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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
, u
g/1
00 c
m^
2
Precoat
Postcoat
60 Days
157 Days
263 Days
365 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
Dis
lod
ge
d u
g/1
00 c
m^
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
, u
g/1
00 c
m^
2
Precoat
Postcoat
60 Days
157 Days
263 Days
365 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 None 22 ± 22
Oil Based 10 ± 3
Water Based 14 ± 7
2 None 32 ± 22
Oil Based 53 ± 35
Water 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 Material
Cu 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 Duration
2x8(1&2) 4 16 120 2
5/4x6WR(3) 3 12 108 2
5/4x6WR(4) 3 6 36 1
5/4x6WR(5) 3 6 36 1
5/4x6(6) 3 6 36 1
5/4x6(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
As/
100c
m^
2
Coupon 1Coupon 2
020406080
100
4 5 6 7
Set #
ug
As/
100c
m^
2
020406080
100
1 2
Board 13, Coupon
ug
As/
100c
m^
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
Wit
hin
Bo
ard
s
Be
wte
en
Bo
ard
s
Be
twe
en
Se
ts Ove
rT
ime
Ave
rag
e %
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
0.0
20.040.0
60.0
80.0100.0
120.0
0.0 100.0 200.0 300.0 400.0
Time, 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,
ug
/100
^2 10A
11
12
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,
ug
/100
^2
16
17
18
Set 7, STD CCA, Home Depot (Boards 19-21) - ARSENIC
0.0
10.0
20.0
30.0
40.0
50.0
0.0 100.0 200.0 300.0 400.0
Time, DaysA
s, u
g/1
00^
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
0.0
10.0
20.0
30.0
40.0
50.0
0 200 400 600 800
Time, Days
As
ug
/100
cm^
2
1
2
3
5
Arsenic, SET3 WR CCA Boards
0.0
20.0
40.0
60.0
80.0
100.0
0 200 400 600 800Time, Days
As
ug
/100
^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)
0.000.501.00
1.502.002.50
0 500 1000
Time, Days
Cr/
As
2x8 boards Set 3 WR
0.00
0.50
1.00
1.50
2.00
2.50
0 100 200 300 400
Time, Days
Cr/
As
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)
0
5
10
15
20
25
30
<=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
, u
g/1
00
cm
^2
Set 1&2(2x8)
Set 6 (5/4x6)
Set 7 (5/4x6)
Set 3
Set 4
Set 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 36
2 16 2-17 7.8 4 51-632 216
3 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
lod
ged
N
orm
aliz
ed t
o 1
st R
ep.
2x8 2x8 5/4x6 WR 5/4x6 WR
5/4x6 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
lod
ged
, µ
g/1
00cm
^2.
2x8 2x8 5/4x6 WR 5/4x6 WR
5/4x6 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
lod
ged
, A
vera
ge
Red
uct
ion
as
a %
of
1st
Rep
.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
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 1s
t P
ass
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 1s
t P
ass
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 1s
t P
ass
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
0.0
50.0
100.0
150.0
1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
Pass 1-5 (D=0, 60,207)
% o
f 1s
t P
ass
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
As
/ 10
0c
m^
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 #
Me
an
As
(u
g/1
00
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
(u
g/1
00
cm
^2
)
Median
Average*
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
rog
ram
s A
rse
nic
0.25
0.40
0.60
2.5
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)