methyl

IN-L9225 IN-JZ789 IN-A4098 2-acid-3-

triuret

Châteaudun <0.001 0.089 0.476 0.31 0.140

Hamburg <0.001 0.410 0.915 0.442 0.218

Jokioinen <0.001 0.203 0.958 0.365 0.130

Kremsmünster <0.001 0.389 0.713 0.382 0.209

Okehampton <0.001 0.518 0.636 0.344 0.175

Piacenza <0.001 0.243 0.587 0.356 0.197

Porto <0.001 0.185 0.396 0.212 0.056

Sevilla <0.001 0.002 0.129 0.040 0.020

Thiva <0.001 0.005 0.190 0.180 0.053



Hamburg <0.001 0.193




Piacenza <0.001 0.104

Porto <0.001 0.052

Sevilla <0.001 0.002

Thiva <0.001 0.002







March


Interception 25%



methyl


triuret

IN-L9223 IN-A4098

Châteaudun <0.001 0.095 0.490 0.142 2.234 0.306

Hamburg <0.001 0.389 0.878 0.230 1.924 0.415

Jokioinen <0.001 0.218 0.915 0.127 3.053 0.332

Kremsmünster <0.001 0.286 0.589 0.194 1.070 0.314

Okehampton <0.001 0.418 0.606 0.171 1.021 0.313

Piacenza <0.001 0.195 0.424 0.166 1.331 0.292

Porto <0.001 0.112 0.360 0.061 0.995 0.194

Sevilla <0.001 0.000 0.117 0.010 1.185 0.018

Thiva <0.001 0.009 0.305 0.106 2.406 0.294



Hamburg <0.001 0.177




Piacenza <0.001 0.064

Porto <0.001 0.068

Sevilla <0.001 0.001

Thiva <0.001 0.006







March


Interception 25%



methyl

IN-L9225 IN-JZ789 IN-L9223 2-acid-3-

triuret

Châteaudun <0.001 0.137 0.656 2.757 0.195

Hamburg <0.001 0.590 1.251 2.387 0.30

Jokioinen <0.001 0.463 1.311 3.498 0.18

Kremsmünster <0.001 0.577 0.977 1.724 0.289

Okehampton <0.001 0.758 0.87 1.353 0.24

Piacenza <0.001 0.357 0.809 2.143 0.274

Porto <0.001 0.277 0.541 1.273 0.077

Sevilla <0.001 0.003 0.176 1.281 0.028

Thiva <0.001 0.008 0.261 2.165 0.073


methyl

IN-L9225 IN-JZ789 IN-A4098

IN-A4098 (DT50 = 167.9 132.4 d;

Kfoc = 45.5 ml/g;

formation fraction from IN-L9225 = 0.14)

2-acid-3-

triuret

Châteaudun <0.001 0.137 0.658 0.441 0.423 0.294 0.196

Hamburg <0.001 0.591 1.254 0.622 0.621 0.394 0.301

Jokioinen <0.001 0.465 1.315 0.519 0.532 0.347 0.18

Kremsmünster <0.001 0.579 0.979 0.541 0.514 0.332 0.29

Okehampton <0.001 0.761 0.872 0.478 0.471 0.289 0.241

Piacenza <0.001 0.358 0.811 0.498 0.487 0.313 0.275

Porto <0.001 0.278 0.542 0.303 0.303 0.194 0.077

Sevilla <0.001 0.003 0.176 0.061 0.076 0.066 0.028

Thiva <0.001 0.008 0.261 0.260 0.231 0.192 0.073



Hamburg <0.001 0.260




Piacenza <0.001 0.140

Porto <0.001 0.070

Sevilla <0.001 0.002

Thiva <0.001 0.003







March


Interception 25%



methyl


triuret

IN-L9223 IN-A4098

Châteaudun <0.001 0.147 0.676 0.142 2.234 0.306

Hamburg <0.001 0.558 1.198 0.230 1.924 0.415

Jokioinen <0.001 0.340 1.254 0.127 3.053 0.332

Kremsmünster <0.001 0.426 0.805 0.194 1.070 0.314

Okehampton <0.001 0.613 0.829 0.171 1.021 0.313

Piacenza <0.001 0.291 0.587 0.166 1.331 0.292

Porto <0.001 0.168 0.498 0.061 0.995 0.194

Sevilla <0.001 0.001 0.161 0.010 1.185 0.018

Thiva <0.001 0.015 0.420 0.142 2.234 0.306



Hamburg <0.001 0.239




Piacenza <0.001 0.086

Porto <0.001 0.092

Sevilla <0.001 0.001

Thiva <0.001 0.008




Focus Crop Maize



emergence

Interception 25%



methyl

IN-L9225 IN-JZ789

IN-L9223 2-acid-3-

triuret

Châteaudun <0.001 0.028 0.172 0.474 0.046

Hamburg <0.001 0.062 0.240 0.497 0.054

Kremsmünster <0.001 0.061 0.187 0.367 0.049

Okehampton <0.001 0.083 0.172 0.294 0.039

Piacenza <0.001 0.049 0.156 0.291 0.042

Porto <0.001 0.019 0.099 0.188 0.012

Sevilla <0.001 0.001 0.059 0.324 0.009

Thiva <0.001 0.015 0.158 0.555 0.039


methyl

IN-L9225 IN-JZ789 IN-A4098 2-acid-3-

triuret

Châteaudun <0.001 0.028 0.172 0.080 0.046

Hamburg <0.001 0.062 0.240 0.098 0.054

Kremsmünster <0.001 0.061 0.187 0.080 0.049

Okehampton <0.001 0.083 0.172 0.079 0.039

Piacenza <0.001 0.049 0.156 0.071 0.042

Porto <0.001 0.019 0.099 0.045 0.012

Sevilla <0.001 <0.001 0.059 0.021 0.009

Thiva <0.001 0.015 0.158 0.092 0.039



Hamburg <0.001 0.004



Piacenza <0.001 0.002

Porto <0.001 0.001

Sevilla <0.001 <0.001

Thiva <0.001 <0.001

Table B.8.384PEARL 4.4.4 – Thifensulfuron-methyl and associated metabolites Scenario Thifensulfuron-

methyl


triuret

IN-L9223 IN-A4098

Châteaudun <0.001 0.039 0.189 0.049 0.447 0.083

Hamburg <0.001 0.088 0.287 0.065 0.606 0.107

Kremsmünster <0.001 0.061 0.179 0.051 0.329 0.077

Okehampton <0.001 0.085 0.178 0.044 0.300 0.082

Piacenza <0.001 0.039 0.157 0.047 0.414 0.081

Porto <0.001 0.016 0.095 0.013 0.184 0.042

Sevilla <0.001 0.002 0.059 0.012 0.365 0.027

Thiva <0.001 0.031 0.007 0.055 0.741 0.107




Focus Crop Maize



emergence

Interception 25%




Hamburg <0.001 0.082



Piacenza <0.001 0.013

Porto <0.001 0.007

Sevilla <0.001 0.001

Thiva <0.001 0.010



Focus Crop Soybeans



March


Interception 25%



methyl

IN-L9225 IN-JZ789 IN-L9223 2-acid-3-

triuret

Piacenza <0.001 0.016 0.066 0.147 0.016


methyl

IN-L9225 IN-JZ789

IN-A4098

2-acid-3-

triuret

Piacenza <0.001 0.016 0.066 0.031 0.016


Piacenza <0.001 0.004


methyl


triuret

IN-L9223 IN-A4098

Piacenza <0.001 0.017 0.070 0.018 0.193 0.032


Piacenza <0.001 0.009


Conclusion

Parent Thifensulfuron-methyl was <0.001μg/l for all scenario, model and crop combinations.

Listed below in Table B.8.390 is a summary of all maximum 80th

percentile annual average

PECgw values for the metabolites that exceeded the 0.1 ug/l limit across all proposed application

schemes from both applicants, and all FOCUS scenarios with either model.

Table B.8.390 Summary of maximum 80th

percentile annual average PECgw values for the

groundwater metabolites of Thifensulfuron-methyl

Metabolite Maximum PECgw

(ug/l)

Application scenario Model

/FOCUS scenario

IN-L9225 1.163

Winter cereals (37.5 g

a.s/ha), winter

application

PELMO 4.4.3,

Jokioinen

IN-JZ789 1.315


a.s/ha) spring

application

PELMO 4.4.3,

Jokioinen

IN-L9223 3.498


a.s/ha) spring

application

PELMO 4.4.3,

Jokioinen

IN-A4098 0.772 0.622*

Spring Winter cereals

(40.8 51 g a.s/ha)

spring application

PEARL 4.4.4,

Kremsmünster

PELMO 4.4.3

Hamburg

2-Acid-3-Triuret 0.305


a.s/ha), winter

application

PEARL 4.4.4,

Hamburg

IN-W8268 0.907

Winter cereals (30 g

a.s/ha) Autumn

application

PELMO 4.4.3,

Jokioinen

*Note the peak PECgw value of 0.622μg/l for IN-A4098 was derived using the originally proposed endpoints. The

UK RMS repeated simulations for a range of the worst case scenarios using IN-A4098 endpoints agreed at the

PRAPeR 126 meeting. This additional modelling confirmed that the original endpoints were more conservative.

The actual peak PECgw values for IN-A4098 using agreed endpoints was reduced to 0.394μg/l for this worst case

scenario (winter cereals, 51 g a.s./ha spring application).

Metabolite IN-V7160 was always predicted to have PECgw values of <0.001 ug/L for all

scenarios. In addition modelling of the highest application rates for winter cereals (winter and

spring application) for IN-A5546 resulted in PECgw values of <0.000001μg/l. The assessment

of IN-A5546 can be considered protective of the leaching risk posed by IN-L9226 as well as

being protective of all other uses.

Across all crops, the PECgw results for metabolite IN-A4098 range from 0.031 to 0.622 0.772

μg/L (0.394μg/l using final agreed endpoints). For metabolite IN-L9225 the PECgw results range

from 0.016 to 1.163 μg/L. For metabolite IN-JZ789 the PECgw range from 0.066 to 1.315 μg/L.

For metabolite IN-L9223 the PECgw results range from 0.147 to 3.498, and for metabolite 2-

Acid-3-triuret the PECgw results range from 0.016 to 0.305 μg/L.


Additionally the UK RMS has modelled metabolite IN-W8268 as parent adjusted for relative

molecular weight and the maximum % observed in soil, with PECgw results ranging from 0.004

to 0.907 μg/L.

The PECgw results of metabolites IN-L9225, IN-JZ789, IN-L9223, IN-A4098 and IN-W8268

are all above the regulatory threshold for non-relevant metabolites of 0.75 μg/L.

The toxicological relevance of metabolites IN-L9225, IN-JZ789, IN-L9223, IN-A4098, 2-acid-3-

triuret and IN-W8268 has been considered in AII, Section 5.8. and they can be regarded as non

relevant metabolites.

B.8.7 Fate and behaviour in air (IIA 7.2.2, IIIA 9.3)

Neither Thifensulfuron-methyl nor any of its principal degradation products have significant

volatility. The vapour pressure of Thifensulfuron-methyl is 5.2 10-9

Pa at 20C. There is no

guidance currently available for conducting meaningful studies regarding the potential

breakdown of Thifensulfuron-methyl or its degradation products in air.

Further, the Henry's law constant of Thifensulfuron-methyl is less than 3 10-2

Pa-m3/mol,

suggesting little potential for volatilisation in the environment. Henry's law constants below 3

10-2

Pa-m3/mol indicate that the compound is less volatile than water and can be considered

essentially non-volatile (Lyman, W.J. et al., 199012

).

Report: Schmuckler, M.E. (1999); Photodegradation oxidative degradation of Thifensulfuron-

methyl


Guidelines: U.S. EPA 796.3900 (1992), OECD Photochemical Oxidative Degradation in the

Environment (1987a, 1988a) Deviations: None



GLP: Not applicable



Previous

evaluation

None: Submitted by DuPont for the purpose of renewal under Regulation

1141/2010

The following study estimating the atmospheric half life of Thifensulfuron-

methyl in air was submitted by DuPont. The study was evaluated by the

UK RMS, who checked the outputs using the more recent version of the

AOP software (v1.92). The UK RMS confirmed the half life of 41.425

hours based on a 12-hour OH radical concentration of 1.5 x 106 OH radicals

per cm3 as reported in the Applicants summary. However it should be noted

that when the half life in hours is converted to days, because the hourly

value assumes a 12 hour day, the half life in days is effectively doubled to

3.5 d. This is greater than the 2 d trigger for potential for long range

12

Lyman W.J, Reehl W.H., Rosenblatt, D.H.,. 1990. Handbook of Chemical Property Estimation Methods. Washington, DC: American Chemical Society.


transport.

Note that the Task Force simply referenced the original Review Report to

address this data requirement. Since this can be regarded as modelling data

based on the structure of the active substance, no further information is

considered necessary from either Applicant.

Executive summary:

An estimation of the photochemical degradation (indirect phototransformation) of

Thifensulfuron-methyl was calculated in accordance with Commission Directive 94/37/EC. The

overall OH rate constant was determined to be 3.0984 10-12

cm3/molecule-sec. The half–life of

Thifensulfuron-methyl for reaction with average daily air concentrations of hydroxyl radicals

(12-hour day, 1.5 106 OH radicals per cm

3) is 41.425 hours (3.5 d). Hydrogen abstraction,

reaction with nitrogen, sulphur, hydroxyl, and addition to the aromatic rings are all predicted to

contribute to the rate of photochemical degradation. The calculation of the second-order rate

constant and associated half-life for the reaction of Thifensulfuron-methyl in the gas phase in the

troposphere was made using the method of Atkinson.


A. MATERIALS

1. Test material: Thifensulfuron-methyl technical

Lot/Batch #: Not applicable - calculation

Purity: Not applicable - calculation

Description: Not applicable - calculation

CAS#: 79277-27-3

Stability of test compound: Not applicable - calculation

2. Soil: Not applicable - calculation

B. STUDY DESIGN


An estimation of the photochemical degradation (indirect phototransformation) of

Thifensulfuron-methyl was calculated. Estimates of the oxidative degradation for

Thifensulfuron-methyl were obtained using The Syracuse Research Corporation (SRC)

Atmospheric Oxidation Program (version 1.83). Estimation methods used by the

program are based upon structure-activity relationship (SAR) methods developed by Dr.

Atkinson and co-workers. The accuracy of the estimation methods used was compared

against 600 experimentally determined hydroxyl radical rate constants and is within a

factor of 2 of the experimental value. An assumed value is a value of a structure fragment

estimated by environmental scientists and not derived from experimental values.

Structures were entered into the program SMILES (Simplified Molecular Input Line

Entry System).

2. Method of calculation

The overall OH reaction rate constant kOH is equal to the sum of the rate constants for

each reaction pathway. The reaction pathways calculated in this experiment were the

Thifensulfuron-methyl radical (OH) addition to the triazine aromatic ring and thiophene


ring, Thifensulfuron-methyl hydrogen abstraction, reactions with nitrogen sulphur and –

OH. All estimations of the rate constant are applicable at T = 298K.

The half-life for Thifensulfuron-methyl in the troposphere is generated form the

instantaneous reaction of hydroxyl radicals in the troposphere, given the average daily air

concentrations of hydroxyl radicals (12-hour day, 1.5 106

OH radicals per cm3) and the

overall OH reaction rate constant previous calculated.

Table B.8.391 Details from SRC Program for Thifensulfuron-methyl

Reaction k (cm3/molecule-sec)

Hydrogen abstraction 1.1832 10-12

Reaction with N, S and –OH 1.0000 10-12

Addition to triple bonds 0.0000 10-12

Addition of olefinic bonds 0.0000 10-12

Addition to aromatic rings 0.9152 10-12

Addition to fused rings 0.0000 10-12

Overall OH rate constant (kOH) 3.0984 10-12

Half-life 41.425 hours (3.5 d)


A. DATA

Estimates of the rate of photochemical oxidative degradation for Thifensulfuron-methyl were

obtained using The Syracuse Research Corporation (SRC) Atmospheric Oxidation Program

(version 1.83). Estimation methods used by the Atmospheric Oxidation Program are based

upon structure-activity relationship (SAR) methods developed by Dr. Roger Atkinson and

co-workers. The overall second order rate constant for the reaction of Thifensulfuron-methyl

in the troposphere is calculated to be 3.0984 10–12 cm3/molecule-sec with a half-life of

41.425 hours (3.5). Results of the individual rate constants, overall rate constant, and the

half life of Thifensulfuron-methyl in the troposphere are detailed in Table .

III. CONCLUSION

The calculation of the second order rate constant and associated half-life T (1/2) E, for the

reaction of Thifensulfuron-methyl in the gas phase in the troposphere, using the method of

Atkinson is provided. The overall OH rate constant is 3.0984 10-12

cm3/molecule-sec. The

half-life of Thifensulfuron-methyl for reaction with average daily air concentrations of hydroxyl

radicals (12-hour day; 1.5 106 OH radicals per cm

3) is 41.425 hours (3.5 d). Hydrogen

abstraction, reaction with nitrogen, sulfur and –OH, and addition to the aromatic rings, are all

predicted to contribute to the rate of photochemical degradation.

(Schmuckler, M., 1999)

Although thifensulfuron methyl would be expected to degrade rapidly in soil and volatilisation

potential is low, the formation of aerosols during spray applications cannot be completely

excluded. Therefore theoretically there is a potential for long range transport. However due to

the rapid degradation in soil, low vapour pressure and high solubility coupled to the relatively

low application rates, in practice this risk is considered negligible.


B.8.8 Predicted environmental concentrations in air (PECa) (IIIA 9.3)

Method of calculation

Expert judgement, based on vapour pressure,

dimensionless Henry's Law Constant and

information on volatilisation from plants and

soil.

PEC(a)

Maximum concentration

Considered negligible

B.8.9 Definition of the residue (IIA 7.3)

The residue definition here is for further risk assessment, i..e all metabolites which have been

included in exposure assessment

In soil parent, IN-L9225, IN-JZ789, IN-A4098, IN-L9223, 2-acid-3-triuret, IN-W8268, IN-

V7160, IN-L9226, IN-A5546 were the major (>10% Applied) components of the residue

In surface water parent, IN-L9225, IN-JZ789, IN-A4098, IN-L9223, 2-acid-3-triuret, IN-W8268,

IN-V7160, IN-L9226, IN-A5546, IN-B5528, IN-RDF00 and IN-D8858 thiopenyl triazinyl amine

13 were the major (>10% Applied) components of the residue

In groundwater parent IN-L9225, IN-JZ789, IN-A4098, IN-L9223, 2-acid-3-triuret, IN-W8268,

IN-V7160, IN-L9226, IN-A5546 were the major (>10% Applied) components of the residue

In air parent (by default)

13

Some uncertainty exists over the structure of a proposed photoproduct identified in the DuPont and Task Force

data sets. The Task Force proposed the structure was thiophenyl triazinyl amine, whilst DuPont proposed the

structure was actually IN-D8856 (arising from photoisomerisation of the thiophene ring). This is further discussed

in Section B.8.4.2 but on the basis of the UK RMS evaluation, the evidence supporting the IN-D8856 structure

seems more plausible. A data requirement for further information on this metabolite has been proposed.


B.8.10 References relied on

The references relied on list has been updated to include the newly submitted data

relied on as well as those original submitted tests and studies that are still considered

relevant to support the application for renewal. Only new studies relied on for the

renewal of approval are included below. For references referring to studies in the

original DAR, see reference list in Volume 2.

Active substance - DuPont

Annex

point

Author Year Title

Source (where different from

company)

Company, Report No.

GLP or GEP status (where

relevant)

Published or Unpublished

Data

protection

claimed

Y/N

Justification

if data

protection is

claimed

Owner Previous

evaluation

IIA 7.1.2 Hawkins

D.R., Elsom

L.F., Kane

T.J.

1991 Anaerobic Soil Metabolism of

14C-triazine-2-labelled-DPX-

M6316.

DuPont report n° AMR 1349-

88.

Huntingdon Research Centre

Ltd., Huntingdon,

Cambridgeshire, U.K.

GLP: No

Published: No

Y but

expired

NA DuPont In DAR

(1996)

IIA 7.1.3 Ferguson, E.

M.

1986 Photodegradation of

[Thiophene-2-14C]DPX-

M6316 and [Triazine-2-

14C]DPX-M6316 on Soil.


86

DuPont de Nemours,

Agricultural Products

Research Division

Experimental Station

Wilmington, Delaware,

U.S.A.

GLP: No

Published: No

Y but

expired

NA DuPont In DAR

(1996)

IIA,

7.1.3/01

McLaughlin,

S.P.

2011 Photodegradation of

[14

C]DPX-M6316 on Soil

Smithers Viscient

DuPont-30224

GLP: Yes

Published: No

Study conducted under

GLP.

Y Provides

supporting

information to

original soil

photolysis

study.

Confirms

presence of

IN-V7160 as a

major photo-

metabolite.

DuPont Submitted

for the

purpose of

renewal

IIA, 7.2 Allen, R. 1987 DPX-M6316 Aerobic

Degradation in Soil.

DuPont report n° 5518-269/18

Hazleton, UK

Y but

expired

NA DuPont In DAR

(1996)


Annex

point

Author Year Title


company)

Company, Report No.


relevant)


Data

protection

claimed

Y/N

Justification

if data

protection is

claimed

Owner Previous

evaluation

GLP: Yes

Published: No

IIA, 7.2 Rhodes, B.

C.

1986 Aerobic Soil Metabolism of [2

14C] 4 Methoxy-6-methyl-

1,3,5-triazine-2-amine.


85

Du Pont de Nemours,

Agricultural Chemicals

Department, Research

Division Experimental Station


U.S.A.

GLP: No

Published: No

Y but

expired

NA DuPont In DAR

(1996)

IIA, 7.2 Manjunatha,

S.

2000 Rates of degradation of IN-

L9225 and IN-L9226

(metabolites of

Thifensulfuron-methyl) in

three aerobic soils

DuPont Report No.: DuPont-

2326

GLP: Yes

Published: No

Y but

expired

NA DuPont In DAR

Addendum

(2000)

IIA, 7.2 Fang, C. 2000 Rates of degradation of IN-

W8268, a metabolite of

Thifensulfuron-methyl, in

three aerobic soils

DuPont Report No.: DuPont-

3039

GLP: Yes

Published: No

Y but

expired

NA DuPont In DAR

Addendum

(2000)

IIA,

7.2/01

Jagtap, S. 2011 Soil degradation of

Thifensulfuron-methyl -

kinetic calculations following

FOCUS kinetics guidelines

Simulogic Environmental

Consulting Pvt. Ltd.

DuPont-18742 EU, Revision

No. 1, Supplement No. 1

GLP: No

Published: No

A new modeling study is

being submitted to take into

account the following

updates:

1. The modeling and/or

persistence endpoints have

been updated to meet the

existing FOCUS kinetics

N - DuPont Submitted

for the

purpose of

renewal


Annex

point

Author Year Title


company)

Company, Report No.


relevant)


Data

protection

claimed

Y/N

Justification

if data

protection is

claimed

Owner Previous

evaluation

guidance.

2. More comprehensive

datasets based upon

additional environmental

fate study results are

available.

3. Updates in the exposure

modeling guidance (e.g.,

EFSA recommendation for

new Q10 value of 2.58)

IIA,

7.2/02

Snyder, N.J. 2012 Soil degradation of


kinetic calculations following

FOCUS kinetics guidelines

Waterborne Environmental,

Inc

DuPont-18742 EU, Revision

No. 2

GLP: No

Published: No




updates:





guidance.


datasets based upon



available.






for the

purpose of

renewal

IIA,

7.2/03

Weber, D. 2011 Aminotriazin: Calculation of

endpoints from aerobic soil

degradation studies for use in

fate modelling Kinetic

analysis according to the

FOCUS guidance

Harlan Laboratories Ltd.

SYN D09681 (M-411174-01-

1)

GLP: No

Published: No

Study provides kinetic

analysis of data from three

N - Syngen

ta

Submitted

for the

purpose of

renewal


Annex

point

Author Year Title


company)

Company, Report No.


relevant)


Data

protection

claimed

Y/N

Justification

if data

protection is

claimed

Owner Previous

evaluation

sumitted studies on

metabolite IN-A4098:

DuPont-1802, AGR15

(M-202633-01-1) and SYN

T001214-06

IIA,

7.2.3/01

Bell, S. 2011 Rate of degradation of [14

C]-

IN-A5546 in five aerobic soils

Charles River Laboratories

(UK)

Dupont-29146

GLP: Yes

Published: No

Major metabolite rate study

required under new

1107/2009 regulation.

Y Major

metabolite rate

study required

under new

1107/2009

regulation.

DuPont Submitted

for the

purpose of

renewal

IIA,

7.2.3/03

Jungmann,

V.,

Nicollier, G.

2006 Rate of degradation of

[triazinyl-6-14

C]-labelled CGA

150829 (metabolite of CGA

152005) in various soils under

aerobic laboratory conditions

at 20 deg. C

Syngenta Crop Protection

SYN T001214-06 (Study

No.12)

GLP: Yes

Published: No

New data on metabolite

IN-A4098.

Y New data on

major

metabolite IN-

A4098

Syngen

ta

Submitted

for the

purpose of

renewal

IIA,

7.2.3/04

Möndel, M. 2001 Degradation and metabolism

of AE F059411 in one soil

under standard conditions

Staatliche Lehr - und

Forschungsanstalt fur

Landwirtschaft, Weinbau und

Gartenbau (SLFA)

Aventis AGR15 (M-202633-

01-1)

GLP: Yes

Published: No

New data on metabolite

IN-A4098.

Y New data on

major

metabolite IN-

A4098

Bayer

CropSc

ience

Submitted

for the

purpose of

renewal

IIA,

7.2.3/06

Tunink, A. 2009 14

C-IN-V7160: Rate of

degradation in five soils

ABC Laboratories, Inc.

(Missouri)

DuPont-27641, Revision No.

1

GLP: Yes

Published: No

Y Major

metabolite rate

study required

under new

1107/2009

regulation

DuPont Submitted

for the

purpose of

renewal


Annex

point

Author Year Title


company)

Company, Report No.


relevant)


Data

protection

claimed

Y/N

Justification

if data

protection is

claimed

Owner Previous

evaluation

Major metabolite rate study

required under new


IIA,

7.4.1/01

Bell, S. 2011 Absorption/desorption of

[14

C]-DPX-M6316

(Thifensulfuron-methyl) via



(UK)

DuPont-30563

GLP: Yes

Published: No


GLP.

Y Additional

data provided

on active

substance and

used in

selecting

modelling

endpoints.

DuPont Submitted

for the

purpose of

renewal

IIA,

7.4.2/02

Bell, S. 2011 Adsorption/desorption of

[14

C]-IN-A5546 via batch

equilibrium method


(UK)

DuPont-30564

GLP: Yes

Published: No

Major metabolite

adsorption/desorption study

required under new


Y Major

metabolite

adsorption

study required

under new

1107/2009

regulation

DuPont Submitted

for the

purpose of

renewal

IIA,

7.4.2/03

Cleland, H.,

Andrews, S.

2011 Adsorption/desorption of

[14

C]-IN-L9223 via batch

equilibrium method


(UK)

DuPont-30424

GLP: Yes

Published: No

Major metabolite


required under new


Y Major

metabolite

adsorption

study required

under new

1107/2009

regulation

DuPont Submitted

for the

purpose of

renewal

IIA,

7.4.2/04

Elliott, T. 2009 14

C-IN-V7160: Batch

equilibrium

(adsorption/desorption) in five

soils

ABC Laboratories, Inc.

(Missouri)

DuPont-27638

GLP: Yes

Published: No

Major metabolite


Y Major

metabolite

adsorption

study required

under new

1107/2009

regulation

DuPont Submitted

for the

purpose of

renewal


Annex

point

Author Year Title


company)

Company, Report No.


relevant)


Data

protection

claimed

Y/N

Justification

if data

protection is

claimed

Owner Previous

evaluation

required under new


IIA,

7.4.2/05

Hein, W. 2001 Adsorption/desorption of AE

F059411-[2-14

C] on one soil

Staatliche Lehr- und

Forschungsanstalt fur

Landwirtschaft, Weinbau und

Gartenbau (SLFA)

AgrEvo OE98/111 (M-

182936-02-1)

GLP: Yes

Published: No

Major metabolite


required under new


Y Newly

submitted for

this active

substance (but

likely to have

been evaluated

in other

substance

DARs)

Bayer

CropSc

ience

Submitted

for the

purpose of

renewal

IIA,

7.4.2/06

Kesterson,

A.

1990 Soil adsorption/desorption of

[14

C]CGA-150829 by the


PTRL

Ciba 470

GLP: Yes

Published: No

Major metabolite


required under new


Y Newly

submitted for

this active

substance (but

likely to have

been evaluated

in other

substance

DARs)

Syngen

ta

Submitted

for the

purpose of

renewal

IIA,

7.4.2/07

Li,Y.,

McFetridge,

R.D.

1996 Batch equilibrium

(adsorption/desorption) study

of a metabolite, triazine amine

(IN-A4098), of DPX-T6376

on soil

DuPont Experimental Station

AMR 3656-95

GLP: Yes

Published: No

Major metabolite


required under new


N - DuPont In DAR

Addendum

(2000)

IIA,

7.4.2/08

Schmidt, E. 1998 Determination of the

adsorption/desorption

behaviour in the system

soil/water in three soil types

according to OECD guideline

#106

Hoechst Schering AgrEvo

GmbH

AgrEvo CP98/014 (M-

182945-01-1)

Y Newly

submitted for

this active

substance (but

likely to have

been evaluated

in other

substance

DARs)

Bayer

CropSc

ience

Submitted

for the

purpose of

renewal


Annex

point

Author Year Title


company)

Company, Report No.


relevant)


Data

protection

claimed

Y/N

Justification

if data

protection is

claimed

Owner Previous

evaluation

GLP: Yes

Published: No

Major metabolite


required under new


IIA 7.4.2 Yeomans, P. 2000 IN-L9225:

Adsorption/desorption in soil

– final report (Study No.

550/60) DuPont-1812

GLP: Yes

Published: No

Y but

expired

NA DuPont In DAR

Addendum

(2000)

IIA 7.4.2 Yeomans, P. 2000 IN-L9226:



550/61) DuPont-1813

GLP: Yes

Published: No

Y but

expired

NA DuPont In DAR

Addendum

(2000)

IIA 7.4.2 Yeomans, P.

and Swales,

S.

2000 IN-W8268:



550/75) DuPont-3172

GLP: Yes

Published: No

Y but

expired

NA DuPont In DAR

Addendum

(2000)

IIA,

7.4.2/09

Stroech, K. 2010 [Triazine-2-14

C]BCS-

CN85650 (AEF059411):

Adsorption/desorption on five

soils

Bayer CropScience

Bayer M1311857-6 (M-

367103-01-1)

GLP: Yes

Published: No

Major metabolite


required under new


Y Major

metabolite

adsorption

study required

under new

1107/2009

regulation

Bayer

CropSc

ience

Submitted

for the

purpose of

renewal

IIA,

7.4.2/10

Suresh, G. 2012 Adsorption-desorption of IN-

JZ789 via batch equilibrium in

five soils

International Institute of

Biotechnology and

Toxicology (IIBAT)

DuPont-34350

GLP: Yes

Published: No

Major metabolite


required under new


Y Major

metabolite

adsorption

study required

under new

1107/2009

regulation

DuPont Submitted

for the

purpose of

renewal


Annex

point

Author Year Title


company)

Company, Report No.


relevant)


Data

protection

claimed

Y/N

Justification

if data

protection is

claimed

Owner Previous

evaluation

IIA,

7.4.2/11

Yeomans,

P., Swales,

S.

2000 [14

C]IN-A4098:


Covance Laboratories Europe

(CLE)

DuPont-3832

GLP: Yes

Published: No

Major metabolite


required under new


Y Newly

submitted for

this active

substance (but

likely to have

been evaluated

in other

substance

DARs)

DuPont Submitted

for the

purpose of

renewal

IIA,

7.5/01

Wardrope,

L.

2011 Hydrolysis of [14

C]-DPX-

M6316 (Thifensulfuron-

methyl) as a function of pH


DuPont-30225

GLP: Yes

Published: No


GLP.

Y New study to

meet the

hydrolysis

data

requirement

DuPont Submitted

for the

purpose of

renewal

IIA,

7.5/02

Wardrope,

L.

2014 Hydrolysis of [14

C]-DPX-

M6316 (thifensulfuron

methyl) as a function of pH-

identification of unknown

polar metabolite


DuPont-30225, Supplement

No. 1

GLP: Yes

Published: No


GLP.

Y New study to

identify major

metabolite in

new

hydrolysis

study

DuPont Submitted

for the

purpose of

renewal

IIA 7.6 Ryan, D. L 1986 The Photodegradation of

[Thiophene-2-14C] DPX-

M6316 and [Triazine-2-14C]

DPX-M6316 in Water.


86

DuPont de Nemours,

Agricultural Products

Research Division

Experimental Station


U.S.A.

GLP: No

Published: No

Y but

expired

NA DuPont In DAR

(1996)

IIA,

7.6/01

Lentz, N.R. 2001 Photodegradation of

Thifensulfuron-methyl in

natural water by simulated

sunlight

Y Acceptable

study

performed to

GLP

DuPont Submitted

for the

purpose of

renewal


Annex

point

Author Year Title


company)

Company, Report No.


relevant)


Data

protection

claimed

Y/N

Justification

if data

protection is

claimed

Owner Previous

evaluation

Ricerca, LLC

DuPont-6047

GLP: Yes

Published: No


GLP.

providing

reliable

endpoints.

IIA,

7.6/02

Umstaetter,

S.

2006 Assessment of the identity of

the photolysis degradation

products of Thifensulfuron-

methyl (DPX-M6316)

observed in sterile buffers and

natural waters (DuPont-6047)

DuPont Stine-Haskell

Research Center

DuPont-20549

GLP: No

Published: No

Identification of major

metabolites in aqueous

photodegradation studies

required under 1107/2009

regulation.

Y Acceptable

study

performed to

GLP

providing

reliable

endpoints.

DuPont Submitted

for the

purpose of

renewal

IIA,

7.6/03

Sharma,

A.K.

2014 Photodegradation of [14

C]-

DPX-M6316 in buffer,

confirmation of structure of

degradate IN-D8858

DuPont Stine-Haskell

Research Center

DuPont-41912

GLP: No

Published: No


for the

purpose of

renewal

IIA,

7.7/01

Barnes, S.P. 2000 DPX-M6316 assessment of

ready biodegradability by

modified Sturm test

Huntingdon Life Sciences Ltd.

DuPont-4373

GLP: Yes

Published: No

Study required under


Y GLP

compliant

study to meet

the ready

biodegradabili

ty data

requirement

DuPont Submitted

for the

purpose of

renewal

IIA 7.8.3 Spare, W.C. 2000 Degradability and fate of

Thifensulfuron methyl in

aerobic aquatic environment

(water/sediment system) –

Revision 1. DuPont-1206

GLP: Yes

Published: No

Y but

expired

NA DuPont In DAR

Addendum

(2000)

IIA,

7.8.3/01

van Beinum,

W.,

Beulke, S.

2006 Calculation of degradation

endpoints from water-

sediment studies for


for the

purpose of


Annex

point

Author Year Title


company)

Company, Report No.


relevant)


Data

protection

claimed

Y/N

Justification

if data

protection is

claimed

Owner Previous

evaluation

Thifensulfuron-methyl (DPX-

M6316) and its metabolites

Central Science Laboratory

DuPont-18745

GLP: No

Published: No




updates:





guidance.


datasets based upon



available.





renewal

IIA,

7.10/01

Schmuckler,

M.E.

1999 Photodegradation oxidative

degradation of Thifensulfuron-

methyl

DuPont Experimental Station

DuPont-3459

GLP: Not applicable

Published: No

DT50 in air has been

estimated via the Atkinson

method and provided in this

renewal dossier.


for the

purpose of

renewal

Active substance – EU TSM Task Force

Annex

point

Author Year Title

Source (where different

from company)

Company, Report No.

GLP or GEP status

(where relevant)


Data

protection

claimed

Y/N

Justification

if data

protection

is claimed

Owner Previous

evaluation

IIA,

7.1.1/01

Simmonds,

M.

2012a [14

C]-Thifensulfuron-

Methyl: Route and Rate

of Degradation in Four

Soils at 20ºC

Y New

acceptable

GLP

compliant

EU TSM

AIR 2 Task

Force

Submitted

for the

purpose of

renewal


Annex

point

Author Year Title


from company)

Company, Report No.

GLP or GEP status

(where relevant)


Data

protection

claimed

Y/N

Justification

if data

protection

is claimed

Owner Previous

evaluation

Battelle UK Ltd. Report

No.: WB/10/004

Cheminova A/S Report

No.: 283 TIM

GLP, Unpublished

Data gap identified

from first EU

evaluation

study

providing

reliable

endpoints

IIA,

7.1.2/01

Simmonds,

R.

2011a [14

C]-Thifensulfuron-

methyl: Anaerobic

degradation in soil


No.: WB/10/005


No.: 244 TIM

GLP, Unpublished

Study required based

on new guidance

Y New

acceptable

GLP

compliant

study

providing

reliable

endpoints

EU TSM

AIR 2 Task

Force

Submitted

for the

purpose of

renewal

IIA

7.1.3/01

Simmonds,

R.

2012 [14

C]-Thifensulfuron-

methyl: Soil Photolysis


No.: WB/10/006


No.: 245 TIM

amendment 1

GLP, Unpublished

Data gap identified

from first EU

evaluation

Y New

acceptable

GLP

compliant

study

providing

reliable

endpoints

EU TSM

AIR 2 Task

Force

Submitted

for the

purpose of

renewal

IIA,

7.2.1/01

Simmonds,

M.

2012a [14

C]-Thifensulfuron-



Soils at 20ºC


No.: WB/10/004


No.: 283 TIM

GLP, Unpublished

IIA, 7.1.1/01

Data gap identified

from first EU

evaluation

Y New

acceptable

GLP

compliant

study

providing

reliable

endpoints

EU TSM

AIR 2 Task

Force

Submitted

for the

purpose of

renewal

IIA,

7.2.1/02

Ford, S. 2012 Thifensulfuron-methyl:

Calculation of Kinetic

Endpoints for Modelling

Purposes from a Study

on Four Laboratory Soils

JSC International

Limited Report No.:

RCH/02/02/KIN1

GLP No, Unpublished

Study required based

on new guidance/ data

N - EU TSM

AIR 2 Task

Force

Submitted

for the

purpose of

renewal


Annex

point

Author Year Title


from company)

Company, Report No.

GLP or GEP status

(where relevant)


Data

protection

claimed

Y/N

Justification

if data

protection

is claimed

Owner Previous

evaluation

requirement

IIA,

7.2.3/01

Simmonds,

M.

2012a [14

C]-Thifensulfuron-



Soils at 20ºC


No.: WB/10/004


No.: 283 TIM

GLP, Unpublished

IIA, 7.1.1/01

Data gap identified

from first EU

evaluation

Y New

acceptable

GLP

compliant

study

providing

reliable

endpoints

EU TSM

AIR 2 Task

Force

Submitted

for the

purpose of

renewal

IIA,

7.2.3/02

Morlock, G. 2006a Degradation of 2-amino-

4-methoxy-6-methyl-

1,3,5-triazine (MM-TA)

in 3 different soils under

aerobic conditions at

20°C in the dark

GAB Biotechnologie

GmbH & GAB Analytik

GmbH Report No.

20051104/01-CABJ


No.: 189 TIM

GLP, Unpublished

Study required as

metabolite considered

potentially relevant

under new data

requirements

Y New

acceptable

GLP

compliant

study

providing

reliable

endpoints

EU TSM

AIR 2 Task

Force

Submitted

for the

purpose of

renewal

IIA,

7.2.3/04

Brice, A.,

Gilbert, J.

2011b Thifensulfonamide:

Aerobic soil degradation.

+ Amendment 1

Covance Laboratories

Ltd. Report No.:

8235715


No.: 199 TIM

GLP, Unpublished

Study required as



under new data

requirements

Y New

acceptable

GLP

compliant

study

providing

reliable

endpoints

EU TSM

AIR 2 Task

Force

Submitted

for the

purpose of

renewal

IIA,

7.2.3/07

Knoch, E. 2012c Aerobic Soil

Degradation of O-

Desmethyl


SGS Institute Fresenius

GmbH Report No.: IF-

11-02083022

Y New

acceptable

GLP

compliant

study

providing

reliable

EU TSM

AIR 2 Task

Force

Submitted

for the

purpose of

renewal


Annex

point

Author Year Title


from company)

Company, Report No.

GLP or GEP status

(where relevant)


Data

protection

claimed

Y/N

Justification

if data

protection

is claimed

Owner Previous

evaluation


No.: 299 TIM

GLP, Unpublished

Study required as



under new data

requirements

endpoints

IIA,

7.2.3/08

Knoch, E. 2012d Aerobic Soil

Degradation of

Thiophene sulfonimide



11-02039256


No.: 297 TIM

GLP, Unpublished

Study required as



under new data

requirements

Y New

acceptable

GLP

compliant

study

providing

reliable

endpoints

EU TSM

AIR 2 Task

Force

Submitted

for the

purpose of

renewal

IIA,

7.2.4/01

Simmonds,

R.

2011a [14

C]-Thifensulfuron-

methyl: Anaerobic

degradation in soil


No.: WB/10/005


No.: 244 TIM

GLP, Unpublished

IIA, 7.1.2/01

Study required based on

new guidance

Y New

acceptable

GLP

compliant

study

providing

reliable

endpoints

EU TSM

AIR 2 Task

Force

Submitted

for the

purpose of

renewal

IIA,

7.4.1/01

Simmonds,

R., Burges,

M.

2012 [14

C]-Thifensulfuron-

methyl: Adsorption to

and desorption from four

soil


No.: WB/10/007


No.: 259 TIM

GLP, Unpublished


new guidance

Y New

acceptable

GLP

compliant

study

providing

reliable

endpoints

EU TSM

AIR 2 Task

Force

Submitted

for the

purpose of

renewal

IIA,

7.4.2/01

Morlock, G. 2006b Determination of the

adsorption/desorption

behaviour of 2-amino-4-

methoxy-6-methyl-1,3,5-

triazine (MM-TA) in

three different soils

GAB Biotechnologie

GmbH & GAB Analytik

GmbH Report No.

Y New

acceptable

GLP

compliant

study

providing

reliable

endpoints

EU TSM

AIR 2 Task

Force

Submitted

for the

purpose of

renewal


Annex

point

Author Year Title


from company)

Company, Report No.

GLP or GEP status

(where relevant)


Data

protection

claimed

Y/N

Justification

if data

protection

is claimed

Owner Previous

evaluation

20051104/01-PCAD


No.: 212 TIM

GLP, Unpublished

Study required as



under new data

requirements

IIA,

7.4.2/02

Brice, A.,

Gilbert, J.

2011c 2-Acid-3-sulfonamide:

Adsorption/ desorption

Study in three soils +

Amendment 1


Ltd. Report No.:

8235718


No.: 202 TIM

GLP, Unpublished

Study required as



under new data

requirements

Y New

acceptable

GLP

compliant

study

providing

reliable

endpoints

EU TSM

AIR 2 Task

Force

Submitted

for the

purpose of

renewal

IIA,

7.4.2/03

Mosely, R. 2011 Thifensulfonamide:

Estimation of soil

adsorption coefficient

(KOC) using high

performance liquid

chromatography (HPLC)


Ltd. Report No.:

8235716


No.: 200 TIM

GLP, Unpublished

Study required as



under new data

requirements

Y New

acceptable

GLP

compliant

study

providing

reliable

endpoints

EU TSM

AIR 2 Task

Force

Submitted

for the

purpose of

renewal

IIA,

7.4.2/04

Knoch, E. 2012f Adsorption of

Thifensulfuron acid on

Soils



12-02135828


No.: 305 TIM

GLP, Unpublished

Study required as



Y New

acceptable

GLP

compliant

study

providing

reliable

endpoints

EU TSM

AIR 2 Task

Force

Submitted

for the

purpose of

renewal


Annex

point

Author Year Title


from company)

Company, Report No.

GLP or GEP status

(where relevant)


Data

protection

claimed

Y/N

Justification

if data

protection

is claimed

Owner Previous

evaluation

under new data

requirements

IIA,

7.4.2/05

Knoch, E. 2012g Adsorption of O-

desmethyl thifensulfuron

acid on Soils



12-02132069


No.: 302 TIM

GLP, Unpublished

Study required as



under new data

requirements

Y New

acceptable

GLP

compliant

study

providing

reliable

endpoints

EU TSM

AIR 2 Task

Force

Submitted

for the

purpose of

renewal

IIA,

7.4.2/07

Knoch, E. 2012i Adsorption of Thiophene

sulfonimide on Soils



12-02132068


No.: 301 TIM

GLP, Unpublished

Study required as



under new data

requirements

Y New

acceptable

GLP

compliant

study

providing

reliable

endpoints

EU TSM

AIR 2 Task

Force

Submitted

for the

purpose of

renewal

IIA,

7.4.2/08

Knoch, E. 2012j Adsorption of O-

desmethyl


on Soils



12-02132071


No.: 303 TIM

GLP, Unpublished

Study required as



under new data

requirements

Y New

acceptable

GLP

compliant

study

providing

reliable

endpoints

EU TSM

AIR 2 Task

Force

Submitted

for the

purpose of

renewal

IIA,

7.4.2/09

Knoch, E. 2012k Adsorption of TIM 2-

acid-3-triuret on Soils



12-02251377


No.: 316 TIM

GLP, Unpublished

Study required as

Y New

acceptable

GLP

compliant

study

providing

reliable

endpoints

EU TSM

AIR 2 Task

Force

Submitted

for the

purpose of

renewal


Annex

point

Author Year Title


from company)

Company, Report No.

GLP or GEP status

(where relevant)


Data

protection

claimed

Y/N

Justification

if data

protection

is claimed

Owner Previous

evaluation



under new data

requirements

IIA,

7.5/01

Simmonds,

R., Buntain,

I.

2012 [14

C]-Thifensulfuron-

methyl: Hydrolysis in

sterile buffer at pH 4, 7

and 9


No.: WB/10/008


No.: 260 TIM

GLP, Unpublished

Previous study not

conducted to current

guidelines and not GLP

Y New

acceptable

GLP

compliant

study

providing

reliable

endpoints

EU TSM

AIR 2 Task

Force

Submitted

for the

purpose of

renewal

IIA,

7.6/01

Oddy, A. 2012 [14

C]-Thifensulfuron-

methyl: Aqueous

Photolysis and Quantum

Yield Determination in

Sterile Buffer Solution


No.: WB/10/009


No.: 284 TIM

GLP, Unpublished

Previous study not

conducted to current

guidelines and not GLP

Y New

acceptable

GLP

compliant

study

providing

reliable

endpoints

EU TSM

AIR 2 Task

Force

Submitted

for the

purpose of

renewal

IIA,

7.8.3/01

Simmonds,

M.

2012b [14

C]-Thifensulfuron-

methyl: Degradation and

retention in two water-

sediment systems


No.: WB/10/010


No.: 285 TIM

GLP, Unpublished


new guidelines

Y New

acceptable

GLP

compliant

study

providing

reliable

endpoints

EU TSM

AIR 2 Task

Force

Submitted

for the

purpose of

renewal


Plant protection product – ‘Thifensulfuron-methyl 50SG’ (DuPont)

Annex

point

Author Year Title


from company)

Company, Report No.

GLP or GEP status

(where relevant)


Data

protection

claimed

Y/N

Justification

if data

protection

claimed

Owner Previous

evaluation

IIIA,

9.4/01



kinetic calculations

following FOCUS

kinetics guidelines

Simulogic

Environmental


DuPont-18742 EU,

Revision No. 1,

Supplement No. 1

GLP: No

Published: No

A new modelling study

is being submitted to

take into account the

following updates:

1. The modelling

and/or persistence

endpoints have been

updated to meet the

existing FOCUS

kinetics guidance.


datasets based upon

additional

environmental fate

study results are

available.

3. Updates in the

exposure modelling

guidance (e.g., EFSA

recommendation for

new Q10 value of 2.58).


for the

purpose of

renewal

IIIA,

9.4/02

Pant, R.,

Jagtap, S.

2012 Predicted environmental

concentrations in soil for


and its metabolites in the

EU

Simulogic

Environmental


DuPont-33592 EU

GLP: No

Published: No





for the

purpose of

renewal


Annex

point

Author Year Title


from company)

Company, Report No.

GLP or GEP status

(where relevant)


Data

protection

claimed

Y/N

Justification

if data

protection

claimed

Owner Previous

evaluation

following updates:

1. The modelling

and/or persistence

endpoints have been

updated to meet the

existing FOCUS

kinetics guidance.


datasets based upon

additional

environmental fate

study results are

available.

3. Updates in the

exposure modelling


recommendation for


IIIA,

9.4/03




following FOCUS

kinetics guidelines

Waterborne

Environmental, Inc

DuPont-18742 EU,

Revision No. 2

GLP: No

Published: No




following updates:

1. The modelling

and/or persistence

endpoints have been

updated to meet the

existing FOCUS

kinetics guidance.


datasets based upon

additional

environmental fate

study results are

available.

3. Updates in the

exposure modelling


recommendation for



for the

purpose of

renewal

IIIA,

9.5/01




for the


Annex

point

Author Year Title


from company)

Company, Report No.

GLP or GEP status

(where relevant)


Data

protection

claimed

Y/N

Justification

if data

protection

claimed

Owner Previous

evaluation


following FOCUS

kinetics guidelines

Simulogic

Environmental


DuPont-18742 EU,

Revision No. 1,

Supplement No. 1

GLP: No

Published: No




following updates:

1. The modelling

and/or persistence

endpoints have been

updated to meet the

existing FOCUS

kinetics guidance.


datasets based upon

additional

environmental fate

study results are

available.

3. Updates in the

exposure modelling


recommendation for


purpose of

renewal

IIIA,

9.5/02

Pant, R.,

Jagtap, S.


concentrations in soil for


and its metabolites in the

EU

Simulogic

Environmental


DuPont-33592 EU

GLP: No

Published: No




following updates:

1. The modelling

and/or persistence

endpoints have been

updated to meet the


for the

purpose of

renewal


Annex

point

Author Year Title


from company)

Company, Report No.

GLP or GEP status

(where relevant)


Data

protection

claimed

Y/N

Justification

if data

protection

claimed

Owner Previous

evaluation

existing FOCUS

kinetics guidance.


datasets based upon

additional

environmental fate

study results are

available.

3. Updates in the

exposure modelling


recommendation for


IIIA,

9.5/03




following FOCUS

kinetics guidelines

Waterborne

Environmental, Inc

DuPont-18742 EU,

Revision No. 2

GLP: No

Published: No




following updates:

1. The modelling

and/or persistence

endpoints have been

updated to meet the

existing FOCUS

kinetics guidance.


datasets based upon

additional

environmental fate

study results are

available.

3. Updates in the

exposure modelling


recommendation for



for the

purpose of

renewal

IIIA,

9.6/01




following FOCUS

kinetics guidelines

Simulogic

Environmental


for the

purpose of

renewal


Annex

point

Author Year Title


from company)

Company, Report No.

GLP or GEP status

(where relevant)


Data

protection

claimed

Y/N

Justification

if data

protection

claimed

Owner Previous

evaluation


DuPont-18742 EU,

Revision No. 1,

Supplement No. 1

GLP: No

Published: No




following updates:

1. The modelling

and/or persistence

endpoints have been

updated to meet the

existing FOCUS

kinetics guidance.


datasets based upon

additional

environmental fate

study results are

available.

3. Updates in the

exposure modelling


recommendation for


IIIA,

9.6/02

Pant, R.,

Jagtap, S.


concentrations of


(DPX-M6316) and

metabolites in

groundwater: A

modelling study

conducted with FOCUS

PEARL 4.4.4

Simulogic

Environmental


DuPont-33593 EU

GLP: No

Published: No




following updates:

1. The modelling

and/or persistence

endpoints have been

updated to meet the

existing FOCUS


for the

purpose of

renewal


Annex

point

Author Year Title


from company)

Company, Report No.

GLP or GEP status

(where relevant)


Data

protection

claimed

Y/N

Justification

if data

protection

claimed

Owner Previous

evaluation

kinetics guidance.


datasets based upon

additional

environmental fate

study results are

available.

3. Updates in the

exposure modelling


recommendation for


IIIA,

9.6/03




following FOCUS

kinetics guidelines

Waterborne

Environmental, Inc

DuPont-18742 EU,

Revision No. 2

GLP: No

Published: No




following updates:

1. The modelling

and/or persistence

endpoints have been

updated to meet the

existing FOCUS

kinetics guidance.


datasets based upon

additional

environmental fate

study results are

available.

3. Updates in the

exposure modelling


recommendation for



for the

purpose of

renewal

IIIA,

9.7/01




following FOCUS

kinetics guidelines

Simulogic

Environmental



for the

purpose of

renewal


Annex

point

Author Year Title


from company)

Company, Report No.

GLP or GEP status

(where relevant)


Data

protection

claimed

Y/N

Justification

if data

protection

claimed

Owner Previous

evaluation

DuPont-18742 EU,

Revision No. 1,

Supplement No. 1

GLP: No

Published: No




following updates:

1. The modelling

and/or persistence

endpoints have been

updated to meet the

existing FOCUS

kinetics guidance.


datasets based upon

additional

environmental fate

study results are

available.

3. Updates in the

exposure modelling


recommendation for


IIIA,

9.7/02

Pant, R.,

Jagtap, S.


concentrations of


(DPX-M6316) and

metabolites in surface

water and sediment:

Modeling for the

European Union

Simulogic

Environmental


DuPont-33594 EU

GLP: No

Published: No




following updates:

1. The modelling

and/or persistence

endpoints have been

updated to meet the

existing FOCUS

kinetics guidance.



for the

purpose of

renewal


Annex

point

Author Year Title


from company)

Company, Report No.

GLP or GEP status

(where relevant)


Data

protection

claimed

Y/N

Justification

if data

protection

claimed

Owner Previous

evaluation

datasets based upon

additional

environmental fate

study results are

available.

3. Updates in the

exposure modelling


recommendation for


IIIA,

9.7/03




following FOCUS

kinetics guidelines

Waterborne

Environmental, Inc

DuPont-18742 EU,

Revision No. 2

GLP: No

Published: No




following updates:

1. The modelling

and/or persistence

endpoints have been

updated to meet the

existing FOCUS

kinetics guidance.


datasets based upon

additional

environmental fate

study results are

available.

3. Updates in the

exposure modelling


recommendation for



for the

purpose of

renewal

IIIA,

9.7/04

van Beinum,

W., Beulke,

S.

2006 Calculation of

degradation endpoints

from water-sediment

studies for


(DPX-M6316) and its

metabolites

Central Science

Laboratory

DuPont-18745


for the

purpose of

renewal


Annex

point

Author Year Title


from company)

Company, Report No.

GLP or GEP status

(where relevant)


Data

protection

claimed

Y/N

Justification

if data

protection

claimed

Owner Previous

evaluation

GLP: No

Published: No




following updates:

1. The modelling

and/or persistence

endpoints have been

updated to meet the

existing FOCUS

kinetics guidance.


datasets based upon

additional

environmental fate

study results are

available.

3. Updates in the

exposure modelling


recommendation for


IIIA,

9.8/01




following FOCUS

kinetics guidelines

Simulogic

Environmental


DuPont-18742 EU,

Revision No. 1,

Supplement No. 1

GLP: No

Published: No




following updates:

1. The modelling

and/or persistence

endpoints have been

updated to meet the

existing FOCUS

kinetics guidance.


datasets based upon

additional

environmental fate

study results are


for the

purpose of

renewal


Annex

point

Author Year Title


from company)

Company, Report No.

GLP or GEP status

(where relevant)


Data

protection

claimed

Y/N

Justification

if data

protection

claimed

Owner Previous

evaluation

available.

3. Updates in the

exposure modelling


recommendation for


IIIA,

9.8/02

Pant, R.,

Jagtap, S.


concentrations of


(DPX-M6316) and

metabolites in surface

water and sediment:

Modeling for the

European Union

Simulogic

Environmental


DuPont-33594 EU

GLP: No

Published: No




following updates:

1. The modelling

and/or persistence

endpoints have been

updated to meet the

existing FOCUS

kinetics guidance.


datasets based upon

additional

environmental fate

study results are

available.

3. Updates in the

exposure modelling


recommendation for



for the

purpose of

renewal

IIIA,

9.8/03




following FOCUS

kinetics guidelines

Waterborne

Environmental, Inc

DuPont-18742 EU,

Revision No. 2

GLP: No

Published: No


for the

purpose of

renewal


Annex

point

Author Year Title


from company)

Company, Report No.

GLP or GEP status

(where relevant)


Data

protection

claimed

Y/N

Justification

if data

protection

claimed

Owner Previous

evaluation




following updates:

1. The modelling

and/or persistence

endpoints have been

updated to meet the

existing FOCUS

kinetics guidance.


datasets based upon

additional

environmental fate

study results are

available.

3. Updates in the

exposure modelling


recommendation for


IIIA,

9.8/04

van Beinum,

W., Beulke,

S.

2006 Calculation of

degradation endpoints

from water-sediment

studies for


(DPX-M6316) and its

metabolites

Central Science

Laboratory

DuPont-18745

GLP: No

Published: No




following updates:

1. The modelling

and/or persistence

endpoints have been

updated to meet the

existing FOCUS

kinetics guidance.


datasets based upon

additional

environmental fate

study results are

available.

3. Updates in the

exposure modelling


for the

purpose of

renewal


Annex

point

Author Year Title


from company)

Company, Report No.

GLP or GEP status

(where relevant)


Data

protection

claimed

Y/N

Justification

if data

protection

claimed

Owner Previous

evaluation


recommendation for


Plant protection product – ‘680 g/kg Water dispersible granule’ (Cheminova) and ‘682 g/kg

Water dispersible granule’ (Rotam)

No AIII studies.


Appendix 1: Graphical Outputs from the FOCUSsw Step 3 simulations

Winter applications to winter cereals at 37.5 g a.s./ha

D1 ditch


D1 Stream


D2 Ditch


D3 Stream


D3 Ditch


D4 Pond


D4 Stream


D5 Pond


D5 Stream


D6 Ditch


R1 Pond


R1 Stream


R3 Stream


R4 Stream


Spring applications to winter cereals at 51 g a.s./ha

D1 Ditch


D1 Stream


D2 Ditch


D2 Stream


D3 Ditch


D4 Pond


D4 Stream


D5 Pond


D5 Stream


D6 Ditch


R1 Pond


R1 Stream


R3 Stream


R4 Stream


Appendix 2: Summaries Of Published Literature Determined To Be Relevant To The

Thifensulfuron-methyl Submission

A literature review is not a mandatory requirement for second stage renewal substances.

However a literature review was supplied as part of the submission by DuPont. No information

from the open literature was provided by the Task Force. The UK RMS has briefly reviewed the

literature review provided by DuPont and the summary of relevant information is provided in this

Appendix.

In general the literature review performed by DuPont appeared to be well conducted and clearly

reported. A range of relevant databases were searched (AGRICOLA, BIOSIS, CABA, Carplus).

The search covered a period of at least 10 years and included the active substance and all

significant metabolites found in the different environmental matrices. The relevance criteria used

were clearly reported (see Table B.8.392 for details). The majority of studies identified in the

initial search were excluded based on consideration of the relevance criteria in Table B.8.392.

For the fate and behaviour references, most were excluded as they failed criteria 4 and/or 5

below. Out of 118 references only 3 remained after the relevance criteria were applied and these

references are summarised in detail below. Prior to each summary the UK RMS has provided a

very brief overview of the reference with regards implications for the EU assessment of


Table B.8.392: Relevance criteria used in the literature review conducted by DuPont

Data requirement(s)

(indicated by the correspondent

OECD data point number(s)) Criteria for relevance

All OECD Data Points 1. The dose levels or application rates reflect the proposed GAP.

2. The test system, target crop, or species are prescribed by

Regulation (EC) No 1107/2009 or the relevance is explained

if not standard.

3. Well identified test material, including its purity and impurity

profile, is described.

4. Study design and/or execution are consistent with relevant

study guidelines.

5. The endpoint is relevant to an OECD data point as prescribed

by Regulations (EU) No 544/2011 and 545/2011.

Toxicological and toxicokinetic studies

(OECD code: IIA 5)

6. Description of the observations, examinations, analysis

performed, or necropsy is well described.

7. The conditions of exposure should be from a legally

registered use of the product.

Residues in or on treated products, food and

feed (metabolism and residues data)

(OECD code: IIA 6)

8. The application method(s) complies with Good Agriculture

Practice (GAP)

9. Appropriate in-life/processing conditions are used and/or are

well described

Fate and behaviour in the environment

(OECD code: IIA 7)

10. The model is appropriate for European regulatory

requirements.

11. The input parameter selection is appropriate based on

European regulatory requirements.

12. The pedoclimatic conditions are appropriate.

Ecotoxicological studies (OECD code: IIA 8) 13. A relevant route of exposure is presented.

The following reference investigated possible increased sorption of the metabolite triazine amine

(IN-A4098) over time. Overall the UK RMS concluded that the study may provide some


evidence of increased sorption over time. However the data was not suitable for inclusion in the

regulatory assessment. It should be noted that no EU agreed guidance on measuring aged

sorption is currently available. The UK RMS notes that in the study below the aqueous fraction

was determined following centrifugation of aged soil samples. In draft guidance on aged

sorption developed by UK CRD, the use of centrifugation to determine the aqueous fraction is

not recommended. Following centrifugation, the remaining soil was subject to a 48 hour

desorption step with CaCl2. In the draft guidance developed by the UK, the aqueous fraction is

recommended to be determined by CaCl2 extraction over 24 hours. These deviations mean that

the data from this study would be unlikely to be acceptable in accordance with the criteria

developed in the UK guidance. However the draft UK guidance still has to be considered by the

EFSA PPR Panel before agreed guidance can be finalised. Overall the results from this study

have no specific consequences for the evaluation of IN-A4098. The standard equilibrium

sorption coefficients reported in Table B.8.394 below are consistent with those from the

regulatory database reported in Table B.8.231. The assumption of equilibrium sorption used in

the groundwater leaching assessment of IN-A4098 is a standard and conservative first tier

assumption. No amendment of the existing assessment is considered required on the basis of this

reference.

Title: Aging of triazine amine in soils demonstrated through sorption, desorption, and bioavailability measurements

Authors: Godskesen, B.; Holm, P.E.; Jacobsen, O.S.; Jacobsen, C.S.

Source: Environmental Toxicology and Chemistry 24(3): 510-516

Executive summary:

The aging of triazine amine in soil was studied during a time course of 119 days by measuring bioavailability in

terms of mineralisation after inoculation of the triazine amine-degrading bacterium Rhodococcus erythropolis TA57.

The bioavailability was measured in four soil samples: A-, B-, and C-horizons from an agricultural soil profile and

in a peat soil. The sorption of triazine amine in the soil samples was quantified during the period of aging in terms

of sorption distribution coefficients (Kd) and desorption distribution coefficients (Kd,des). Measures of bioavailability

and triazine amine concentration in the non-available fraction showed effects of aging in the soils that were rich in

organic matter. The triazine amine bioavailability declined significantly during the aging period in soils containing

greater than 2% organic carbon, whereas the B- and C-horizons showed no signs of aging, in agreement with their

low content of organic material. Corresponding to this, desorption decreased significantly in the A-horizon but,

surprisingly, not in the peat soil. Analyses by thin-layer chromatography indicated an association of aqueous

triazine amine and dissolved organic matter in the peat soil. This gives an explanation for both the significant

decrease in bioavailability and the noncorresponding stability of the nonavailable (i.e., nondesorbed) fraction.


A. MATERIALS

1. Test material: [2-14

C]-triazine amine



2. Soils:

The study was conducted with four different soil types. Sieved and air-dried soils were

stored in a plastic bag prior to experimentation. A summary of the physical and chemical

properties of the soils is provided in Table B.8.393. The percent sand, silt, and clay are

quoted on the basis of the USDA classification.


3. Sorption and desorption experiments

Sorption and desorption isotherm experiments were performed according to the

Organisation for Economic Cooperation and Development guidelines for the testing of

chemicals. One gram of soil (dry wt) and 4 mL of 0.01 M CaCl2 were equilibrated at

10C for 24 h in 13-mL centrifuge glass tubes with Teflon

-lined screw caps on an end-

over-end shaker (20 rpm). Afterward, 1 mL of triazine amine solution in 0.01 M CaCl2

was added to obtain the six initial dissolved concentrations in the soil systems (0.01, 0.1,

0.5, 1, 2, and 3 mg L-1

) and, at each initial concentration, a radioactivity of 1.000 dpm

mL-1

. The triazine amine distribution coefficients for sorption (Kd) and desorption (Kd,des)

are given as the triazine amine concentration (L kg-1

) in the soil solid phase divided by the

triazine amine solution concentration after 48 h of equilibration. 4. Effect of pH on triazine amine sorption

Triazine amine sorption and desorption experiments at pH 4, 5.5, 6.5, and 8 were

determined. Soils and CaCl2 solutions (each 10 g dry wt of soil and 40 mL of 0.01 M

CaCl2, respectively) were pH-adjusted by addition of small amounts of 1 M NaOH or

HCl. Addition of triazine amine at 0.1 mg L-1

and radioactivity of 1000 dpm mL-1

,

shaking of the sample, and harvest were performed as above. The pH was measured at

the end of the experiment to detect a possible change in pH. 5. Aging experiments

Bioavailability as well as sorption and desorption were quantified six times (Days 1, 6,

28, 63, 91, and 119) during the 119-day period of aging. At Day 0, 60 and 6 g (dry wt) of

each soil were placed in, respectively, 250- or 100-mL air-tight glass flasks (total, 140

flasks). The naturally moist soils were amended with an aqueous solution of triazine

amine and 0.01 M CaCl2 to reach a water content of 80% of the WHC. The

bioavailability experiment was carried out at one triazine amine concentration (0.206 mg

kg-1

dry wt) and the sorption and desorption experiments at four concentrations (0.021,

0.103, 0.206, and 0.411 mg kg-1

dry wt). This experiment was performed under sterile

conditions to prevent contamination with microorganisms different from the indigenous

organisms. Control microcosms were prepared without triazine amine. All samples were

incubated at 10C in the dark. At the end of each period of aging, the soil with aged

triazine amine was split into three replicates that were used for either bioavailability or

sorption tests. Sterile vials containing 3 or 2 mL of 0.5 M NaOH were enclosed inside

each flask to trap mineralised 14

CO2. The NaOH was transferred to 10 mL of scintillation

fluid, left for 24 hours in darkness to eliminate chemo- and photoluminescence, and

counted by LSC as described previously. 6. Measurements of sorption and desorption of triazine amine during aging

Concentration of [14

C]triazine amine in the aqueous phase was measured with LSC as

described above after centrifugation (1700 g, 15 min, 20C) of the soil samples

(triplicates of 2 g dry wt) in centrifuge tubes and filtered through 0.45-mm polyvinyl

fluoride cutoff filters (LIDA Maxi-Spiny, Kenosha, Wisconsin, USA). The solid phase

was transferred to 13-mL centrifuge tubes, and 10 mL of 0.01 M CaCl2 were added to

allow the sorbed triazine amine to desorb. The tubes were mixed in a rotator, and the 14

C

in the supernatant was determined after 48 hours as previously described. The isotherms

were shown to be linear. Sorption of triazine amine to the filter was investigated and it

was found that 3% was removed from the aqueous phase when supernatant passed

through the filter in the centrifuge tube. Results were corrected for this removal. Mass

balances were calculated as the sum of the mineralised 14

C fraction, the 14

C in the

aqueous phase, the desorbed fraction, and the sorbed 14

C.


7. Measurement of bioavailability using R. erythropolis TA57 during aging

Rhodococcus erythropolis TA57 were recovered from frozen cultures on a 1/10 Tryptic

Soy (Becton Dickinson, Sparks, Maryland, USA) Broth agar plate. We previously

isolated the strain R erythropolis TA57 because of its ability to mineralise triazine amine.

One colony was inoculated into the growth medium containing triazine amine as the only

nitrogen source and incubated on a horizontal shaker (150 rpm, 30C). Several

equivalent portions (1:1 glycerol:growth culture) were stored at -80C. Three days before

sampling during the aging period, 2 mL of glycerol-growth culture were thawed and

inoculated into 25 mL of new growth medium (150 rpm, 30C, exactly 72 hours). Cells

were immediately harvested by centrifugation at 7600 g for 10 min at 20C and washed

twice with phosphate buffer (0.01 M, pH 7.4). The washed culture was inoculated into

the aged soils at a density of 108 cells g

-1 (dry wt) and incubated at 10C for 7 days. The

aged soil (glass flasks containing 60 g dry wt) was split in six replicates. The inoculation

of the R. erythropolis TA57 was carried out in triplicates (10 g dry wt each), and three

controls without the test bacteria were included to test both the effect of splitting the aged

soils and adding the phosphate buffer on mineralisation. Mineralisation was measured by

enclosing a CO2 trap in the flasks and replacing it (2 mL of 0.5 M NaOH) frequently. A

second control was included to study the effect of amending the soil with dead R.

erythropolis TA57 cells (108 autoclaved cells g

-1). None of the controls showed any

effect on mineralisation. 8. Association of triazine amine to dissolved organic carbon

At the end of the aging period, the 14

C content in the aqueous phase of the soil aged 119

days was examined to determine whether the triazine amine molecule had been

transformed using TLC. Samples from the aqueous phase were placed on a Silica 60

plate (Merck, Darmstadt, Germany) and developed for 80 mm in an automatic developing

chamber (ADC, Camag, Switzerland) using a 50:50 (v/v) acetonitrile/water solution as

solvent. After development, the plates were exposed to a phosphor storage screen for 24

hours, and the screen was analysed using the Cycloney Storage Phosphor System

(Packard BioScience, Meriden, Connecticut, USA). The intensity of the TLC bands was

integrated using OptiQuant software (Packard BioScience).

9. Statistical analysis

Data from the aging experiment were analysed using Statistical Analysis System Version

8.1 (SAS Institute, Cary, NC, USA). All experiments were carried out in triplicate.


A EFFECT OF SOIL CHARACTERISTICS ON SORPTION AND DESORPTION OF

TRIAZINE AMINE

General physical and chemical characteristics of the four soil samples are presented in Table

B.8.393. The soils showed different abilities for sorbing and desorbing triazine amine.

Table B.8.394 summarises the triazine amine Kd and Kd,des values in the four soils.


Table B.8.393

Characteristics of soils: Dry weight, water-holding capacity, and organic material

Horizon/

soil

pH

OM(%) OC(%) N(%)

Particle size distribution

%

H2O WHC H2O CaCl2 Clay Silt Sand

A 6.5 4.9 3.6 2.1 0.076 3 1.6 95.4 7.7 0.33

B 7.2 5.3 0.44 0.26 0.0045 1.5 1.5 97 3.8 0.35

C 7.4 5.4 0.29 0.11 0.0019 1 0 99 4.4 0.26

Peat 5.5 4.6 89 52 3.33 - - - 78.3 1.00

Table B.8.394

Triazine amine coefficients of distribution in four soils

A-horizon B-horizon C-horizon Peat soil

Kd (L kg-1

) 1.6 0.84 0.86 13

Kd,des (L kg-1

) 5.6 5.1 6.5 36

B. EFFECT OF SOIL PH ON SORPTION

During the aging experiments, the pH remained stable throughout the 119-day period,

indicating that changes in pH did not influence the aging processes in the present study.

C. SORPTION AND DESORPTION OF TRIAZINE AMINE DURING AGING

Trends in Kd and Kd,des values calculated by use of sorption and desorption isotherms are

illustrated as a function of the aging period in Figure Figure B.8.41. No changes are seen for

the mineral soils, whereas sorption and desorption increase strongly over time in the A-

horizon soil. In Figure B.8.42, the effect of aging on the distribution of triazine amine in the

nonavailable (Cs), available (Caq), desorbable, and mineralised fractions are plotted as

histograms. The nonavailable fraction is calculated as the nondesorbed triazine amine, which

under the circumstances in this specific experiment appear to be nonavailable to the

microorganisms.

D. MEASUREMENT OF BIOAVAILABILITY BY INOCULATION OF R. ERYTHOPOLIS

TA57

Accumulated mineralisation by R. erythropolis TA57 determined for specified 7-day time

periods in all four soils during the aging period are a measure of bioavailability. Results

from the four soils are presented in Figure B.8.43, and statistical data are included in Figure

B.8.43. Bioavailability decreased significantly (p >0.05) in the peat soil and in the A-horizon

soil after 28 d of aging (Figure B.8.43). A similar reduction in bioavailability was not

observed in the B- and C-horizons because of low content of organic matter.


Figure B.8.41

Coefficients of distribution regarding (a) sorption (Kd values) and (b) desorption

(Kd,des values) shown as a function of the period of aging


Figure B.8.42

Histograms (% distribution) of four fractions of triazine amine in the soil system during an

aging period of 119 days


Figure B.8.43

Bioavailability of triazine amine measures as 14

CO2 evolved from mineralisation of

triazine amine by the inoculated Rhodoccus erythropolis TA57 (108 cells g

-1 for 7

days) in four different soils at six sampling days during a 119-day aging period

III. CONCLUSION

Bioavailability of triazine amine to R. erythropolis TA57 was significant reduced in the peat soil

and the A-horizon (containing .2% organic carbon) as residence time proceeded. We observed

no aging in the B- and C-horizons, measuring neither bioavailability nor nonavailable fraction.

The difference in aging among the four soils most likely can be explained by the high organic

material content of the peat soil and the A-horizon, and we conclude that the aging of triazine

amine is correlated to the organic material. Thus, triazine amine becomes nonbioavailable to R.

erythropolis TA57 in soils with high organic material content, whereas soils with a low organic

material content do not affect the bioavailability of the compound to the same degree.

(Godskesen, B.; Holm, P.E.; Jacobsen, O.S.; Jacobsen, C.S., 2005)


The following study provided additional information on the sorption of triazine amine (IN-

A4098) in a range of Danish soils. The study concluded that sorption of this metabolite was

positively correlated with soil clay content and negatively correlated with soil pH. This

conclusion differed slightly from the UK RMS assessment of the standard regulatory data base of

sorption studies on IN-A4098. From the standard regulatory database (see Table B.8.231 for

summary), considering the data set as a whole, there did not appear to be any strong correlation

between soil properties and sorption potential (for example between %OC and Kf, or between pH

and Kf or Kfoc). Some of the correlation may have been masked by the fact that studies were

performed under slightly varying conditions (temperature, soil:solution ratio, equilibrium time

etc) over a period of nearly 20 years. Based on the range of soils tested and the range of sorption

parameters (n=23) the UK RMS considered it appropriate to use a median Kfoc of 62.3ml/g

combined with an arithmetic mean 1/n of 0.903. Some important differences were noted in the

conduct of the sorption studies in this reference. Samples were incubated at 10°C for 96 hours

during the equilibrium phase. This compared with incubations at 20 to 25°C for up to 48 hours

in the standard regulatory studies. The pH range of the soils tested below was noted to be lower

than tested in the regulatory database (e.g. 4.1 to 6.3 in the literature reference compared to 5.4 to

7.9 in the regulatory database). Based on the Kd values derived from this study, sorption was

observed to be significantly higher in the literature reference compared to the regulatory

database. For example, Kd values below in the A horizon soils ranged from 3.78 to 125 kg/l. In

Table B.8.231, where Kd was reported, it ranged from 0.2 to 6.9. Since the datasets appear to

provide very different measures of sorption the UK RMS concluded it would not be appropriate

to combine them. However the UK RMS considered it reasonable to conclude that basing the

groundwater leaching assessment on the standard regulatory studies would be conservative

because these studies gave a lower estimate of sorption potential of IN-A4098. The difference in

sorption may have been a result of equilibrium time or temperature, or a result of testing more

acidic soils. Overall the UK RMS concluded that the existing leaching assessment using

standard input parameters was acceptable and no amendment of the existing assessment was

considered required on the basis of this reference.

Title: Variation of MCPA, metribuzine, methyltriazine-amine and glyphosate degradation,

sorption, mineralization and leaching in different soil horizons

Authors: Jacobsen, C. S. et al.

Source: Environmental Pollution 156 (2008) 794–802 OECD Summary

Executive summary:

Pesticide mineralisation and sorption were determined in 75 soil samples from 15 individually

drilled holes through the vadose zone along a 28-km long transect of the Danish outwash plain.

Mineralisation of the phenoxyacetic acid herbicide MCPA was high both in topsoils and in most

subsoils, while metribuzine and methyltriazine-amine was always low. Organic matter and soil

pH was shown to be responsible for sorption of MCPA and metribuzine in the topsoils. The

sorption of methyltriazine-amine in topsoil was positively correlated with clay and negatively

correlated with the pH of the soil. Sorption of glyphosate was tested also high in the subsoils.

One-dimensional MACRO modelling of the concentration of MCPA, metribuzine, and

methyltriazine-amine at 2 m depth calculated that the average concentration of MCPA and

methyltriazine-amine in the groundwater was below the administrative limit of 0.1 mg/L in all

tested profiles while metribuzine always exceeded the 0.1 mg/L threshold value.



A. MATERIALS

1. Test material: 14

C-metsulfuron methyl

2. Soils

Sampling was performed at 15 locations placed on a 28-km long transect of the Karup

outwash plain in northwest Jutland, Denmark. Sampling of approximately 10 kg

disturbed soil was performed in the A-, B- and C-horizon from the side of a dogged hole.

For the measurement of soil hydraulic properties, five soil cores (100 cm3, inner diameter

= 6.10 cm, depth = 3.42 cm) were retrieved from the A-, B-, and C-horizon in metal

cylinders forced into the undisturbed soil by means of a hammer. From the 20 cm drilling

cores, the 100 cm3

soil cores were retrieved in the laboratory using the same method as in

the field. The soil samples were treated differently depending on the uses. For grain size

distribution and content of organic material the soil was air dried at room temperature.

For geochemical analysis the soil was air dried and sieved through a 2-mm sieve. For

pesticide sorption analysis the soil was sieved through a 4-mm sieve and air dried. For

pesticide degradation and mineralisation analysis, and microbial counts the soil was

frozen at -18ºC until 10 days before analysis at which time the soil was allowed to thaw

and resituate at 10ºC for 10 days prior to analysis. The soil texture, i.e., clay (<2 mm),

silt (2–63 mm), and sand (63–500 mm), was measured in the 75 individual soil samples

by chemical dispersion with Na2PO7 followed by hydrometric determination of clay and

silt and by wet sieving of sand. The division between fine and coarse sand is 200 mm.

Total organic carbon (Corg) content was determined on ball-milled subsamples using a

LECO CNS-1000 analyser with IR detector (LECO Corporation, St. Joseph, Michigan,

USA). The 100 cm3 soil cores for the measurement of hydraulic properties were

protected from evaporation and physical disruption and stored at 2–5ºC until analysis

took place.

3. Mineralisation and dissipation experiments

Mineralisation experiments were performed by adding 14

C-labelled pesticides in a total

concentration of 1.0 mg pesticide kg-1

(dry weight) soil and incubating at 10ºC in the

dark. Sample 14

CO2 was captured in alkaline carbonate traps. Radioactivity was then

converted to percent mineralisation of total pesticide amended to the microcosms.

Metabolic activity was verified in the samples by measuring the mineralisation of 14

C-Na-

acetate under aerobic conditions. The soils were extracted at given time-points by

accelerated solvent extraction followed by extract analysis by LC-MS/MS.

4. Sorption experiments

Adsorption was determined in triplicate for the four herbicides, using 14

C-labelled test

items. Air-dried soil samples were sieved to <2 mm and transferred to 13 mL Pyrex

glass with Teflon

screw-caps. A sample to solution ratio of 1:10 was used for

glyphosate because this herbicide is highly adsorbed and a ratio of 1:1 was used for

MCPA, metribuzine, and methyltriazine-amine as these herbicides sorb to a lesser extent.

The liquid phase consisted of 0.01 M CaCl2 for MCPA, metribuzine, and methyl triazine-

amine as recommended by the OECD guidelines for sorption studies (OECD, 1997) and

0.01 M KCl2 for glyphosate as Ca2Cl may form complexes with this herbicide.

An herbicide concentration of 250 μg kg-1

was used per soil. The treated soils were

incubated on an orbital shaker at 10ºC for 96 h then centrifuged (30 min at 2700 g) and

supernatant removed from the pellet. The 14

C in the supernatant was measured by and the


sorption coefficient (Kd) was calculated. The pH of the 0.01 M CaCl2 was measured in

one of each triplicate samples. A control was carried out for mineralisation of 96 h

duration and the mineralisation was in all cases deemed insignificant.

5. Soil hydraulic properties

The soil cores were placed on top of a sandbox and saturated with water from below.

Soil water characteristics were then determined by draining the soil samples successively

to predefined matric potentials of -10, -16, -50, -100, -160, -500, -1000, and -15500 cm

H2O using a sandbox for potentials from -10 to -100 cm H2O and a ceramic plate for

potentials from -160 to -1000 cm H2O. Soil water characteristic at a matrix potential of -

15500 cm H2O was measured after the soil had been ground and sieved through a 2 mm

sieve. After the soil water characteristic was determined, the 100 cm3 soil cores were re-

saturated and the saturated hydraulic conductivity, Ks, measured using the constant head

method. Finally the cores were oven-dried at 105C for 24 h and weighed in order to

determine the dry weight.

6. MACRO modelling

The modelling of pesticide leaching involved simulation of pesticide leaching using the

MACRO (v4.3) model for three soil profiles in a deterministic way using in situ measured

data in order to rank these profiles relatively with respect to the magnitude of leached

pesticides from the root zone. The MACRO model (v4.3) is a dual-porosity model and

considers a complete water balance, including precipitation (rain, snow, and irrigation),

variably saturated flow, losses to field drainage systems, evapotranspiration, and root

water uptake. The main goal of MACRO modelling was to obtain relative measures of

pesticide leaching suitable for comparison of leaching through soils utilising all the

collected data on soil hydraulic and compound specific properties, dissipation, and

sorption.

7. Partial least squares regression (PLS-R)

Sorption coefficients measurements (Kd values) correlation to soil properties was

investigated by partial-least-squares regression (PLS-R) using MatLab (version 7.1,

Mathworks Inc., USA) with the PLS-toolbox software (PLS-Toolbox 3.5, Eigenvector

Research Inc., USA).


A. TEXTURAL CHARACTERISATION

Soil characteristics are presented in Table B.8.395.


Table B.8.395

Texture and pH of soils in the plough layer

B. MINERALISATION AND DISSIPATION EXPERIMENTS

The mineralisation of 14

C-methyl triazine amine was very low in all soils tested and below

the 14

C-impurity level.

C. SORPTION EXPERIMENTS

Sorption of methyl triazine-amine does not follow the simple relation to organic matter as

seen for MCPA and metribuzine (see Table B.8.396). Methyl triazine amine sorption is not

only determined by the content of total carbon in the soil samples. Although most of the 15

profiles (except profiles 8 and 11) show a higher sorption in the A-horizon compared to the

corresponding B- and C-horizons, no clear correlation exist to the total carbon content of soil

samples. This can be exemplified with the very high sorption found in profile 12

(Simmelkjær), which has a low content of total carbon. The partial least square analysis

reveals that clay (0.7) and pH (0.8) is the most important component determining

methyltriazine-amine sorption in the A-horizon samples of the profiles (Table B.8.397).

Partial least squares analysis for sorption of methyltriazine-amine to the subsoil components

is not provide clear correlation to any soil property.

Table B.8.396: Kd values for triazine amine (IN-A4098)


Table B.8.397

Partial least squares regression coefficient matrix for methyl-triazine amine

sorption (Kd) for the soil parameters in the A-, B- and C- horizons

Soil horizon Clay Silt Fine sand Course sand Gravel Organic C pH

A-horizon 0.71 Nd 0.17 -0.36 0.43 -0.18 -0.85

B-horizon 0.28 0.26 0.04 -0.36 0.16 0.25 -0.16

C-horizon Nd Nd Nd Nd Nd Nd Nd

Note: Only methyl-triazine amine sorption results are presented in the table.

D. SOIL HYDRAULIC PROPERTIES

The saturated hydraulic conductivity (Ks) of the test soils was lowest in the A-horizon where

the majority of soil profiles showed values between 100 and 1000 cm d-1

(Figure B.8.45)

compared to B- and C-horizons. The variation between the individual soil profiles was

relatively high and there seemed not to be any relationship between Ks and the distance from

the glacier front. Also there seemed not to be any clear relationships between Ks and any of

the soil texture fractions (including soil organic carbon). Hydraulic properties of the soil

showed a relatively low water holding capacity for all profiles and horizons with a sharp

decrease in soil water content from saturation to -50 cm H2O reflecting a high content of soil

pores with equivalent pore diameters above 60 m. For the A-horizon, Hallundbæk (site 15)

showed the highest water holding capacity whereas in the B-horizon it was Ruskær (site 5)

that showed the highest water holding capacity. In the C-horizon at the opposite, Ruskær

showed the lowest water holding capacity.

E. MACRO MODELING

The one-dimensional dual-porosity model MACRO (v4.3) (Jarvis, 2002) was used for

simulation of compound concentrations at 2 m depth below soil surface for the three soil

profiles Stubkjær, Ilskov, and Simmelkjær. In all three profiles DT50 values were obtained

for methyltriazine-amine (Table B.8.398). These three profiles were deterministically


modelled. Very low concentrations were simulated for methyltriazine-amine (MTA) as

compared to metribuzine. The results of the modelling showed that the average

concentration of methyltriazine-amine at 2 m depth in the groundwater was below the

administrative limit of 0.1 mg/L in all tested profiles.

Table B.8.398

DT50 values for methyltriazine-amine

Soil Soil horizon DT50 (d)

A 87

B 61

C 43

A >1000

B 82

C Nd

A 67

B 68

C Nd

Nd = not detected

Stubkjær

Ilskov

Simmelkjær

Note: Only methyl-triazine amine sorption results are presented in the table.


Figure B.8.44

Location of the fifteen profiles on the Karup Outwash Plain in Jutland, Denmark


Figure B.8.45

Saturated hydraulic conductivity (Ks) measured in three depths from the 15 soil profiles


III. CONCLUSION

The relationship of degradation, sorption, and mineralisation on the leaching potential of

methyltriazine-amine in soil was presented. The data suggests that the relative simulated

leaching of methyltriazine-amine results in only very small simulated concentrations at a depth of

2 m. Methyltriazine-amine does not follow the simple rule that increased organic matter leads to

increased sorption. The sorption of methyltriazine-amine in topsoil was positively correlated

with clay and negatively correlated with the pH of the soil. One-dimensional MACRO

modelling of the concentration of MCPA, metribuzine and methyltriazine-amine at 2 m depth

calculated that the average concentration of MCPA and methyltriazine-amine in the groundwater

was below the administrative limit of 0.1 mg/L in all tested profiles while metribuzine always

exceeded the 0.1 mg/L threshold value.

(Jacobsen, C. S. et.al, 2008)

The following study provided field scale measurements of transport of Thifensulfuron-methyl via

field drains. The relevance to EU conditions could not be ascertained from the study, which was

performed under irrigated conditions in Canada (Saskatchewan). However Thifensulfuron-

methyl was detected in field drains and estimated losses of <0.3% active substance were

reported. In general this finding supports the results of the standard FOCUSsw exposure

modelling, where under certain use conditions and scenarios, drainflow was shown to be the

principal route of exposure. Since the relevance of the results to EU conditions is not known, the

UK RMS concluded that this study has no direct consequences for the EU assessment and no

amendment of the existing assessment is considered required on the basis of this reference.

Title: Leaching of three sulfonylurea herbicides during sprinkler irrigation

Authors: Cessna, A.J.; Elliott, J.A.; Bailey, J.

Source: Journal of Environmental Quality (2010), 39(1), 365-374 CODEN: JEVQAA; ISSN:

0047-2425

Executive summary:

Sulfonylurea herbicides are widely applied on the Canadian prairies to control weeds in a variety

of crops. Several sulfonylurea herbicides are mobile in soil, and there is concern about their

possible movement to ground water. This study was performed to assess the susceptibility of

three sulfonylurea herbicides commonly used in prairie crop production to leach under a worst-

case scenario. Thifensulfuron-methyl, tribenuron methyl, and rimsulfuron were applied to a 9-ha

tile-drained field, and then approximately 300 mm of irrigation water were applied over a 2-week

period using a center pivot. The commencement of tile-drain flow corresponded to the rise of the

water table above tile-drain depth, and peak flow rates corresponded to the greatest depths of

ground water above the tile drains. The volume of irrigation water intercepted by the tile drains

in each quadrant was determined by site hydrolysis and represented <10% of the irrigation water

applied. Concentrations of Thifensulfuron-methyl, tribenuron methyl, and rimsulfuron in the

tile-drain effluent ranged (analysed by liquid chromatography/tandem mass spectrometry) from

2.0 to 248 ng L-1

, not detected (nd) to 55 ng L-1

, and nd to 497 ng L-1

, respectively. Total

herbicide transport from the root zone in each quadrant was estimated at <0.5% of the amount of


each sulfonylurea herbicide applied. Thifensulfuron-methyl was the only herbicide detected in

ground water, with concentrations ranging from 1.2 to 2.5 ng L-1

. With the frequency and

amount of rainfall typically encountered in the prairie region of Canada, detectable concns. (> 1

ng L-1

) of these sulfonylurea herbicides in ground water would be unlikely.


The study site, which consisted of a 8.9-ha tile-drained field situated on the Canada-

Saskatchewan Irrigation Diversification Centre at Outlook, Saskatchewan, was leveled for

irrigation (early 1950s) and has a gentle slope (0.5%) from east to west. The soil is a Dark

Brown Chernozem (Typic Haploboroll) and was mapped as a Bradwell loam (Strushnoff and

Acton, 1987). Sand content of the soil varied from 30.9% in the upper 0.25 m to 59.4% at 0.75

to 1.0 m, whereas analogous values for clay were 16.1 and 17.6%. Organic carbon content

decreased with depth, from 1.6% in the upper 0.25 m to 0.5% at 0.75 to 1.0 m. The pH of the

soil increased with depth, from 7.8 in the surface soil layer to 8.4 at 0.75 to 1.0 m. The soils at

the site are underlain by a low-hydraulic-conductivity (k <10−7

m s−1

) clay layer of varying depth

and thickness (Maathius et al.., 1988). In a transect that passed across the study site, the depth of

the layer varied from 3 m on the western edge of the field to 1.5 m just east of the field. The

field is irrigated by a center pivot (installed in 1986) such that the irrigated portion of the field is

approximately 5.9 ha. The tile-drain system, with a 15-m spacing of the lateral drains, was

installed in 1994 and is considered to be well equilibrated. Single piezometers, consisting of

polyvinyl chloride pipe equipped with a stainless steel screen, had been installed midway

between tile drains, close to the center of each quadrant of the study site to a depth of 4.5 m in

April 1998. The depths of the tile drains on either side of the piezometers ranged from 1.6 m on

the NW quadrant to 1.79 m on the NE quadrant. Commercially available dry flowable

formulations of the selected herbicides were used in this study and were applied using a tractor-

pulled sprayer. On 24 September 2004, rimsulfuron (Prism; Dupont Canada, Inc., Mississauga,

Ontario, Canada) was applied to the NW and SW quadrants of the tile-drained study site at a rate

of 14.7 g ha−1

. Immediately afterward, a 2:1 mixture of Thifensulfuron-methyl and tribenuron-

methyl (Refine Extra Toss-N-Go; Dupont Canada, Inc., Mississauga, ON, Canada) was applied

to all four quadrants at a rate of 14.7 g ha−1

(equivalent to 9.8 g ha−1

Thifensulfuron-methyl and

4.9 g ha−1

tribenuron-methyl).

Daily samples of tile-drain effluent were collected from each quadrant using an automated water

sampler equipped with 2-L glass collection jars (Streamline Model 800SL; American Sigma,

Medina, NY). Piezometer water was sampled five times: (i) before herbicide application (23

September), (ii) just after tile-drain effluent began to flow from all four tile drains (1 October),

(iii) at cessation of irrigation (10 October), (iv) on the last day tile-drain effluent was sampled (17

October), and (v) approximately 1month later (10 November).

Tile-drain effluent and piezometer water samples were subjected to solid-phase extraction as

described previously. A subsample (500 mL) was passed through an Oasis hydrophilic-lipophilic

cartridge (Waters Corp., Milford, MA) under vacuum. After drying under vacuum, the cartridge

was eluted with acetone:methanol, the eluate was evaporated to dryness, and the resulting residue

was dissolved in acetonitrile before liquid chromatography/tandem mass spectrometry analysis.

An Alliance 2695 Separations Module interfaced with a Micromass Quattro Ultima mass

spectrometer (Waters Corp.) equipped with an electrospray ionisation interface set to positive ion

mode was used to analyse all sample extracts.



The sulfonylurea herbicides were detected in the first sample of tile-drain effluent collected from

each quadrant (Figure B.8.46). The concentrations of the three sulfonylurea herbicides in the

tile-drain effluent (applied at 4.9-14.7 g ha−1) generally ranged from 2 to 12 ng L−1

. The

calculated total mass of each herbicide lost in the tiledrain water from each of the quadrants was

used to estimate what proportion of the corresponding amounts applied was lost via the tile

drains (Table B.8.399). Based on herbicide concentrations in the tile-drain effluent, less than

0.3% of the amount of each herbicide applied was lost in the tile-drain effluent.

Figure B.8.46

Sulfonylurea herbicide concentrations in the tile-drain effluent with time from the

(A) northwest (NW), (B) southwest (SW), (C) northeast (NE), and (D) southeast

(SE) quadrants of the study site

Table B.8.399

Mass transport and percent loss of the sulfonylurea herbicides in the tile-drain

effluent from 27 Sept. to 17 Oct. 2004


III. CONCLUSIONS

The tile drain effluent from each quadrant of the field represents the average water movement

from 1.48 ha, the irrigated area in each quadrant. The NW and SW quadrants were

hydrologically very similar but quite different from the NE and SE quadrants, which were also

similar to each other but hydrologically less active than the NW and SW quadrants. As expected,

more herbicide was leached in the more hydrologically active NW and SW quadrants. However,

not all the variability in transport could be explained by the hydrology of the site. The pattern of

herbicide loss and relative mass transport of the three herbicides differed between the two west

quadrants that were hydrologically similar, and the reasons for the variability were not apparent

from the herbicide physical-chemical properties. Nonetheless, under the conditions of this field

study, there was evidence for preferential flow of Thifensulfuron-methyl, tribenuron methyl, and

rimsulfuron to the depth of the tile drains with the infiltrating irrigation water. All three

herbicides were present in the tile-drain effluent in low (nanograms per liter) concentrations, but

only Thifensulfuron-methyl was found in samples of shallow ground water. The total movement

of each of the three herbicides below the root zone in each quadrant of the study site was <0.5%

of the amounts applied.

(Cessna, A.J.; Elliott, J.A.; Bailey, J., 2010)

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