Arsenic Dislodged from CCA Arsenic Dislodged from CCA Surfaces – Effects of CoatingsSurfaces – Effects of Coatings

David StilwellDavid Stilwell

EFFECTS OF COATINGS ON ARSENIC EFFECTS OF COATINGS ON ARSENIC DISLODGED FROM THE SURFACEDISLODGED FROM THE SURFACE

The Coatings Polyurethane (Sapolin, floor and deck enamel) Acrylic Latex (REZ, deck stain, Solid Color) Oil based, with alkyd resins (Olympic, Deck Stain,

Semitransparent) Spar varnish (Last n’ Last, marine and door)

Coat top surface of 2x8 CCA boards. 16 Coupons from 4 boards (4 replicates for each

coating)

Average Arsenic Dislodged from Average Arsenic Dislodged from Surface Surface BeforeBefore, After, and up to One , After, and up to One

Year After CoatingYear After Coating

0

5

10

15

20

25

Poly Acrylic Varnish Oil

Coating

Ars

enic

, ug/

100

cm^2

PrecoatPostcoat60 Days157 Days263 Days365 Days

ArsenicArsenic

ARSENIC (ug/100cm^2)ARSENIC (ug/100cm^2)

Polyurethane Acrylic Varnish OilPrecoat 17±9 24±8 20±10 18±9Postcoat 0.1 0.2 0.7 0.960 Day 0.4 1.3 0.8 3.4

157 Day 0.2 0.4 0.3 0.6263 Day 0.2 0.2 0.1 0.6365 Day 0.7 0.3 0.5 3.5

Oil Coating – By Board –Oil Coating – By Board –Time Effects – High and Low Sample Time Effects – High and Low Sample Days Match (Day 60 and 365 all high)Days Match (Day 60 and 365 all high)

0

5

10

15

20

25

1-4 1-5 3-3 5-4

Board and Coupon #

As D

islo

dged

ug/

100

cm^2

Precoat

Postcoat

Day 60

Day 157

Day 263

Day 365

Average Chromium Dislodged from Average Chromium Dislodged from Surface Surface BeforeBefore, After, and up to One , After, and up to One

Year After CoatingYear After Coating

0

5

10

15

20

25

30

Poly Acrylic Varnish Oil

Coating

Ars

enic

, ug/

100

cm^2

PrecoatPostcoat60 Days157 Days263 Days365 Days

ChromiumChromium

Chromium (ug/100cm^2)Chromium (ug/100cm^2)

Polyurethane Acrylic Varnish OilPrecoat 18±13 22±8 22±13 17±10Postcoat 0.1 0.4 0.8 1.160 Day 0.6 0.6 1.2 2.8

157 Day 0.2 0.2 0.3 0.7263 Day 0.2 0.1 0.1 0.5365 Day 0.2 0.1 0.5 3.5

Coatings Test ConclusionsCoatings Test Conclusions Polyurethane, Acrylic, and Spar: >95% Reduction Oil Based Finish: 80-97% Reduction, Average=90% Oil Finish wears Uniformly and Does not Chip –

May Be Preferred on Foot Traffic Surfaces Application of these coatings effectively eliminated

any surface removable arsenic for up to one year. Better Side By Side Comparisons Need to be Carried

Out (Different Coatings on Matched Surfaces compared to uncoated – Correct for time effects observed on a particular sample date)

Coatings Test ConclusionsCoatings Test Conclusions

Spar Varnish Deteriorated after One Year Test did not determine how well these coatings

would stand up to wear and tear (Foot Traffic). Consult with paint dealer. See Consumer Reports (June 98, 99)

“Exterior Deck Treatments Test”

Durability of Finishes Durability of Finishes Feist and Ross, “Performance and Durability of Feist and Ross, “Performance and Durability of Finishes on Previously Coated CCA-Treated Wood” Finishes on Previously Coated CCA-Treated Wood” 1995, Forest Products Journal 1995, Forest Products Journal

Fully Pigmented > Semitransparent > Unpigmented Stains need refinishing after two years or less Paints (Film Formers including Acrylics) Could

Hold up for More Than Two Years Wood Surfaces only Subjected to Weather, not

Wear as in Foot Traffic Results are in General agreement with Consumer

Reports June 98 and 99

California StudyCalifornia Study Polyurethane and Oil Based Stains worked Polyurethane and Oil Based Stains worked initially, but less clear over timeinitially, but less clear over time. (n=?). (n=?)

As (ug/100 cm^2)

Time Oil Based Polyu Before 31-314 1100 (Pier) After 6-11 10 6 Months 1-13 NA 2 Years 54 12-65

CPSC – Oil and Water Based CPSC – Oil and Water Based Stains – No effectStains – No effect

Sample Coating (n=3) As (ug/100cm^2)1 None22 ± 22

Oil Based 10 ± 3Water Based 14 ± 7

2 None32 ± 22Oil Based 53 ± 35Water Based 52 ± 26

Do Coatings Reduce As Do Coatings Reduce As Dislodged From Surface?Dislodged From Surface?

This Work Yes California Yes Riedel et al. (1991)* Mixed CPSC NO Lebow and Evans (1999)* NO* See Final Expo.doc, Lebow and Evans Fe2O3 + Acrylic Before

Pressure Treatment (It would be good idea to try Fe2O3 Primer After)

Coatings Future WorkCoatings Future Work

Focus on Oil Based, Acrylic, Polyurethane and specialty coatings (Fe2O3 Primer, Linseed Oil- WeatherBos etc.).

Compare Environmental Test Chambers, To Real Weathering Applications With and Without Physical Wear (Such as Foot Traffic).

Water Repellent Stains? – Do any of Them Form Barrier?

Arsenic Dislodged from CCA Arsenic Dislodged from CCA SurfacesSurfaces

David StilwellDavid Stilwell

WOOD PRESERVATIVESWOOD PRESERVATIVES

Extends life of wood Protects wood from harmful organisms

such as termites and fungi Reduces use of forest products In trade, potential for harmful

environmental effects caused by the preservatives

ENVIRONMENTAL ISSUES ON THE USE OF ENVIRONMENTAL ISSUES ON THE USE OF CCA TREATED WOODCCA TREATED WOOD

Translocation of CCA to Soil and Water via; Leaching of CCA from wood Runoff from lumber yards Sawdust and physical wearing of the wood By Cleaning – Sanding and Power washing.

Human exposure to Arsenic in CCA Dislodged from CCA wood surfaces (hand to mouth- children) Exposure during construction (sawdust) Plant uptake

Impact on Beneficial Marine Organisms Cu and As Toxicity

Disposal of Old Wood

STUDIES UNDERWAY AT CAES

Cu, Cr, and As in Soils Under Decks and Highway Noise Barriers

Built With CCA Wood Arsenic Dislodged from CCA Wood

Surfaces Plant uptake of Arsenic CCA Leaching Characterization (time,

coating effects, etc...)

Arsenic Dislodged From CCA Arsenic Dislodged From CCA Treated Wood SurfacesTreated Wood Surfaces

Copper, Chromium and Arsenic Dislodged Copper, Chromium and Arsenic Dislodged from CCA Treated Wood Surfacesfrom CCA Treated Wood Surfaces

Controversy on how much arsenic children are exposed to by physical contact with CCA treated wood surfaces.

Such surfaces include playground equipment and decks built with CCA treated wood.

Exposure is hand to mouth. Our study attempts to estimate this exposure

by analysis of copper, chromium, and arsenic in wipe samples taken on CCA wood surfaces.

SURVEY ON ARSENIC SURVEY ON ARSENIC DISLODGED FROM WOODDISLODGED FROM WOOD

Boards Purchased at Lumber Yards Amounts, Variability, Weathering and

Coating Effects CCA Wood Surfaces

Playgrounds Decks (Not Done) Picnic Tables (Not Done)

Method That Was Used – Method That Was Used – (Similar to CPSC)(Similar to CPSC)

Attach Polyester wipe to 3x5 wood block and place on sample surface.

Place a 1.25 kg mass on block Pull swipe/block assembly across sample

surface 5 cycles Remove the wipe by folding inward, return it

to sample cup, and add 100ml of 10% HNO3. Digest for 2 hours at 60 degrees C.

Wipe Apparatus – Wipe Apparatus – Following CPSCFollowing CPSC

Procedure Test- Recovery of CCA Extract on Glass

DAMP >> DRY Cu, Cr, As Recovery >90 % Using Damp Wipes

020406080

100120

Alphadry

Alphadamp

Alpha10 dry

Alpha10 damp

Nylondry

Nylondamp

Swipe MaterialCu As Cr

Survey- Wood Purchased at Survey- Wood Purchased at Lumber YardsLumber Yards

6 Sets of 8 ft. boards from 3 Lumber Yards Each Set 3-4 Boards Each Board Cut into 1-2 ft. coupons Test between 2-4 Coupons from Each Board 4 Sets consisted of Regular CCA Wood and 3

Sets Consisted of CCA Wood Plus Water Repellent Treatment (WR)

Sampling Duration; 1-2 years each Set

Board Survey – (0.4 lbs/ft^3). Board Survey – (0.4 lbs/ft^3). WR is Water Repellent + CCAWR is Water Repellent + CCA

Type (SET) Boards Coupons Samples Duration2x8(1&2) 4 16 120 25/4x6WR(3) 3 12 108 25/4x6WR(4) 3 6 36 15/4x6WR(5) 3 6 36 15/4x6(6) 3 6 36 15/4x6(7) 3 6 36 1

TOTAL 19 52 372

Variability Variability and and

Time (weathering) EffectsTime (weathering) Effects

Sampling Scheme – Nested Sampling Scheme – Nested DesignDesign

…..

Coupons(2 or 4 per board)

Boards(3-4 per set)

Sets (n=6)

Over Time (one or two years)

…

Test CouponsTest Coupons

020406080

100

13 14 15

Board# (Set 5 WR CCA)

ug A

s/100

cm^2 Coupon 1

Coupon 2

020406080

100

4 5 6 7

Set #

ug A

s/100

cm^2

020406080

100

1 2

Board 13, Coupon

ug A

s/100

cm^2

Set ug As/100cm^24 57 +/- 95 51+/- 236 79 +/- 337 23 +/-8

Variability Example, Day 35 Sets 4-7

Variability (%RSD)(Sets 4-7, nested design)

39 4536

17

0102030405060

With

inBo

ards

Bew

teen

Boar

ds

Betw

een

Sets Ove

rTi

me

Aver

age

%RS

D

Variability – Between Boards Within a Set and Over Time –Variability – Between Boards Within a Set and Over Time –Tends to Follow Same Order (10>11>12, 13>14,15)Tends to Follow Same Order (10>11>12, 13>14,15)

WR Boards – No Marked Decrease Over 1 YearWR Boards – No Marked Decrease Over 1 Year

Set 5, WR CCA, Thompsonized (Boards 13-15) - ARSENIC

0.020.040.060.080.0

100.0120.0

0.0 100.0 200.0 300.0 400.0Time, Days

As,

ug/

100^

2 13

14

15

Set 4, Lowes WR CCA, Top Choice (Boards 10A-12)

0.020.040.060.080.0

100.0120.0

0.0 100.0 200.0 300.0 400.0

Time, Days

As, u

g/10

0^2 10A

1112

Variability – Between Boards Within a Set and Over TimeVariability – Between Boards Within a Set and Over TimeTends to Follow Same Order, Tends to Follow Same Order, STD CCA Boards – Decrease Over 1 Year, to Steady State?- See 2 STD CCA Boards – Decrease Over 1 Year, to Steady State?- See 2 Year DataYear Data

Set 6, STD CCA, Lowes (Boards 16-18) - ARSENIC

0.0

50.0

100.0

150.0

0.0 100.0 200.0 300.0 400.0

Time, Days

As, u

g/10

0^2

16

17

18

Set 7, STD CCA, Home Depot (Boards 19-21) - ARSENIC

0.010.0

20.030.0

40.050.0

0.0 100.0 200.0 300.0 400.0

Time, DaysAs

, ug/

100^

2

19

20

21

Variability – Between Boards Within a Set and Over TimeVariability – Between Boards Within a Set and Over Time2 YEAR RESULTS 2 YEAR RESULTS - One Regular CCA (2x8) the Other WR CCA (Set3)- One Regular CCA (2x8) the Other WR CCA (Set3)

2x8 CCA Wood, Arsenic, Each Point Avg of 4 Coupons

0.010.020.030.040.050.0

0 200 400 600 800

Time, Days

As u

g/10

0cm

^2 1

2

3

5

Arsenic, SET3 WR CCA Boards

0.020.040.060.080.0

100.0

0 200 400 600 800Time, Days

As u

g/10

0^2

678

NO MAJOR TREND OVER 2 YEARSNO MAJOR TREND OVER 2 YEARS

Time Effects - All Sets Time Effects - All Sets (Normalized to D=1)(Normalized to D=1)

0.00

0.50

1.00

1.50

2.00

0 200 400 600 800

Time, Days

y(t)/

y(o)

Cr/As Ratio - Tends to Increase over Time – Cr/As Ratio - Tends to Increase over Time – Suggests Surface Becomes Relatively Suggests Surface Becomes Relatively Depleted in Arsenic (Theory Cr/As = 1.1) Depleted in Arsenic (Theory Cr/As = 1.1)

0.000.501.001.502.002.50

0 500 1000

Time, Days

Cr/

As

2x8 boards Set 3 WR

0.000.501.001.502.002.50

0 100 200 300 400

Time, Days

Cr/A

s

Set 4 WR Set 5 WR Set 6 Set 7

Variability and Time Effects- Variability and Time Effects- ConclusionsConclusions

Within Board Variability (17%) much less than other sources.

Variability Between Boards, Sets and Time about Equal (39, 45, 36 %).

Within a Set the As dislodged tended to follow the same board order over time (High Boards stayed High Low Ones Stayed Low).

Cr/As Ratio increases with weathering Decrease in As over time not shown by this data.

Amounts of Arsenic Amounts of Arsenic Dislodged from the SurfaceDislodged from the Surface

Coupons Playscapes Comparisons

OVERALL RESULTS-OVERALL RESULTS-TEST COUPONS (µg As/100 cm^2)TEST COUPONS (µg As/100 cm^2)

TYPE RANGE AVG. MEDIAN

Reg.(n=192) 5-122 24±20 18

WR (n=180) 8-110 43±20 40

ALL 5-122 34±22 27(n=372)

Histogram All Sets (from Avg. Histogram All Sets (from Avg. Freq.. of Each Set)Freq.. of Each Set)

05

1015202530

<=10 >10-20

>20-30

>30-40

>40-50

>50-60

>60-70

>70-80

>80-90

>90-100

>100

ug As/100 cm^2

Freq

uenc

y (5

)

Average Arsenic Dislodged- By set-Average Arsenic Dislodged- By set-Avg. Deviation (error bars); 49%Avg. Deviation (error bars); 49%

0

25

50

75

100

RegCCA

WR-CCA

As,

ug/

100c

m^2

Set 1&2(2x8)Set 6 (5/4x6)Set 7 (5/4x6)Set 3Set 4Set 5

OVERALL RESULTS (n=372)-OVERALL RESULTS (n=372)-TEST COUPONS Cu, Cr, As TEST COUPONS Cu, Cr, As

(µg As/100 cm^2)(µg As/100 cm^2)

Element Range Avg. Median

Cu 3-69 22±12 20

Cr 4-231 51±37 42

As 5-122 34±22 27

Playscape SurfacesPlayscape Surfaces

Playscape SurfacesPlayscape Surfaces

Arsenic Dislodged (µg/100 cm^2) From Arsenic Dislodged (µg/100 cm^2) From Municipal CCA Wood Playscape SurfacesMunicipal CCA Wood Playscape Surfaces

# Planks(Decking) Supports (Poles)*n Range Avg. n Range Avg..

1 14 2-45 10.5 3 15-67 362 16 2-17 7.8 4 51-632 2163 15 3-22 8.2 3 21-135 63

Overall 2-45 7.6 15-632 116

Supports > Planks. But Supports Sampled In Different Manner (By Hand, Not Block). Pole Results Should Only be Considered Indicative.

Why Were Test Coupons > Why Were Test Coupons > Playscape Surface?Playscape Surface?

Arsenic dislodged (µg/100 cm^2) from coupon surfaces averaged 34, but those from playscapes averaged 8.

Time Effects (Playscapes Sampled 1x) Aging Effects/Weathering Physical Wearing (By Repeated Physical

Contact )

EFFECTS OF CONSECUTIVE EFFECTS OF CONSECUTIVE PASSES ON THE SAME SURFACEPASSES ON THE SAME SURFACE

Relevant to planks, hand-rails and other surfaces that are frequently contacted.

7 test coupons from 5 separate batches of boards (2x8, 5/4x6 reg and WR)

5 Passes each board following Standard Procedure (Each Pass is 5 Repetitions Back and Forth)

EFFECTS OF CONSECUTIVE EFFECTS OF CONSECUTIVE PASSES ON THE SAME SURFACEPASSES ON THE SAME SURFACE

0

25

50

75

100

125

1 2 3 4 5

Pass #

Ars

enic

Dis

lodg

ed

Nor

mal

ized

to 1

st R

ep.

2x8 2x8 5/4x6 WR 5/4x6 WR5/4x6 WR 5/4x6 Reg 5/4x6 Reg

EFFECTS OF CONSECUTIVE PASSES ON EFFECTS OF CONSECUTIVE PASSES ON THE SAME SURFACETHE SAME SURFACE

0

25

50

75

100

125

1 2 3 4 5

Pass #

Ars

enic

Dis

lodg

ed,

µg/1

00cm

^2.

2x8 2x8 5/4x6 WR 5/4x6 WR5/4x6 WR 5/4x6 Reg 5/4x6 Reg

AVERAGE AMOUNTS OF ARSENIC DISLODGED AVERAGE AMOUNTS OF ARSENIC DISLODGED AFTER CONSECUTIVE SAMPLINGS AFTER CONSECUTIVE SAMPLINGS

0

25

50

75

100

125

1 2 3 4 5

Pass #

Ars

enic

Dis

lodg

ed, A

vera

ge

Red

uctio

n as

a %

of 1

st R

ep.

Normalized to Rep. 1 = 100%

EFFECTS OF CONSECUTIVE PASSES ON THE SAME EFFECTS OF CONSECUTIVE PASSES ON THE SAME SURFACE -WR CCA BoardsSURFACE -WR CCA Boards

(Weathered for 0,60 and 207 days) (Weathered for 0,60 and 207 days)

WR CCA BOARDS

050

100150

1 2 3 4 5 1 2 3 4 5 1 2 3 4 5

Pass (D=0,60,207)

% o

f 1st

Pas

s

Rejuvenation

2x8 boards

0

50

100

150

200

1 2 3 4 5 1 2 3 4 5 1 2 3 4 5

Pass (d=0,60,207)

% o

f 1st

Pas

s

Rejuvenation

EFFECTS OF CONSECUTIVE PASSES ON THE EFFECTS OF CONSECUTIVE PASSES ON THE SAME SURFACE –2x8 CCA BoardsSAME SURFACE –2x8 CCA Boards (Weathered for 0,60 and 207 days) (Weathered for 0,60 and 207 days)

Reg 5/4x6 boards- Lowes STD

0

50

100

150

1 2 3 4 5 1 2 3 4 5 1 2 3 4 5

Pass (d=0,60,207)

% o

f 1st

Pas

s Rejuvenation

EFFECTS OF CONSECUTIVE PASSES ON THE EFFECTS OF CONSECUTIVE PASSES ON THE SAME SURFACE -Reg CCA BoardsSAME SURFACE -Reg CCA Boards (Weathered for 0,60 and 207 days) (Weathered for 0,60 and 207 days)

AVERAGES - Each Set

0.050.0

100.0150.0

1 2 3 4 5 1 2 3 4 5 1 2 3 4 5

Pass 1-5 (D=0, 60,207)

% o

f 1st

Pas

s Rejuvenation

EFFECTS OF CONSECUTIVE PASSES ON THE EFFECTS OF CONSECUTIVE PASSES ON THE SAME SURFACE –Average Each SetSAME SURFACE –Average Each Set

(Weathered for 0,60 and 207 days) (Weathered for 0,60 and 207 days)

CONCLUSIONS ON THE EFFECTS OF CONCLUSIONS ON THE EFFECTS OF CONSECUTIVE PASSES ON THE SAME SURFACECONSECUTIVE PASSES ON THE SAME SURFACE

The amounts of CCA material dislodged from the surfaces tends to decrease with increased contact frequency

So, comparatively less CCA could be dislodged from wood surfaces that are frequently contacted.

Most Consistent with new boards Rejuvenation Effect after 60 Days Weathering Weathered boards may approach steady state

Comparisons -Comparisons -Reference – Reference –

Table 5 in EPA’sTable 5 in EPA’s FINAL EXPO.DOC FINAL EXPO.DOC

From Table 5 - Summary of Dislodged From Table 5 - Summary of Dislodged Arsenic on Wet WipesArsenic on Wet Wipes – 6 Groups, 18 Data Sets – 6 Groups, 18 Data Sets

1

100

10000

0 5 10 15 20

Table 5 Entry # (Final Expo.Doc)

ug A

s/ 1

00cm

^2

Min

Mean

Max

From Table 5 - Summary of Dislodged From Table 5 - Summary of Dislodged Arsenic on Wet Wipes - Arsenic on Wet Wipes - – 6 Groups, 18 Data Sets – 6 Groups, 18 Data Sets

1

10

100

1000

0 5 10 15 20

Table 5 Entry #

Mea

n As

(ug/

100

cm^2

)

Calif

CT

Riedel

Osmose

W&G

D&M

From Table 5 - Summary of From Table 5 - Summary of Dislodged Arsenic -Dislodged Arsenic -

10 Groups, 43 Data Sets10 Groups, 43 Data SetsMedian Average Average*

Wet (n=18) 70 123 ± 227 75 ± 74Dry (n=7) 32 203 ± 399 64 ± 67Dry Hand (n=8) 26 65 ± 68 56 ± 53Vac Brush (n=10) 160 614 ± 731 475 ± 446

*Omit 1 High 1 Low

From Table 5 - Summary of Dislodged From Table 5 - Summary of Dislodged Arsenic -10 Groups, 43 Data SetsArsenic -10 Groups, 43 Data Sets

0

100

200

300

400

500

Wet Dry DryHand

VacBrush

METHOD

As

(ug/

100

cm^2

)

MedianAverage*

Comparisons and ConclusionsComparisons and Conclusions

Huge Variations Between Groups, Within Groups Comparing Surfaces, and Within a Group of Samples (Min to Max)

Variation in Results Methods Surfaces – Retention, Age, etc.

Limited Data on Method Comparison Vac Brush > Wet > Dry > Dry Hand ?

For Wet, Dry and Hand Methods Median 26-70 ug As/100 cm^2 Average 65-203 ug As/100 cm^2

Comparisons and ConclusionsComparisons and Conclusions

Arsenic Above The Detection Limits Were Found in Most Studies

Results Highly Variable Need for Uniform Method Need For Lab Studies – Leach Model –

Arsenic on Surface as a function of Diffusion From Interior, Leaching From Surface, Particles Removed From Surface

Comparisons and ConclusionsComparisons and Conclusions

Vacuum Brush Much Higher Than Other Methods – Suggests a Potential Hazard When Scrubbing, Sanding, or Power Washing Old Wood Surfaces

Theory - Amount of As in a Volume ( 100cm^2 * Thickness) Theory - Amount of As in a Volume ( 100cm^2 * Thickness) – Removed by Contact, Sanding or Power Washing– Removed by Contact, Sanding or Power Washing

0

50

100

150

200

0 5 10

Microns of Wood Removed

Mic

rogr

ams

Arse

nic

0.250.400.602.5

Retention (lbs/ft^3)

Human Hair 20 to 150 microns

Higher Values in Wipe Samples (>100-200)May Indicate High Retention

SUGGESTIONSSUGGESTIONS No Animal or Children’s Play areas under decks Paint or Stain CCA Wood Surfaces Regularly Alternative Materials for Contact Surfaces

Wood treated with preservatives which contain no arsenic Cedar

Composite Woods- Trex etc. Plastic Timber Stone or Concrete Blocks

TREXTREX

AcknowledgementsAcknowledgements

Katja Gorny, Mike Toner, Eric Mull, TJ Graetz, Becca Ostman (interns)

Craig Musante (CAES)