risk analysis of contaminated sites: human health and ecological risk assessment f. quercia, anpa...

Risk Analysis of Contaminated Sites:Human Health and Ecological Risk

AssessmentF. Quercia, ANPA

Workshop ICS/UNIDO - Fundacion Mamonal

Environmental Pollution and Applicability of Remediation Technologies in Latin-American Countries

Cartegena des India, 4-7 Dec., 2000

Cartagen des India, 4-7.12.2000 3

Land use oriented and risk-based soil management

M ob ile p ollutio n:C le a n up b y coste ffec tivemea ns

Iimmo bile p ollution:C le a n up only if the re iis a c learb enefit

C ontac t zone . Q ua lity re la ted to la nduse


DefinitionsDefinitions

• Risk assessment is an objective, scientific evaluation of the likelihood of unacceptable impacts to human health and the environment

• Risk is the combination of:

– exposure to toxic substances

– hazard/toxicity of substances


Human HealthRisk Assessment


Quantitative Risk AssessmentForward versus Backward R.A.

Quantitative orAbsolute R.A.

• FW: Assesses baseline risks related to site contamination levels

• BW:Defines generic guideline values and site-specific clean up goals related to target risk levels


Risk Assessment: forward procedure

ObservedConcentration

EstimatedExposure

EstimatedRisk

Baseline Risk AssessmentBaseline Risk Assessment


I. Hazard Identification

II.Exposure Assessment

Desk StudyPrelim. CSM

Exploratory SIRefined CSM

Identification of sources,pathways and receptors

Assess source - pathway - receptorlinkages and estimate exposure

III.Dose/Response Assessment

IV: RiskAssessment

Assesscontaminantshuman toxicity

Combine exposureand toxicologicalevaluations

NoteCSM = conceptual site model


Source-pathway-receptorSource-pathway-receptor

one or more routes or means by, or through, which a receptor is being exposed to, or affected by, a contaminant or could be so exposed or affected

Pathway

a substance which has the potential to cause harm to human health or the environment

Source

Receptoran individual which is being, or could be, harmed by the source

IDENTIFY AND Characterize S - P - R

TO BUILD SITE CONCEPTUAL MODEL

IDENTIFY AND Characterize S - P - R

TO BUILD SITE CONCEPTUAL MODEL


SourcesSources

Free / immiscible product

Water phase with dissolved contamination

Air phase with vapours

Solid phase with adsorbed contamination


Risk estimation and evaluationRisk estimation and evaluation

• Uncertainties– Contamination data

• chemical species• concentrations• spatial and temporal effects

– Characteristics of the sub-surface

– Existence/characteristics of pathways

– Identity and location of receptors - now and in the future

– Fate and transport modelling• model selection• validation

– Exposure assessment

– Toxicology


ChallengesChallenges

• Public acceptability of risk-based approach• Uncertainty, sensitivity and conservatism• Validation• Information overload

– hundreds of R&D projects

– hundreds of publications

– matching research to need

• Integration of different aspects• Availability of practical “tools”


Characterize Characterize SourcesSources::

map of lead map of lead concentration concentration in surface soil in surface soil (<1,5 m deep)(<1,5 m deep)

Characterize Characterize SourcesSources::

map of lead map of lead concentration concentration in surface soil in surface soil (<1,5 m deep)(<1,5 m deep)

584620m 584660m 584700m 584740m 584780m

9688

80m

9689

20m

9689

60m

9690

00m

9690

40m

0

500

50000

300000

notinterpolatedarea

mg/kg d.w.

100

1000

100000

Hazard Assessment: Spot Contaminants of Concern


Exposure Assessment

Objectives:

• assess contaminant concentration and exposure

to contact media at receptor contact points

Data and tools:

• data from source, site and receptor characterization

. conceptual model parametrization

. use of fate and transport (F&T) models


Data for Exposure Assessment• Chemicals: Chemicals: chemical and physical parameters describing chemical and physical parameters describing

environmental mobility, persistency, volatility, bioaccumulation environmental mobility, persistency, volatility, bioaccumulation potentialpotential

• Site/pathways: Site/pathways: physical/chemical parameters describing local soil, physical/chemical parameters describing local soil, air and water resources conditionsair and water resources conditions

• Receptors: Receptors: data describing land use and receptor exposure data describing land use and receptor exposure characteristics ( exp. routes and parameters)characteristics ( exp. routes and parameters)

Choose Contaminants of ConcernChoose Contaminants of Concern Choose relevant pathwaysChoose relevant pathways Choose receptors and locationChoose receptors and location

---------------------------------------------------------------------------------------


Exposure Scenario for residential useExposure Scenario for residential use

Transport of leachate to groundwater

Drinking water consumptionDust inhalation

Vapor inhalation

Transport of vapors

Dermal contactSoil ingestion

Vapors and dust inhalation

Groundwater flow


Exposure flowchartExposure flowchart

Soil

Groundwater

Air

Groundwatertransport

Drinking wateringestion

Soil ingestion

Dermalcontact

Vapour and dustindoor and outdoorinhalation

SourcesMigrationroutes

Exposure pathways

Air diffusion and dispersion

Industrial

Receptors

Residential


AT BW

ED EF CR CE

E = Exposure [mg/kg - day]CR = Contact rate [mg/day]EF = Exposure frequency [day/year]ED = Exposure duration [year]BW = Body weight [kg]AT = Averaging time [year]C = Concentration of contaminant in soil [mg/kg]

Exposure AssessmentExposure Assessment


UFxMF

RfD NOAELdose (mg/kg/day)

response

a

SF

response

dose (mg/kg-day)

Carcinogenic effects

b

Toxic effects

RfD = Reference Dose (or TDI) for threshold substances [mg/kg - day]

SF = Slope Factor (or CPS) for non-threshold substances [1/(mg/kg - day)]

RfD = Reference Dose (or TDI) for threshold substances [mg/kg - day]

SF = Slope Factor (or CPS) for non-threshold substances [1/(mg/kg - day)]

Dose/Response (Toxicity) Assessment

Dose/Response (Toxicity) Assessment


Risk Assessment Risk Assessment

RISK = EXPOSURE x TOXICITYRISK = EXPOSURE x TOXICITY

Threshold non-cancer substances :

TDI

EHI

HI = Hazard Index E = Chronic Exposure[mg/kg-day]

TDI = Toxicity [mg/kg-day]

Non-threshold cancer substances:

SFER R = incremental lifetime cancer risk

E = Chronic Lifetime Exposure [mg/kg-day], SF = Toxicity [1/(mg/kg-day)]

Acceptable Risk Criteria: HI = 1R = 1E-6 1E-4


Generic versus site-specific R.A.

• Generic R.A. implies conservative assumptions of potential exposure scenarios, site, contaminants and receptor properties

• Site-specific R.A. implies investigations for collection of local environmental data, construction of conceptual model with actual exposure scenarios


Risk assessment: backward procedure

Acceptable Risk

AcceptableDose

AcceptableConcentration


Backward tiered procedure to assess remediation goals from target risk levels

Generic Risk Assessment

computes

Guideline Screening or Trigger values

(for most sensitive or different landuses)

Tier 1 site concentrations exceed Guideline values

Site Specific Risk Assessment

Tier 2 computes

Site Specific Clean up objectives


ASTM/RBCA

Tiered procedure

ASTM/RBCA

Tiered procedure


ASTM/RBCA

• Standard ASTM E1739/95 and PS104/98 for risk-based corrective actions on contaminated sites

• Streamlined tiered procedure for decision making• Tier1 develops RBSLs (Risk-Based Screening Levels)

look-up tables for each pathway against which site concentrations are compared

• Tier 2 and Tier3 develop SSTLs (Site specific Target Levels) as site-specific cleanup objectives


Main features of RBCA

• Risk protection level is the same at each Tier

• As data from investigation increase more focused quality objectives are defined

• Tier 1 receptor location is on site on top or below source area according to a conservative assumption

• Tier 2 and 3 receptor position may be at actual location (compliance point)


Tier 1: How Soil RBSL are definedTier 1: How Soil RBSL are defined

• For each chemical RBSL are defined for different land uses, i.e.:

. residential/agricolture/recreational . commercial/industrial . groundwater extraction for drinking• The following pathways may be included: . soil ingestion . dermal contact . outdoor and indoor dust inhalation . indoor and outdoor dust inhalation . groundwater drinking• Target receptor for each land use is located right above

the contaminated soil source

• For each chemical RBSL are defined for different land uses, i.e.:

. residential/agricolture/recreational . commercial/industrial . groundwater extraction for drinking• The following pathways may be included: . soil ingestion . dermal contact . outdoor and indoor dust inhalation . indoor and outdoor dust inhalation . groundwater drinking• Target receptor for each land use is located right above

the contaminated soil source


Groundwater protection : Tier 2 compliance point

Point ofcompliance

(edge of site)

compliance point (receptor) might be located at some distance from the source


Ecological Risk Assessment(ERA)

32Cartagen des India, 4-7.12.2000

EEC ProcedureIdentificazione

dell'Hazard

Valutazionedell'Esposizione:Stima del PEC

Valutazione tossicologica:Stima del PNEC

PEC/PNEC

>1

Altri test odati possonoabbassare ilPEC/PNEC

Misure diriduzione delrischio

Test e dati

addizionali

>1PEC/PNEC

Non occorronoaltri test o misure diriduzione del rischio

No

Si

No

Si

Non occorronoaltri test o misure diriduzione del rischio

NoSi


Available Tools

• Ecotoxicological tests data: chronic NOEC/LOEC or acute LEC data from experiments (for screening values)

• PNEC statistical extrapolations from toxicity data (for screening values)

• Biological assays (site-specific)• Biomonitoring (site-specific)• Biomarkers (site-specific)


Example:The Netherlands

• Generic risk assessment

(potential risks) for the

development of

Intervention Values, Target Values and Soil use specific Remediation Objectives

• Site specific risk assessment (actual risks) for deciding about urgency of remediation and priorities


Intervention Values

• Indicate a serious contamination

• Human health risk protection criteria:TDI and 1E-6/year excess cancer risk residential with vegetable garden exposure

scenario (multifunctional) soil ingestion, inhalation, crop consumption

• Ecological risk protection criteria: HC50 (protection of 50% species) derived by

NOEC (No Observed Effect Concentration), LOEC (Lowest Observed EC)or LEC (Lethal EC)data

adjustment to soil clay content and organic matter


Target Values

• Indicate a clean soil

• Ecological risk protection criteria: negligible risk level:1% of HC5 (protects

95% of species) negligible risk level soil concentration is

summed to background value for metals


Ecotoxicological risk-based criteria

Response

Dose

NOEC

1] Compute mean and SD of log NOEC2] Estimate the frequency distribution

of log NOEC

safety factor

Intervention value

5%50%log NOEC

Target value

No Observed Effect Concentrations fordifferent species are used to estimate afrequency distribution of NOEC's on alogarithmic scale. Percentiles (5% and50%) are used to derive target andintervention values.


Soil-use based Remediation Objectives

• Generic criteria for top soil, non-mobile pollutants and following land uses:

Residential and recreational green areasNon-recreational public green areasBuilt-in and paved areasAgricultural areas and nature reserves

• Objectives protect from both human health and ecotoxicological risks


Site-specific Risk Assessment

• For remediation urgency:• Assess site-specific risk by CSOIL model adapted

to local site exposure scenario• Assess ecological risks by pragmatic procedure

based on:area sensitivityHC50 site area for biodiversity preservationbioassays

Note: use of risk assessment to develop site-specific remediation goals is not yet regulated

Note: use of risk assessment to develop site-specific remediation goals is not yet regulated


Ecological Risk Assessment (ERA) needs

• An analytical framework is needed

• Limited experience with terrestrial ecosystems is available

• Ecosystem health needs to be defined

• Fit for use and land use based soil ecological objectives are seeked

• Site specific ERA approaches are needed


RiskRisk estimation and evaluation estimation and evaluation

• Uncertainties

– Contamination data

• chemical species

• concentrations

• spatial and temporal effects

– Characteristics of the sub-surface

– Existence/characteristics of pathways

– Identity and location of receptors - now and in the future

– Fate and transport modelling

• model selection

• validation

– Exposure assessment

– Toxicology


ChallengesChallenges

• Public acceptability of risk-based approach

• Uncertainty, sensitivity and conservatism

• Validation

• Information overload

– hundreds of R&D projects

– hundreds of publications

– matching research to need

• Integration of different aspects

• Availability of practical “tools”

risk analysis of contaminated sites: human health and ecological risk assessment f. quercia, anpa...

Documents

risk estimation

ecological risk assessmentf

target risk levelscartagen

clean uponlyifthereiis

conceptual site modelcartagen

exposure assessmentchemicals

vapourssolid phase

clearbenefitcontact