Transcript Filter Press Trials

Arsenic Dislodged from CCA
Surfaces – Effects of Coatings
David Stilwell
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
Precoat
Postcoat
60 Days
157 Days
263 Days
365 Days
Arsenic, ug/100 cm^2
25
20
15
10
5
Arsenic
0
Poly
Acrylic
Varnish
Coating
Oil
ARSENIC (ug/100cm^2)
Precoat
Postcoat
60 Day
157 Day
263 Day
365 Day
Polyurethane Acrylic
17±9
24±8
0.1
0.2
0.4
1.3
0.2
0.4
0.2
0.2
0.7
0.3
Varnish
20±10
0.7
0.8
0.3
0.1
0.5
Oil
18±9
0.9
3.4
0.6
0.6
3.5
As Dislodged ug/100 cm^2
Oil Coating – By Board –
Time Effects – High and Low Sample
Days Match (Day 60 and 365 all high)
25
Precoat
20
Postcoat
15
Day 60
10
Day 157
Day 263
5
Day 365
0
1-4
1-5
3-3
Board and Coupon #
5-4
Average Chromium Dislodged from
Surface Before, After, and up to One
Year After Coating
Precoat
Postcoat
60 Days
157 Days
263 Days
365 Days
Arsenic, ug/100 cm^2
30
25
20
15
10
5
0
Poly
Acrylic
Varnish
Coating
Oil
Chromium
Chromium (ug/100cm^2)
Precoat
Postcoat
60 Day
157 Day
263 Day
365 Day
Polyurethane Acrylic Varnish
18±13
22±8 22±13
0.1
0.4
0.8
0.6
0.6
1.2
0.2
0.2
0.3
0.2
0.1
0.1
0.2
0.1
0.5
Oil
17±10
1.1
2.8
0.7
0.5
3.5
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
 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





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=?)
As (ug/100 cm^2)
 Time
Before
 After
 6 Months
 2 Years

Oil Based
31-314
6-11
1-13
54
Polyu
1100 (Pier)
10
NA
12-65
CPSC – Oil and Water Based
Stains – No effect
Sample
1
2
Coating (n=3) As (ug/100cm^2)
None
22 ± 22
Oil Based
10 ± 3
Water Based
14 ± 7
None
32 ± 22
Oil Based
53 ± 35
Water Based
52 ± 26
Do Coatings Reduce As
Dislodged From Surface?
 This
Work
 California
 Riedel et al. (1991)*
 CPSC
 Lebow and Evans (1999)*
Yes
Yes
Mixed
NO
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
 Focus
on Oil Based, Acrylic, Polyurethane and
specialty coatings (Fe2O3 Primer, Linseed OilWeatherBos 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
Surfaces
David Stilwell
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

Translocation of CCA to Soil and Water via;





Human exposure to Arsenic in CCA




Dislodged from CCA wood surfaces (hand to mouthchildren)
Exposure during construction (sawdust)
Plant uptake
Impact on Beneficial Marine Organisms


Leaching of CCA from wood
Runoff from lumber yards
Sawdust and physical wearing of the wood
By Cleaning – Sanding and Power washing.
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
Treated Wood Surfaces
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
 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 –
(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
Procedure Test- Recovery of
CCA Extract on Glass
DAMP >> DRY
Cu, Cr, As Recovery >90 %
Using Damp Wipes
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
Type (SET)
2x8(1&2)
5/4x6WR(3)
5/4x6WR(4)
5/4x6WR(5)
5/4x6(6)
5/4x6(7)
Boards
4
3
3
3
3
3
TOTAL
19
Coupons
16
12
6
6
6
6
52
Samples
120
108
36
36
36
36
372
Duration
2
2
1
1
1
1
Variability
and
Time (weathering) Effects
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
1
ug As/100cm^2
100
80
60
40
20
0
2
100
80
60
40
20
0
Coupon 1
Coupon 2
13
Board 13, Coupon
14
15
Board# (Set 5 WR CCA)
ug As/100cm^2
ug As/100cm^2
Variability Example,
Day 35 Sets 4-7
100
80
60
40
20
0
Set
4
5
6
7
4
5
6
Set #
7
ug As/100cm^2
57 +/- 9
51+/- 23
79 +/- 33
23 +/-8
39
45
36
Over
Time
Between
Sets
17
Bewteen
Boards
60
50
40
30
20
10
0
Within
Boards
Average %RSD
Variability (% RSD)
(Sets 4-7, nested design)
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
Set 5, WR CCA, Thompsonized (Boards
13-15) - ARSENIC
120.0
100.0
80.0
60.0
40.0
20.0
0.0
10A
11
12
0.0
100.0 200.0 300.0 400.0
Time, Days
As, ug/100^2
As, ug/100^2
Set 4, Lowes WR CCA, Top Choice
(Boards 10A-12)
120.0
100.0
80.0
60.0
40.0
20.0
0.0
13
14
15
0.0
100.0
200.0
Tim e, Days
300.0
400.0
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
Set 6, STD CCA, Lowes (Boards 16-18) ARSENIC
Set 7, STD CCA, Home Depot (Boards 1921) - ARSENIC
17
18
100.0
50.0
0.0
0.0
100.0
200.0
300.0
Time, Days
400.0
As, ug/100^2
As, ug/100^2
16
150.0
50.0
19
40.0
20
21
30.0
20.0
10.0
0.0
0.0
100.0
200.0
300.0
Time, Days
400.0
Variability – Between Boards Within a Set and Over Time
2 YEAR RESULTS
- One Regular CCA (2x8) the Other WR CCA (Set3)
2x8 CCA Wood, Arsenic, Each Point
Avg of 4 Coupons
Arsenic, SET3 WR CCA Boards
50.0
40.0
1
30.0
2
20.0
3
10.0
5
As ug/100^2
As ug/100cm^2
100.0
6
7
8
80.0
60.0
40.0
20.0
0.0
0.0
0
200
400
Time, Days
600
800
0
200
400
600
Time, Days
NO MAJOR TREND OVER 2 YEARS
800
Time Effects - All Sets
(Normalized to D=1)
2.00
y(t)/y(o)
1.50
1.00
0.50
0.00
0
200
400
Time, Days
600
800
2.50
2.00
1.50
1.00
0.50
0.00
Cr/As
Cr/As
Cr/As Ratio - Tends to Increase over Time –
Suggests Surface Becomes Relatively
Depleted in Arsenic (Theory Cr/As = 1.1)
0
500
1000
2.50
2.00
1.50
1.00
0.50
0.00
0
Time, Days
2x8 boards
Set 3 WR
100
200
300
400
Time, Days
Set 4 WR
Set 5 WR
Set 6
Set 7
Variability and Time EffectsConclusions
 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
 Coupons
 Playscapes
 Comparisons
OVERALL RESULTSTEST 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
(n=372)
5-122
34±22
27
Histogram All Sets (from Avg.
Freq.. of Each Set)
Frequency (5)
30
25
20
15
10
5
0
<=10 >10- >20- >30- >40- >50- >60- >70- >80- >90- >100
20 30 40 50 60 70 80 90 100
ug As/100 cm^2
Average Arsenic Dislodged- By setAvg. Deviation (error bars); 49%
As, ug/100cm^2
100
75
50
25
0
Reg
CCA
WR-CCA
Set
Set
Set
Set
Set
Set
1&2(2x8)
6 (5/4x6)
7 (5/4x6)
3
4
5
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
Arsenic Dislodged (µg/100 cm^2) From
Municipal CCA Wood Playscape Surfaces
#
Planks(Decking)
n
Range Avg.
Supports (Poles)*
n Range
Avg..
1
2
3
14
16
15
3
4
3
Overall
2-45
2-17
3-22
10.5
7.8
8.2
2-45
7.6
15-67
51-632
21-135
36
216
63
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?
 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
 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)
Arsenic Dislodged
Normalized to 1st Rep.
EFFECTS OF CONSECUTIVE
PASSES ON THE SAME SURFACE
125
100
75
50
25
0
1
2
3
4
5
Pass #
2x8
5/4x6 WR
2x8
5/4x6 Reg
5/4x6 WR
5/4x6 Reg
5/4x6 WR
Arsenic Dislodged,
µg/100cm^2.
EFFECTS OF CONSECUTIVE PASSES ON
THE SAME SURFACE
125
100
75
50
25
0
1
2
3
4
5
Pass #
2x8
5/4x6 WR
2x8
5/4x6 Reg
5/4x6 WR
5/4x6 Reg
5/4x6 WR
Arsenic Dislodged, Average
Reduction as a % of 1st Rep.
AVERAGE AMOUNTS OF ARSENIC DISLODGED
AFTER CONSECUTIVE SAMPLINGS
125
Normalized to Rep. 1 = 100%
100
75
50
25
0
1
2
3
Pass #
4
5
EFFECTS OF CONSECUTIVE PASSES ON THE SAME
SURFACE -WR CCA Boards
(Weathered for 0,60 and 207 days)
WR CCA BOARDS
% of 1st Pass
Rejuvenation
150
100
50
0
123451234512345
Pass (D=0,60,207)
EFFECTS OF CONSECUTIVE PASSES ON THE
SAME SURFACE –2x8 CCA Boards
(Weathered for 0,60 and 207 days)
2x8 boards
% of 1st Pass
Rejuvenation
200
150
100
50
0
1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
Pass (d=0,60,207)
EFFECTS OF CONSECUTIVE PASSES ON THE
SAME SURFACE -Reg CCA Boards
(Weathered for 0,60 and 207 days)
% of 1st Pass
Reg 5/4x6 boards- Lowes STD
150
Rejuvenation
100
50
0
1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
Pass (d=0,60,207)
EFFECTS OF CONSECUTIVE PASSES ON THE
SAME SURFACE –Average Each Set
(Weathered for 0,60 and 207 days)
% of 1st Pass
AVERAGES - Each Set
Rejuvenation
150.0
100.0
50.0
0.0
1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
Pass 1-5 (D=0, 60,207)
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
ug As/ 100cm^2
From Table 5 - Summary of Dislodged
Arsenic on Wet Wipes
– 6 Groups, 18 Data Sets
10000
Min
100
Mean
Max
1
0
5
10
15
Table 5 Entry # (Final Expo.Doc)
20
Mean As (ug/100 cm^2)
From Table 5 - Summary of Dislodged
Arsenic on Wet Wipes – 6 Groups, 18 Data Sets
1000
Calif
100
CT
Riedel
10
Osmose
1
W&G
0
5
10
15
Table 5 Entry #
20
D&M
From Table 5 - Summary of
Dislodged Arsenic 10 Groups, 43 Data Sets
Median
Wet (n=18)
70
Dry (n=7)
32
Dry Hand (n=8)
26
Vac Brush (n=10) 160
*Omit 1 High 1 Low
Average
Average*
123
203
65
614
75
64
56
475
±
±
±
±
227
399
68
731
±
±
±
±
74
67
53
446
From Table 5 - Summary of Dislodged
Arsenic -10 Groups, 43 Data Sets
As (ug/100 cm^2)
500
400
300
Median
200
Average*
100
0
Wet
Dry
Dry
Vac
Hand Brush
METHOD
Comparisons and Conclusions


Huge Variations Between Groups, Within Groups
Comparing Surfaces, and Within a Group of Samples
(Min to Max)
Variation in Results



Limited Data on Method Comparison


Methods
Surfaces – Retention, Age, etc.
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
 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
 Vacuum
Brush Much Higher Than Other
Methods – Suggests a Potential Hazard
When Scrubbing, Sanding, or Power
Washing Old Wood Surfaces
Micrograms Arsenic
Theory - Amount of As in a Volume ( 100cm^2 * Thickness)
– Removed by Contact, Sanding or Power Washing
200
Retention (lbs/ft^3)
150
0.25
0.40
100
0.60
2.5
50
Higher Values in Wipe
Samples (>100-200)
May Indicate
High Retention
0
0
5
Microns of Wood Removed
10
Human Hair
20 to 150 microns
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
Acknowledgements
 Katja
Gorny, Mike Toner, Eric Mull, TJ
Graetz, Becca Ostman (interns)
 Craig Musante (CAES)