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STILWELL2001

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Information about STILWELL2001
Education

Published on April 18, 2008

Author: Bernardo

Source: authorstream.com

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Slide1:  Arsenic Dislodged from CCA Surfaces – Effects of Coatings David Stilwell EFFECTS OF COATINGS ON ARSENIC DISLODGED FROM THE SURFACE:  EFFECTS OF COATINGS ON ARSENIC DISLODGED 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 Surface Before, After, and up to One Year After Coating:  Average Arsenic Dislodged from Surface Before, After, and up to One Year After Coating Arsenic ARSENIC (ug/100cm^2):  ARSENIC (ug/100cm^2) Oil Coating – By Board – Time Effects – High and Low Sample Days Match (Day 60 and 365 all high):  Oil Coating – By Board – Time Effects – High and Low Sample Days Match (Day 60 and 365 all high) Slide6:  Average Chromium Dislodged from Surface Before, After, and up to One Year After Coating Chromium Chromium (ug/100cm^2):  Chromium (ug/100cm^2) Coatings Test Conclusions:  Coatings 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 Conclusions:  Coatings 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 Feist and Ross, “Performance and Durability of Finishes on Previously Coated CCA-Treated Wood” 1995, Forest Products Journal :  Durability of Finishes Feist and Ross, “Performance and Durability of Finishes on Previously Coated CCA-Treated Wood” 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 Study Polyurethane and Oil Based Stains worked initially, but less clear over time. (n=?) :  California Study Polyurethane and Oil Based Stains worked initially, but less clear over time. (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 Stains – No effect:  CPSC – Oil and Water Based Stains – 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 Dislodged From Surface?:  Do Coatings Reduce As 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 Work:  Coatings 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? Slide15:  Arsenic Dislodged from CCA Surfaces David Stilwell WOOD PRESERVATIVES:  WOOD 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 CCA TREATED WOOD:  ENVIRONMENTAL ISSUES ON THE USE OF CCA 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 Slide18:  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 Treated Wood Surfaces:  Arsenic Dislodged From CCA Treated Wood Surfaces Slide20:  Copper, Chromium and Arsenic Dislodged from 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 DISLODGED FROM WOOD:  SURVEY ON ARSENIC DISLODGED FROM WOOD Boards Purchased at Lumber Yards Amounts, Variability, Weathering and Coating Effects CCA Wood Surfaces Playgrounds Decks (Not Done) Picnic Tables (Not Done) Slide22:  Method That Was Used – (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 – Following CPSC:  Wipe Apparatus – Following CPSC Slide24:  Procedure Test- Recovery of CCA Extract on Glass DAMP >> DRY Cu, Cr, As Recovery >90 % Using Damp Wipes Survey- Wood Purchased at Lumber Yards:  Survey- Wood Purchased at Lumber 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). WR is Water Repellent + CCA:  Board Survey – (0.4 lbs/ft^3). WR 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 and Time (weathering) Effects:  Variability and Time (weathering) Effects Sampling Scheme – Nested Design:  Sampling Scheme – Nested Design ….. Coupons (2 or 4 per board) Boards (3-4 per set) Sets (n=6) Over Time (one or two years) … Test Coupons:  Test Coupons Slide30:  Set ug As/100cm^2 4 57 +/- 9 5 51+/- 23 6 79 +/- 33 7 23 +/-8 Variability Example, Day 35 Sets 4-7 Variability – Between Boards Within a Set and Over Time – Tends to Follow Same Order (10>11>12, 13>14,15) WR Boards – No Marked Decrease Over 1 Year:  Variability – Between Boards Within a Set and Over Time – Tends to Follow Same Order (10>11>12, 13>14,15) WR Boards – No Marked Decrease Over 1 Year Variability – Between Boards Within a Set and Over Time Tends to Follow Same Order, STD CCA Boards – Decrease Over 1 Year, to Steady State?- See 2 Year Data:  Variability – Between Boards Within a Set and Over Time Tends to Follow Same Order, STD CCA Boards – Decrease Over 1 Year, to Steady State?- See 2 Year Data Variability – Between Boards Within a Set and Over Time 2 YEAR RESULTS - One Regular CCA (2x8) the Other WR CCA (Set3):  Variability – Between Boards Within a Set and Over Time 2 YEAR RESULTS - One Regular CCA (2x8) the Other WR CCA (Set3) NO MAJOR TREND OVER 2 YEARS Time Effects - All Sets (Normalized to D=1):  Time Effects - All Sets (Normalized to D=1) Cr/As Ratio - Tends to Increase over Time – Suggests Surface Becomes Relatively Depleted in Arsenic (Theory Cr/As = 1.1) :  Cr/As Ratio - Tends to Increase over Time – Suggests Surface Becomes Relatively Depleted in Arsenic (Theory Cr/As = 1.1) Variability and Time Effects- Conclusions:  Variability and Time Effects- Conclusions 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 Dislodged from the Surface :  Amounts of Arsenic Dislodged from the Surface Coupons Playscapes Comparisons OVERALL RESULTS- TEST COUPONS (µg As/100 cm^2):  OVERALL RESULTS- 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. Freq.. of Each Set):  Histogram All Sets (from Avg. Freq.. of Each Set) Average Arsenic Dislodged- By set- Avg. Deviation (error bars); 49%:  Average Arsenic Dislodged- By set- Avg. Deviation (error bars); 49% OVERALL RESULTS (n=372)- TEST COUPONS Cu, Cr, As (µg As/100 cm^2):  OVERALL RESULTS (n=372)- TEST COUPONS Cu, Cr, As (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 Surfaces:  Playscape Surfaces Playscape Surfaces:  Playscape Surfaces Arsenic Dislodged (µg/100 cm^2) From Municipal CCA Wood Playscape Surfaces:  Arsenic Dislodged (µg/100 cm^2) From Municipal 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 > Playscape Surface?:  Why Were Test Coupons > 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 PASSES ON THE SAME SURFACE:  EFFECTS OF CONSECUTIVE PASSES 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) Slide48:  EFFECTS OF CONSECUTIVE PASSES ON THE SAME SURFACE Slide49:  EFFECTS OF CONSECUTIVE PASSES ON THE SAME SURFACE Slide50:  AVERAGE AMOUNTS OF ARSENIC DISLODGED AFTER CONSECUTIVE SAMPLINGS Normalized to Rep. 1 = 100% EFFECTS OF CONSECUTIVE PASSES ON THE SAME SURFACE -WR CCA Boards (Weathered for 0,60 and 207 days):  EFFECTS OF CONSECUTIVE PASSES ON THE SAME SURFACE -WR CCA Boards (Weathered for 0,60 and 207 days) Rejuvenation EFFECTS OF CONSECUTIVE PASSES ON THE SAME SURFACE –2x8 CCA Boards (Weathered for 0,60 and 207 days):  Rejuvenation EFFECTS OF CONSECUTIVE PASSES ON THE SAME SURFACE –2x8 CCA Boards (Weathered for 0,60 and 207 days) EFFECTS OF CONSECUTIVE PASSES ON THE SAME SURFACE -Reg CCA Boards (Weathered for 0,60 and 207 days):  Rejuvenation EFFECTS OF CONSECUTIVE PASSES ON THE SAME SURFACE -Reg CCA Boards (Weathered for 0,60 and 207 days) EFFECTS OF CONSECUTIVE PASSES ON THE SAME SURFACE –Average Each Set (Weathered for 0,60 and 207 days):  Rejuvenation EFFECTS OF CONSECUTIVE PASSES ON THE SAME SURFACE –Average Each Set (Weathered for 0,60 and 207 days) CONCLUSIONS ON THE EFFECTS OF CONSECUTIVE PASSES ON THE SAME SURFACE:  CONCLUSIONS ON THE EFFECTS OF CONSECUTIVE 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 - Reference – Table 5 in EPA’s FINAL EXPO.DOC:  Comparisons - Reference – Table 5 in EPA’s FINAL EXPO.DOC From Table 5 - Summary of Dislodged Arsenic on Wet Wipes – 6 Groups, 18 Data Sets:  From Table 5 - Summary of Dislodged Arsenic on Wet Wipes – 6 Groups, 18 Data Sets From Table 5 - Summary of Dislodged Arsenic on Wet Wipes - – 6 Groups, 18 Data Sets:  From Table 5 - Summary of Dislodged Arsenic on Wet Wipes - – 6 Groups, 18 Data Sets From Table 5 - Summary of Dislodged Arsenic - 10 Groups, 43 Data Sets:  From Table 5 - Summary of Dislodged Arsenic - 10 Groups, 43 Data Sets From Table 5 - Summary of Dislodged Arsenic -10 Groups, 43 Data Sets:  From Table 5 - Summary of Dislodged Arsenic -10 Groups, 43 Data Sets Comparisons and Conclusions:  Comparisons 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 Conclusions :  Comparisons 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 Conclusions :  Comparisons 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) – Removed by Contact, Sanding or Power Washing:  Theory - Amount of As in a Volume ( 100cm^2 * Thickness) – Removed by Contact, Sanding or Power Washing Retention (lbs/ft^3) Human Hair 20 to 150 microns Higher Values in Wipe Samples (>100-200) May Indicate High Retention SUGGESTIONS:  SUGGESTIONS 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 TREX:  TREX Acknowledgements:  Acknowledgements Katja Gorny, Mike Toner, Eric Mull, TJ Graetz, Becca Ostman (interns) Craig Musante (CAES)

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