r/EPA
This interim report does not represent and should not be construed to represent
any Agency determination or policy. The Agency plans to finalize this report
after all of the data have been collected and evaluated and after the report
undergoes independent external peer review.
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
Category Il/Sampling and Analysis
EPA Report: EPA/600/R-05/050
-------
Mark Mason
EPA Work Assignment Manager
Date
4/29/05
Victor D'Amato
ARCADIS Work Assignment Leader
Date
Paul Graff '' i
EPA QA Representative
c^YluiA^-
Date
4/29/05
Laura Beach Nessley //
ARCADIS QA Officer "
Date
Nader Elkassabany
EPA—OPP Representative
1 Date
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
Category I I/Sampling and
Analysis
EPA Report:
EPA/600/R-05/050
Prepared for:
U.S. Environmental Protection Agency
Air Pollution Prevention and Control Division
Research Triangle Park,
North Carolina 27711
Prepared by:
ARCADIS G&M, Inc.
4915 Prospectus Drive, Suite F
Durham,
North Carolina 27713
Tel 919 544 4535
Fax 919 544 5690
Contract Number:
EP-C-04-023
Work Assignment Number 1-05
Our Ref.:
RN990231.0005
9 May 2005
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Table of Contents
List of Tables
List of Figures
Appendices (contained on CD-Rom)
Acronym List
Executive Summary
1. Project Description and Organization
1.1 Overall Project Objectives
1.2 Background
1.3 Experimental Design and Scope
1.4 Data Quality Objectives
1.5 Project Organization and Responsibilities
2. Test Methods
2.1 Overall Study Design
2.1.1 Scope
2.1.2 Data Product and Use
2.1.3 Study Limitations
2.1.3.1 Stress Factors
2.1.3.2 Application Technique
2.1.3.3 Surface Preparation for Coating
2.1.3.4 Type and Condition of Aged Wood
2.1.3.5 Re-rubbing Effects and Baseline Sampling
2.1.3.6 Effects of Nailholes and Other Surface Irregularities
2.1.3.7 Test Specimen Lengths
VII
XI
xiv
1
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2
4
5
5
9
9
9
10
10
11
11
11
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12
14
14
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Table of Contents
2.1.3.8 Abrasion Effects 15
2.1.3.9 CCAAnalytes and Speciation 15
2.1.3.10 Other Limitations 15
2.2 Selection of Wood Sources 16
2.3 Preparation and Characterization of Wood Sources 20
2.4 Wood Core Sampling and Analysis 23
2.5 Minideck Construction 23
2.6 Selection of Coatings 28
2.7 Coating Application 31
2.8 Outdoor Weathering 35
2.9 Timeline 40
2.10 Wipe Sampling 40
2.10.1 EPA Wipe Method (Adaptation of Referenced CPSC Staff Method) 44
2.10.2 EPA Acid-Wash, Rinse, and Saturate with Dl Water Wipe
Preparation Technique (A2 Method) 45
2.10.3 EPA2X Dl Water Wipe Preparation Technique (2X Method) 45
2.10.4 CPSC Staff 1X0.9% Saline Wipe Preparation Technique (CPSC
Method) 46
2.10.5 EPA Laboratory Wipe Extraction and Analysis Techniques 47
2.10.6 CPSC Staff Technique Laboratory Wipe Extraction and Analysis
Techniques 49
2.10.7 Differences Between EPA and CPSC Staff Wipe and Sample
Preparation Procedures 49
2.10.8 Wipe Sampling Method Limitations and Recommendations for
Improvements 50
2.11 Preparation and Analysis of Coating Samples 50
2.12 Archiving of ICP-MS Samples 51
2.13 Moisture Analysis of Wood Specimens 51
2.14 Photographs 51
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Table of Contents
2.15 Miscellaneous Samples
2.16 Quality Control Samples
2.16.1 Positive (CCA-Treated, Uncoated) Controls
2.16.2 Negative (Untreated, Uncoated) Controls
2.16.3 Cross-Contamination Controls
2.16.4 Wipe Frequency (Rewipe, Abrasion) Controls
2.16.5 Analytical (Contract Laboratory) Control Samples
3. Data Reduction and Analysis Methods
3.1 Data Reduction
3.1.1 Calculation of DA from Extraction Fluid Concentrations
3.1.2 Calculation of Percent Reduction of DA
3.2 Data Reporting
3.3 Relational Databasing
3.4 Statistical Analysis Approach
3.4.1 Wipe Method Correction Factors
3.4.2 Intercoating Comparison and Ranking
3.4.3 Wipe Frequency and Number of Wipe Analysis
4. Results and Discussion
4.1 Wood Characterization Data
4.2 Coating Application Data
4.3 Wood Core Sample Data
4.4 Baseline Wipe Sample Data
4.4.1 Baseline Sample Proximity Analysis
4.4.2 Core Sample-Baseline DA Correlation Analysis
4.5 Weather Data
4.6 Coating Performance Data
4.6.1 Coating Performance (DA vs Time)
51
52
52
53
53
53
54
55
55
55
55
58
58
59
59
60
61
62
62
64
64
80
96
103
104
108
108
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Table of Contents
4.6.2 Statistical Analysis and Coating Rankings 108
4.6.3 Inter-and Intra-Coating Comparisons 114
4.6.3.1 Method 1. Using Unique Single Baselines for Each PSA 117
4.6.3.2 Method 2. Using Average Baseline and Sample DA
Calculated for Each Grouping of Source, Sampling Interval,
and Coating 121
4.6.3.3 Method 3. Using the Average of the Positive Control
Minideck (#13) DA Values for each Grouping of Source and
Wipe Interval as Baseline 126
4.6.3.4 Method 4. Estimating Coating Efficacy Relative to Deck 13
Calculated Using the Analysis of Variance Model That Was
Used to Compare Coatings 131
4.6.3.5 Summary and Comparison of Efficacy Calculations 134
4.6.4 Coating Appearance 142
4.7 Abrasion and Rewipe Analysis 142
4.8 Miscellaneous Samples 144
4.8.1 Brush Washwater Samples 144
4.8.2 Cross Contamination and Negative Control Deck Sample Results 145
5. Data Validation and Quality Assurance and Quality Control 149
5.1 Assessing DQI Goals 149
5.1.1 Precision 149
5.1.2 Accuracy and Bias 150
5.1.3 Completeness 156
5.2 Quality Control Checks 156
5.2.1 Blanks 157
5.2.1.1 Wipe Blank Study 157
5.2.1.2 Blanks During Sampling Events 158
IV
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Table of Contents
5.2.2 Initial Spike Study
5.2.3 Laboratory Control Samples
5.3 Data Validation Summary
5.4 Deviations from the QAPP
5.5 Audits
6. Conclusions
7. References
158
160
160
160
161
164
167
List of Tables
Table 1-1. Data Quality Indicator Goals for Critical Measurements
Table 1-2. Contact Information for Key Project Staff
Table 2-1. Wood Specimens used to Construct Minidecks
Table 2-2. Selected Products for Evaluation
Table 2-3. Timeline Showing History of Project to Date
Table 2-5. Vantage ProPlus Weather Station Data
Table 2-6. NOAA-Generated Weather Data
Table 2-7. Miscellaneous Samples to be Collected
Table 3-1. Relational Database Table Summary
Table 4-1. Source Wood Characterization Data Summary
Table 4-2. Coating Application Data Summary
Table 4-3. Wood Core Sample Results for Source A
Table 4-4. Wood Core Sample Results for Source C
Table 4.5 Comparison of Nominal, Source A, and Source C CCA Actives
Composition
Table 4-6. Baseline Wipe Sample Summary for Source Deck A
27
31
34
39
39
52
58
62
65
68
73
78
81
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Table of Contents
Table 4-7. Baseline Wipe Sample Summary for Source Deck C 85
Table 4-8. UV Index and Exposure Category 105
Table 4-10. Average DAs (ug/cm2)vs Sampling Interval 111
Table 4-11. Average DCr(ug/cm2) vs Sampling Interval 112
Table 4-12. Average DCu (ug/cm2) vs Sampling Interval 113
Table 4-13. DA Reduction using Method 1 117
Table 4-14. DA Reduction Using Method 2 121
Table 4-15. DA Reduction Using Method 3 126
Table 4-16. Composite DAs Reduction Efficiencies for Source A, per Method 4, with
95% CL 132
Table 4-17. Composite DAs Reduction Efficiencies for Source C, per Method 4, with
95% CL 132
Table 4-18. Composite DCr Reduction Efficiencies, for Both Sources Combined, per
Method 4, with 95% CL 133
Table 4-19. Composite DCu Reduction Efficiencies, for Both Sources Combined,
per Method 4, with 95% CL 133
Table 4-20. Comparison of DAs Efficacy Calculation Methods, Methods 1, 2, and 3,
Source A 134
Table 4-21. Comparison of DAs Efficacy Calculation Methods, Methods 1, 2, and 3,
Source C 137
Table 4-22. Comparison of Efficacy Calculation Methods, for Arsenic at 11 Months,
Both Sources Combined 139
Table 4-23. Summary of Visual Observations of Minidecks 143
Table 4-24. Brush Sample CCA Analyte Concentrations 144
Table 4-25. Summary of Cross-Contamination and Blank Control Minideck Results 146
Table 4-26. Summary of Cross-Contamination Data for All Coatings. 147
Table 5-1. Data Quality Indicator Goals for Critical Measurements 149
Table 5-2. Precision of Duplicate Samples 151
Table 5-3. Spike Results 155
Table 5-4. Polywipe Blank Analyses 157
Table 5-5. Results from a September 2003 Wipe Comparison Study 157
VI
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Table of Contents
Table 5-6. Results of Spiking onto Glass 159
Table 5-7. Results of Spiking Wipes Directly 159
List of Figures
Figure 1-1. Wood Member Nomenclature 4
Figure 1-2. Organizational Chart for Weathering Testing 7
Figure 2-1. ERC Deck Map 18
Figure 2-2. Views of ERC Deck (note that moisture stains were temporary and that
boards under benches were not used to construct minidecks) 18
Figure 2-3. New Hill Deck Map 19
Figure 2-4. Views of New Hill Deck 19
Figure 2-5. Specimen identification and baseline sampling scheme example. 23
Figure 2-6. Schematic of Minideck Construction 25
Figure 2-7. Sample Minideck Photo 26
Figure 2-8 Photograph of Minideck Site (note weather monitoring station on
right)Table 2-4. Minideck Block Assignments (Blocks correspond to
those identified in Appendix E) 36
Table 2-4. Minideck Block Assignments (Blocks correspond to those identified in
Appendix E) 37
Figure 2-9 CPSC Wipe Sampling Apparatus 43
Figure 4.1 Coating Application (total of triplicate minidecks and both A and
C sources) 67
Figure 4-2. Distribution (top) and box (bottom) plot, baseline DAs, by Coating,
Source A 90
Figure 4-3. Distribution (top) and box (bottom) plot, baseline DCr, by Coating,
Source A 91
Figure 4-4. Distribution (top) and box (bottom) plot, baseline DCu, by Coating,
Source A 92
Figure 4-5. Distribution (Top) and Box (Bottom) Plot, Baseline DAs, by Coating,
Source C 93
VII
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Table of Contents
Figure 4-6. Distribution (Top) and Box (Bottom) Plot, Baseline DCr, by Coating,
Source C 94
Figure 4-7. Distribution (Top) and Box (Bottom) Plot, Baseline DCu, by Coating,
Source C 95
Figure 4-8. Mean vs Position and MSD vs Distance for Source A DAs Baseline 97
Figure 4-9. Mean vs Position and MSD vs Distance for Source A DCr Baseline 98
Figure 4-10. Mean vs Position and MSD vs Distance for Source A DCu Baseline 99
Figure 4-11. Mean vs Position and MSD vs distance for Source C DAs Baseline 100
Figure 4-12. Mean vs Position and MSD vs Distance for Source C DCr Baseline 101
Figure 4-13. Mean vs Position and MSD vs Distance for Source C DCu Baseline 102
Figure 4-14. Wood Core Concentration versus Baseline DA for Source A Boards 103
Figure 4-15. Wood Core Concentration versus Baseline DA for Source C Boards 104
Figure 4-16. Solar Radiation Data Summary 105
Figure 4-17. UV Index Data Summary 106
Figure 4-18. Rainfall Data Summary 106
Figure 4-19. Temperature Data Summary 107
Figure 4-20. Humidity Data Summary 107
Figure 4-21. Average DAs vs Time for All Coatings 111
Figure 4-22. Average DCrvs Time for All Coatings 112
Figure 4-23. Average DCu vs time for All Coatings 113
Figure 4-24. Arsenic Reduction Efficacy Line Plot by Coating - All Time Periods 115
Figure 4-25. Arsenic Reduction Efficacy Line Plot by Coating -at Time =11 Months 115
Figure 4-26. Chromium Reduction Efficacy Line Plot by Coating-All Time Periods 115
Figure 4-27. Chromium Reduction Efficacy Line Plot by Coating - at Time =11
Months 116
Figure 4-28. Copper Reduction Efficacy Line Plot by Coating -All Time Periods 116
Figure 4-29. Copper Reduction Efficacy Line Plot by Coating - at Time =11 Months 116
Figure 4-30. Arsenic Coating Efficacy for Source A Specimens Using Analysis
Method 1 120
VIM
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Table of Contents
Figure 4-31. Arsenic Coating Efficacy for Source C Specimens Using Analysis
Method 1 121
Figure 4-32. Arsenic Coating Efficacy for Source A Specimens Using Analysis
Method 2 125
Figure 4-33. Arsenic Coating Efficacy for Source C Specimens Using Analysis
Method 2 126
Figure 4-34. Arsenic Coating Efficacy for Source A Specimens Using Analysis
Methods 130
Figure 4-35. Arsenic Coating Efficacy for Source C Specimens Using Analysis
Methods 131
IX
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Table of Contents
Appendices (contained on CD-Rom)
Appendix A. Wipe Comparison Report
Appendix B. Specimen Characterization Form
Appendix C. Wood Preparation Flow Sheets
Appendix D. Coating Application Data Form
Appendix E. Site Layout Plan
Appendix F. Weather Data Confirmation Details
Appendix G. Sampling Event Data Form
Appendix H. Database Design Schematic
Appendix I. Specimen Characterization Data
Appendix J. Specimen Wood Core Data
Appendix K. Specimen Baseline Data
Appendix L. Baseline Box Plots, by Board
Appendix M. Weather Data
Appendix N. Baseline and PSA Wipe Sampling Data
Appendix O. Distribution and Box Plots, by Coating, sorted by Sampling Event and
Source
Appendix P. Coating Efficacy Plots by Analysis Method
Appendix Q. Three-Dimensional Coating Ranking Plots, sorted by Sampling Event and
Source
Appendix R. Minideck Photo Log
Appendix S. Cross-Contamination (Untreated) Sample Data
Appendix T. Negative Blank Control (BC) Sample Data
Appendix U. Data Validation Reports
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Acronym List
Acronym List
As
av
AWPA
BL
CCA
CD-Rom
CL
CLP
CPSC
DA
DAs
DCr
DCu
DI
DPD
DQI
EPA
ERC
FIFRA
H&S
ICP
ICP-MS
ID
Arsenic
Average
American Wood Preservers' Association
Baseline
Chromated Copper Arsenate
Compact Disk - Read Only Memory
Confidence Limits
Contract Laboratory Program
Consumer Product Safety Commission
Dislodgeable CCA Wood Analytes
Dislodgeable Arsenic
Dislodgeable Chromium
Dislodgeable Copper
Deionized Water
Dew Point Depression
Data Quality Indicator
United States Environmental Protection Agency
Environmental Research Center (old building)
Federal Insecticide Fungicide and Rodenticide Act
Health and Safety
Inductively Coupled Plasma
Inductively Coupled Plasma—Mass Spectrometry
Identification
XI
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Acronym List
mph Miles Per Hour
MS Matrix Spikes
MS/MSD Matrix Spikes and Matrix Spike Duplicates
MSB Matrix Spike Duplicates
NCDC National Climate Data Center
NE Northeast
NFG National Functional Guidelines
NOAA National Oceanic and Atmospheric Administration
NOPW Number of Previous Wipes
NW Northwest
NWS National Weather Station
OLS On-Site Laboratory Support
OPP Office of Pesticide Programs
pcf Pounds per Cubic Foot
PEA Performance Evaluation Audit
PFA Perfluoroalkoxy
PM Project Manager
PSA Primary Sampling Area
PTFE Polytetrafluoroethylene
QA/QC Quality Assurance and Quality Control
QAPP Quality Assurance Project Plan
RDU Raleigh—Durham International Airport
RPD Relative Percent Difference
RSD Relative Standard Deviation
RSD/RPD Relative Standard Deviation or Relative Percent Deviation
XII
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Acronym List
RTF Research Triangle Park
SAP Scientific Advisory Panel
Std. Dev. Standard Deviation
STL Severn Trent Laboratory
SYP Southern Yellow Pine
TFE Tetrafluoroethylene
TTPW Time (Months) Since the Previous Wipe
U.S. United States
WA Work Assignment
UV Ultraviolet
XIII
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Executive Summary
Executive Summary
EPA is approximately 20 months into a project to evaluate the performance of wood
coatings for preventing arsenic, chromium, and copper exposure from the surfaces of
CCA treated wood. Potential dermal exposure, as measured by wipe sampling
dislodgeable CCA chemicals from the wood surfaces, is the primary evaluation criteria
for the coatings testing in this study, but EPA is also concerned with exposure due to
ingestion and inhalation. Ingestion is related to dermal exposure because of hand-to-
mouth activities, particularly in children. Likewise, inhalation may potentially pose an
exposure route when consumers are preparing wood surfaces for coating and recoating.
The data collected and reported in this interim data report, which reports on results of
the study through 11 months, will be used to inform the EPA risk assessment and to
provide consumers recommendations on mitigating exposure to CCA on residential
structures, such as decks. A critical component of this project is the development of a
robust protocol for evaluating coating performance in mitigating exposure, since
standardized protocols generally do not yet exist. As such, considerable effort has been
placed on the development of the testing plan and the report addresses the development
of test protocols in some detail.
The testing protocol involved the construction of a series of miniature decks
(minidecks) to each of which one of twelve coatings was applied. Each minideck
contained four CCA-treated boards: two from a relatively old source deck and two
from a relatively new source deck. Each coating was applied to three minidecks and
there are also three positive control (treated, uncoated) minidecks and one negative
control (untreated, uncoated) minideck for a total of 40 minidecks. After coating, the
minidecks have been subjected to natural outdoor weathering at a controlled site in
North Carolina where an array of climatological measurements are recorded on a near-
continuous basis. Dislodgeable CCA (DA) has been measured using a wipe sampling
technique pre-coat (baseline), and at 1, 3, 7, and 11 months after coating in an effort to
assess coating performance over time, subject to natural outdoor weathering. A number
of other samples have been taken, as have visual observations, all of which are reported
and discussed in the ensuing report.
The primary purpose of this study is to provide EPA with data needed to make and
support guidance to consumers regarding mitigating health risks associated with the
continued use of CCA treated wood structures, like decks. As such, the coatings that
were tested were ranked based on their performance. Upper tier performers generally
reduced dislodgeable arsenic (DAs) by about 90% or greater after 11 months, middle
XIV
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Executive Summary
tier performers generally reduced DAs by about 75% or greater at 11 months, and
lower tier performers generally reduced DAs by about 75% or less at 11 months.
While the top two performers were film-forming coatings - the only two paints tested
(coatings #9 and #10) - several other, more typical deck treatment products performed
almost as well. The painted minidecks show significant weathering, with an oil-based
paint seeming to resist chipping better than a water-based paint. However, there are
significant concerns about the applicability of using paints as coatings for exposed
outdoor surfaces subject to abrasion. Weathered paints can have a noticeably poor
appearance, necessitating frequent recoating. Additionally, the chipping of paints and
surface preparation techniques for recoating, which typically include sanding, can
generate dust which may make inhalation of CCA-contaminated particles a serious
health risk.
Another film-former, an elastic vinyl product designed to encapsulate CCA wood
(coating #11), performed very well initially, but appeared to fall off slightly in
comparison to other high-performing products over time. This product additionally
exhibited significant biological growth and associated discoloration.
Within the remaining coatings, no clear trends with respect to product type or
characteristics are immediately evident. The best non-film-forming products were
identified as coatings #1, #3, and #8. Coating #1 is an oil-based semitransparent sealant
in cedar tone. Coating #1 additionally contains a UV blocking agent. Another coating
containing a UV blocker (coating #7) did not perform as well. Coating #3 is a clear,
oil-based, acrylic, deep tone base stain to which no pigment had been added prior to
application. Coating #8 is a clear, water-based, acrylic, tint base, solid stain to which
no pigment had been added prior to application.
Additionally, we can say that:
« Rinsing the wood surfaces reduces DA measured by wipe sampling, although it
may simply relocate the CCA chemicals to other places where exposure is
possible.
" Coating the wood surfaces further reduces DA over uncoated surfaces.
" Weathering reduces the effectiveness of coatings as seen by increases in DA.
xv
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Executive Summary
" Some coatings perform better than others in terms of DA reduction but there are
inconsistencies between coatings within the same classification.
" Coating product trade names are not tied to specific formulations, potentially
complicating the ability to communicate results and guidance effectively with the
public.
Significant findings with regards to the test protocol include the following:
" The protocol appears robust and could be used by the coatings industry to develop
coatings and to verify coating performance for CCA exposure mitigation.
" Cross-contamination has not been a problem.
" Baseline (pre-coat) DA can be determined either for each specific wipe area or
averaged over each board. Precoat measurements should preferably be taken both
before and after preparing the wood surface (e.g., washing, rinsing, etc.) for
coating.
" The effects of abrasion resulting from the wipe sampling method used for this
study appear to be negligible, thus avoiding potential complications, or false
positive interferences, as a result of the sampling methodology.
" Rewipe effect - that is, the reduction in DA post-sampling may be significant.
« There appears a relatively strong correlation between DAs, DCr, and DCu. That is,
wipe areas with high DA measurements for one CCA analyte generally also have
high DA measurements for the other CCA analytes.
« The method by which coating efficacies are calculated or modeled did not appear
to have an appreciable effect on the rank order of coatings.
The project will continue with sampling events having already been conducted at 15
and 19 months, and planned for 23 months post-coating.
Abrasion is considered another likely important coating performance factor which is
not vigorously tested by the protocol currently employed. Future studies may include
an assessment of the effect of abrasion on coating performance.
XVI
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
1. Project Description and Organization
1.1 Overall Project Objectives
The primary objective of this project is to evaluate the ability of selected coatings to
reduce the amount of dislodgeable chromated copper arsenate (CCA) analytes (DA)
on the surfaces of CCA-treated wood. Two sources of weathered CCA-treated
southern yellow pine (SYP) were harvested from in-service decks and used to
construct a series of miniature decks (minidecks), onto which selected coatings have
been applied. Dislodgeable arsenic (DAs), chromium (DCr), and copper (DCu) are
measured at specified intervals. The coated lumber is subjected to natural weathering
outdoors. The ability of the coatings to reduce DA as the wood and coatings weather
is being evaluated by periodically determining the amount of DA removed from the
surface of the wood specimens using a wipe technique.
For the purposes of this study, DA is defined as the amount of CCA analyte removed
from the surface of the test specimen by the dermal wipe procedure (with minor
modifications) developed and demonstrated by the staff of the Consumer Product
Safety Commission (CPSC), which is a collaborator on this project via an
interagency agreement (CPSC-I-03-1235) between the United States Environmental
Protection Agency (EPA) and CPSC. EPA-CPSC staff wipe comparison data (refer
to EPA Wipe Comparison Study Report in Appendix A) indicates that measured DA
values are method-specific and may depend upon a number of variables including
wipe material, device used, number of passes, moisture content of the wipe, and the
area of the surface wiped. It is believed that DA measured via the wipe sampling
procedures utilized in this study is proportional to the surface area wiped. Other
researchers have measured DA and reported DA on a mass per area wiped basis
(Stilwell, et al., 2003; Stilwell 2003a, 2003b). Therefore, for the purposes of this
study, DA is expressed in units of mass per surface area wiped (ug/cm2).
The data obtained will be used by EPA and CPSC staff in support of efforts to inform
the public regarding the use and maintenance of existing CCA-treated wood
products, such as decks and playground equipment. A supplemental objective of this
study is to evaluate and demonstrate the use of the test protocol and to begin to
understand its utility and realism, and to identify future research needs. This second
objective is relevant because there are currently no standardized protocols for
determining the efficacy of coatings to reduce DA from CCA-treated wood. In this
regard, the test is a pilot study that may set the stage for systematic development of
standardized test methods that will promote development, evaluation, and
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demonstration of products that mitigate the potential for dermal contact with DA
from CCA-treated wood.
Note that few products are currently manufactured explicitly for the purpose of
reducing DA from CCA-treated wood. Hence, EPA is primarily evaluating the
efficacy of products to perform a task that is not necessarily related to the
manufacturer's design or intent. As such, the test results should not be construed to
represent an evaluation of a product's effectiveness for those purposes for which it
was designed and warranted by the manufacturer.
This interim data report covers all baseline measurements taken, wood preparation
and coating application data, and mitigation sampling at 1, 3, 7, and 11 months after
coating application, in addition to other supporting data collected as part of the study
to date. The test plan is described in detail in the Category 2 QAPP entitled,
"Evaluation of the Effectiveness of Coatings in Reducing Dislodgeable Arsenic,
Chromium, and Copper from CCA Treated Wood," dated September 24, 2003 (U.S.
EPA 2003).
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
1.2 Background
CCA is a wood preservative registered under FIFRA (Federal Insecticide, Fungicide,
and Rodenticide Act) by EPA Office of Pesticide Programs (OPP) and impregnated
under pressure to protect wood from decay and insect damage. In October 2001,
EPA-OPP prepared a preliminary deterministic exposure assessment for selective
internal and external peer review comments as an interim report intended to address
child residential "playground" exposures. In addition, EPA requested guidance from
the FIFRA Scientific Advisory Panel (SAP) for risk mitigation measures such as
sealants and coating processes. The SAP Panel made "recommendations regarding
the need for additional studies in this area..." because the "weight-of-evidence from
available studies indicates that certain coatings can substantially reduce dislodgeable
and leachable CCA chemicals." The Panel also recommended that "EPA inform the
public of the ability of certain coatings to substantially reduce leachable and
dislodgeable CCA chemicals..."
In March 2003, the registrants of CCA wood preservatives signed an agreement with
EPA for voluntary cancellation of CCA-treated wood for residential uses (such as
playsets and decks) effective beginning January 1, 2004. However, existing decks
and playsets made of CCA-treated wood will still be in use. Therefore, the potential
remains for dermal contact with arsenic, chromium, and copper residues on treated
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
surfaces, and the risk, especially to the most susceptible subpopulation, infants and
small children, due to their close contact with surfaces and hand-to-mouth activities,
is a concern. This project will provide EPA with information that can be used to
provide the public with guidance on the use of coatings to prevent contact with DA
from CCA-treated wood.
To provide consumers with effective guidance, EPA must have a basic understanding
of the impact of key variables on the efficacy of coating and sealant systems. Key
environmental variables include exposure to natural weathering phenomena
including ultraviolet (UV) radiation, condensation, precipitation, and thermal shock.
Efficacy of coatings may also be impacted by level and fixation of CCA treatment,
age and condition of the wood at the time of coating, and type and dimensions of the
treated wood. Due to the large number of variables, and EPA's desire to provide
guidance quickly for in-service wood, this project evaluates selected coatings applied
to aged CCA-treated wood [southern yellow pine (SYP)] exposed to natural outdoor
weathering at a site in North Carolina. Accelerated chamber weathering testing was
originally contemplated as a component of this study, but the decision was made,
based on available resources and peer review comments, to focus on the more
realistic outdoor testing strategy. An accelerated weathering chamber testing protocol
may be developed as a companion piece to this research, although a number of
technical and logistical issues must first be resolved. Accelerated weathering has the
potential to allow an evaluation of the impact of weathering on efficacy of coatings
in reducing DA in a relatively short time period (e.g., less than one year). While the
study includes weathering, which is known to be a major factor in the degradation of
coatings over time, it does not include abrasion, which is likely to be significant,
particularly for walking surfaces, such as those on decks. Thus, abrasion testing has
also been considered as a companion piece to the testing described herein.
Before proceeding further, it is essential to define the terminology used in this report.
Wood nomenclature used in this report is defined in Figure 1-1. Note that a "board"
is defined as the unit of wood purchased or removed from an existing structure, while
"specimen" refers to the pieces of each board cut for this project (note that
"specimens" are sometimes called "coupons" in weathering testing jargon).
Furthermore, areas on specimens that were wipe-sampled during each sampling
interval are termed "primary sampling areas" (PSA), in contrast to adjacent areas
which were not sampled at each interval. Each specimen used in this project
contained one PSA and one adjacent area.
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
6" (nominal)
/ /
f /
f
Top Face -« —
t
cM"^™v,m*iii Bottom Face
General Direction of Grain — r-
4
T
Uncut Edge
$
/* cut End
Figure 1-1. Wood Member Nomenclature
Note that all sampling was done on the top faces of the boards; that is, the face of the
board that was originally exposed, facing up, on the source deck. Furthermore, note
that a "grain-up" or "bark side up" board is defined as one where the tree rings,
evident on the cut end of the board, form a convex pattern (a "hill") when observed
with the face of the board that was exposed on the source deck facing up. Likewise, a
"grain-down" or "bark side down" board is defined as one where these rings form a
concave (a "valley") pattern when the exposed face is facing up. Since wood tends to
deform along these ring lines, grain orientation may be an important variable in the
measurement and mitigation of DA on surfaces of CCA-treated wood. Grain-down
boards tend to deform in a manner which "cups" and holds water and moisture, while
grain-up boards tend to deform in a manner which sheds water from the surface of
the board. For this reason, it is typically recommended to build outdoor structures,
like decks, with boards oriented grain-up, though it appears that many contractors do
not control this particular variable and grain-up and grain-down boards are
commonly found randomly located within a single deck.
1.3 Experimental Design and Scope
Weathering tests are being conducted using minidecks which are exposed to natural
weathering conditions outdoors at a site in North Carolina. Because no standard
outdoor weathering protocols for testing the efficacy of coatings in reducing DA
exposure currently exist, the project can be thought of as a pilot study. It is hoped
that the results gained through its execution not only support EPA's goals of
evaluating and reducing risk of contact with chemicals dislodged from CCA-treated
wood, but also provide a framework of methodology to inform the design of future
studies (in addition to identifying areas needing future study).
Minideck surfaces were constructed of alternating untreated and CCA-treated
specimens. The treated specimens were taken from two in-service CCA wood source
decks. Prior to coating the minidecks, baseline DA concentrations were determined
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
by averaging the results of wipe samples from areas adjacent to the sampling areas
which have been and are being sampled at regular intervals after coating. The
minidecks were then prepared for coating according to that coating manufacturer's
recommendations. As such, some of the minidecks were treated differently than
others, depending on their coating. Coating was then applied to each minideck (three
minidecks per coating) per coating manufacturer's instructions. After allowing the
coatings to dry and cure, the minidecks were subjected to natural weathering
outdoors at a site in North Carolina. Then, at specified intervals (1 month, 3 months,
7 months, and 11 months after coating), each specimen was wipe-sampled for
measurement of DA.
1.4 Data Quality Objectives
The critical measurements for the natural weathering tests are total arsenic, total
chromium, and total copper concentrations, which are subsequently converted to
dislodgeable arsenic, chromium, and copper, which are reported on a mass per unit
area basis. Data quality indicator (DQI) goals for concentration in terms of accuracy,
precision, and completeness, as established in the QAPP for this project, are shown
in Table 1-1. The QA review of the data, discussed in detail in Section 5,
recommends different DQI goals, based on the results of this project to date. Such
recommendations will be valuable to researchers designing and conducting similar
future studies.
Table 1-1. Data Quality Indicator Goals for Critical Measurements
Analyte
Arsenic (total)
Chromium (total)
Copper (total)
Method
SW-846 Method 6020 (modified)
SW-846 Method 6020 (modified)
SW-846 Method 6020 (modified)
Accuracy
(%Recovery)
90-110
90-110
90-110
Precision
(%RSD/RPD)
10
10
10
Completeness
(%)
90
90
90
1.5 Project Organization and Responsibilities
The EPA Work Assignment Manager for this project is Mark Mason, who
coordinates involvement by other EPA staff and CPSC staff via an interagency
agreement (CPSC-I-03-1235) between EPA and CPSC staff, as appropriate. Paul
Groff, EPA's QA Officer for this project reviews project QAPPs and reports, audits
sampling methodology, and has stop-work authority on the project. Key CPSC staff
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
includes Jacque Ferrante, Dave Cobb, and Joel Recht. Key EPA Office of Pesticide
Programs (OPP) staff includes Jack Housenger, Norm Cook, Nader Elkassabany,
Timothy Leighton, and Jonathan Chen. The ARCADIS work assignment leader
(WAL) is Victor D'Amato, who is intimately involved with most facets of the project
including test plan development, data analysis, data reporting, project and fiscal
management, and regular reporting tasks. Libby Nessley, with ARCADIS, serves
EPA by providing quality assurance and quality control (QA/QC) management
services, while Todd Thornton and Jerry Revis, both with ARCADIS, serve EPA by
providing health and safety management services. Kevin Bruce, with ARCADIS, is
the overall on-site laboratory support (OLS) project manager. Johannes Lee, with
ARCADIS, is the assistant project manager for the OLS contract, and, as such,
provides a variety of administrative support functions. Matt Clayton, with
ARCADIS, procured, characterized, cut, prepared and coated wood samples, in
addition to coordinating preparation of the test site. Peter Kariher, Michele Addison,
and Sara Easterly, all with ARCADIS, have taken samples, prepared samples via
digestion, and shipped digested wipe and control samples to the subcontract
analytical laboratory, Severn Trent Laboratory (STL)-Savannah (Angie
Weimerskirk, Project Manager). Michele Addison also manages the data generated
via this study in addition to supporting other key project tasks. Krich Ratanaphruks,
with ARCADIS, provides relational database and data management support and was
responsible for producing many of the data analysis report graphics in this report.
Len Stefanski, an EPA contractor at North Carolina State University, provides
detailed statistical support to the analysis and interpretation of the data. An
organizational chart is provided as Figure 1-2. Table 1-2 provides contact
information for project staff.
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
EPA OPP Project Manager
Nader Elkassabany
EPA WA Manager
Mark Mason
PS Project M n ger
Jacque Ferrante
EPAQA
Paul Groff
Work Assignment Leader
Wood Prep/ oating
Applic tion
Matt Clayton
Analytical Prepar tion
Peter Kariher
S mpling/An lytic I
Prepartion
Sara Easterly
Relation I Dat b se
Development
Krich Ratanaphruks
Figure 1-2. Organizational Chart for Weathering Testing
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Table 1-2. Contact Information for Key Project Staff
Staff Contact
Mark Mason
Paul Groff
Jacque Ferrante
Dave Cobb
Joel Recht
Jack Housenger
Tim Leighton
Norm Cook
Nader Elkassabany
Jonathan Chen
Victor D'Amato
Libby Nessley
Todd Thornton
Jerry Revis
Kevin Bruce
Peter Kariher
Matt Clayton
Krich Ratanaphruks
Michele Addison
Angle Weimerskirk
Len Stefanski
Organization
EPA
EPA
CPSC
CPSC
CPSC
EPA-OPP
EPA-OPP
EPA-OPP
EPA-OPP
EPA-OPP
ARCADIS
ARCADIS
ARCADIS
ARCADIS
ARCADIS
ARCADIS
ARCADIS
ARCADIS
ARCADIS
STL-Savannah
NCSU
Position
Work Assignment (WA)
Manager
EPA QA Manager
Health Sciences
Lab Sciences
Lab Sciences
Associate Director
Exposure Assessor
Branch Chief
Project Manager
Toxicologist
WA Leader
QA Manager
Health & Safety (H&S)
Manager
H&S Manager
PM, Advisor
Lab Scientist
Lab Scientist
Database Analyst
Data Management
Analytical Manager
Statistician
Phone Number
(919)541-4835
(919)541-0979
(301 ) 504-7259
(301)421-6421
(301)421-6421
(703)308-8163
(703) 305-7435
(703) 308-8253
(703) 308-8783
(703)305-1287
(919)544-4535
(919)544-4535
(919)544-4535
(919)544-4535
(919)544-4535
(919)544-4535
(919)544-4535
(919)544-4535
(919)544-4535
(912)354-7858
(919)515-1945
E-mail Address
Mason. Mark.® epa.gov
Groff.Paul@epa.gov
jferrante@cpsc.gov
dcobb@cpsc.gov
jrecht@cpsc.gov
Housenger.Jack@epa.gov
Leighton.Timothy@epa.gov
Cook.Norm@epa.gov
Elkassabany.Nader@epa.gov
Chen.Jonathan@epa.gov
vd'amato@arcadis-us.com
lnessley@arcadis-us.com
tthornton@arcadis-us.com
jrevis@arcadis-us.com
kbruce@arcadis-us.com
pkariher@arcadis-us.com
mclayton@arcadis-us.com
kratanaphruks@arcadis-us.com
maddison@arcadis-us.com
aweimerskirk@stl-inc.com
stefanski@stat.ncsu.edu
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2. Test Methods
The following subsections describe in detail the methods used in this study,
including, but not limited to the selection of materials for testing, construction of
minidecks, preparation of wood surfaces to be coated, application of selected
coatings to the CCA-treated substrates, site preparation and maintenance, weather
monitoring, and sampling and analysis procedures.
2.1 Overall Study Design
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
2.1.1 Scope
Twelve (12) coatings have been applied to minidecks constructed using two sources
of aged CCA-treated wood, as well as new untreated wood as blank, cross-
contamination controls. Each minideck contains nine decking specimens: two
specimens from each of the aged wood sources (one specimen with bark side up
grain orientation and one with bark side down orientation), separated by specimens
of new untreated wood (all positioned bark side up) to prevent cross-contamination
and to serve as blank controls to assess cross-contamination potential as a result of
splash-over of rain water, for example. The minidecks were constructed with each of
the aged wood specimens facing up; that is, with the same top face as the specimen
had during its exposure on its source structure. Each of the twelve coatings has three
(i.e., triplicate) associated minidecks constructed. Additionally, three uncoated
minidecks are used as controls. Each aged wood specimen has been wipe-sampled
from the same area at 1, 3, 7, and 11 months after coating. The results of samples
taken 1 month after coating essentially yield "initial efficacy" results which may
provide some information on the relationship between initial and longer-term
efficacy and could thus inform the design of a relatively rapid screening study if
appropriate. It is also significant that the samples taken 1 month after coating were
taken from sampling areas that had never been sampled previously.
Coated minidecks are exposed to natural weathering conditions at a controlled site in
North Carolina for which high quality meteorological data has been routinely
collected; these data have been used to confirm the weather monitoring data collected
during this project. Additionally, three identical, but uncoated, minidecks and one,
untreated, uncoated minideck are included as controls. The position of each minideck
on the site was randomized at the start of the test, though their directional orientation
was the same. DA was determined via wipe sampling at prescribed intervals. These
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
DA results were compared with baseline DA in order to determine efficacy (percent
reduction in DA) of each coating and to rank coatings at each sampling event.
Baseline measurement of DA as well as routine wipe samples for measurement of
DA after coating application and as weathering progressed, were the primary samples
taken during this testing. Supporting samples collected include wood core samples,
and liquid samples of the coatings applied, among others. The natural outdoors
weathering study methods are described in more detail later in the ensuing
subsections.
2.1.2 Data Product and Use
The outdoor weathering test offers a means of evaluating the efficacy of coatings on
horizontal surfaces with stresses on the specimens resulting from their attachment to
the minideck support members and of course, per exposure to natural weathering
conditions.
The efficacy of each coating in reducing DA on aged CCA-treated wood has been
evaluated as a function of time exposed to natural weathering outdoors.
Post-coat DA has been determined by wipe sampling triplicate specimens of each
coating on each of two aged wood sources with two different bark orientations.
Percent reduction in DA has been calculated using several alternate computational
techniques, described in more detail in Sections 3 and 4. Coatings have been ranked
according to their efficacy based on average percentage reduction of DA.
2.1.3 Study Limitations
While the primary objective of the testing reported herein was to evaluate coatings
for their efficacy in reducing DA when coated wood is subjected to weathering,
available resources were limited and dictated that the project be focused in a way that
precluded the ability to answer all of the myriad questions raised in the development
and evaluation of this test protocol. Difficult choices had to be made in a number of
important areas in order to meet the resource and time constraints posed by this
project. The objective of the following discussion in this section is to better define
study limitations, and unanswered questions that may be applicable as a focus for
future research work.
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
2.1.3.1 Stress Factors
Due to the relatively small size of the minidecks, the stress factors generated by
attached specimens during weathering may not be representative of those generated
in full-sized structures. However, a 16-inch on-center placement of fastening screws
has been used in the construction of the minidecks, as typical in the construction of
full-sized decks.
2.1.3.2 Application Technique
It is possible that the method of applying coatings may contribute to measured DA
levels. For example, applying coating using a brush may cause physical displacement
of dislodged analytes and subsequent mixing with the applied coating or
displacement of the analyte to the finished coated surface. As such, a pre-
qualification study to evaluate coating application techniques (e.g., brush versus
spray) was considered as a screening test component, but later determined to be
outside of the scope and resource allocation available for this project. Wood was
prepared and coatings were applied per manufacturer's instructions. A brush
application coating technique was used for each coating. It is believed that such a
technique represents the most common method employed by residential users of deck
coatings.
2.1.3.3 Surface Preparation for Coating
The preparation of the wood surface prior to coating may be important in several ways.
First, it is possible that the surface preparation method itself may constitute a
significant exposure activity. For example, sanding CCA wood surfaces without proper
respiratory equipment may facilitate exposure via inhalation. The surface preparation
technique may also impact the pre-coat DA levels (see further discussion of this in
section 2.1.3.5 in the discussion of baseline measurements) as well as future migration
of CCA analytes to the surface of the wood. In this study, the coating manufacturer's
printed instructions with regards to surface preparation were followed strictly. Baseline
measurements, used in some calculations of efficacy, were taken prior to any surface
preparation or rinse step.
2.1.3.4 Type and Condition of Aged Wood
Only two sources of aged CCA-treated wood are being tested, which is not likely to
be representative of the universe of CCA wood structures currently in service. For
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
this study, the two sources represent different ages and conditions of the same
species wood (southern yellow pine).
2.1.3.5 Re-rubbing Effects and Baseline Sampling
A significant logistical issue arises as a result of the sampling process itself and the
fact that the wipe sampling technique changes the surface of the wood in at least two
ways: by removing the CCA on the surface of the wood, and by potentially abrading
the wood or its coating.
Ideally, initial surface wipe samples would be taken from each sampling area to be
further tested. However, several studies suggest that, as could reasonably be
expected, the act of wipe sampling the surfaces of CCA-treated wood removes a
considerable amount of the DA from a test specimen (CPSC staff 2003a, Stilwell
2003a). Furthermore, wipe sampling is a form of "abrasion" which is suspected to be
a significant variable in determining both uncoated DA as well as durability and
efficacy of tested coatings. Clearly, there is virtually no alternative to wipe sampling
coated surfaces to determine DA (except perhaps by leachate sampling for which no
transfer relationships have been developed that relate mass leached from a sample to
amount transferred to a hand). While it may be possible to attempt to artificially
correct DA results for the effects of rerubbing (i.e., per the analysis of appropriate
control samples and subsequent modification of measured DA on individual
specimens), the decision was made to not sample the PSAs prior to coating, as such
an approach could cause data analysis and complications in determining coating
efficacy. The PSAs are those areas that were wipe-sampled during each sampling
event (i.e., at 1, 3, 7, and 11 months after coating). Areas on the minidecks adjacent
to the PSAs (termed "baseline areas" because they were used to calculate specimen-
specific baseline DA values) were sampled prior to coating, as will be discussed in
more detail below. However, subsequent post-coat samples from these baseline areas
were not used in the calculation of percent reduction (efficacy) or for ranking
coatings based on their performance. These baseline areas were, however,
periodically re-wipe-sampled during the study in an attempt to answer specific
questions regarding the study design (including an assessment of the effect of
rewiping on DA measured), as will also be discussed in more detail below.
Individual specimen-specific baseline values of DA were instead determined for each
PSA to be coated and tested by averaging the DAs from the two adjacent wipe
sampling areas on either side of the PSA. This step avoided any data analysis and
coating efficacy complications that may have arisen from coating pre-wiped testing
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Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
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9 May 2005
areas on the specimens. In selecting this method of baseline determination, existing
data supported the assumption that intraboard (within-board) variability was
relatively low. Research by Stilwell (2003a) showed an intraboard variability (RSD)
of 17% versus an interboard (between-board) variability of 39%. It was further
assumed that the variability would be even less for sampling areas that were closer to
one another (intraboard, interspecimen variability between adjacent sampling areas),
although this assumption was not supported by the data gathered for this project
(Section 4.4.1).
Some consideration was given to wipe sampling the PSAs prior to coating and then
waiting or even exposing the test specimen to weathering to induce more migration
of CCA analytes to the surface of the specimen prior to coating. While this concept
may be sound, the existing data supporting the design of such a method is fairly
limited (Stilwell 2003a). That is, it has not yet been well-established how much time
must elapse or under what conditions specimens must be maintained to ensure that
surficial CCA analyte concentrations have rebounded to pre-wipe conditions.
Another option would have been to simply take an average of a number of initial DA
measurements taken from sampling areas that would then be discarded and not used
for the study in any other way. In such an approach, the baseline values used would
not be unique to a specific PSA. Instead, a single baseline DA value might be used
for numerous PSAs or even for all of the PSAs in the study. However, it was thought
that this option might not provide the level of data resolution and statistical power
required to adequately establish coating efficacy data for this project.
The final option that was seriously considered was to wipe sample the undersides of
the test specimens to establish the baseline DA for each specimen. This was seen as a
potentially good option for new CCA-wood specimens, but not for aged specimens,
as their top faces are well defined and of much greater interest (given that these faces
are the ones to which users are most likely to be exposed) than their bottom faces.
The top faces of aged CCA wood specimens would be expected to have considerably
different characteristics than their bottom faces, because, for example, they may have
been exposed to direct sunlight, abrasion, and so forth, while their bottom faces have
not. While the same is not necessarily true of new CCA wood, CPSC staff data
suggests that sample variability along the length of a given board is less that the
variability between the top and bottom faces of a specimen, even for new CCA-
treated lumber (CPSC staff 2003a). As such, and as previously indicated, the
weathering test employed a method whereby the DA of adjacent sampling areas were
averaged in order to establish unique baseline DA values for each individual PSA.
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Evaluation of the
Effectiveness of Coatings in
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Arsenic, Chromium, and
Copper from CCA Treated
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9 May 2005
It must also be noted here that baseline samples were taken using wipes that had
been pre-washed in nitric acid to remove any trace contaminants. It was later
determined that subsequent DI water rinsing steps were not sufficient in removing
the nitric acid. It was decided to not continue to use this method of pre-washing
wipes for the coating efficacy sampling events (samples taken 1, 3, 7, 11 months
after coating) due to concerns about the unnatural and likely detrimental effect of the
acid wipe on the coating. Therefore, subsequent sampling was done with "out of the
bag" wipes, simply wetted with DI water. These methods are described in more
detail in Section 2.10.
In the analysis of the data collected, several alternate methods to calculate efficacy
have actually been utilized, several of which use unique baseline DA values
calculated as the average of the DA of sampling areas adjacent to the PSAs.
Alternate efficacy calculation methods utilize average DA values for uncoated
positive control minidecks used in the study. These data analysis techniques and their
effects on calculated efficacy will be discussed in more detail in Sections 3 and 4.
2.1.3.6 Effects of Nailholes and Other Surface Irregularities
Nailholes, knots, and other surface irregularities can be expected to have an impact
on wipe sampling and measured DA. As such, these surface features have been
avoided to the extent possible in this study. In particular, nailholes were completely
avoided during wipe sampling events (wipe samples are taken between adjacent sets
of nailholes). Furthermore, existing aged wood specimen nailholes were reused when
assembling minidecks. Other surface irregularities were avoided as much as possible
when selecting specimens to be used for assembling minidecks. To the extent that
such irregularities could not be avoided, each specimen and sampling area were
characterized visually in two ways: by filling out a specimen characterization form
(described further in Section 2.3 and included in Appendix B) and via a photo record
of each specimen, which included pre- and post-coating photographs of each
minideck and photographs of each minideck prior to each regular sampling event.
2.1.3.7 Test Specimen Lengths
Eighty-six cm (34 in) specimens were used to construct the minidecks. A 38-cm (15-
inch) wipe sampling length was used so that wipe samples could be taken from the
area between existing nailholes spaced approximately 16-inches on-center. This is a
shorter wipe length than that employed in the CPSC staff sampling protocol. While it
is unclear to what extent wipe length has an effect on measured DA, data is presented
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
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9 May 2005
in units of (ig/cm2 based upon the assumption that measured DA correlates with
wipe length. These results are easily converted to a mass per sample basis by
multiplying by the area sampled.
2.1.3.8 Abrasion Effects
The effects of abrasion (e.g., by repeated contact and walking) have not yet been
rigorously tested in this project, although we have attempted to derive some
indication of its impact via comparisons of measured DA from the PSAs with those
from the adjacent areas which are not wiped at each sampling interval, by
considering the wipe sampling technique itself as a form of mild abrasion. The effect
of abrasion on DA as well as on coating efficacy and durability is a major issue that
should be addressed in future study efforts. Additionally, the transfer of CCA
analytes via feet, pets, and other potential contact routes may be important but has
not been addressed by this study to date.
2.1.3.9 CCA Analytes and Speciation
The speciation of CCA analytes could be an important determinant of contact risks.
Only total arsenic, total chromium, and total copper are routinely measured in this
study, due to resource limitations, as speciating CCA analytes is significantly more
complex and costly.
2.1.3.10 Other Limitations
The following issues, among others, are not rigorously addressed by the proposed
study:
" Performance of coatings on wood of different dimensions to which users may be
exposed
" Performance of coatings on wood species other than SYP
« Directional exposure effects (e.g., south- versus north-facing decks)
" Performance of coatings in different climatic regions
" Performance of coatings on wood members oriented vertically or at angles
" Performance of coatings following various wood preparation techniques
" Recoat performance
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
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9 May 2005
2.2 Selection of Wood Sources
Because of the large number of variables that may affect the weathering of existing
CCA-treated wood structures, establishing a consistent and representative source of
aged wood for these tests was relatively challenging. It is expected that different
sources of aged wood may have considerably different characteristics which are
likely to impact coating performance. Because resources for this project were
limited, only two sources of aged wood were used, each taken from a single existing
outdoor structure; for this project, the source structures were residential and
commercial decks.
Predetermined criteria were established in order to rank and select from candidate
aged wood source structures. It was preferred that one aged wood source be
relatively highly weathered, in service for between 5 and 10 years with no washing
solutions or coatings having been applied within the past 5 years. The second wood
source was preferably in relatively good condition, up to 5 years old, and with no
history of washing or coating. To the extent possible, wood from the selected
structures was taken from areas of the structure that had been exposed to similar
abrasion (traffic) and weathering patterns. Of utmost concern was testing two sources
of aged wood, where boards taken from each source structure were of a relatively
consistent quality with respect to other boards taken from that source. The following
were important characteristics to be considered and recorded with respect to the
source of aged wood used.
" Location, site
" Type of use (e.g., residential deck, etc.)
« Age
" Abrasion pattern
" Exposure orientation (directional)
" Exposure level (shading vs direct exposure, etc.)
" Treatment history
" General condition (qualitative)
" Nailhole spacing
" Lengths and number of boards
" Grain orientation of boards
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Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
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9 May 2005
Information on these characteristics was gathered for multiple candidate sources
which were then critically analyzed by EPA and ARCADIS for conformance with
specified criteria and completeness of specified information about the source, in
order to select aged wood sources.
Two excellent sources of aged wood were selected, based on these criteria. The two
structures have the following characteristics.
Environmental Research Center (ERC) Deck: This structure was located outside of
the cafeteria of EPA's old (leased) Research Triangle Park facility. It was a stand-
alone deck with generally full exposure (except for several boards - which were not
used - located under attached benches), with only moderate shading by adjacent
buildings during low sun positions. Given its open, stand-alone nature, abrasion
patterns appeared very consistent and the boards were visually similar to one another.
Additional information on this source was gathered as it was being dismantled under
the supervision of ARCADIS. The deck was constructed of SYP, treated to 0.40
pound per cubic foot (pcf) with Ground Contact CCA-C. This source was
approximately 7 years old and was believed to have received one application of a
standard deck sealant near the beginning of its use (over 5 years ago). The overall
condition of the wood was considered fair: the coloration was gray and there was
slight-to-moderate splintering. Specific locations and orientations of individual
boards were documented during dismantling of the source structure; a map of the
structure showing the location of each specimen tested was prepared. This map is
shown in Figure 2-1. Photos are provided in Figure 2-2. This deck is referenced as
the "A" source.
New Hill Deck: This source, donated for use during this project, was taken from an
outdoor deck on a private residence. It represents an ideal source of relatively new,
good-condition, aged CCA-treated wood. The coloration of the wood was light
brown and relatively bright and there was minimal splintering. The New Hill Deck
was an exposed, attached structure. There was no noticeable biological growth or
other dampness-related defects. The deck was constructed of SYP, treated to 0.40 pcf
with Ground Contact CCA-C, had been in service for just over one year, and had
never been cleaned or treated. Specific locations and orientations of individual
boards were documented during dismantling of the source structure; a map of the
structure showing the location of each specimen tested was prepared. This map is
shown in Figure 2-3. Photos are provided in Figure 2-4. This deck is referenced as
the "C" source.
17
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
BENCH LIMITS^
Figure 2-1. ERG Deck Map
Figure 2-2. Views of ERC Deck (note that moisture stains were temporary and that
boards under benches were not used to construct minidecks)
18
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Figure 2-3. New Hill Deck Map
Figure 2-4. Views of New Hill Deck
19
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
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Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
2.3 Preparation and Characterization of Wood Sources
Wood specimens were prepared using aged, in-service SYP that was originally
CCA-C treated to 0.40 pcf, in nominal 5/4" x 6" cross-sectional dimensions, taken
from the source structures previously described. Care was taken to minimize
handling and abrasion of the primary (i.e., 6" width) faces of the treated source
boards, with the short edges of the board preferentially held during transport and
cutting. New 5/4" x 6" SYP that was not CCA treated was used for the blank control
specimens and the cross-contamination control specimens that were located at the
ends of each minideck and between each of the four CCA-treated boards on each
minideck.
For each aged CCA-treated board, the total board length was recorded along with
visually-observable source wood characteristics, including predominant grain
orientation (up versus down), predominant grain type (percent flat versus percent
edge grain), predominant ring spacing (tight, medium, wide), predominant wood
season (percent early versus percent late wood), and predominant wood type (percent
heartwood versus percent sapwood). The percentages of the various grain
characteristics, where reported, were gross visual observations and should only be
considered estimates.
Grain orientation was assessed by viewing the end of a board and noting the shape
of the grain pattern. A concave or "U" shape would be considered "grain down",
while a convex or "hill" shape would be considered "grain up". The significance is
that boards will tend to deform or warp over time in the direction of their grain. That
is, a grain down board will tend to "cup" and may hold water, while a grain up board
will tend to shed water.
Grain type was assessed by noting whether the board was cut across the grain (flat
grain) or perpendicular through it (edge grain).
Ring spacing was determined by viewing the spacing of the tree's rings and
recording whether they were spaced tightly, widely, or in-between (medium).
Wood season was determined based on the prevalence of large cells, or small dense
cells within a growth ring. Early wood is characterized by large-celled, less dense
wood, while late wood is characterized by small-celled, dense wood. If a majority of
the concentric growth rings were light in color, a high percentage of early wood
(springwood) would be indicated. Conversely, if the rings were predominantly dark
20
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
in color, late wood (summerwood) would be indicated. For characterizing the wood
season, boards vastly predominant in one or the other were characterized as such. If,
on the other hand, the dark and light-colored portions of the growth ring were more
equally distributed, an approximate percentage split was recorded.
The wood type was determined by noting the relative color of the wood grain, with
darker colors reflecting heartwood (from the center of the tree) and lighter colors
reflecting sapwood (from the outer rings of the tree).
These visual assessments were made by an ARCADIS chemical engineer with no
formal training in wood products or the timber industry.
Aged boards were cut using a circular table saw into lengths required for use as test
specimens for the weathering tests. The outdoor, natural weathering tests required
specimens of approximately 86 cm (34") lengths. These lengths were cut in such a
manner as to capture three sets of existing nailholes on each aged wood specimen,
and required that the nailholes were spaced on 16-inch centers as typical. Of utmost
concern was that the PSAs be segments of the specimen with a 38-cm (15-in) or
more clear distance between adjacent nailholes. Nailholes were not wiped during
either the baseline or routine wipe sampling events. The saw was decontaminated
between cutting the different types of wood utilized (aged CCA versus untreated) and
the untreated wood was cut separately (after installation of a new blade) to prevent
cross-contamination of samples. Decontamination followed a similar protocol to that
used to clean the wipe sampling device between samples [i.e., using a deionized (DI)
water moistened cloth wipe]. Where possible, the ends of each board were removed
and archived and segments between each 86-cm test specimen were removed and
archived, with some of these interior segments used to characterize the source wood
via moisture content measurement and wood core sampling for total arsenic,
chromium, and copper analyses. 86-cm wood specimens were visually inspected to
ensure that they did not have excessive amounts of deformities, presence of
heartwood, knots, resin pockets, or other defects. Each segment was identified with a
unique alphanumeric code as follows:
" Aged board codes were prefixed by the letter "A" for source A, the ERC Deck
source, and "C" for source C, the New Hill Deck (note that a source B was
harvested but subsequently disqualified for use in the study).
" Each aged board from the two sources was identified with a unique letter (A, B, C,
and so forth).
21
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
" Each space between adjacent nailholes was identified with an alphanumeric code,
where the prefix "BL" refers to segments used for establishing baseline
characteristics, while the prefix "M" refers to segments that were to be regularly
wiped; that is, the PSAs. These codes were suffixed with sequential numbering (1,
2,3,...) along the length of each source board.
" Unused, unwiped segments were designated with the prefix "X".
The specimen identification criteria presented above is illustrated by the example
schematic in Figure 2-5. In this example, BL1, BL2, BL3, BL4, and BL5 would be
wipe-sampled before cutting the board shown. These results would be used to
establish baseline DA values for PSAs Ml, M2, and M3. After cutting the boards to
harvest 86-cm specimens (illustrated in the figure by the dashed boxes) for minideck
construction, BL2 and BL5 would be subsequently used for taking one core sample
each for total arsenic, chromium, and copper analyses, as well as moisture content.
Ml, M2, and M3 would be wipe-sampled during routine sampling events to
determine coating efficacy. BL1, BL3, and BL4 would be wipe-sampled only
periodically in an effort to determine the effects of abrasion and rewiping on coating
efficacy and DA.
All cut specimens were identified on one cut end or uncut edge with its identification
code, as well as with its "top" side using permanent marker. All numbered specimens
were qualitatively and semi-quantitatively characterized for visually-observable
wood condition characteristics, with data recorded on a standardized wood
characterization data sheet (Appendix B). The characteristics recorded included
knotting (number of knots for that specimen was recorded), splintering, cracking, and
rotting (for these last three, a rating of 1 to 5, with 5 being like new wood and 1
being complete failure, was assigned). Additionally a photo record was made of all
specimens which includes photographs taken at the beginning of the test (i.e., pre-
coating), as well as at each sampling event after coating. Remaining segments of
wood were retained and archived.
22
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
// X1 jf"/f BL1 / M1 // BL2 .••'
BL3 // 7-2 ,-•'/ BL4 / M3 // BLB / X3
-
86- cm sp e cim en
86- cm sp e cim en
86- cm sp e dm en
Board "A"
Figure 2-5. Specimen identification and baseline sampling scheme example.
2.4 Wood Core Sampling and Analysis
Up to four wood core samples were taken from each CCA treated board used to
construct mindecks for this study. Core samples were generally taken from "typical"
areas of the board being tested, so that the "average" would be representative. All of
the segments of wood that were sampled have been archived, so specific samples could
be qualitatively evaluated or resampled if necessary. Individual core samples were
taken by advancing a %-inch diameter drill bit through the entire 1-inch (5/4" nominal)
thickness of the board and collecting the wood shavings. Note that in commercial
practice cores are typically only from the narrow faces of the boards (as opposed to the
wide faces that were sampled here), and the assay zone is only the outer 15 mm of the
core.
The wood shavings were then dried to constant weight in a drying oven at
approximately 105 °C. The dry weight of the sample was recorded. The wood shavings
were then digested in concentrated nitric acid using a similar protocol to that defined in
Section 2. 10.5 for the wipe samples. 10 mL of concentrated nitric acid was added to
the wood in a digitube and the digitube was digested in a metals digestion system
(Environmental Express HotBlock). After digestion, the sample was brought up to
standard volume by adding DI water to a volumetric flask. This procedure is consistent
with American Wood Preservers Association (AWPA) Standard A7-93 (microwave
assisted nitric acid digestion). Digestates were analyzed by ICP-MS in a manner
identical to that described in Section 2.10.5 for the wipe samples. This is consistent
with AWPA Standard A21-00.
2.5 Minideck Construction
After cutting and marking specimens with their identification codes, source wood
specimens were transported to the minideck host site, where the minidecks were
23
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
constructed per the drawing in Figure 2-6, after which the surfaces of the minidecks
were prepared (e.g., washed, rinsed, etc.) in strict accordance with the particular
coating manufacturer's recommendations for coating aged wood using their product.
Flow sheets generically detailing the wood preparation procedures employed for each
coating are provided as Appendix C. The surfaces of the minidecks for each coating
(except coating #7, which did not call for a rinse prior to coating) were at least rinsed
with a pressure washer at a 1,000-3,000 psi setting. Ten of the coatings also had a
deck cleaning product applied, as specified in their instructions. Note that specific
products used to prepare the minidecks for coating are not provided in order to
maintain coating confidentiality. It is important to note here that the baseline
measurements were taken before the wood surfaces were rinsed or otherwise
prepared for coating. Thus, it is possible that the surface preparation procedures
themselves may have impacted DA results during subsequent sampling events. The
surfaces of the positive ("coating #13") and negative control minidecks were rinsed
with a pressure washer at a 1,000-3,000 psi setting.
The minideck surfaces were initially constructed without leaving spaces between the
boards. When this mistake was discovered, the three internal untreated boards per
deck were removed and planed as described in Section 2.9. After this step, the
surfaces were rerinsed with tap water and allowed to dry before coating.
Each of the 12 coatings and an uncoated positive control had three minidecks
constructed (identified as 1-A, 1-B, 1-C, 2-A, and so on). Each minideck contained
two 86-cm aged source "A" specimens, two 86-cm aged source "C" specimens, and
five 86-cm untreated wood specimens. Furthermore, there was one minideck
constructed similarly, except that its five specimens were all untreated SYP. Its three
center specimens were wipe-sampled at the prespecified regular sampling event
intervals as blanks (negative controls).
24
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
0
^ "]
VI
"
_/^ALL FASTENERS
UNTREATED 5V'x6"
AGED SOURCE A
UNTREATED
AGED SOURCE B
UNTREATED
AGED SOURCE A'
UNTREATED
AGED SOURCE B'
UNTREATED
Figure 2-6. Schematic of Minideck Construction
(Note that untreated 34" specimens were planed so that 1/8" of space was provided between each pan- of specimens)
New 4" x 4" CCA-C treated wood posts were used in the construction of the
minidecks. Specimens were screwed directly into a grid of 2" x 4" untreated SYP
supports. These supports were slightly offset above the tops of the posts to ensure
that the treated posts did not have the opportunity to directly contact (and perhaps
contaminate) the wood specimens used as the minideck decking. Plastic-coated
screws were advanced through existing nailholes on the treated specimens in order to
secure decking specimens to the minideck frames. For the untreated specimens,
which were new at the time of construction, the same coated screws were used to
attach them to the supports. The minidecks are free-standing (i.e., posts are not set
into the ground). A photograph of a typical minideck is provided as Figure 2-7. Table
2-1 shows which specimens were used on each minideck. Specimens were matched
with minidecks randomly.
25
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Figure 2-7. Sample Minideck Photo
26
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Table 2-1. Wood Specimens used to Construct Minidecks
Coating #
1
2
3
4
5
6
7
8
9
10
Deck ID
1-A
1-B
1-C
2-A
2-B
2-C
3-A
3-B
3-C
4-A
4-B
4-C
5-A
5-B
5-C
6-A
6-B
6-C
7-A
7-B
7-C
8-A
8-B
8-C
9-A
9-B
9-C
10-A
10-B
10-C
A-up
A-AE-M1
A-V-M3
A-AJ-M1
A-O-M3
A-BC-M2
A-AR-M1
A-T-M1
A-AG-M3
A-AD-M2
A-T-M2
A-BC-M1
A-I-M3
A-U-M2
A-AD-M1
A-AR-M3
A-U-M1
A-AC-M2
A-BC-M3
A-O-M2
A-V-M1
A-AJ-M3
A-AR-M2
A-I-M1
A-AG-M4
A-T-M3
A-AC-M1
A-AG-M2
A-AD-M3
A-X-M1
A-AJ-M2
A - down
A-Z-M1
A-AT-M3
A-BW-M4
A-BY-M2
A-AH-M4
A-P-M1
A-L-M3
A-AF-M1
A-BW-M2
A-BG-M4
A-AH-M1
A-Q-M2
A-L-M2
A-Z-M3
A-BG-M3
A-BY-M1
A-AN-M3
A-P-M2
A-Y-M2
A-AH-M3
A-BW-M1
A-BY-M3
A-AT-M1
A-Z-M2
A-P-M3
A-AE-M2
A-AN-M1
A-BG-M2
A-Y-M1
A-Q-M3
C-up
C-N-M1
C-BE-M2
C-S-M2
C-BZ-M3
C-BI-M1
C-BY-M2
C-N-M3
C-BJ-M2
C-CD-M1
C-CD-M2
C-BM-M2
C-AC-M1
C-AC-M2
C-BM-M3
C-CA-M1
C-BZ-M2
C-AJ-M1
C-S-M3
C-N-M2
C-BY-M1
C-BZ-M4
C-BE-M1
C-AC-M3
C-CA-M2
C-AP-M1
C-BI-M2
C-BZ-M1
C-AP-M3
C-BJ-M1
C-BU-M2
C-down
C-BO-M2
C-CC-M1
C-AA-M2
C-E-M3
C-AN-M1
C-BX-M3
C-CE-M2
C-AN-M3
C-AA-M1
C-AD-M2
C-AM-M2
C-BT-M4
C-CE-M1
C-BO-M1
C-AD-M3
C-AA-M3
C-AI-M1
C-CC-M2
C-AM-M3
C-BX-M1
C-E-M2
C-AE-M3
C-AM-M1
C-BX-M2
C-BW-M1
C-AN-M2
C-AE-M2
C-AD-M1
C-AK-M4
C-BT-M2
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
27
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Coating #
11
12
13
Deck ID
11-A
11-B
11-C
12-A
12-B
12-C
13-A
13-B
13-C
A-up
A-U-M3
A-X-M2
A-AJ-M4
A-O-M1
A-AC-M3
A-V-M2
A-AG-M1
A-I-M2
A-X-M3
A - down
A-Q-M1
A-AH-M2
A-BW-M3
A-AN-M2
A-AE-M3
A-L-M1
A-Y-M3
A-AT-M2
A-BG-M1
C-up
C-AP-M2
C-BE-M3
C-BJ-M3
C-AJ-M2
C-BI-M3
C-BM-M1
C-S-M1
C-AJ-M3
C-BU-M1
C-down
C-AI-M3
C-BW-M2
C-AE-M1
C-AM-M4
C-AD-M4
C-BT-M1
C-E-M1
C-AI-M2
C-BT-M3
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
2.6 Selection of Coatings
The selection of coatings to be tested was critical and because of the number and
variety of potentially applicable coatings on the market and the budgetary constraints
of testing programs, was likely to be a limitation of any such evaluation of coatings.
To put this task into perspective, the goal of selecting coatings was to distill a
universe of hundreds or even thousands of potentially applicable coatings to 12 to be
tested. While beyond the scope of this project, a thorough review of available
coatings and their formulations and application techniques is needed to more
completely understand the characteristics that may impact DA (this could include
more focused involvement by the wood coating industry). For this project however,
the approach was to gather basic formulation and, to a lesser extent, application
information, for a number of products with reasonable availability to the project team
in North Carolina (where the project site is located). This survey of available
products was primarily conducted using Internet searches and visits to local retail
hardware and home improvement stores. These searches allowed for the
development of a "master list" of specific products. This master list of potential
products included approximately 125 entries, including some products that are
broadly intended for outdoor wood use, as well as some products that are not
necessarily intended for such uses, but that were identified by the project team as
promising.
The list is in spreadsheet format and includes fields for manufacturer, product name,
product type, cover, base, and main ingredients. It must be noted that there are
various levels of classifications for coatings and that no single standard can be
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Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
applied to adequately categorize each and every product identified. Additionally,
many products overlap categories. Nevertheless, in order to communicate effectively
about the products considered and tested, and maintain the confidentiality of product
names, an attempt has been made to classify the products considered. As such,
several main descriptors of coatings were used. These include: base (oil vs water),
cover (clear, semi-transparent, opaque), and product type, which for this exercise, has
been broken out into the following: paints, primers, sealants, stains, and other. The
"other" category embodies a vast variety of products, including, but not limited to:
varnishes, epoxies, lead encapsulation products, rubber coatings, fiberglass coatings,
elastic vinyl coatings, preservatives, and other plastic coatings. Additional
classification descriptors include ingredients (primarily alkyd or acrylic) and surface
(penetrating vs film-forming).
The master list of about 125 products includes roughly 25 paints, 5 primers, 20 wood
sealants, 50 stains, and 25 "other" products. Out of the paints, approximately 2/3 are
water-based with the balance oil-based. Likewise, for the primers, two are oil-based
while three are water-based. For the wood sealants and stains, most products are oil-
based with a handful water-based. The cover - that is, the opacity of the coating on
its substrate - for each of these product types is quite variable, and in fact, one "type"
of coating may be available in a range of covers from clear to opaque. Likewise, the
surface for each of the listed product types may also be variable, depending on the
product. Paints and primers will almost invariably be considered film-forming
products, while sealants, stains, and certainly "other" products may be penetrating or
film-forming depending on their specific formulation. Existing research on coating
efficacy suggests that film-forming coatings may be more effective, though they may
also be more subject to unsightly and potentially compromising deterioration via
abrasion. In particular, Lebow (2001) reported that each of three tested coatings
significantly reduced leaching of CCA wood analytes from treated wood specimens,
but that the two film-formers (latex and oil-based paints) reduced CCA analytes to
below detection levels while the other coating (an oil water-repellant deck stain) did
not. After an extensive literature (published and unpublished) review, Miller (2001)
clearly recommends that CCA-treated picnic tables in Florida be preferentially
coated with acrylic latex exterior flat house and trim solid color paint. She further
emphasizes that more opaque sealants appear to provide better erosion prevention
and longer protection when subject to weathering.
"Stains" can often be purchased as a base or pre-tinted. Stain bases generally require
the addition of pigmentation (a "tint") to impart color. The tints that are added to a
stain base may not be unique to that product manufacturer. Rather, the tints used may
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
be similar to those that would be added to say a paint base. With pigmentation
added, the properties of the product should otherwise remain intact, because the
amount of tint added is comparatively small (something on the order of one ounce of
tint to one gallon of stain might be typical). The pigments that could be added could,
for example, increase the UV protection (because of the opacity). On the other hand,
characteristics like waterproofing and biocidal properties of coatings are less likely to
be influenced by the addition of pigmentation. For this study, the "stains" were used
as-is; that is, no pigmentation was added. For some of the stains, pigments had been
preadded, while for others, the stains used were actually bases only, without
pigmentation.
From the master list, 12 distinct products were selected for further evaluation based
on the following criteria. Coating selection preference was given to:
1. Products that are commonly used for outdoor wood treatment (i.e., decks), with
preference given to those that either have been tested or identified as promising
by other researchers. These primarily include stains and sealants.
2. Products that may not be widely available, but that have been identified by their
manufacturers to prevent DA exposure from CCA-treated wood.
3. Products that are relatively straightforward for consumers to apply (i.e., products
that require professional application were disqualified). Multiple product systems
generally were not considered, although it is recognized that some common
products (e.g., paints) may require the application of another product as a primer.
These situations were considered on a case-by-case basis.
4. Products that are not film formers. The overriding concern with film-formers is
that they generally require sanding in preparation for recoating. Sanding may
create a significant CCA dust inhalation hazard, thus making the use of film-
forming products undesirable. Additionally, film-formers - paints in particular -
are not as commonly used for coating decks and other outdoor structures as other
products. There are concerns that film-forming sealants may perform well at
first, but have significant potential for chipping and cracking over time and
exposure to weathering and particularly abrasion, necessitating recoating.
Nevertheless, to ensure that the list of coatings contained a wide range of
products, it was decided to round out the list with two "porch and patio" paints
(one water- and one oil-based) and the two other film-formers identified in #2
above that were specifically marketed to prevent DA exposure.
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Thus, in addition to the two paints selected (refer to #4 above) and two products
specifically marketed to prevent DA exposure (refer to #2 above), eight (8)
representatives of the combined stains and sealants category were selected based on
having four oil-based products and four water-based products, with one
representative of the four specifying alkyd as the main ingredient, one specifying
acrylic, one specifying both alkyd and acrylic as the main ingredients, and one
specifying neither. Using these criteria to select products resulted in two products in
each of the water- and oil-based subsets being classified as "sealants," with the other
two classified as "stains."
Table 2-2 generically (to preserve required product confidentiality) lists and
characterizes the 12 products selected for the study.
Table 2-2. Selected Products for Evaluation
#
1
2
3
4
5
6
7
8
9
10
11
12
13
Product Type
Sealant
Sealant
Stain
Stain
Sealant
Sealant
Stain
Stain
Paint
Paint
Other
Other
No coating
Base
Oil
Oil
Oil
Oil
Water
Water
Water
Water
Water
Oil
Cover
Semi
Clear
Clear
Clear
Clear
Clear
Semi
Clear
Opaque
Opaque
Clear
Clear
Main Ingredients
Acrylic, alkyd, urethane
Acrylic
Alkyd
Acrylic, alkyd
Alkyd
Acrylic
Acrylic
Alkyd, polyurethane
Elastic vinyl
Polymer
Comments
"Cedar" with UV blocker
"Clear"
"Deep tone base"
"Clear stain"
"Clear"
"Clear"
"Cedar" with UV blocker
"Tint base, solid" with no tint added*
"Gray". Latex, designed for porches and
floors
"Gray". Designed for porches and floors
Designed for CCA encapsulation
Designed for CCA encapsulation
Uncoated control minidecks
* note that the labeling for product #8 specifically states that it must be tinted before use.
2.7 Coating Application
Minidecks were constructed as described in Section 2.4. After construction and
baseline characterization of DA (described previously), all exposed surfaces of the
decks were coated in accordance with coating manufacturers' recommendations,
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
including any wood preparation procedures instructed by the manufacturer as stated
in the product's literature. Specific wood preparation flow schematics are provided
for each coating in Appendix C. Coatings were applied to fully cover the top faces,
exposed uncut edges, and cut ends of CCA-treated wood specimens in accordance
with manufacturers' recommendations. For the paints, products #9 and 10, a common
latex primer was first applied in accordance with the paint and primer manufacturers'
instructions. Top faces were coated first, followed by the exposed edges and the cut
ends. Because the coatings' manufacturers generally recommended that application
not be done during periods of direct sunlight, a tent was set up on site temporarily to
allow for coating minidecks in the shade. After 24-hours initial coating drying in the
shade, minidecks were manually relocated to allow additional drying in exposed
conditions.
Two types of brushes were used to apply coatings to the minidecks. They were both
2" chip brushes with either natural bristles or polyolefin bristles (to apply coatings
that recommended a synthetic bristled brush). Prior to coating application, both brush
types were analyzed in order to ensure that they did not contribute significant
amounts of arsenic, chromium, or copper to the wood surfaces. Each type of brush
used was prequalified for use per a set of two control samples whereby two brushes
of each type were agitated in a 250 mL vessel containing 40 mL of deionized water
for 30 seconds. The liquid samples were than transferred to Digitubes for digestion.
Four milliliters of nitric acid were added to each tube and the samples were then
digested at 95 °C for two hours. Digested samples were sent to STL for analysis.
These results are presented in Section 4.8.1.
Dedicated brushes were used to apply each coating to each substrate (wood type) on
each deck. In other words, a different brush was used to apply coating to each of the
aged wood sources and to the new untreated wood surfaces. Thus, three brushes were
used for each minideck. Untreated surfaces were coated first, followed by the aged
CCA surfaces. Brushes were prepared for initial coating application in accordance
with brush manufacturer's recommendations. After a particular coating was applied
to a given group of triplicate minidecks, used brushes were archived.
Separate aliquots of coating were used for each minideck in order to prevent cross-
contamination of coating by re-dipping the brush applicator. In addition, to prevent
cross-contamination, separate aliquots were used for each of the aged CCA treated
and new untreated boards. Thus, three aliquots of coating were used for each
minideck: one for the "A" specimens, one for the "C" specimens, and one for the
untreated (termed "N") specimens. Separate aliquots of coating liquid were poured
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
into disposable plastic graduated volumetric beakers, which were discarded after
application of that coating to each given set of two specimens. The disposable
beakers were acid-washed using a procedure similar to that specified in Section
2.10.5 prior to use. Coating remaining in similar beakers (i.e., the three beakers for
each replicate of substrate and coating) were composited so that one sample was
retained for each coating and wood type (new and untreated and the two, aged, CCA-
treated sources). These samples are currently stored in sealed, unused paint
containers and archived for possible future analyses. Application procedures and any
notable observations were documented for each coating.
The weight of coating applied to each substrate on each minideck was determined as
follows: A 200 to 300-mL aliquot of coating was transferred directly from the
original coating container into a 400-mL graduated beaker. The starting volume of
coating in the beaker and the final volume (after squeezing out excess coating from
the brush used) were recorded and, from these, a calculation of the volume of coating
applied was made. Additionally, the container containing the unused coating along
with the new brush to be used for applying a given coating to a given substrate on a
given minideck was pre-weighed. After coating was applied, the final weight of
beaker and brush was measured and recorded. The weight applied was thus
calculated as the difference between the initial and the final weights. Unused aliquots
of each coating tested are to be sampled in duplicate, prepared, and analyzed in
accordance with methods specified in Section 2.11.
A coating application data form was completed for each coating. A sample form is
provided as Appendix D. Results are presented in Section 4-2.
The sequence of minideck construction, preparation, and sampling is summarized
below; the actual timeline for these tasks is listed in Table 2-3.
1. Map, harvest, and label boards from source structure
2. Transport boards to staging area
3. Identify and characterize each sampling area and specimen
4. Conduct baseline sampling
5. Cut specimens to specified lengths
6. Construct minideck tops (nine boards affixed to untreated support frame)
7. Wash minideck tops in accordance with coating manufacturer's recommendations
8. Transport minideck tops to test site
9. Fasten minideck tops to posts
10. Coat minideck tops in the shade in accordance with manufacturer's
recommendations
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
11. Allow to dry in shade for 24 hours, then allow full exposure
Table 2-3. Timeline Showing History of Project to Date
Task
Harvested source A wood
Moved source A wood to ARCADIS Facilities Lab
Baseline source A wipe samples
Harvested source C wood
Baseline source C wipe samples
Decks tops built
Prepare and rinse tops
Deck tops transported to Jenkins Road site
Deck tops set on legs
Planing, spacing, and re-rinsing of tops
Coating
Field site landscaping
Installation of plastic ovals
Decks moved to field
1 month post-coat sampling event
Relocate decks temporarily (Hurricane Isabel)
3 month post-coat sampling event
7 month post-coat sampling event
Weeding at field site
9 month post-coat sampling event
Weeding at field site
Weeding at field site
15 month post-coat sampling event
EPA Field Audit
19 month post-coat sampling event
Start Date
3/19/2003
6/20/2003
6/25/2003
7/1/2003
7/3/2003
7/16/2003
7/21/2003
7/22/2003
7/25/2003
8/1/2003
8/6/2003
8/18/2003
8/20/2003
9/1/2003
9/10/2003
9/17/2003
11/10/2003
3/3/2004
6/21/2004
7/6/2004
8/18/2004
11/1/2004
11/18/04
11/18/04
3/29/05
End Date (if more than 1 day)
3/21/2003
7/11/2003
7/11/2003
7/18/2003
8/4/2003
8/11/2003
8/19/2004
9/12/2003
9/19/2003
11/12/2003
3/5/2004
6/25/2004
7/9/2004
11/22/04
3/31/05
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
2.8 Outdoor Weathering
The objective of the natural weathering tests is to evaluate the effects of weathering
in an actual outdoor environment on the efficacy of selected coating products in
reducing DA from aged, in-service CCA-treated wood.
Outdoor weathering tests simply involve exposing the minidecks described
previously to natural outdoor climatic conditions at a test facility in Research
Triangle Park (RTF), North Carolina. Minidecks are arranged on-site in a grid with
specific minidecks randomly assigned to gridded blocks at the start of testing with
the following qualifications: minidecks featuring the same coating were not allowed
in the same row, column, or diagonally immediately adjacent to one another.
Minideck layout on the site was documented. The site layout showing sequentially
numbered minideck locations is provided as Appendix E. The location of each
minideck is summarized in Table 2-4. Note that the blocks listed in Table 2-4
correspond to those shown on the site plan in Appendix E. A photograph of the
minideck site is provided in Figure 2-8.
The site was prepared for testing by:
" Setting up deposition samplers (constructed of new untreated wood) on-site and
periodically wipe sampling them to assess the potential for atmospheric deposition
of CCA analytes, in order to qualify the site. The results of the deposition samples
showed that background levels of CCA analytes were negligible.
" Delineating a currently grassed, relatively remote area for testing minidecks, and
preparing the area by tilling the ground to 6" total depth, leveling it to remove
potholes, and lightly rolling it to prevent dust and erosion and prepare for
graveling, but not overly compacting it. This area was then gridded using
landscaping fabric and crushed stone to prevent vegetative growth, which would
require maintenance, such as mowing, that might result in unacceptable impacts to
the decks (e.g., dust and grass clippings). Note that the crushed stone and
landscape fabric that were used were tested for arsenic content, which was
determined to be negligible. The site layout is shown in Appendix E. Note that the
space underneath the minidecks was not covered with landscape fabric or gravel.
Vegetation in these areas is controlled manually, by hand, to accommodate
bioavailability testing being conducted by other researchers.
« Delineating the perimeter of minideck test area to alert landscape maintenance staff
to avoid the area. Note that the site is sufficiently remote that vandalism is not a
problem. In fact, the site currently hosts valuable atmospheric monitoring
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
equipment that has not received any extraordinary security. The entrance road to
the site has a gate that is locked every evening at 6:00 pm until the next morning.
Clearance of saplings from the area to prevent unwanted shading.
After placement within their assigned gridded spots, minidecks were leveled in
both directions. Level placement was confirmed using an engineer's level, with
untreated 2" x 4" spacer blocks to prevent direct contact between the level and the
untreated end pieces of the minidecks.
Figure 2-8 Photograph of Minideck Site (note weather monitoring station on right)
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Table 2-4. Minideck Block Assignments (Blocks correspond to those identified in
Appendix E)
Minideck
1-A
1-B
1-C
2-A
2-B
2-C
3-A
3-B
3-C
4-A
4-B
4-C
5-A
5-B
5-C
6-A
6-B
6-C
7-A
7-B
7-C
8-A
8-B
8-C
Block
6
29
22
39
7
33
36
10
14
37
23
5
25
43
9
13
28
45
2
41
34
18
32
48
Minideck
9-A
9-B
9-C
10-A
10-B
10-C
11-A
11-B
11-C
12-A
12-B
12-C
13-A
13-B
13-C
BC
NC
LH
SC1
SC2
SC3
LC1
LC2
LC3
Block
46
3
26
42
27
24
30
4
20
1
35
21
19
40
12
8
47
15
31
38
16
44
11
17
BC =the blank, negative control, minideck
NC = 1 minideck with no CCA wood used (for a related
bioavailability study being conducted)
LH = 1 uncoated CCA minideck for leachate collection (for
a related bioavailability study being conducted)
SC1, SC2, SC3 = 3 soil controls (for a related bioavailability
study, no minidecks are located in these blocks)
LC1, LC2, LC3 = 3 leachate controls (for a related
bioavailability study, no minidecks are located in these
blocks)
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Weather data have been collected for the outdoor weathering tests using a Davis
Instruments Vantage ProPlus weather monitoring station. The station is located as
shown on the site plan in Appendix E, and in the photo in Figure 2-8. No substantial
differences in exposure across the minideck site have been noted. Through the use of
available software (WeatherLink for VantagePro), data from the weather station has
been compiled and downloaded to a Microsoft Excel file. The WeatherLink software
allows the user to store data in the VantageProPlus console and download to a
computer at their convenience. Data routinely collected via the Vantage ProPlus are
listed in Table 2-5.
The National Oceanic and Atmospheric Administration (NOAA) in RTP, North
Carolina, has collected data on wind speed and direction, temperature, precipitation
amount, direct solar radiation, and total solar radiation at the site used for minideck
weathering. A summary of the data collected by NOAA at the site are listed in
Table 2-6. Other parameters are collected by the NOAA's National Climate Data
Center (NCDC), at their Raleigh-Durham International Airport (RDU) weather
station, and are available in monthly summaries, detailing specified conditions on a
daily basis. The weather data available from NOAA at the test site, however, had
generally been collected on strip charts requiring conversion to allow comparison
with data obtained from the Vantage ProPlus weather station.
The test site NOAA metrology instrumentation is calibrated against working
standards that are traced to world standards at Eppley Laboratories. This calibration
has been done periodically based on the stability of the instrument. The temperature
system has been checked against certified data from NOAA's RDU weather station
on stable days and also with a sling psychrometer. The weighing rain gage has been
calibrated with weights and also against a manual rain gage with each precipitation
event. The Aerovane wind system records wind speed in miles per hour (mph) and
only begins to register at 3 mph. It has also been checked against RDU on stable
windy days. The operators of the weathering monitoring equipment have a great deal
of experience and their involvement and oversight has been important for QA/QC.
NOAA-generated data from the test site were compared to data from the Vantage
ProPlus weather monitoring station dedicated for use during this project. Spot checks
of all parameters common to both the NOAA and Vantage ProPlus unit were
conducted and showed good agreement. Because the on-site NOAA weather data
became unavailable several months into the study, certified data from NOAA's RDU
station has also been used to confirm the on-site weather monitoring station data.
Details of these spot check results are provided in Appendix F. All sets of
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
comparisons are in good agreement, thus confirming the accuracy of the on-site
weather monitoring station data.
Table 2-5. Vantage ProPlus Weather Station Data
Barometric Pressure
Inside Humidity
Outside Humidity
Dew Point
Rainfall
Rate of Rainfall
Solar Radiation
UV Index & Dose
Inside Temperature
Outside Temperature
Apparent Temperature
Wind Speed
Predominant Wind Direction
Wind Chill
Units
inHg
%
%
°F
in
in/hr
W/m2
index
°F
°F
°F
mph
mm Hg
°C
mm
mm/hr
Meds
°C
°C
°C
m/s
hPa (Tor)
km/h
mb
N, NNE, NE, ENE, E, ESE, SE, SSE, S,
SSW, SW, WSW, W, WNW, NW, NNW
°F
°C
The data can be archived at 1 min, 5 min, 10 min, 15 min, 30 min, 1 h, or 2 h.
Data is archived at 30-minute intervals.
All data points are discrete except for Rate of Rainfall and UV Dose.
Table 2-6. NOAA-Generated Weather Data
Parameter
Required
Irradiance (UV)
Temperature
Precipitation, Duration
Precipitation, Amount
Dew Point (Measure of dew formation)
Unit
W/m2
°F
hours
inches
°F
Remarks
Direct and total radiation is available.
Can be determined from strip chart, although
certain losses may occur due to evaporation.
Automated rain gage.
Dew point could be used to calculate dew
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Parameter
Wind direction + speed
Unit
Remarks
point depression (diff. with temp.) If DPD is
small, there is likely to be dew overnight.
2.9 Timeline
The history of this project is summarized in Table 2-3.
Several items in the timeline require clarification:
1. Planing, spacing, re-rinsing of tops: After constructing the minideck tops, it was
discovered that no space was left between boards, as typically recommended in
the construction of decks. To resolve this issue, all of the untreated boards (five
per minideck) were removed by backing out their plastic coated screws. They
were then planed sufficiently on either edge enough to be spaced using 16p nails
from adjacent boards. They were then reattached and the deck tops were rinsed
with tap water and allowed to dry sufficiently before coating.
2. Installation of plastic ovals: A side project is being conducted by EPA at this site
to look at bioavailability of CCA wood analytes in the soils beneath the
minidecks. To accommodate this research, oval plastic barriers are used to
segregate surficial soil immediately beneath the decks with surrounding soil. The
minideck example photo in Figure 2-7 clearly shows the plastic barrier
referenced.
3. Hurricane Isabel deck relocation: Shortly into the study, Hurricane Isabel
threatened the mid-Atlantic U.S. coast. Fearing tree or other storm damage, all of
the minidecks were collected from the site and brought indoors until the storm
passed, when they were relocated to the test site.
2.10 Wipe Sampling
Wipe samples were taken directly from the top faces of the four aged specimens per
minideck by wiping the specimens per the procedures described in this section on
site. Wipe samples were taken between nailholes, with care not to wipe over
nailholes. Each specimen has three sets of nailholes and thus two possible sampling
40
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
areas. One sampling area was used to help establish baseline DA concentrations.
These areas were wipe-sampled using wipes that had been pre-washed in nitric acid,
in an attempt to remove trace contaminants from the wipes, as described in Section
2.10.2. The other sampling area was not wipe-sampled prior to coating and was used
as the PSA. These areas were wipe-sampled using wipes that were straight out of the
bag, as described in Section 2.10.3, to avoid any potential detrimental effects of
residual acid from the wipe washing procedure on the performance of the coatings.
Wipe samples were taken from the top faces of each specimen only. The length of
the wipe was 15 inches to avoid contact with nailholes which are typically spaced 16
inches on-center.
Wipe comparison testing (Appendix A) has revealed that wipes with higher moisture
contents (i.e., higher spiked DI water content) yield higher DA values than do drier
wipes. Thus, the surface moisture of the minideck specimens when they are wiped
may be expected to also impact DA. It is difficult to adequately ascertain the surface
moisture of a specimen, particularly quantitatively. The interior moisture content of a
specimen may be measured using the techniques described in Section 2.13, which
include oven-drying and moisture probe methods. However, both of these
quantitative measures could compromise the integrity of the specimen, and perhaps
more importantly, its coating. Therefore, for this project, several more qualitative
measures have been taken to qualify and document wipe-sampling events:
" Wipe sampling events were only conducted when specimens appeared dry and
when weather forecasts indicated that there was a reasonable likelihood that
consistent, relatively dry weather (i.e., no rain) would prevail for the entire
sampling event. Actual climatic conditions were recorded and well-documented
throughout the entire study, including sampling events.
" During each sampling event, each minideck was digitally photographed, with
wiped and unwiped areas identified, in a running photolog.
Individual baseline DA values were determined for each PSA on each specimen to be
coated and tested. The baseline DA of a PSA was determined by averaging the pre-
coating baseline DAs from the two adjacent BL specimens on either side of the PSA,
as described in Section 2.1.
As previously indicated, routine wipe sampling of test specimens was conducted at 1,
3, 7, and 11 months after coating. Future events have been conducted at 15 and 19
41
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
months, and are planned at 23 months post-coat. During each sampling event, a
sampling event data form was completed. A blank form is provided in Appendix G.
Furthermore, a variety of routine control samples were taken. These include:
« Three negative control wipe samples taken from the blank minideck constructed
using a total of five untreated, uncoated specimens. These control measurements
provide an indication of whether there is significant atmospheric deposition of
CCA analytes at the site.
" One minideck per coating has its baseline-sampled areas (its sampling areas
identified with the BL prefix) on each of its aged specimens additionally sampled
during each third routine sampling event. In other words, one of the triplicate
minidecks has its baseline areas wipe-sampled during the first, fourth and seventh
sampling events, one has its baseline areas wipe-sampled during the second and
fifth sampling events, and one has its baseline areas wipe-sampled during the third
and sixth sampling events. It was hoped that these samples would provide some
information on "rerubbing effect," as discussed in Section 2.1.3, and may, upon
comparison with results from adjacent areas wiped more frequently, provide
information on the effects of abrasion induced by wipe sampling on coating
efficacy and DA.
" During each wipe sampling event, one untreated (but coated, for minidecks
prefixed 1 through 12) specimen from each minideck was wipe-sampled. Since
there are five untreated specimens on each minideck, there are a total of 10 such
potential sampling areas. The specific areas sampled during each routine sampling
event were randomly selected for each minideck and were different for each
sampling event.
Wipe sampling techniques utilized are based on the method developed and
documented by CPSC staff, using the wipe sampling device designed and
constructed by CPSC staff, shown in Figure 2-9. The CPSC staff wipe sampling
device utilizes a 1.1 kg disc that is approximately 8.65 cm in diameter as the wiping
block (note that the actual width of 5/4" x 6" decking is approximately 5.5" or 14
cm). With the 38-cm wipe length utilized, the sampling area is approximately 314
cm2. The referenced CPSC staff method has been described previously (CPSC staff
2003b). There are several differences between the procedures employed by EPA and
those employed by CPSC staff. The EPA wipe technique is described in detail below,
along with wipe preparation and sample extraction and analysis procedures for both
42
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researchers, while the differences between techniques are enumerated in Section
2.10.7.
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Figure 2-9 CPSC Wipe Sampling Apparatus
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
2.10.1 EPA Wipe Method (Adaptation of Referenced CPSC Staff Method)
The wipe method employed by EPA for the referenced minideck study is as follows:
1. Prior to starting a new wipe sample, sampling staff put on new pairs of
disposable nitrile or latex gloves. Then, the rubber-coated side of the steel
rubbing disk is covered with plastic wrap (SaranWrap or similar). The wetted
wipe is then removed from the PTFE tube, folded in half, and placed over the
plastic wrap and secured with a plastic tie-wrap strap.
2. The disk is lowered so that it is in contact with the wood.
3. Sampling staff slide the disc along the tracks of the sampling apparatus forward
and backward for five 38-cm (15-inch) strokes between nailholes while another
person holds the end of the wiping device in place. A stroke consists of one
forward and back movement. The speed of sampling is variable depending on the
quality of the area being wipes, with rougher wipe areas requiring longer
sampling times (slower average speeds). Smooth wipe areas may take one
second to wipe in each direction, while rough areas may take up to 30 seconds.
Splinters and sampling area imperfections can "hold up" the sampler requiring
the person doing the wipe to adjust the horizontal force they exert on the weight
to continue moving it forward. So, during most of the "additional time" required
to sample rough surfaces, the block is stationary: the motion is more stop-start
for rough surfaces versrus a slow and consistent horizontal motion. If the wipe
areas were all smooth, the sample speed would have been very consistent.
4. The wipe is rotated 90° on the rubbing disk, which is then slid forward and back
for five more strokes, for a total of 10 front-and-back strokes.
5. Sampling staff then remove the wipe from the disk and place it back into its
PTFE extraction vessel. Wood splinters larger than a grain of rice are removed
prior to placing the wipe in the extraction vessel.
6. After the sample is taken, the plastic wrap is discarded and the wiping apparatus
is decontaminated by wiping the rails of the apparatus which were in contact
with the wood surfaces with lint-free wipes wetted with DI water. Then the
apparatus is checked for structural integrity and any loose bolts are tightened.
Finally, sampling staff remove and discard their gloves and, for the next sample,
steps 1 through 6 are repeated.
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
2.10.2 EPA Acid-Wash, Rinse, and Saturate with Dl Water Wipe Preparation Technique
(A2 Method)
For the baseline samples, the following acid-wash wipe preparation procedure was
employed:
1. Wipes (TexWipes TX1009 cleanroom wipes, 100% continuous filament
polyester) are cut in half using a new razor blade that had been cleaned using
acetone and a lint-free wiper (i.e., Kimwipe) on a lab bench which has also been
cleaned with acetone.
2. After cutting, the half-wipes are placed in a wide mouth glass bottle and soaked
in a 10% solution of Trace Metals Grade Nitric Acid.
3. The bottle is placed in an oven at 85 °C overnight.
4. The bottle is removed from the oven, nitric acid solution is decanted, and wipes
are rinsed in the bottle five times with deionized H2O.
5. After the final rinse, each wipe is then removed and squeezed by hand so that
they are damp but no more water could be removed. This technique was
subsequently determined to yield moisture contents of2.1±0.1(l standard
deviation) times the dry wipe weight.
6. The damp wipes are individually placed into individual Digitubes until they are
used for wipe sampling.
Note that nitrile gloves are worn during all handling of wipes.
2.10.3 EPA 2X Dl Water Wipe Preparation Technique (2X Method)
The EPA wipe preparation procedure for subsequent sampling events (samples
taken 1,3,7, 11 months after coating) for the referenced minideck study was as
follows:
1. Wipes (TexWipe TX1009 cleanroom wipes, 100% continuous filament
polyester) are cut in half using a new razor blade or scissors cleaned using
acetone and a lint-free wipe (i.e., Kimwipe) on a lab bench which has also been
cleaned with acetone.
45
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
2. After cutting, the half-wipes are inserted into PTFE tubes, into which two times
the wipe weight in DI water is added to be soaked up by the wipe. Therefore the
wet wipe, as used, is three times its dry weight.
3. Wetted wipes are stored in their sealed PTFE tubes until use. Sampling staff
cutting, transferring, and wetting the wipes wears nitrile or latex gloves.
2.10.4 CPSC Staff 1X 0.9% Saline Wipe Preparation Technique (CPSC Method)
The wipe method employed by CPSC staff for their related minideck study was as
follows:
1. Wipes (TexWipes TX1009 cleanroom wipes, 100% continuous filament
polyester) are cut into quarters using scissors cleaned with acetone and a lint-free
wiper (e.g., Kimwipe).
2. After cutting, the wipes are weighed and then soaked in 0.9% saline solution.
The wipes are squeezed and shaken until the wipe weighs twice its dry weight
(i.e., it is retaining an equal weight of saline solution).
3. Wetted wipes are stored in sealed glass test tubes until use. Sampling staff
cutting, transferring, wetting and sampling the wipes wears nitrile or latex
gloves.
4. The rubber-coated side of the steel rubbing disk is covered with a clean piece of
Parafilm for each sample wipe. The wetted wipe is removed from the test tube
and placed over the Parafilm. The wipe is secured to the disk with a rubber band
and hose clamp. The wipe should be smoothly stretched over the disk.
5. The wipe-covered disk is attached to the lower arm of the wiper.
6. The wipe covered rubbing disk is placed at one end of the wiper. Then the wiper
is placed over the area of the board to be sampled. The rubbing disk is then slid
along the tracks of the wiper forward and back for five 50-cm strokes. The
rubbing disk is lifted from the board, rotated 90°, and slid forward and back five
more strokes for a total of 10 strokes. As for the EPA method, the speed of
sampling is variable depending on the quality of the area being sampled.
46
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
7. The wipe is removed from the disk. Any wood splinters larger than a grain of
rice are removed. The edges of the wipe that did not contact the board during
sampling are cut and the wipe is placed back in the glass test tube, and covered.
Any splinters are noted.
8. After the sample is taken, the Parafilm strip is discarded and the wiping
apparatus is decontaminated by wiping the rails that are in contact with the wood
surfaces with lint-free wipes wetted with DI water. Then the apparatus is checked
for structural integrity and any loose bolts are tightened. Finally, sampling staff
remove and discard their gloves and for the next sample, steps 4 through 7 are
repeated.
2.10.5 EPA Laboratory Wipe Extraction and Analysis Techniques
Wipe samples were prepared for analysis using techniques similar to those employed
by other researchers including CPSC staff (2003) and Stilwell, et al. (2003), adapted
for use with laboratory equipment available for this project. As such, amicrowave-
or heat-assisted extraction and digestion procedure comparable to that used in prior
studies, and similar to SW-846 Methods 3051 and 3052, was employed. Steps
involved in the extraction procedure are outlined following:
1. Pre-cleaned disposable digestion vessels are used for sample collection and
digestion. All volumetric glassware is prepared by acid cleaning. Volumetric
glassware is cleaned by leaching with hot 1:1 nitric acid for a minimum of two
hours, then rinsed with deionized water and dried in a clean environment.
2. 30 ± 0.1 mL 10% nitric acid (trace metal grade HNO3, DI H2O) is added slowly
to the digestion vessel containing the wipe sample to allow for pre-extraction.
Once any initial reaction has ceased, the sample is capped and introduced into an
Environmental Express HotBlock metals digestion system. Using this device, 54
samples may be digested in a single batch.
3. Using temperature and pressure curves developed under other research programs
for EPA as a guide, the vessels are placed into the digestion system and heated
for 1 hour at 95 °C.
4. After digestion system extraction, sample vessels are allowed to cool for a
minimum of 5 min. prior to removing them from the system. Then the liquid is
poured off into a 100 mL volumetric flask. As much extraction liquid as possible
47
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
is squeezed by hand from each wipe; the funnels and flask necks are rinsed with
DIH2O.
5. The extracted wipe is then placed back into the extraction flask with an
additional 30 mL of 10% HNO3.
6. Again, the vessels are placed into the digestion system and heated for 1 hour at
95 °C.
7. After extraction, the liquid is poured off into the aforementioned 100 mL
volumetric flask. As much extraction liquid as possible is squeezed by hand from
each wipe and the funnels and flask necks are rinsed with DI H2O.
8. The wipe is placed back into the extraction vessel and 20 mL of 10% HNO3 is
added to each extraction vessel before the digestion system cycle is repeated.
9. The extract is then poured into the 100 mL volumetric flask. Deionized water is
used to rinse the extraction vessel; rinsate is added to the lOOmL volumetric
flask. If necessary, deionized water is added to take the contents to the 100 mL
level.
10. The contents of the 100 mL flasks are then transferred to and stored in two
plastic tubes (duplicate or split samples) with plastic caps. One is sent to a
contract laboratory for analysis, while the other is archived, under refrigeration
or freezer storage. These tubes are manufactured by SCP Science and are
certified contaminant-free.
Note that nitrile or latex gloves are worn during all handling of wipes.
Per the specified analytical method, the hold time for all metals other than mercury is
6 months, and samples are stored at 4 °C until analysis. Sample containers are of
tetrafluoroethylene (TFE) or perfluoroalkoxy (PFA) in accordance with the analytical
method recommendations.
Analyses for total arsenic, chromium, and copper are conducted by STL in Savannah,
Georgia, using a modification of SW-846 Method 6020 (ICP-MS). STL utilizes ICP-
MS for arsenic analysis, modifying the technique to utilize hydrogen plasma, rather
than argon as classically performed. This modification eliminates concerns over the
formation of Ar40Cl35, which can create a positive bias when measuring As. STL-
48
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Savannah's analytical method has reporting limits of 0.10 (ig/L for all three CCA
analytes (this corresponds to a DA of 0.000032 (ig/cm2)
STL is an accredited laboratory, participating in the Contract Laboratory Program
(CLP), as well as numerous state programs. In addition to prequalifying the
laboratory for use in the minideck study, each set of samples submitted includes
blind blanks and spiked samples, allowing for continued monitoring of laboratory
performance.
2.10.6 CPSC Staff Technique Laboratory Wipe Extraction and Analysis Techniques
The extraction and analysis procedures used by CPSC staff are outlined as follows:
1. After sampling, the wipes are carefully rolled up and placed back in the glass test
tube in which the wipe was stored prior to sampling.
2. 20 ± 0.1 mL of 10% nitric acid (trace metal grade HNO3, DIH2O) is added to
each test tube containing a sample wipe. The test tubes are covered.
3. The test tubes are placed in a hot water bath at 60 °C overnight (approximately
15-24 hours). The test tubes are removed from the water bath and allowed to cool
to room temperature.
4. The test tubes are vortexed prior to analysis to ensure mixing. The wipe remains
in the test tube throughout the extraction and analysis process.
5. Analysis for total arsenic, chromium, and copper are conducted at the CPSC
laboratory in Gaithersburg, Maryland using a modification of EPA Method
200.7. CPSC staff utilizes ICP for analysis.
2.10.7 Differences Between EPA and CPSC Staff Wipe and Sample Preparation
Procedures
Differences between the CPSC staff and EPA 2X methods for collection and analysis
of surrogate wipes on CCA-treated wood are as follows:
1. ARCADIS uses plastic wrap to cover the rubber-coated side of the rubbing disk
rather than Parafilm.
49
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
2. C-clamps are not used by EPA to secure the horizontal wiper (because the
boards being wiped are part of a deck structure). An assistant holds the wiper in
place.
3. In the EPA method, poly wipes are immediately placed directly into the vessels
in which extraction will take place.
4. A three-step extraction and digestion procedure, as detailed above, is used by
EPA rather than the CPSC staff one-step water bath extraction and digestion.
5. EPA uses a 2x DI water spike (wetted wipe weight is three times the dry wipe
weight) to pre-wetthe wipes while CPSC staff uses a Ix 0.9% saline solution
spike (wetted wipe weight is two times the dry wipe weight).
6. EPA uses a 38-cm (15-in) wipe length (nominal 314 cm2 sampling area) and
samples between nailholes of boards supported 16 inches on-center, while CPSC
staff uses a 50-cm (19.7-in) wipe length (nominal 386 cm2 sampling area).
2.10.8 Wipe Sampling Method Limitations and Recommendations for Improvements
Wipe sampling is typically a relatively imprecise method of sampling. During this
study, several notable observations have been made regarding the wipe sampling
procedure. Most notably, the apparatus does not always appear to apply even wipe
sampling pressure during sampling, particularly if the wood member is even slightly
deformed, warped, or cupped. It appears that the rigid structure of the weighted disc to
which the wipe is affixed does not allow for much in the way of "form-fitting" the
wood member being sampled. The use of a less rigid face for the weight (perhaps
something like a beanbag or gel-filled pad) may allow the wipe to fit better to the areas
being sampled. An additional concern is that the average "speed" of wipe sampling
may vary depending on the roughness of the surface being sampled. This appears
difficult to avoid in that nearly any wipe sampling method utilizing a cloth or fabric
wipe will occasionally hang up on rough or splintered surfaces.
2.11 Preparation and Analysis of Coating Samples
Total arsenic, chromium, and copper in the coatings themselves will be determined in
a manner similar to that used to analyze the wipe samples (acid digestion and
extraction followed by ICP-MS). The coating to be analyzed will be thoroughly
shaken to ensure homogeneity and then an aliquot transferred to a tared PTFE
digestion vessel and allowed to dry. Following loss of volatiles through drying, the
50
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
residue will be digested using concentrated nitric acid as described in EPA SW-846
Method 3052. Hydrofluoric acid will be added if necessary to ensure complete
digestion in accordance with the method. The digestate will be quantitatively
transferred to a volumetric flask and diluted to a known volume prior to submission
to the contract laboratory for ICP-MS analysis (SW-846 Method 6020).
2.12 Archiving of ICP-MS Samples
Analysis of the samples by ICP-MS consumes only a fraction of the submitted
sample. ARCADIS is archiving an aliquot of each digestate until the completion of
the project. Samples are being archived by storing them in TFE or PFA containers
under refrigeration. Additionally, any remaining sample volume at the contract
analytical laboratory was archived until the analytical results were confirmed.
2.13 Moisture Analysis of Wood Specimens
Wood moisture content was measured using a hand-held meter, after the technique
had been qualified and calibrated via side-by-side testing with the drying oven
technique, ASTM D4442 (Primary Oven Drying). Per ASTM D4442, a small
representative wood sample was weighed prior to drying overnight at 103° C in a
forced air oven. After 24 hours, the sample was cooled in a desiccator, weighed, then
returned to the oven. The process was repeated until weight changes between
weighings was within ±5%.
2.14 Photographs
Digital photographs of each minideck were taken before coating and monthly
sampling events.
2.15 Miscellaneous Samples
Other miscellaneous samples that were collected, and archived or analyzed are
summarized in Table 2-7.
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Table 2-7. Miscellaneous Samples to be Collected
Sample Description
'Unaltered coating
Leftover brush-applied coating
Brush wash water
Wood
# Samples Analyzed
2 for each coating
N/A
2 for each brush type
Up to 4 cores per board
# Samples to be Archived
Leftover coating to be stored
1 for each coating and wood type
Brushes are retained
Leftover wood is stored
*Not yet done
Unless otherwise stated, all samples indicated in Table 2-7 to be archived shall be
held at least until the initial report of results has been finalized. Longer archiving
times for certain samples may be warranted upon further consideration.
2.16 Quality Control Samples
A variety of control samples were taken. These include the following: 1. positive
(CCA-treated, uncoated) controls, 2. negative (untreated, uncoated) controls, 3.
cross-contamination controls, 4. wipe frequency (rewipe, abrasion) controls. Each is
discussed briefly below.
2.16.1 Positive (CCA-Treated, Uncoated) Controls
The three minidecks prefixed by the number 13 are constructed in exactly the same
way as the minidecks for coatings #1 through #12, except that they are not coated. The
results from these minidecks, therefore, can be used to determine how the DA values
change overtime without considering the effect of coating. As such, average baseline
DA values can be calculated at each sampling event by simply using the results from
the positive control minidecks. These baselines can then be used to define alternate
methods of calculating coating efficacy. The advantage to using the positive control
minidecks for this purpose is that other potentially important factors are incorporated in
the minideck 13 results, including: the effect of rinsing the boards pre-coating (via
comparison of pre-coat and samples taken 1 month after coating for the positive
control minidecks), the effect of weathering between subsequent sampling events, and
the effect of climatic conditions during the sampling itself. For example, it may be that
the DA results per the sampling technique employed in this study correlate with some
climatic condition (e.g., higher DA with higher relative humidity). The use of the
positive control minideck DA results thus allows for this and other potential sources of
bias to be factored out in the calculation of efficacy.
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
2.16.2 Negative (Untreated, Uncoated) Controls
The single uncoated minideck, labeled BC (for "blank control"), consisting of five
untreated specimens, was used to routinely take blank samples to measure the
background levels or atmospheric deposition of analytes. Wipe samples were taken
from the same areas of the middle three boards on this deck during each monitoring
event, similar to samples taken from the other minidecks.
2.16.3 Cross-Contamination Controls
The untreated specimens separating the CCA-treated test specimens on each deck serve
as sources for cross-contamination control samples. During each wipe sampling event,
one untreated (but coated, for minidecks prefixed 1 through 12) specimen from each
minideck was wipe-sampled. Since there are five untreated specimens on each
minideck, there are a total of 10 potential sampling areas. The specific areas sampled
during each routine sampling event were randomly selected for each minideck and
were different for each sampling event. The results of these samples have been used to
assess the level of cross-contamination expected for adjacent samples as a result of, for
example, splash-over of rainwater from one specimen to the next.
2.16.4 Wipe Frequency (Rewipe, Abrasion) Controls
Each CCA-treated test specimen on each minideck includes two sampling areas: a PSA
(prefixed "M") and an adjacent baseline sampled area (prefixed "BL"). BL areas are
those that were initially wiped prior to coating to establish baseline DA. A subset of the
BL areas are resampled during each sampling event. Specifically, all of the BL areas
on one of the three minidecks per coating (as well as the positive control minidecks)
are sampled during each sampling event. Therefore, since there are three minidecks per
coating, a given BL area is resampled every third sampling event. In other words, one
of the triplicate minidecks has its baseline areas wipe-sampled during the first, fourth
and seventh sampling events, one has its baseline areas wipe-sampled during the
second and fifth sampling events, and one has its baseline areas wipe-sampled during
the third and sixth sampling events. As such, the coatings on these sections of lumber
have not been abraded by wiping to the same extent as the coatings on the PSAs in
order to assess the effect that wiping has on coating efficacy. It was hoped that these
samples would provide some information on "rerubbing effect," as discussed in
Section 2.1.3, and may, upon comparison with results from adjacent areas wiped more
frequently, provide information on the effects of abrasion induced by wipe sampling on
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
coating efficacy and DA. Additional information regarding the analysis of this data
can be found in Sections 3.4.3 and 4.7.
2.16.5 Analytical (Contract Laboratory) Control Samples
A series of laboratory control samples were sent with each batch of samples tested by
the subcontract analytical laboratory. Each set of digested wipe samples submitted to
the subcontract analytical laboratory included 5% additional blind field blanks
(extracted unused wet wipes), one blind blank (extraction fluid only), one set of three
different concentration-spiked samples, and duplicates (split samples) for 5% of the
wipe sample digestates being analyzed to assess laboratory performance. Control
samples were not identified as such to the contract laboratory performing the
analyses. So, for example, assuming that a total of 200 wipe samples were taken for
this study, shipped to the subcontract laboratory in a single batch, the following
additional samples were included:
" Ten (10) field blank samples prepared by taking unused wetted wipes and
extracting them in accordance with the procedures previously specified
" One (1) blank consisting of extraction fluid only
" One (1) digestion fluid sample spiked to 1.0 (ig/L (0.015 (ig in 15 mL digestion
fluid) with As, Cr, and Cu
" One (1) digestion fluid samples spiked to 50 (ig/L (0.75 (ig in 15 mL digestion
fluid) with As, Cr, and Cu
" One (1) digestion fluid samples spiked to 1000 (ig/L (15 (ig in 15 mL digestion
fluid) with As, Cr, and Cu
« Ten (10) duplicates (selected split samples of digested wipes from actual samples
generated)
Furthermore, the subcontract analytical laboratory analyzed project-specific post-
digestion spiked samples for each analyte, in addition to equipment blanks run on
each batch of samples analyzed for this project.
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3. Data Reduction and Analysis Methods
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
3.1 Data Reduction
3.1.1 Calculation of DA from Extraction Fluid Concentrations
Raw data from the subcontract analytical laboratory were reported in units of (ig/L
and represents the mass of analyte per unit volume of extraction solution sent to the
laboratory. For standard wipe sample results, data were reduced in order to
characterize the mass of analyte per unit surface area wipe-sampled, in units of
(ig/cm2, using the following equation:
V
1000
A
(Equation 3.1)
Where: CDA = DA of a sample ((ig/cm2)
CDF = Concentration of analyte in extraction fluid ((ig/L)
V = Total volume of extraction fluid (mL)
A = Area of wiped surface (cm2) = 314 cm2
3.1.2 Calculation of Percent Reduction of DA
Raw data from the subcontract analytical laboratory are reported in units of (ig/L and
converted to DA (the mass of analyte per unit surface area wipe-sampled), in units of
(ig/cm2, per Equation 3.1. Because there are different ways of assessing efficacy, for
this project, efficacy (percent reduction) for each coating has been calculated using
four alternate methods. The results of all four methods (described below) are
reported.
The first and second methods (Methods 1 and 2) used to calculate percent reduction
utilized Equation 3.2:
RDA ~
C -C
initial final
r
^^ ivii-tinl
xlOO
(Equation 3.2)
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Where: RDA = Reduction in DA (%)
Qmtiai = Baseline DA ((ig/cm2)
Cfinai = Final DA (|ig/cm2)
In method 1, RDA is calculated for each PSA at each of the four sampling events. The
RDA results are then averaged by groupings of coating (coatings #1 through #13),
source (A versus C), and sampling interval (1 through 4). This method can be thought
of as "calculating the average of the efficacies".
In method 2, averages are first taken of Cmitiai for each grouping of coating and source,
pre-coating (baseline), and then of Cfmai which is the average DA for each grouping of
coating, source, and sampling interval. Then, Equation 3.2 is then used to calculate RDA
for each grouping of coating, source, and interval, based these averages. This method
can be thought of as "calculating the efficacy based on the averages".
Method 3 utilizes a different equation, Equation 3.3, for calculating efficacy, and is
based on the average positive control minideck (i.e., coating #13) results for each
source and time interval. The equation used is as follows:
VT-j *
—• deckl3,time=t,source=s ^ coating=c,time=t,source=s
Cv deck\?>,time=t,source=s
~ .-..-.
X 1 UU
(Equation 3.3)
Where: RDA = Reduction in DA (%
C decki3,time=t,source=s = Average DA for "M" labeled samples for
coating #13 for given source wood, at specified time interval
C coatmg=c,time=t,source=s = Average DA for "M" labeled samples for
specified coating, given source wood, and at specified time interval
In method 4, the estimates of coating efficacy relative to coating #13 were calculated
using the analysis of variance model used to compare and rank coatings (described in
Section 3.4.2). Using standard linear model results, estimated differences in coating
main effects on the log-scale, Q-Ci3, were calculated along with lower and upper
56
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
confidence limits. The efficacy (RDA,I) of coating i to coating #13 was then calculated
per Equation 3.4.
RDA, i=l- exp(Q - C13) (Equation 3.4)
Where: RDA.I = Reduction in DA for a given coating, coating i (%)
Q = DA for coating i, averaged over all conditions
Cis = DA for coating #13, averaged over all conditions
A similar calculation applied to the lower and upper confidence limits of the estimated
effect difference provided the upper and lower confidence limits of the estimated
efficacies.
In effect, this approach yields a composite measure of efficacy averaged over both
source decks, all time periods, and the grain orientation of the boards, and after
adjusting for baseline measurements. The statistical model has the conceptual form:
ln(DA/DABL) => coating + sourcedeck + grain + interaction_terms
where DABL represents the baseline DA results, and "coating" models the main effect
of the coating; "sourcedeck" models the main effect of the source deck, and so on.
This approach has the advantage of correlating well with the statistical method used to
compare coating performance (Section 3.4.2); the models are essentially the same, but
their application is different. Furthermore, the model results are based on the effects of
the coatings after adjusting for baseline measurements.
A fundamental characteristic of this approach is that it averages over the other factors
(source, grain orientation, and sampling interval). This can be both good and bad. For
example, it is certainly possible the efficacies of the coatings might depend on one or
more of these other factors, and method 4 averages over all of these factors. The
dominant factor, however, is probably elapsed time since coating. So by computing an
average (over time) efficacy, in some approximate sense an average annual efficacy is
being computed. In other words, method 4 is best targeted to answer the question:
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Effectiveness of Coatings in
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Arsenic, Chromium, and
Copper from CCA Treated
Wood
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EPA Report EPA/600/R-05/050
9 May 2005
"what is the yearly-exposure efficacy of a coating from time of application to one
year later?"
3.2 Data Reporting
For each series of tests, raw and reduced data are reported, as applicable. Coating
efficacy results are expressed in terms of DA (jig/cm2) and percent reduction. All
data validation criteria have been reported along with the associated data.
3.3 Relational Databasing
Data have been compiled using a relational database that includes a variety of
information. A schematic of the database design is provided in Appendix H.
The relational database was constructed to store pertinent experimental data and
observations. The database is constructed using Microsoft Access 2002 (XP) while
the database format was maintained at the Microsoft Access 2000 version to assure
wide compatibility. The database is designed to balance the normal form
considerations and the speed and convenience of usage. Most fields in a particular
table are directly related to its primary key to reduce the information redundancy.
Table 3-1 shows the 6 primary tables and their associated primary and foreign keys.
Table 3-1. Relational Database Table Summary
Table Name
SpecimenList
IntervalData
InfoDecks
InfoCoatings
Board Info
Iku Specimens Type
Description
Table composed of all specimens and
the directly related data such as name
of specimen, core concentrations, and
moisture content.
Table consisted of data pertaining to a
particular sampling event.
Table consisted of data specific to
each minideck.
Table consisted of coating data
Table consisted of data pertaining to
each board such as length, grain, and
bark face.
Type of specimen, including blank,
sample, and unused.
Keys
Primary Key: SpcID
Foreign Key:
SpcDeckID,
DatalD,
SpcType
Primary Key: Data ID
Primary Key: MiniDeckID
Foreign Key: Coating ID
Primary Key: CoatingID
Primary Key:BrdlD
Primary Key: SpcTypelD
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
3.4 Statistical Analysis Approach
3.4.1 Wipe Method Correction Factors
Toward the beginning of this study, a separate wipe comparison study was
conducted, with a main goal of determining whether a correction was needed to
convert the baseline (precoat) wipe sample results taken using acid washed wipes
(the "A2" method) to the 2X method (as used for the subsequent sampling events)
wipe preparation results, and, if so, what the correlation equations should be. Other
factors were considered as variables including: grain orientation (up, down), source
deck (A, C), sample date (1 month, 3 months, 7 months, 11 months), rinse (rinsed,
unrinsed), and prep lab (EPA, CPSC). "Unrinsed" boards in this context refers to
boards that were taken directly from storage and wipe-sampled, while "rinsed"
boards were thoroughly hosed down with tap water and allowed to dry for several
days before wipe sampling. "Prep lab" refers to which laboratory digested or
extracted the wipes and subsequently either analyzed the samples in-house (CPSC)
or sent them out to a subcontract laboratory for analysis (EPA). The full wipe
comparison report is provided as Appendix A but the main results affecting this
study are summarized herein.
Statistical model selection was used to identify calibration equations for predicting
method 2X DA measurements from method A2 DA measurements and the other
factors, including grain orientation (up, down), source deck (A, C), sample date (1
month, 3 months, 7 months, 11 months), rinse (rinsed, unrinsed), and prep lab (EPA,
CPSC). Based on these analyses, separate calibration equations are suggested for
rinsed and unrinsed boards, but not for any of the other factors. In other words, when
models for predicting DA using 2X wipes from DA using A2 wipes, grain, source
deck, sample date, rinse, and prep lab are considered, the identified prediction model
depends only on DA using A2 wipes and rinse.
The wipe method correction factors are summarized as follows:
For arsenic:
Rinsed Specimens: As-2X = 1.42 (As-A2), 95% Confidence Interval: (1.18, 1.66)
Unrinsed Specimens: As-2X= 0.80 (As-A2), 95% Confidence Interval: (0.72, 0.88)
The R-square value for the combined models is 0.78
59
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
For chromium:
Rinsed Specimens: Cr-2X= 1.31 (Cr-A2), 95% Confidence Interval: (1.05, 1.57)
Unrinsed Specimens: Cr-2X = 0.81 (Cr-A2), 95% Confidence Interval: (0.73, 0.89)
The R-square value for the combined models is 0.62.
For copper:
Rinsed Specimens: Cu-2X = 1.18 (Cu-A2), 95% Confidence Interval: (0.94, 1.42)
Unrinsed Specimens: Cu-2X= 0.83 (Cu-A2), 95% Confidence Interval: (0.75, 0.91)
The R-square value for the combined models is 0.81.
Because the baseline analyses for this study were done on unrinsed boards, the
unrinsed specimen equations were used to adjust the baseline results accordingly. In
this report, only "corrected" baseline (samples taken before coating) DA is reported.
Likewise, reported values which are calculated using baseline DA in the calculation
(e.g., the percent reduction values) always use the corrected baseline values. DA from
all subsequent sampling events are reported uncorrected, as they were conducted using
the 2X wipe method.
3.4.2 Intercepting Comparison and Ranking
Standard analysis-of-variance methods were used to analyze the data for the purpose of
comparing coatings. The particular analysis-of-variance model used was chosen to
match the experimental design. The key features of the design are the longitudinal
(time series) nature of the study, the replication of mini decks for each coating in the
study, the use of boards from two source decks, the placement of boards in both grain-
up and grain-down positions, and the baseline measurements for each board. Apart
from the additional feature of baseline measurements, the design (in terms of the main
factors: coating, source deck, grain orientation, and time) is similar to that of a split
plot in space and time as described in Steel, et al. (1997).
The specimen-specific baseline measurements were used to normalize the main study
measurements from the corresponding specimen. For the analysis of DA
measurements, the dependent variable used in the analysis of variance was
ln(DA/DABL), the natural logarithm of DA/DABL, where DA is the DA measured on a
given PSA during a given sampling interval, and DABL is the corresponding PSA-
specific baseline arsenic value. DCr and DCu measurements were analyzed similarly.
The analysis on the log-ratio scale has some important advantages. The fact that the
60
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
baseline measurements were made using a different wipe preparation method (A2)
than the main-study measurements (2X), and that statistical analysis of available data
suggested that A2 method measurements are approximately proportional to 2X method
measurements (Appendix A) means that the constant of proportionality becomes an
additive constant on the log scale, and thus does not affect comparisons among
coatings. Taking logarithms also homogenizes residual variation among treatments,
thereby ensuring greater conformance with the standard analysis-of-variance
distributional assumptions.
In summary, the statistical model used was a split plot in space and time with
minidecks playing the role of plots, coating as the whole plot factor, and source deck
and grain as the split plot factors. The model differed slightly from a textbook split plot
in that the replication was not in blocks. The model was fit using standard software for
mixed analysis of variance models.
3.4.3 Wipe Frequency and Number of Wipe Analysis
Although the experiment was not specifically designed to provide detailed
information about the effects of wipe frequency (rewipe effect) and the number of
previous wipes (abrasion), the data collected provide a limited opportunity to
investigate these factors. To this end two new predictive variables were defined for
the purpose of quantifying the amount of previous wiping and the elapsed time since
the previous wipe:
1) NOPW = number of previous wipes;
2) TTPW = time (months) since the previous wipe.
The first, NOPW, is a surrogate for total prior post-coat abrasion; and the second,
TTPW, measures wipe frequency, or more specifically, the time interval between
wipe samples on a given sampling area. Possible effects of these two factors were
investigated using the combined dataset {i.e., both the sample [M] and baseline [BL]
DA results}. The statistical model used was that described in Section 3.4.2
augmented with linear terms in the new variables NOPW and TTPW. The model
facilitated the investigation of trends (either increasing or decreasing) in NOPW and
TTPW after adjusting for all of the other factors. Because the experiment was not
designed specifically for the purpose of assessing abrasion and wipe-frequency
effects, the information in the data for assessing these factors is not great, and the
analysis was intended primarily for exploratory purposes.
61
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
4. Results and Discussion
4.1 Wood Characterization Data
A variety of source board characterization data was collected for the wood harvested
and used to construct the minidecks for this project. Source wood characterization
data are summarized in Table 4-1. Additionally, each specimen used in the
construction of the minidecks was semiquantitatively rated on several
characterization factors. These results are provided in full in Appendix I. Note that
Table 2-1 can be used to cross-reference minidecks with specimens (and thus source
boards).
Table 4-1. Source Wood Characterization Data Summary
Board
ID
A-AC
A-AD
A-AE
A-AF
A-AG
A-AH
A-AJ
A-AN
A-AR
A-AT
A-BC
A-BG
A-BW
A-BY
A-F
A-l
A-L
A-O
A-P
Board
Length
(in)
181.4375
182.75
184.1875
185.0
186.25
187.5
190.125
178.375
161.25
147.0
163.0
193.25
178.875
162.875
156.0625
157.0
160.625
164.25
165.375
Board
Length
(cm)
460.9
464.2
467.8
469.9
473.1
476.3
482.9
453.1
409.6
373.4
414.0
490.9
454.3
413.7
396.4
398.8
408.0
417.2
420.1
Predominant
Grain Type
40F/60E
Flat-Grained
Flat-Grained
Flat-Grained
Flat-Grained
40F/60E
30F/70E
Flat-Grained
Flat-Grained
20F/80E
Flat-Grained
Flat-Grained
Flat-Grained
30F/70E
30F/70E
Flat-Grained
Flat-Grained
Flat-Grained
50/50
Predominant
Grain
Orientation
Up
Up
Up
Down
Up
Down
Up
Down
Up
Down
Up
Down
Down
Down
Up
Up
Down
Up
Up
Predominant
Ring Spacing
Tight
Wide
Medium
Medium
Wide
Tight
Wide
Wide
Medium
Medium
Wide
Medium
Wide
Medium
Tight
Wide
Wide
Medium
Predominant
Wood Type
Sapwood
Sapwood
Sapwood
20H/80S
Sapwood
Heartwood
Heartwood
Sapwood
Heartwood
Heartwood
Sapwood
Sapwood
Heartwood
Heartwood
Sapwood
Sapwood
Sapwood
Heartwood
Sapwood
Predominant
Wood
Season
Late
Early
Early
70E/30L
Early
Early
Late
Late
Early
Late
Early
Early
Early
Early
Late
Late
Early
60E/40L
Early
62
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Board
ID
A-Q
A-T
A-U
A-V
A-X
A-Y
A-Z
C-AA
C-AC
C-AD
C-AE
C-AI
C-AJ
C-AK
C-AM
C-AN
C-AP
C-BE
C-BI
C-BJ
C-BM
C-BO
C-BT
C-BU
C-BW
C-BX
C-BY
C-BZ
C-CA
Board
Length
(in)
166.3125
170.4375
171.6875
172.875
175.5
176.625
177.75
160.0
191.5
192.125
191.625
192.125
193.625
186.875
191.9375
191.875
174.25
178.375
188.125
177
192.625
188.5
192.625
156.375
156.375
192.375
174
192.125
156.625
Board
Length
(cm)
422.4
432.9
436.1
439.1
445.8
448.6
451.5
406.4
486.4
488.0
486.7
488.0
491.8
474.7
487.5
487.4
442.6
453.1
477.8
449.6
489.3
478.8
489.3
397.2
397.2
488.6
442.0
488.0
397.8
Predominant
Grain Type
40F/60E
Flat-Grained
Flat-Grained
Flat-Grained
Flat-Grained
Flat-Grained
Flat-Grained
Flat-Grained
Flat-Grained
Flat-Grained
Flat-Grained
Flat-Grained
Flat-Grained
30F/70E
Flat-Grained
30F/70E
Flat-Grained
Flat-Grained
Flat-Grained
Flat-Grained
Flat-Grained
Flat-Grained
30F/70E
Flat-Grained
30F/70E
30F/70E
Flat-Grained
Flat-Grained
Flat-Grained
Predominant
Grain
Orientation
Down
Up
Up
Up
Up
Down
Down
Down
Up
Up
Down
Down
Up
Down
Down
Down
Up
Up
Up
Up
Up
Down
Down
Up
Down
Up
Up
Up
Up
Predominant
Ring Spacing
Wide
Medium
Close
Medium
Medium
Wide
Medium
Tight
Medium
Wide
Medium
Medium
Tight
Medium
Tight
Medium
Medium
Wide
Wide
Tight
Medium-wide
Tight
Wide
Tight
Medium
Wide
Medium
Medium
Predominant
Wood Type
Heartwood
Sapwood
Heartwood
Heartwood
Sapwood
Sapwood
Sapwood
Sapwood
Sapwood
Heartwood
Sapwood
Sapwood
Sapwood
Sapwood
Sapwood
Heartwood
Heartwood
Sapwood
Heartwood
Sapwood
Sapwood
Sapwood
Heartwood
Sapwood
Heartwood
Heartwood
Sapwood
Sapwood
Sapwood
Predominant
Wood
Season
Early
Late
50/50
Late
Early
Early
50/50
Late
Late
Early
Early
Early
Early
Early
Early
Early
60E/40L
70E/30L
Early
Early
Early
Early
Early
40E/60L
Early
Early
Early
Early
Late
63
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Board
ID
c-cc
C-CD
C-CE
C-E
C-N
C-S
Board
Length
(in)
174
174.5
174.5625
136
152.25
189.1875
Board
Length
(cm)
442.0
443.2
443.4
345.4
386.7
480.5
Predominant
Grain Type
Flat-Grained
Flat-Grained
Flat-Grained
40F/60E
Flat-Grained
Flat-Grained
Predominant
Grain
Orientation
Down
Up
Down
Down
Up
Up
Predominant
Ring Spacing
Medium
Tight
Medium
Medium
Medium
Wide
Predominant
Wood Type
Sapwood
Heartwood
Sapwood
Heartwood
Sapwood
Sapwood
Predominant
Wood
Season
Early
Late
Early
Early
50/50
Early
4.2 Coating Application Data
The volumes of coating applied to the A boards, the C boards, and the N boards (the
untreated boards) on each minideck were determined as was the mass of coating
applied (no coating mass data are provided for coating #1, because the decision to
measure mass was made after the coating #1 decks were coated). These data are
summarized in Table 4-2. Figure 4.1 shows the total volume and mass of each
coating applied sorted by coating ID. Note that coatings were applied in strict
accordance with manufacturers' printed instructions, including the number of
coatings to apply. Film thickness proved to be quite difficult to measure on wood
substrates, so film thicknesses were only measured on several minidecks; these data
are not presented.
4.3 Wood Core Sample Data
Each source board used in the construction of the minidecks had up to four core
samples taken from it. They were subsequently digested and analyzed for CCA
content. The wood core data are presented in Table 4-3 (for source A) and Table 4-4
(for source C), with averages, standard deviations, and relative standard deviations
(RSD) presented for each board and with summary statistics at the end of each table
for each source (A and C). Note that some of the boards listed in the tables below
were not used to construct minidecks; however, they are included here for
completeness. Complete data showing the results of each individual measurement are
provided in Appendix J.
64
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Table 4-2. Coating Application Data Summary
Minideck
ID
1-A
1-B
1-C
N
Average
Std. Dev.
RSD
2-A
2-B
2-C
N
Average
Std. Dev.
RSD
3-A
3-B
3-C
N
Average
Std. Dev.
RSD
4-A
4-B
4-C
N
Average
Std. Dev.
RSD
5-A
5-B
5-C
N
Average
Std. Dev.
RSD
A Board App.
Vol. (mL)
100
100
100
3
100.0
0.0
0.0%
70
60
60
3
63.3
5.8
9.1%
80
80
70
3
76.7
5.8
7.5%
60
60
60
3
60.0
0.0
0.0%
25
25
30
3
26.7
2.9
10.8%
C Board App.
Vol. (mL)
60
80
80
3
73.3
11.5
15.7%
55
45
55
3
51.7
5.8
11.2%
50
50
60
3
53.3
5.8
10.8%
30
45
40
3
38.3
7.6
19.9%
30
25
35
3
30.0
5.0
16.7%
N Board App.
Vol. (mL)
100
90
110
3
100.0
10.0
10.0%
65
55
70
3
63.3
7.6
12.1%
110
90
110
3
103.3
11.5
1 1 .2%
55
60
80
3
65.0
13.2
20.4%
50
30
65
3
48.3
17.6
36.3%
A Board App.
Mass (g)
-
-
-
0
-
-
-
53.5
52.4
46.6
3
50.8
3.7
7.3%
23.4
22.3
26.1
3
23.9
2.0
8.2%
38.3
47.3
44.1
3
43.2
4.6
10.6%
30.4
32.9
27.2
3
30.2
2.9
9.5%
C Board App.
Mass (g)
-
-
-
0
-
-
-
46
39.9
50.5
3
45.5
5.3
11.7%
15.1
12.9
18.2
3
15.4
2.7
17.3%
38.3
35.5
43.1
3
39.0
3.8
9.9%
27.2
28.4
33
3
29.5
3.1
10.4%
N Board App.
Mass (g)
-
-
-
0
-
-
-
49.3
47.2
57.1
3
51.2
5.2
10.2%
36.4
40
35.9
3
37.4
2.2
6.0%
42.5
47.6
55.4
3
48.5
6.5
13.4%
51.8
52.1
62.3
3
55.4
6.0
10.8%
65
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Minideck
ID
6-A
6-B
6-C
N
Average
Std. Dev.
RSD
7-A
7-B
7-C
N
Average
Std. Dev.
RSD
8-A
8-B
8-C
N
Average
Std. Dev.
RSD
9-A
9-B
9-C
N
Average
Std. Dev.
RSD
10-A
10-B
10-C
N
Average
Std. Dev.
RSD
A Board App.
Vol. (mL)
60
50
45
3
51.7
7.6
14.8%
40
50
50
3
46.7
5.8
12.4%
50
50
45
3
48.3
2.9
6.0%
35
35
45
3
38.3
5.8
15.1%
80
60
70
3
70.0
10.0
14.3%
C Board App.
Vol. (mL)
40
70
40
3
50.0
17.3
34.6%
35
45
40
3
40.0
5.0
12.5%
40
30
35
3
35.0
5.0
14.3%
15
30
30
3
25.0
8.7
34.6%
80
50
60
3
63.3
15.3
24.1%
N Board App.
Vol. (mL)
70
50
45
3
55.0
13.2
24.1%
45
55
45
3
48.3
5.8
11.9%
50
60
60
3
56.7
5.8
10.2%
30
40
15
3
28.3
12.6
44.4%
115
100
100
3
105.0
8.7
8.2%
A Board App.
Mass (g)
51.3
36.2
48.5
3
45.3
8.0
17.7%
38
51.2
53.6
3
47.6
8.4
17.6%
45.9
41.9
34.8
3
40.9
5.6
13.8%
34.5
34.1
39.3
3
36.0
2.9
8.0%
34.6
33.4
31.6
3
33.2
1.5
4.5%
C Board App.
Mass (g)
43.3
48.1
38.9
3
43.4
4.6
10.6%
33.9
42.8
37
3
37.9
4.5
11.9%
30.6
36.4
32.4
3
33.1
3.0
9.0%
27.9
33.1
35.2
3
32.1
3.8
11.7%
29.3
24.6
24.4
3
26.1
2.8
10.6%
N Board App.
Mass (g)
54
49.4
46.7
3
50.0
3.7
7.4%
43.7
52.3
47.9
3
48.0
4.3
9.0%
46.4
52.6
50.7
3
49.9
3.2
6.4%
52.2
46.4
47.2
3
48.6
3.1
6.5%
58.4
53.3
49.5
3
53.7
4.5
8.3%
66
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Minideck
ID
11-A
11-B
11-C
N
Average
Std. Dev.
RSD
12-A
12-B
12-C
N
Average
Std. Dev.
RSD
13-A
13-B
13-C
N
Average
Std. Dev.
RSD
A Board App.
Vol. (mL)
90
80
80
3
83.3
5.8
6.9%
60
60
70
3
63.3
5.8
9.1%
-
-
—
0
-
-
-
C Board App.
Vol. (mL)
85
90
65
3
80.0
13.2
16.5%
40
50
50
3
46.7
5.8
12.4%
-
-
—
0
-
-
-
N Board App.
Vol. (mL)
110
95
75
3
93.3
17.6
18.8%
80
90
90
3
86.7
5.8
6.7%
-
-
—
0
-
-
-
A Board App.
Mass (g)
82
77.6
80.9
3
80.2
2.3
2.9%
58.3
63.5
64.9
3
62.2
3.5
5.6%
-
-
—
0
-
-
-
C Board App.
Mass (g)
73
57.8
52.6
3
61.1
10.6
17.3%
48.9
44.7
52.4
3
48.7
3.9
7.9%
-
-
—
0
-
-
-
N Board App.
Mass (g)
80.5
110.7
109.5
3
100.2
17.1
17.1%
71.6
85.3
88.8
3
81.9
9.1
11.1%
-
-
—
0
-
-
-
11
Figure 4.1 Coating Application (total of triplicate minidecks and both A and C sources)
67
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Table 4-3. Wood Core Sample Results for Source A
Statistical
Parameter
Wood Core As
(mg/kg)
Wood Core Cr
(mg/kg)
Wood Core Cu
(mg/kg)
Board A-AB
N
Average
Std. Dev.
RSD
3
2148.4
179.2
8.3%
3
2704.3
224.9
8.3%
3
1698.4
87.9
5.2%
Board A-AC
N
Average
Std. Dev.
RSD
4
1499.9
327.5
21.8%
4
1959.0
204.7
10.5%
4
1224.0
134.6
11.0%
Board A-AD
N
Average
Std. Dev.
RSD
4
2675.3
75.5
2.8%
4
3280.5
335.5
10.2%
4
1791.4
191.6
10.7%
Board A-AE
N
Average
Std. Dev.
RSD
4
851.1
977.9
114.9%
4
1023.2
1190.2
116.3%
4
610.5
656.1
107.5%
Board A-AF
N
Average
Std. Dev.
RSD
3
1424.4
142.2
10.0%
3
1691.5
188.9
1 1 .2%
3
982.9
118.5
12.1%
Board A-AG
N
Average
Std. Dev.
RSD
4
1865.1
395.9
21.2%
4
2227.3
413.3
18.6%
4
1288.3
323.4
25.1%
Board A-AH
N
Average
Std. Dev.
RSD
4
1106.0
738.1
66.7%
4
1293.7
871.1
67.3%
4
770.8
530.6
68.8%
68
-------
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Statistical
Parameter
Wood Core As
(mg/kg)
Wood Core Cr
(mg/kg)
Wood Core Cu
(mg/kg)
Board A-AJ
N
Average
Std. Dev.
RSD
4
1238.3
886.2
71.6%
4
2007.8
484.7
24.1%
4
1090.7
501.1
45.9%
Board A-AK
N
Average
Std. Dev.
RSD
4
2008.6
1115.4
55.5%
4
2192.7
1220.4
55.7%
4
1256.0
661.9
52.7%
Board A-AN
N
Average
Std. Dev.
RSD
3
2116.7
228.0
10.8%
3
2656.0
222.4
8.4%
3
1667.6
89.7
5.4%
Board A-AR
N
Average
Std. Dev.
RSD
4
382.8
444.9
116.2%
4
499.1
518.6
103.9%
4
281.1
275.6
98.1%
Board A-AZ
N
Average
Std. Dev.
RSD
4
2501.0
642.6
25.7%
4
2967.5
544.5
18.4%
4
1781.7
213.5
12.0%
Board A-BC
N
Average
Std. Dev.
RSD
3
1846.0
144.2
7.8%
3
2543.7
295.1
1 1 .6%
3
1515.8
229.7
15.2%
Board A-BE
N
Average
Std. Dev.
RSD
3
35.7
6.4
18.1%
3
36.6
4.6
12.6%
3
27.4
6.2
22.5%
69
-------
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Statistical
Parameter
Wood Core As
(mg/kg)
Wood Core Cr
(mg/kg)
Wood Core Cu
(mg/kg)
Board A-BG
N
Average
Std. Dev.
RSD
4
2188.1
370.5
16.9%
4
2589.0
346.8
13.4%
4
1543.0
202.2
13.1%
Board A-BN
N
Average
Std. Dev.
RSD
1
1521
-
-
1
1741
-
-
1
1079
-
-
Board A-BW
N
Average
Std. Dev.
RSD
2
1452.3
126.1
8.7%
2
1692.5
236.2
14.0%
2
1013.2
193.5
19.1%
Board A-BY
N
Average
Std. Dev.
RSD
3
1149.7
220.3
19.2%
3
1404.1
220.7
15.7%
3
859.3
121.1
14.1%
Board A-l
N
Average
Std. Dev.
RSD
3
1953.0
382.9
19.6%
3
2270.1
285.5
12.6%
3
1218.6
195.3
16.0%
Board A-L
N
Average
Std. Dev.
RSD
3
1510.1
309.2
20.5%
3
1954.2
276.7
14.2%
3
1206.2
221.6
18.4%
Board A-N
N
Average
Std. Dev.
RSD
4
1117.7
616.5
55.2%
4
1333.5
722.8
54.2%
4
825.0
512.7
62.1%
70
-------
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Statistical
Parameter
Wood Core As
(mg/kg)
Wood Core Cr
(mg/kg)
Wood Core Cu
(mg/kg)
Board A-O
N
Average
Std. Dev.
RSD
3
1598.4
51.2
3.2%
3
2191.4
297.7
13.6%
3
1292.2
188.2
14.6%
Board A-P
N
Average
Std. Dev.
RSD
3
1763.6
275.4
15.6%
3
2189.6
416.1
19.0%
3
1209.0
245.9
20.3%
Board A-Q
N
Average
Std. Dev.
RSD
3
2549.2
433.5
17.0%
3
3177.5
554.1
17.4%
3
2002.8
301.6
15.1%
Board A-R
N
Average
Std. Dev.
RSD
3
1913.6
435.3
22.7%
3
2606.8
135.5
5.2%
3
1558.4
146.8
9.4%
Board A-S
N
Average
Std. Dev.
RSD
3
1559.7
92.3
5.9%
3
1824.3
138.3
7.6%
3
1027.1
107.8
10.5%
Board A-T
N
Average
Std. Dev.
RSD
3
1927.8
105.9
5.5%
3
2316.2
140.7
6.1%
3
1375.7
67.6
4.9%
Board A-U
N
Average
Std. Dev.
RSD
2
885.0
1193.5
134.9%
2
1146.3
1568.0
136.8%
2
711.3
943.0
132.6%
71
-------
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Statistical
Parameter
Wood Core As
(mg/kg)
Wood Core Cr
(mg/kg)
Wood Core Cu
(mg/kg)
Board A-V
N
Average
Std. Dev.
RSD
3
759.8
305.4
40.2%
3
1012.6
364.8
36.0%
3
535.1
199.2
37.2%
Board A-X
N
Average
Std. Dev.
RSD
4
1711.8
424.4
24.8%
4
2387.5
325.8
13.6%
4
1461.6
149.6
10.2%
Board A-Y
N
Average
Std. Dev.
RSD
3
2696.8
524.4
19.4%
3
3250.2
614.1
18.9%
3
1847.6
309.0
16.7%
Board A-Z
N
Average
Std. Dev.
RSD
3
2496.0
710.0
28.4%
3
2921.6
613.2
21.0%
3
1618.5
327.1
20.2%
For All A Boards
N
Average
Std. Dev.
RSD
Min
Max
104
1645.4
787.7
47.9%
28
3445
104
2045.3
917.0
44.8%
34
3933
104
1203.4
543.5
45.2%
21
2186
72
-------
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Table 4-4. Wood Core Sample Results for Source C
Statistical
Parameter
Wood Core As
(mg/kg)
Wood Core Cr
(mg/kg)
Wood Core Cu
(mg/kg)
Board C-AA
N
Average
Std. Dev.
RSD
4
2185.7
787.9
36.0%
4
2302.8
707.9
30.7%
4
1517.3
309.9
20.4%
Board C-AC
N
Average
Std. Dev.
RSD
4
2051.2
520.2
25.4%
4
2171.9
618.7
28.5%
4
1346.4
405.0
30.1%
Board C-AD
N
Average
Std. Dev.
RSD
4
1730.6
206.5
11.9%
4
1729.0
250.8
14.5%
4
1075.2
182.0
16.9%
Board C-AE
N
Average
Std. Dev.
RSD
3
2405.2
939.4
39.1%
3
2323.8
753.8
32.4%
3
7803.6
11584.3
148.4%
Board C-AH
N
Average
Std. Dev.
RSD
4
1546.6
155.1
10.0%
4
1561.7
186.6
12.0%
4
941.9
78.4
8.3%
Board C-AI
N
Average
Std. Dev.
RSD
3
2650.3
428.2
16.2%
3
2709.7
612.8
22.6%
3
1607.3
369.4
23.0%
Board C-AK
N
Average
Std. Dev.
RSD
4
225.6
222.2
98.5%
4
248.5
206.2
83.0%
4
151.7
116.2
76.6%
73
-------
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Statistical
Parameter
Wood Core As
(mg/kg)
Wood Core Cr
(mg/kg)
Wood Core Cu
(mg/kg)
Board C-AM
N
Average
Std. Dev.
RSD
4
2580.4
207.0
8.0%
4
2597.1
181.5
7.0%
4
1527.5
194.8
12.8%
Board C-AN
N
Average
Std. Dev.
RSD
4
874.1
484.3
55.4%
4
886.8
458.3
51.7%
4
540.6
239.0
44.2%
Board C-AP
N
Average
Std. Dev.
RSD
4
2555.5
667.7
26.1%
4
2653.5
648.8
24.5%
4
1706.5
387.1
22.7%
Board C-AS
N
Average
Std. Dev.
RSD
4
1490.2
1261.6
84.7%
4
1495.9
1233.2
82.4%
4
921.2
733.4
79.6%
Board C-BE
N
Average
Std. Dev.
RSD
4
2784.7
314.3
11.3%
4
2649.8
251.9
9.5%
4
1612.9
160.1
9.9%
Board C-BI
N
Average
Std. Dev.
RSD
2
1279.4
114.0
8.9%
2
1203.1
182.6
15.2%
2
688.3
125.7
18.3%
Board C-BJ
N
Average
Std. Dev.
RSD
3
2037.8
727.8
35.7%
3
1995.6
745.1
37.3%
3
1260.2
534.0
42.4%
74
-------
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Statistical
Parameter
Wood Core As
(mg/kg)
Wood Core Cr
(mg/kg)
Wood Core Cu
(mg/kg)
Board C-BL
N
Average
Std. Dev.
RSD
4
3157.9
573.8
18.2%
4
3162.5
378.9
12.0%
4
1979.2
204.9
10.4%
Board C-BM
N
Average
Std. Dev.
RSD
3
1463.8
1317.7
90.0%
3
1451.8
1308.3
90.1%
3
933.4
893.2
95.7%
Board C-BN
N
Average
Std. Dev.
RSD
1
2544
-
-
1
2602
-
-
1
1648
-
-
Board C-BO
N
Average
Std. Dev.
RSD
4
1518.7
679.7
44.8%
4
1488.4
655.8
44.1%
4
888.8
410.0
46.1%
Board C-BP
N
Average
Std. Dev.
RSD
3
2603.7
680.8
26.1%
3
2748.1
881.2
32.1%
3
1722.1
555.3
32.2%
Board C-BR
N
Average
Std. Dev.
RSD
3
1431.9
149.1
10.4%
3
1380.3
142.4
10.3%
3
809.9
113.0
13.9%
Board C-BT
N
Average
Std. Dev.
RSD
1
1386
-
-
1
1367
-
-
1
831
-
-
75
-------
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Statistical
Parameter
Wood Core As
(mg/kg)
Wood Core Cr
(mg/kg)
Wood Core Cu
(mg/kg)
Board C-BU
N
Average
Std. Dev.
RSD
3
2855.0
588.9
20.6%
3
3128.9
684.7
21.9%
3
1867.3
395.2
21.2%
Board C-BW
N
Average
Std. Dev.
RSD
3
562.0
293.5
52.2%
3
571.1
304.6
53.3%
3
347.5
151.6
43.6%
Board C-BX
N
Average
Std. Dev.
RSD
4
2301.4
993.6
43.2%
4
2309.6
991.5
42.9%
4
1469.8
626.1
42.6%
Board C-BY
N
Average
Std. Dev.
RSD
3
2507.9
528.2
21.1%
3
2578.5
459.8
17.8%
3
1790.5
312.3
17.4%
Board C-BZ
N
Average
Std. Dev.
RSD
4
1343.2
439.5
32.7%
4
1486.0
559.1
37.6%
4
847.4
337.1
39.8%
Board C-CA
N
Average
Std. Dev.
RSD
3
3171.3
581.7
18.3%
3
3224.6
490.2
15.2%
3
1983.8
287.8
14.5%
Board C-CC
N
Average
Std. Dev.
RSD
2
1435.9
12.7
0.9%
2
1356.5
32.2
2.4%
2
807.2
2.0
0.2%
76
-------
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Statistical
Parameter
Wood Core As
(mg/kg)
Wood Core Cr
(mg/kg)
Wood Core Cu
(mg/kg)
Board C-CD
N
Average
Std. Dev.
RSD
4
1194.1
798.9
66.9%
4
1162.8
777.0
66.8%
4
671.2
449.8
67.0%
Board C-CE
N
Average
Std. Dev.
RSD
2
2425.5
435.9
18.0%
2
2425.5
435.9
18.0%
2
1520.8
284.8
18.7%
Board C-E
N
Average
Std. Dev.
RSD
3
2946.3
1236.1
42.0%
3
2832.7
1330.9
47.0%
3
1627.9
451.5
27.7%
Board C-N
N
Average
Std. Dev.
RSD
3
2988.3
549.8
18.4%
3
2966.6
618.7
20.9%
3
1832.1
465.0
25.4%
Board C-S
N
Average
Std. Dev.
RSD
4
3675.9
1047.1
28.5%
4
3736.5
840.9
22.5%
4
2173.5
310.8
14.3%
ALL C Boards
N
Average
Std. Dev.
RSD
Min
Max
107
2074.2
990.1
48.9%
65
4624
107
2095.8
997.4
48.8%
96
4624
107
1465.0
2016.1
138.6%
57
21179
AWPA standards allow the actives composition of CCA-C - the formulation used to
treat the wood used in this study - to vary between 44.5 - 50.5% for CrO3, 17.0 -
77
-------
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
21.0% for CuO, and 30.0 - 38.0% for As2O5 in a specific assay zone, the outer 0.6
in (15 mm) (Lebow, 1996). Knowing that the source wood for this project was
treated to target retentions of 0.40 pounds per cubic foot (pcf), hypothetical, ideal
actives composition (analyte concentrations) can be calculated for each CCA analyte:
0.190 pcf (86.1 g/cf) CrO3, 0.074 pcf (33.6 g/cf) CuO, and 0.136 pcf (61.7 g/cf)
As2O5. Furthermore, the average dry, pretreatment density of SYP is 32 pcf, or 14.5
kg/cf. Thus, predicted levels of CCA analytes in the study wood core samples can be
approximated as:
CrO3 (86.1 g/cf)/(14.5 kg/cf)x(1000 mg/g) = 5,938 mg/kg
CuO (33.6 g/cf) / (14.5 kg/cf) x (1000 mg/g) = 2,317 mg/kg
As2O5 (61.7 g/cf) / (14.5 kg/cf) x (1000 mg/g) = 4,255 mg/kg
The overall average results in Tables 4.3 and 4.4 (note that these are reported as
elemental solid-phase concentrations) compare favorably with expected ratio of
concentrations of CCA analytes, although there are some wood core sample
datapoints that are clear outliers and overall variability is relatively high at about
50% RSD. Note that these RSDs listed should not be interpreted as indicators of data
quality, but rather as indicators of the natural variability in wood core CCA
concentrations within and between boards. Additionally, because of the way that
boards are cut from the tree, taking core samples from the wide face - as done in this
study - increases the likelihood that heartwood will be sampled. If the narrow faces
had been sampled, sapwood would have more consistently been sampled and the
values would have likely been more consistently high and less variable. A summary
of the nominal (ideal), source A, and source C CCA actives composition is provided
in Table 4.5.
Table 4.5 Comparison of Nominal, Source A, and Source C CCA Actives Composition
As (mg/kg)
As as As2O5 (mg/kg)
As205 (%)
Cr (mg/kg)
Cr as CrO3 (mg/kg)
Cr03 (%)
Cu (mg/kg)
Cu as CuO (mg/kg)
Nominal CCA
4,255
34.0(30.0-38.0)
5,938
47.5 (44.5-50.5)
2,317
Source A
1,645
2,522
31.7
2,045
3,933
49.4
1,203
1,506
Source C
2,075
3,182
35.2
2,095
4,029
44.5
1,465
1,834
78
-------
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
CuO (%)
18.5(17.0-21.0)
18.9
20.3
79
-------
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
4.4 Baseline Wipe Sample Data
Each source board used in the construction of the minidecks had at least two baseline
wipe samples taken from it prior to coating. These samples were digested, and
analyzed for CCA content. The baseline wipe sample results were used to establish
baseline DA concentrations for the PSAs on the minidecks and then to assess coating
efficacy (via calculation methods 1 and 2, as described in Section 3.1.2) by
calculating percent reduction in DA post-coat, at various time (sampling) intervals.
However, it is also instructive to look at the baseline data on its own, to assess the
variability of DA across each board (intraboard) and between boards (interboard) and
source decks. Table 4-6 (for source A) and Table 4-7 (for source C) provide
summary statistics for each board and each source deck. The full dataset showing the
individual specimen baseline values is provided in Appendix K. The tables show
averages, standard deviations, and relative standard deviation (RSD) for each board
and include summary statistics at the end of each table for each source (A and C). As
with the wood core sample results, RSDs should not be interpreted as indicators of
data quality, but rather as indicators of natural variability within and between boards.
Like the wood core sample data, overall baseline wipe sample variability is relatively
high (around 50% RSD). Intraboard variability (that is, variability between sampling
area DAs along a given board) likewise varies: some are relatively low (5-20% RSD)
while others are quite high (>50% RSD). While its overall (interboard) variability
was relatively high, the newer C deck appears to have significantly lower intraboard
variability than the A source deck. For reference, research by Stilwell (2003a)
showed an intraboard variability (RSD) of 17% versus an interboard (between-board)
variability of 3 9%.
Figures 4-2 through 4-7 provide simple distribution and box plots of the baseline
data. Similar plots are provided, grouped by board instead of coating, in Appendix L.
The figures are grouped by analyte and source, and plot coating on the x-axis versus
baseline DA on the y-axis. The top plot in each figure plots simple data distribution,
showing all of the baseline data points, sorted by coating. The bottom plot in each
figure is a box plot which provides an excellent visual summary of many important
aspects of the distribution. The box stretches from the lower hinge (defined as the
25th percentile) to the upper hinge (defined as the 75th percentile) and therefore
contains the middle half of the scores in the distribution. The median is shown as a
line across the box. Therefore, % of the distribution is between this line and the top
of the box and % of the distribution is between this line and the bottom of the box.
80
-------
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
The plus symbol (+) shows the mean. In these plots, the bars on either side of the
box define the minimum and maximum.
Table 4-6. Baseline Wipe Sample Summary for Source Deck A
Statistical
Parameter
DAs
(MQ/cm2)
DCr
(MQ/cm2)
DCu
(MQ/cm2)
Board A-AC
N
Average
Std. Dev.
RSD
5
1.63
0.41
24.9%
5
1.62
0.28
17.0%
5
0.74
0.25
34.0%
Board A-AD
N
Average
Std. Dev.
RSD
5
2.79
0.60
21 .4%
5
3.05
0.44
14.4%
5
1.43
0.45
31 .4%
Board A-AE
N
Average
Std. Dev.
RSD
5
1.36
0.29
21 .2%
5
1.87
1.11
59.4%
5
1.01
0.30
30.0%
Board A-AF
N
Average
Std. Dev.
RSD
2
1.58
0.94
59.3%
2
1.48
0.83
56.1%
2
0.83
0.56
67.4%
Board A-AG
N
Average
Std. Dev.
RSD
6
1.42
0.63
44.5%
6
1.50
0.66
43.7%
6
0.65
0.16
24.6%
Board A-AH
N
Average
Std. Dev.
RSD
6
0.70
0.29
41 .2%
6
0.72
0.24
33.8%
6
0.46
0.15
33.1%
81
-------
Statistical
Parameter
DAs
(MQ/cm2)
DCr
(MQ/cm2)
DCu
(MQ/cm2)
Board A-AJ
N
Average
Std. Dev.
RSD
6
1.76
0.20
1 1 .4%
6
1.93
0.21
10.9%
6
0.86
0.13
14.9%
Board A-AN
N
Average
Std. Dev.
RSD
5
3.89
1.26
32.4%
5
4.94
1.86
37.6%
5
0.63
0.14
22.6%
Board A-AR
N
Average
Std. Dev.
RSD
5
1.73
1.17
67.6%
5
1.68
1.30
77.5%
5
0.91
0.64
70.0%
Board A-AT
N
Average
Std. Dev.
RSD
5
1.32
0.28
20.9%
5
1.57
0.40
25.2%
5
0.75
0.13
16.7%
Board A-BC
N
Average
Std. Dev.
RSD
5
1.57
0.41
26.2%
5
1.84
0.41
22.5%
5
0.72
0.08
10.5%
Board A-BG
N
Average
Std. Dev.
RSD
6
1.54
0.27
17.3%
6
1.50
0.35
23.0%
6
0.73
0.12
16.9%
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
82
-------
Statistical
Parameter
DAs
(MQ/cm2)
DCr
(MQ/cm2)
DCu
(MQ/cm2)
Board A-BM
N
Average
Std. Dev.
RSD
3
1.42
0.51
35.7%
3
1.68
0.54
32.2%
3
0.51
0.17
32.8%
Board A-BW
N
Average
Std. Dev.
RSD
6
0.81
0.28
34.3%
6
0.71
0.25
35.2%
6
0.50
0.17
34.3%
Board A-BY
N
Average
Std. Dev.
RSD
5
1.53
0.51
33.5%
5
1.57
0.51
32.6%
5
0.91
0.30
33.0%
Board A-l
N
Average
Std. Dev.
RSD
5
1.74
0.51
29.1%
5
2.16
0.36
16.7%
5
0.76
0.15
19.5%
Board A-L
N
Average
Std. Dev.
RSD
5
0.75
0.20
26.3%
5
0.85
0.20
23.5%
5
0.45
0.07
15.4%
Board A-O
N
Average
Std. Dev.
RSD
5
2.17
0.69
31 .6%
5
2.38
0.81
34.3%
5
0.95
0.26
27.0%
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
83
-------
Statistical
Parameter
DAs
(MQ/cm2)
DCr
(MQ/cm2)
DCu
(MQ/cm2)
Board A-P
N
Average
Std. Dev.
RSD
5
2.12
1.09
51 .5%
5
1.73
1.00
57.8%
5
1.12
0.25
22.3%
Board A-Q
N
Average
Std. Dev.
RSD
5
2.70
1.05
38.9%
5
2.80
1.19
42.6%
5
1.10
0.35
31 .8%
Board A-T
N
Average
Std. Dev.
RSD
5
2.19
0.60
27.3%
5
2.17
0.57
26.4%
5
1.18
0.41
34.5%
Board A-U
N
Average
Std. Dev.
RSD
5
0.95
0.41
42.9%
5
1.11
0.52
47.0%
5
0.54
0.16
29.0%
Board A-V
N
Average
Std. Dev.
RSD
5
1.60
0.66
41.1%
5
1.70
0.62
36.1%
5
0.67
0.23
33.9%
Board A-X
N
Average
Std. Dev.
RSD
5
1.75
0.50
28.4%
5
1.66
0.49
29.4%
5
0.66
0.18
27.0%
Board A-Y
N
Average
Std. Dev.
RSD
5
3.95
1.75
44.2%
5
4.33
1.53
35.3%
5
1.33
0.47
35.2%
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
84
-------
Statistical
Parameter
DAs
(ug/cm2)
DCr
(ug/cm2)
DCu
(ug/cm2)
Board A-Z
N
Average
Std. Dev.
RSD
5
2.34
0.29
12.3%
5
2.61
0.40
15.4%
5
0.96
0.14
14.7%
All A Boards
N
Average
Std. Dev.
RSD
Min
Max
130
1.81
1.02
43.4%
0.38
5.85
130
1.96
1.19
39.3%
0.31
7.38
130
0.82
0.36
56.5%
0.24
2.19
Table 4-7. Baseline Wipe Sample Summary for Source Deck C
Statistical
Parameter
DAs
(ug/cm2)
DCr
(ug/cm2)
DCu
(ug/cm2)
Board C-AA
N
Average
Std. Dev.
RSD
5
0.63
0.17
27.4%
5
0.84
0.20
23.5%
5
0.31
0.07
22.2%
Board C-AC
N
Average
Std. Dev.
RSD
6
0.85
0.10
1 1 .8%
6
1.17
0.14
1 1 .7%
6
0.44
0.04
10.1%
Board C-AD
N
Average
Std. Dev.
RSD
7
0.68
0.16
23.8%
7
0.91
0.17
18.6%
7
0.34
0.07
21 .3%
Board C-AE
N
Average
Std. Dev.
RSD
6
1.67
0.30
18.1%
6
2.29
0.31
13.7%
6
0.62
0.09
15.2%
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
85
-------
Statistical
Parameter
DAs
(MQ/cm2)
DCr
(MQ/cm2)
DCu
(MQ/cm2)
Board C-AI
N
Average
Std. Dev.
RSD
5
0.95
0.15
15.7%
5
1.30
0.12
8.9%
5
0.49
0.05
10.0%
Board C-AJ
N
Average
Std. Dev.
RSD
5
1.39
0.08
5.7%
5
1.85
0.15
8.2%
5
0.75
0.09
12.2%
Board C-AK
N
Average
Std. Dev.
RSD
2
0.59
0.07
12.3%
2
0.88
0.05
6.1%
2
0.48
0.04
7.4%
Board C-AM
N
Average
Std. Dev.
RSD
6
1.06
0.20
18.5%
6
1.45
0.28
19.2%
6
0.55
0.06
10.9%
Board C-AN
N
Average
Std. Dev.
RSD
5
1.24
0.31
24.9%
5
1.36
0.72
53.0%
5
0.54
0.09
16.7%
Board C-AP
N
Average
Std. Dev.
RSD
5
0.53
0.15
28.6%
5
0.83
0.19
23.2%
5
0.41
0.13
30.9%
Board C-BE
N
Average
Std. Dev.
RSD
5
1.39
0.19
14.0%
5
1.73
0.29
16.8%
5
0.83
0.49
58.7%
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
86
-------
Statistical
Parameter
DAs
(MQ/cm2)
DCr
(MQ/cm2)
DCu
(MQ/cm2)
Board C-BI
N
Average
Std. Dev.
RSD
5
0.81
0.17
21 .0%
5
1.09
0.21
19.0%
5
0.63
0.15
23.6%
Board C-BJ
N
Average
Std. Dev.
RSD
5
2.32
0.61
26.5%
5
2.77
0.53
19.3%
5
1.38
0.37
26.7%
Board C-BM
N
Average
Std. Dev.
RSD
7
0.67
0.16
24.7%
7
0.98
0.22
22.7%
7
0.33
0.07
19.7%
Board C-BO
N
Average
Std. Dev.
RSD
4
0.70
0.05
7.6%
4
1.01
0.11
1 1 .3%
4
0.40
0.07
17.5%
Board C-BP
N
Average
Std. Dev.
RSD
5
0.73
0.22
30.1%
5
1.02
0.31
30.3%
5
0.32
0.07
22.1%
Board C-BT
N
Average
Std. Dev.
RSD
6
0.53
0.08
15.6%
6
0.74
0.12
15.9%
6
0.35
0.08
23.7%
Board C-BU
N
Average
Std. Dev.
RSD
3
0.92
0.26
28.9%
3
1.29
0.32
25.0%
3
0.56
0.24
43.4%
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
87
-------
Statistical
Parameter
DAs
(MQ/cm2)
DCr
(MQ/cm2)
DCu
(MQ/cm2)
Board C-BW
N
Average
Std. Dev.
RSD
3
0.48
0.20
42.1%
3
0.64
0.18
28.0%
3
0.32
0.03
9.1%
Board C-BX
N
Average
Std. Dev.
RSD
5
0.94
0.31
33.4%
5
1.31
0.45
34.7%
5
0.44
0.14
32.2%
Board C-BY
N
Average
Std. Dev.
RSD
3
0.65
0.05
8.1%
3
0.96
0.06
6.7%
3
0.36
0.03
7.1%
Board C-BZ
N
Average
Std. Dev.
RSD
7
0.71
0.30
42.2%
7
1.06
0.40
37.2%
7
0.46
0.14
31 .4%
Board C-CA
N
Average
Std. Dev.
RSD
3
0.67
0.21
30.7%
3
0.96
0.24
25.5%
3
0.47
0.05
1 1 .4%
Board C-CC
N
Average
Std. Dev.
RSD
4
0.80
0.14
18.0%
4
1.11
0.17
15.1%
4
0.55
0.05
8.9%
Board C-CD
N
Average
Std. Dev.
RSD
5
1.40
0.47
33.9%
5
1.79
0.56
31.2%
5
1.02
0.34
33.5%
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
-------
Statistical
Parameter
DAs
(MQ/cm2)
DCr
(MQ/cm2)
DCu
(MQ/cm2)
Board C-CE
N
Average
Std. Dev.
RSD
3
1.38
0.26
18.5%
3
1.87
0.30
15.9%
3
1.14
0.23
20.4%
Board C-E
N
Average
Std. Dev.
RSD
5
1.44
0.28
19.3%
5
1.72
0.28
16.1%
5
0.52
0.06
1 1 .3%
Board C-N
N
Average
Std. Dev.
RSD
5
1.25
0.18
14.3%
5
1.51
0.17
1 1 .2%
5
0.38
0.05
12.5%
Board C-S
N
Average
Std. Dev.
RSD
5
1.34
0.59
44.2%
5
1.75
0.72
41.0%
5
0.40
0.11
27.2%
All C Boards
N
Average
Std. Dev.
RSD
Min
Max
140
1.00
0.48
51 .7%
0.28
3.05
140
1.33
0.57
57.1%
0.20
3.56
140
0.54
0.29
46.2%
0.21
1.96
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
89
-------
Baseline Arsenic (ug/cnrC) by Coating, Precoat Source = A
Arsenic
6
5-
4-
3-
1 2 3 4 5 6 7 8 9 10 11 12 13
Coating ID
Arsenic (ug/cmxx2) by Coating, Precoat, Source = A
6-
5-
C
4 ~
c
e
n
t 3-
r
t
n
1 -
o-
-,-_
T
-
f
I
i
T
— i
]
T
-f-
1
T
r=n
•t
T
^
*
^z
i
+
^^
n
: Q
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
1 2 3 4 5 6 7 8 9 10 11 12 13
Coating ID
Figure 4-2. Distribution (top) and box (bottom) plot, baseline DAs, by Coating, Source A
90
-------
Baseline Chromium (ug/cm2) by Coaling, Precoat, Source = A
Chr orni urn
6'
5'
4
3
21
C
o
n
c
e
n
t 4
r
t
i
o
n
6-
2-
o-
I 2 1 4 5 6 7 8 9 10 11 12 13
Coating ID
Chromium (ug/cm~2) by Coating, Precoat Source = A
?
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
1 2 3 4 5 6 7 8 9 10 11 12
Coating ID
Figure 4-3. Distribution (top) and box (bottom) plot, baseline DCr, by Coating, Source A
91
-------
Baseline Copper (ug/om2) by Coating, Precoat, Source = A
Copper
1.6;
1.5:
1 .4
1.3
1.2:
1 . 1
1.0;
0.9;
0.8:
0.7f
0.6
0.: j ]
-+ +
* •+
1 2 J 4 5
6 7 8
Cooting ID
10 11 12 13
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Copper (ug/cm'x2) by Coating, Precoat, Source = A
1.75 -
1 .50 -
.25 -
C
o
n
c
e
n
t 1.00 -
r
t
i
o
n
0.50 -
0.25 -
T
+
T
-i
:
i-
+
—
c-1
--
+
1 T
—
T
4-
T
+
T
T r
^
I
-h
T ;
±
--
T
0
2 3 4 5 6 7 8 9 10 11 12 13
Coat ing ID
Figure 4-4. Distribution (top) and box (bottom) plot, baseline DCu, by Coating, Source A
92
-------
Arsenic
31
2-
Baseline Arsenic (ug/cm2) by Coating, Precoat, Source = C
1 1 3 4 5 6 7 8 9 10 11 12 13
Coat ing ID
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Arsenic (ug/cmxs2) by Coating, Precoat, Source = C
3.0-
2,5 -
C
A
n 2.0-
c
e
n
t 1.5-
r
a
t
' 10-
0
n
0.5-
o -
I
+
T r .
n
qp
T
n
L
j.
i
h
r
b
- 1
n
d
L Y Y I
t-
+
X
-t-
TT
I u
H
-
-^
T
•*•
+
MM
f y ^ y i
5 6 7 8 9 10
Coat ing ID
II 12
Figure 4-5. Distribution (Top) and Box (Bottom) Plot, Baseline DAs,
by Coating, Source C
93
-------
Baseline Chromium (ug/cm2) by Coating, Precoat, Source = C
Chr orni urn
4-
3-
2-
1-
o-
4
4
:
t +
+ 4
* * t * *
4 * * * * ,
* * * 4 4 : ,
^ 4 *
•H
I 2
4 5 6 7 8 9 10 11 12 13
Coating ID
Chromium (ug/cm'x2) by Coating, Precoat, Source = C
3.5-
3.0-
C
X 2.5-
c
e
n
t 2.0-
r
(i
t
' 1 5-
0
n
i.o-
0.5-
•\
-
T
+
C
3
T
.
h
T
I
n
y
-^-
1 j
T
1
— t—
—
T
T -
7
4
^
T
,
--
-=-1
< i
4
ig i
1 2 3 4 5 6 7 8 9 10 11 12 13
Coating ID
Figure 4-6. Distribution (Top) and Box (Bottom) Plot, Baseline DCr,
by Coating, Source C
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
94
-------
Baseline Copper (ug/cm2) by Coating, Precoat, Source = C
Copper
1.6"
1.4
1.3
1. 1
1.0;
0.9-
0.8
0.7-
0.6;
0.5-
0.4:
6 7 8
Cooting ID
10 11 12 13
1.75 H
1.5C '
.25 -
C
o
n
c
e
n
t 1.00
r
a
t
0.75 -
0.50 -
0.25H
Copper (ug/cm's2) by Coating, Precoat, Source = C
i
T
T
2345678
Coat ing ID
9 10 11 12 U
Figure 4-7. Distribution (Top) and Box (Bottom) Plot, Baseline DCu,
by Coating, Source C
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
95
-------
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
4.4.1 Baseline Sample Proximity Analysis
An analysis was conducted to shed light on the method by which precoat baseline
values were determined for this study. That is, to determine whether there was a
stronger DA correlation between sampling areas closer on a board then between those
further apart. The results are graphically summarized in Figures 4-8 through 4-13. In
summary, such a trend was not discovered. In other words, there is no statistical
evidence that surfaces closer to one another on a given board are more strongly
correlated than those surfaces that are further apart. This finding would tend to suggest
that using a simple board-specific average baseline could be as appropriate as the
method that was utilized in the study (averaging adjacent sampling areas).
Figures 4-8 through 4-13 each contain two plots and are grouped by source and CCA
analyte. The top plot shows the mean of the natural logarithms of baseline DA (y-axis)
versus position on the x-axis, where position is measured sequentially from the far end
of a given board. The first position (1) would be between the first two sets of nailholes,
position 2 would be between the second and third sets of nailholes, and so on. Note that
there is much less data for calculating the means the further along a board, since some
boards are shorter than others. Therefore, means at positions 8 and 9 for example
should be viewed considering that they may have been calculated using only a few data
points.
The bottom plot in each figure shows the mean of the squared differences between DA
measured at each of the sampling areas along each board. Distance, on the x-axis, is
calculated as the number of "positions" between each set of pairwise samples. So, a
distance of 1, for example would be for sampling areas that were adjacent to one
another, while a distance of 4 would be for sampling areas separated by three other
possible sampling area segments (four sets of nailholes). If there had been a belter
correlation between DA from sampling areas closer together, then we would see lower
MSDs corresponding to lower distances. Instead, we see very weak or no trends in this
regard.
96
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0.8
0.6
J 04
0.2
0.6
0.5
Q
Si 0 3
to
jf
Position
23456789
Distance
Figure 4-8. Mean vs Position and MSD vs Distance for Source A DAs Baseline
Evaluation of the
Effectiveness of Coatings in
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Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
97
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0.8
0.6
1 0.4
0.6
0.5
V
2! 0.3
s
0.2
Position
12345
Distance
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Figure 4-9. Mean vs Position and MSD vs Distance for Source A DCr Baseline
98
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0.05
-0.05
-0.1
1
re
CD
J= -0.25
i
^ -0.3
-0.4
-0.45
0.35
0.3
9 13
Position
4 5
Distance
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Figure 4-10. Mean vs Position and MSD vs Distance for Source A DCu Baseline
99
-------
0.3
-0.3
-0.4
0.25
10
Position
4 6
Distance
Figure 4-11. Mean vs Position and MSD vs distance for Source C DAs Baseline
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
100
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0.5
10.3
3 0.2
468
Position
10
0.35
0.3
4 6
Distance
Figure 4-12. Mean vs Position and MSD vs Distance for Source C DCr Baseline
Evaluation of the
Effectiveness of Coatings in
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Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
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9 May 2005
101
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•a. -o.3
.£ -04
s
flj
£9-
~- -0.5
-0.6
-0.7
-0.8
V
2! 0.08
to
D
D-
t/1
S 0.06
0.04
0.02
10
Position
4 6
Distance
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Figure 4-13. Mean vs Position and MSD vs Distance for Source C DCu Baseline
102
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Evaluation of the
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Wood
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9 May 2005
4.4.2 Core Sample-Baseline DA Correlation Analysis
Average DA versus average wood core sample concentration has been plotted for each
board for which averages were available. The plots are presented as Figures 4-14 and
4-15 below for the A and C source boards, respectively. It appears that there is some
correlation between high DA and high core concentrations, particularly at the higher
concentrations and for source A. Note that CCA analyte concentrations are plotted as
elemental concentrations in Figures 4-14 and 4-15.
I
D) 3
n o
O O O ED
n
n
O D O fi o° 00
o
DA . A
D
D
n
1000 1500 2000
CCA Analyte (mg/kg)
Figure 4-14. Wood Core Concentration versus Baseline DA for Source A Boards
103
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Evaluation of the
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9 May 2005
o n
n
o
n n
n
n
o
OA
n
n
o
n
o
iS V>
A
DA A
A A
00 A
A A
cr
O
n
-O-
~r_r
O
o
A A
A
n
o°
o
1500 2000 2500
CCAAnalyte(mg/kg)
Figure 4-15. Wood Core Concentration versus Baseline DA for Source C Boards
4.5 Weather Data
A number of climatological measurements have been made at 30-minute intervals
during this study, as described in Section 2.8. The most relevant parameters in terms
of coating performance and sampling are: Solar Radiation (in Watts per square
meter), UV Index, Rainfall (in inches), Temperature (in degrees F), and Relative
Humidity (in %). Figures 4-16 through 4-20 plot daily average and running
cumulative totals for each parameter versus time, with the exception of the rainfall
plot (Figure 4-18) which shows daily total precipitation and cumulative total versus
time. On all plots, the dates of the sampling events are superimposed for reference.
Complete weather data collected through month 11 post-coating are provided in
Appendix M.
UV Index is an intensity measurement first defined by Environment Canada and
since adopted by the World Meteorological Organization. UV Index assigns a
number between 0 and 16 to the current UV intensity. The U.S. EPA categorizes the
104
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Wood
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9 May 2005
Index values as shown in Table 4-8. The lower the number, the lower the danger of
sunburn. The index values recorded by the Vantage ProPlus are the result of real time
measurements. In Figure 4-17, daily average values are presented graphically versus
time.
Table 4-8. UV Index and Exposure Category
Index Values
0-2
3-4
5-6
7-9
10+
Exposure Category
Minimal
Low
Moderate
High
Very High
350
8/17/2003 10/6/2003 11/25/2003 1/14/2004 3/4/2004 4/23/2004 6/12/2004 8/1/2004 9/20/2004
Date
Figure 4-16. Solar Radiation Data Summary
105
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8/17/2003 10/6/2003 11/25/2003 1/14/2004
8/1/2004 9/20/2004
Figure 4-17. UV Index Data Summary
8/17/2003 10/6/2003 11/25/2003 1/14/2004 3/4/2004 4/23/2004 6/12/2004 8/1/2004 9/20/2004
Figure 4-18. Rainfall Data Summary
Evaluation of the
Effectiveness of Coatings in
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Arsenic, Chromium, and
Copper from CCA Treated
Wood
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106
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Evaluation of the
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Wood
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9 May 2005
t = 1 month 11 = 3 month
9/10/03 11/10/03
8/17/2003 10/6/2003 11/25/2003 1/14/2004 3/4/2004 4/23/2004 6/12/2004 8/1/2004 9/20/2004
Figure 4-19. Temperature Data Summary
8/17/2003 10/6/2003 11/25/2003 1/14/2004 3/4/2004 4/23/2004 6/12/2004 8/1/2004 9/20/2004
Date
Figure 4-20. Humidity Data Summary
107
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4.6 Coating Performance Data
Table 2-2 is recreated here as Table 4-9 for convenience in reviewing this section. A
complete set of wipe sampling data, including data for both the PSA (M) samples
and baseline (BL) samples at each sampling event, is provided in Appendix N.
4.6.1 Coating Performance (DA vs Time)
Baseline and time series DA values for each CCA analyte, sorted by coating, and
averaged over the combined A and C sources are summarized in Tables 4-10 through
4-12. These data are shown graphically in Figures 4-21 through 4-23. Several very
general things can be said of the data as a whole. First, each coating, as well as the
positive controls (uncoated minidecks), show a significant decrease in DA between
baseline (precoat) and samples taken 1 month after coating. This shows a clear impact
on DA from rinsing or washing the minidecks. Second, the coated minidecks all have
lower DA than the positive controls, which indicates that coating (using any of the
coatings tested) mitigates DA to some degree. Third, DA goes up with time after
coating, most likely due to the effects of weathering and possibly abrasion on the
coating, although it should be noted that the uncoated positive controls show similar,
though generally less pronounced, trends.
The comparative performance of the coatings is discussed in detail in Section 4.6.2.
4.6.2 Statistical Analysis and Coating Rankings
The statistical methods used to obtain the results in this section are described in
Section 3.4.
Evaluation of the
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Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Table 4-9. Coating IDs and Descriptions
#
1
2
3
4
5
6
7
Product Type
Sealant
Sealant
Stain
Stain
Sealant
Sealant
Stain
Base
Oil
Oil
Oil
Oil
Water
Water
Water
Cover
Semi
Clear
Clear
Clear
Clear
Clear
Semi
Main Ingredients
Acrylic, alkyd, urethane
Acrylic
Alkyd
Acrylic, alkyd
Alkyd
Comments
"Cedar" with UV blocker
"Clear"
"Deep tone base"
"Clear stain"
"Clear"
"Clear"
"Cedar" with UV blocker
108
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Evaluation of the
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9 May 2005
#
8
9
10
11
12
13
Product Type
Stain
Paint
Paint
Other
Other
No coating
Base
Water
Water
Oil
Cover
Clear
Opaque
Opaque
Clear
Clear
Main Ingredients
Acrylic
Acrylic
Alkyd, polyurethane
Elastic vinyl
Polymer
Comments
"Tint base, solid" with no tint added*
"Gray". Latex, designed for porches and floors
"Gray". Designed for porches and floors
Designed for CCA encapsulation
Designed for CCA encapsulation
Uncoated control minidecks
* note that this product's labeling specifically states that it must be tinted before use.
An analysis of variance mixed model, similar to a split plot model in space and time,
was fit to the data for the purpose of identifying major sources of variation and
ultimately for comparing coating effectiveness after baseline adjustment, averaged
over the four time periods. The objective of the analysis with regard to coatings was
to identify groups of coatings exhibiting statistically distinguishable or
indistinguishable performance. The response variable analyzed was Y =
ln(DA/DABL) where DA is, as defined earlier, the compound of interest (As, Cr, Cu)
measured in the longitudinal study, and DABL is the corresponding baseline
measurement. For efficacious coatings, DA should be small relative to DABL, and
thus small values of Y on average indicate better coating performance. The split-plot
analysis of variance model included fixed effects: coating (1-13), source deck (A, C),
board face (up, down), time period (1, 2, 3, 4), and their interactions of all orders.
There were three replicate minidecks for each whole-plot treatment (coating). Error
terms for the split plot model were obtained from the nested effects:
minideck(coating), minideck*sourcedeck*boardface*(coatl), and minideck(time),
and the interaction term, mdeck*coatl*time. The model was chosen to enable
comparison of coatings averaged overtime. To this end, pairwise comparisons of
coatings were performed and the results are displayed in Figures 4-24 through 4-29.
The graphical displays were constructed by first ordering the coatings by their
average performance.
Then all possible pairs of coatings were tested for statistical significance at the 0.05
level of significance, adjusted using Tukey's multiple comparison procedure. Pairs of
coatings sharing a common underline are not significantly different, but those that do
not share a common underline are significantly different. The analysis was done
twice for all three CCA analytes, once using the data from all time periods (Figures
4-24, 4-26, and 4-28), and again using the data from only the fourth time period
(Figures 4-25, 4-27, 4-29).
109
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Wood
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9 May 2005
110
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Evaluation of the
Effectiveness of Coatings in
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Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Table 4-10. Average DAs (ug/cm ) vs Sampling Interval
Coating
Coating 1
Coating 2
Coating 3
Coating 4
Coating 5
Coating 6
Coating 7
Coating 8
Coating 9
Coating 10
Coating 1 1
Coating 12
Coating 13
Baseline
1.360
1.361
1.408
1.346
1.159
1.343
1.323
1.388
1.428
1.602
1.276
1.435
1.658
1 Month
0.060
0.136
0.026
0.100
0.176
0.102
0.094
0.053
0.009
0.009
0.005
0.077
0.474
3 Months
0.034
0.053
0.014
0.051
0.126
0.051
0.070
0.016
0.009
0.008
0.009
0.061
0.321
7 Months
0.058
0.067
0.044
0.077
0.144
0.112
0.069
0.023
0.020
0.023
0.034
0.123
0.391
11 Months
0.117
0.245
0.089
0.185
0.485
0.162
0.254
0.061
0.032
0.038
0.056
0.336
0.889
1.000 -
0.100
0.010
0.001
-Coating 1
Coating 4
-Coating 7
Coating 10
Coating 1 3
-Coating 2
-Coating 5
-Coating 8
Coating 11
Coating 3
-Coating 6
Coating 9
Coating 12
Time (months after coating)
Figure 4-21. Average DAs vs Time for All Coatings
111
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Table 4-11. Average DCr (pg/cm ) vs Sampling Interval
Coating
Coating 1
Coating 2
Coating 3
Coating 4
Coating 5
Coating 6
Coating 7
Coating 8
Coating 9
Coating 10
Coating 1 1
Coating 12
Coating 13
Baseline
1.542
1.540
1.606
1.601
1.352
1.542
1.589
1.679
1.658
1.794
1.504
1.845
1.918
1 Month
0.079
0.235
0.007
0.175
0.344
0.143
0.147
0.040
0.002
0.004
0.002
0.131
0.721
3 Months
0.060
0.092
0.005
0.087
0.255
0.064
0.112
0.015
0.002
0.006
0.005
0.103
0.503
7 Months
0.095
0.097
0.021
0.102
0.238
0.124
0.092
0.024
0.006
0.012
0.026
0.176
0.498
11 Months
0.256
0.434
0.126
0.399
0.890
0.226
0.381
0.090
0.021
0.043
0.091
0.544
1.262
•& 0100
Time (months after coating)
Figure 4-22. Average DCr vs Time for All Coatings
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
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112
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Table 4-12. Average DCu (|jg/cm2) vs Sampling Interval
Coating
Coating 1
Coating 2
Coating 3
Coating 4
Coating 5
Coating 6
Coating 7
Coating 8
Coating 9
Coating 10
Coating 1 1
Coating 12
Coating 13
Baseline
0.710
0.712
0.747
0.684
0.611
0.591
0.612
0.689
0.667
0.829
0.636
0.616
0.682
1 Month
0.041
0.098
0.026
0.059
0.079
0.063
0.071
0.033
0.011
0.013
0.018
0.038
0.226
3 Months
0.061
0.062
0.037
0.051
0.112
0.050
0.080
0.049
0.023
0.041
0.043
0.048
0.190
7 Months
0.058
0.056
0.041
0.053
0.084
0.055
0.055
0.031
0.013
0.027
0.030
0.061
0.164
11 Months
0.185
0.280
0.173
0.279
0.370
0.139
0.203
0.070
0.021
0.073
0.076
0.245
0.402
1.000 -
—•—Coating 1
— *— Coating 4
— I— Coating 7
Coating 10
*-Coating 13
—•—Coating 2
-*-Coating 5
Coating 8
Coating 1 1
Coating 3
—•—Coating 6
Coating 9
Coating 12
10
Time (months after coating)
Figure 4-23. Average DCu vs time for All Coatings
Evaluation of the
Effectiveness of Coatings in
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Arsenic, Chromium, and
Copper from CCA Treated
Wood
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9 May 2005
113
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Evaluation of the
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Arsenic, Chromium, and
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Wood
Interim Data Report
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9 May 2005
For example, for As using data for all time periods, the IDs of the coatings ranked
in order from lowest mean DA (best performing) to highest mean DA (worst
performing) appear in Figure 4-24. Thus coating #9 performed best. However, it is
not possible to statistically distinguish the performance of coating #9 from that of
coatings #10 and #11 (all three share a common underline), and it is inappropriate to
claim that #9 is better than #10 or #11; however, coating #9 performed significantly
better than all other coatings (#9 does not a share a common underline with any
coatings other than #10 and #11). Note that coatings #1, #6, #2, #4, #12, and #7 share
a common underline and thus their performances are statistically indistinguishable.
When interpreting the results in Figures 4-24 through 4-29, it should be kept in mind
that statistical significance depends to a great extent on the sample size.
Consequently, fewer statistically significant results are to be expected from the
analyses that used only data from the fourth time period. This manifests with bigger
groups having greater overlap (longer, overlapping lines). In light of this sample-size
effect, the results for all time periods and the fourth time period only are in good
agreement. Furthermore, the coating performances are reasonably consistent across
compounds as well (e.g., coatings #9 and #10 are the top two performers for all
compounds, except copper at 11 months after coating, where coating #9 leads the
pack, but coating #8 finishes just above coating #10).
4.6.3 Inter- and Intra-Coating Comparisons
Summaries of coating performance, expressed both in terms of percent reduction, as
well as in absolute measurement for each CCA analyte are provided in this section.
As described in Section 3.1.2, four different techniques were used to calculate
efficacy or percent reduction in DA or rank coatings by efficacy. These results
obtained by each of these methods are presented in the following subsections.
Distribution and box plots, sorted by coating, and grouped by sampling event and
source are provided in Appendix O to compliment the efficacy and ranking data
presented in this section. These allow one to visually assess the variability in the time
sequence data.
114
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Arsenic, Chromium, and
Copper from CCA Treated
Wood
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9 May 2005
9 10 11 3 8 1 6 2 4 12 7 5 13
Figure 4-24. Arsenic Reduction Efficacy Line Plot by Coating -All Time Periods
9 10 8 11 3 1 6 4 2 7 12 5 13
Figure 4-25. Arsenic Reduction Efficacy Line Plot by Coating - at Time =11 Months
9 10 11 3 8 1 6 7 12 4 2 5 13
Figure 4-26. Chromium Reduction Efficacy Line Plot by Coating -All Time Periods
115
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Evaluation of the
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Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
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9 May 2005
10 8 11 3 6 1 7 4 2 12 5 13
Figure 4-27. Chromium Reduction Efficacy Line Plot by Coating - at Time = 11 Months
9 10 8 11 3 1 6 12 4 2 7 5 13
Figure 4-28. Copper Reduction Efficacy Line Plot by Coating - All Time Periods
9 8 10 11 3 6 1 7 12 2 4 13 5
Figure 4-29. Copper Reduction Efficacy Line Plot by Coating - at Time = 11 Months
116
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4.6.3.1 Method 1. Using Unique Single Baselines for Each PSA
The efficacy results using method 1 are summarized in Table 4-13, grouped first by
Sampling Interval, then by Coating ID, then by Source. Figures 4-30 and 4-31 show
graphically the efficacy data generated for DAs by this method, grouped by Source A
and C, respectively. Similar plots are provided for DCr and DCu analytes in
Appendix P.
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Table 4-13. DA Reduction using Method 1
Source
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
Interval
(month)
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
3
3
Coating ID
1
1
2
2
3
3
4
4
5
5
6
6
7
7
8
8
9
9
10
10
11
11
12
12
13
13
1
1
Average
%DAs Red.
96.7
94.0
93.8
79.1
97.1
99.5
92.7
88.9
88.1
76.6
93.2
92.7
94.6
89.7
95.9
96.1
99.0
99.6
99.2
99.8
99.3
99.8
95.7
94.0
64.5
68.7
97.9
96.9
Average
%DCr Red.
96.8
92.3
89.5
74.0
99.2
99.7
87.8
84.8
77.0
64.5
91.3
92.5
89.2
89.2
98.2
96.9
99.9
99.8
99.7
99.7
99.8
99.8
93.8
91.8
55.7
57.0
96.9
94.8
Average
%Cu Red.
95.8
91.3
90.5
74.9
96.7
95.4
90.9
86.2
85.6
84.8
90.8
86.1
88.3
85.3
96.0
93.9
98.6
97.3
98.5
97.6
97.4
96.0
93.6
92.8
63.1
63.4
93.2
87.4
117
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Evaluation of the
Effectiveness of Coatings in
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Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Source
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
Interval
(month)
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
7
7
7
7
7
7
7
7
7
7
7
7
7
Coating ID
2
2
3
3
4
4
5
5
6
6
7
7
8
8
9
9
10
10
11
11
12
12
13
13
1
1
2
2
3
3
4
4
5
5
6
6
7
Average
%DAs Red.
97.1
93.4
98.4
99.6
96.8
93.7
90.5
85.6
96.7
97.0
95.2
92.6
99.1
98.5
99.2
99.3
99.4
99.4
99.0
99.5
96.3
96.2
78.5
74.3
96.9
93.6
95.5
93.3
95.1
98.3
92.7
94.8
87.9
84.5
92.3
95.0
95.5
Average
%DCr Red.
94.8
91.8
99.6
99.8
95.2
91.2
82.6
75.8
96.3
96.9
90.3
92.9
99.5
98.7
99.9
99.9
99.6
99.5
99.5
99.7
94.7
94.0
71.2
67.9
95.5
90.6
93.8
92.3
98.1
98.8
92.2
93.1
83.1
76.8
92.5
95.6
92.9
Average
%Cu Red.
93.1
86.3
96.0
92.2
93.3
86.9
80.4
76.4
94.2
87.4
86.4
83.8
95.8
88.5
97.2
94.3
95.4
91.6
94.0
90.8
93.2
86.9
72.8
63.3
94.0
87.0
93.9
87.3
94.7
92.8
92.2
88.6
85.2
82.0
92.8
86.5
92.5
118
-------
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Source
c
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
Interval
(month)
7
7
7
7
7
7
7
7
7
7
7
7
7
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
Coating ID
7
8
8
9
9
10
10
11
11
12
12
13
13
1
1
2
2
3
3
4
4
5
5
6
6
7
7
8
8
9
9
10
10
11
11
12
12
Average
%DAs Red.
94.1
98.6
98.0
98.3
98.6
98.2
99.0
95.0
98.7
91.7
94.2
69.2
74.2
93.8
86.5
85.2
71.9
92.0
94.6
85.9
83.1
63.4
45.2
86.2
87.6
84.1
77.6
95.7
94.9
96.9
97.6
97.5
96.7
94.1
96.1
75.2
79.5
Average
%DCr Red.
94.3
99.0
98.1
99.7
99.4
99.3
99.2
96.4
98.7
91.5
91.1
69.0
71.1
88.0
75.4
76.4
60.4
92.6
90.5
75.8
65.2
41.8
11.4
84.3
84.9
75.5
74.8
95.5
93.7
98.2
98.7
97.7
96.5
92.4
92.8
70.9
61.7
Average
%Cu Red.
88.2
97.2
92.2
98.6
96.5
96.8
95.1
94.0
95.3
91.6
85.8
75.5
69.2
82.7
54.2
74.5
28.4
85.3
63.7
69.6
23.6
46.5
9.5
86.5
61.4
73.8
51.3
94.1
81.9
97.1
95.7
91.2
87.8
89.0
82.2
76.7
21.7
119
-------
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Source
A
C
Interval
(month)
11
11
Coating ID
13
13
Average
%DAs Red.
43.3
25.4
Average
%DCr Red.
34.9
9.7
Average
%Cu Red.
55.2
-3.6
o 60.0
I
30.0
20.0
B
0%AsRed. T = 1
• %AsRed. T = 3
A%AsRed. T = 7
O%AsRed. T = 11
B •
6 7
Coating ID
Figure 4-30. Arsenic Coating Efficacy for Source A Specimens Using Analysis Method 1
120
-------
S. 50.0
-H-
O
o
tj
o
o
O%AsRed. T=1
• %AsRed. T = 3
&%AsRed. T = 7
O%AsRed. T=11
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Coating ID
Figure 4-31. Arsenic Coating Efficacy for Source C Specimens Using Analysis Method 1
4.6.3.2 Method 2. Using Average Baseline and Sample DA Calculated for Each Grouping of
Source, Sampling Interval, and Coating
The efficacy results using method 2 are summarized in Table 4-14, grouped first by
Sampling Interval, then by Coating ID, then by Source. Figures 4-32 and 4-33 show
graphically the efficacy data generated for DAs by this method, grouped by Source A
and C, respectively. Similar plots are provided for DCr and DCu in Appendix P.
Table 4-14. DA Reduction Using Method 2
Source
A
C
A
C
A
C
A
Interval
(month)
1
1
1
1
1
1
1
Coating
1
1
2
2
3
3
4
Average
%DAs Red.
96.7
93.8
93.9
81.6
97.2
99.6
94.4
Average
%DCr Red.
96.9
92.3
89.8
76.6
99.4
99.7
91.2
Average
%DCu Red.
95.7
92.0
90.9
77.0
97.0
96.5
92.7
121
-------
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Source
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
Interval
(month)
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
3
3
3
3
3
3
3
3
3
3
3
3
Coating
4
5
5
6
6
7
7
8
8
9
9
10
10
11
11
12
12
13
13
1
1
2
2
3
3
4
4
5
5
6
6
Average
%DAs Red.
89.3
89.0
78.1
92.0
93.1
94.7
89.9
96.0
96.3
99.2
99.8
99.2
99.8
99.4
99.9
94.8
94.1
72.7
68.4
97.8
97.1
97.1
94.1
98.6
99.7
97.0
94.7
91.2
85.7
95.7
97.1
Average
%DCr Red.
85.8
81.2
66.5
89.1
92.6
91.7
89.5
98.1
97.1
99.9
99.9
99.7
99.8
99.8
99.9
93.2
92.2
64.8
58.0
96.8
95.2
94.9
92.6
99.7
99.8
95.8
92.8
85.2
76.2
94.9
96.9
Average
%DCu Red.
89.4
86.9
87.2
91.3
86.8
90.0
85.7
96.0
93.9
98.8
97.6
98.6
98.1
97.6
96.7
94.0
93.5
68.5
64.2
93.0
88.8
93.6
86.5
96.2
94.4
94.3
90.0
83.7
79.0
94.5
87.6
122
-------
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Source
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
Interval
(month)
3
3
3
3
3
3
3
3
3
3
3
3
3
3
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
Coating
7
7
8
8
9
9
10
10
11
11
12
12
13
13
1
1
2
2
3
3
4
4
5
5
6
6
7
7
8
8
9
Average
%DAs Red.
95.4
93.6
99.1
98.4
99.3
99.6
99.5
99.6
99.1
99.6
95.5
96.3
84.1
72.9
97.0
93.6
95.5
94.1
95.9
98.5
93.9
95.0
89.0
85.2
89.7
94.9
95.0
94.4
98.6
98.1
98.4
Average
%DCr Red.
92.5
93.6
99.5
98.6
99.9
99.9
99.6
99.6
99.6
99.7
94.4
94.4
77.6
66.7
96.2
90.8
94.1
93.1
98.7
98.9
93.7
93.6
86.1
77.9
89.0
95.5
94.1
94.5
99.0
98.1
99.7
Average
%DCu Red.
88.4
84.8
95.6
88.4
97.4
94.8
95.7
93.9
94.3
92.0
94.1
89.2
76.5
64.8
94.2
88.1
94.3
87.8
95.6
94.1
93.4
90.5
87.4
84.8
93.6
86.8
92.9
87.9
97.3
92.4
98.7
123
-------
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Source
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
Interval
(month)
7
7
7
7
7
7
7
7
7
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
Coating
9
10
10
11
11
12
12
13
13
1
1
2
2
3
3
4
4
5
5
6
6
7
7
8
8
9
9
10
10
11
11
Average
%DAs Red.
98.9
98.2
99.2
96.0
98.9
90.5
94.0
77.3
74.4
94.1
87.0
85.4
74.7
93.1
95.2
87.0
84.9
65.6
46.3
88.5
86.9
82.0
78.9
95.8
95.4
97.6
98.2
97.6
97.8
94.7
96.7
Average
%DCr Red.
99.5
99.4
99.4
97.5
99.0
90.1
91.2
75.5
71.4
89.1
76.0
77.0
63.6
94.3
91.4
79.7
68.3
51.0
13.9
86.3
84.2
76.3
75.6
95.2
94.0
98.6
99.0
97.7
97.4
93.7
94.1
Average
%DCu Red.
96.7
97.1
96.2
94.8
95.9
92.0
87.0
78.8
71.1
83.3
59.3
75.9
29.9
87.3
69.0
74.5
37.3
55.3
19.8
87.0
62.6
75.4
53.0
94.2
82.6
97.3
96.0
91.5
90.8
90.3
85.7
124
-------
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Source
A
C
A
C
Interval
(month)
11
11
11
11
Coating
12
12
13
13
Average
%DAs Red.
75.1
80.4
56.4
23.8
Average
%DCr Red.
73.5
63.7
47.3
10.1
Average
%DCu Red.
78.3
31.9
61.5
6.2
§ 60
B
O%Red. AsT= 1
• %Red. AsT= 3
A%Red. AsT= 7
O%Red. AsT= 11
B
8
6 7
Coating ID
o
A
O
Figure 4-32. Arsenic Coating Efficacy for Source A Specimens Using Analysis Method 2
125
-------
0
o
£
-o-
o
o
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Coating ID
Figure 4-33. Arsenic Coating Efficacy for Source C Specimens Using Analysis Method 2
4.6.3.3 Method 3. Using the Average of the Positive Control Minideck (#13) DA Values for each
Grouping of Source and Wipe Interval as Baseline
The efficacy results using method 3 are summarized in Table 4-15, grouped first by
Sampling Interval, then by Coating ID, then by Source. Figures 4-34 and 4-35 show
graphically the efficacy data generated for DAs by this method, grouped by Source A
and C, respectively. Similar plots are provided for DCr and DCu in Appendix P.
Table 4-15. DA Reduction Using Method 3
Source
A
C
A
C
A
C
A
Coating ID
1
1
2
2
3
3
4
Interval
(month)
1
1
1
1
1
1
1
Average
%DAs Red.
91.1
80.0
82.0
50.7
92.8
98.0
84.7
Average
%DCr Red.
93.7
81.8
77.9
51.1
98.9
99.2
80.7
Average
%DCu Red.
86.2
75.6
68.2
39.7
90.9
85.1
78.5
126
-------
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Source
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
Coating ID
4
5
5
6
6
7
7
8
8
9
9
10
10
11
11
12
12
1
1
2
2
3
3
4
4
5
5
6
6
7
7
Interval
(month)
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
3
3
3
3
3
3
3
3
3
3
3
3
3
3
Average
%DAs Red.
67.5
74.9
39.3
78.8
78.1
86.3
68.2
89.6
87.0
97.6
99.3
97.2
99.5
98.6
99.5
83.1
84.9
89.7
89.1
85.2
81.5
93.8
98.3
86.1
81.3
65.6
53.8
80.6
89.1
79.6
76.5
Average
%DCr Red.
67.9
68.2
27.7
78.9
82.0
82.5
75.2
96.0
92.1
99.8
99.8
99.3
99.5
99.7
99.6
80.0
84.5
90.0
85.6
82.8
80.5
99.0
99.2
85.4
79.2
60.6
35.1
84.5
90.6
75.3
80.8
Average
%DCu Red.
66.9
67.4
61.2
78.5
62.6
72.5
62.4
87.6
82.3
96.0
93.8
94.8
93.3
94.3
88.6
83.4
82.7
69.8
65.3
69.9
64.1
84.5
75.4
77.4
68.3
45.5
35.3
81.7
64.4
57.1
59.3
127
-------
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Source
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
Coating ID
8
8
9
9
10
10
11
11
12
12
1
1
2
2
3
3
4
4
5
5
6
6
7
7
8
8
9
9
10
10
11
Interval
(month)
3
3
3
3
3
3
3
3
3
3
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
Average
%DAs Red.
95.9
93.6
96.4
98.6
96.7
98.7
96.6
98.4
75.0
89.1
90.4
74.6
84.1
80.4
87.4
91.6
80.0
81.2
70.0
49.1
67.1
80.1
84.3
78.2
95.6
91.5
94.2
96.2
92.5
97.0
89.5
Average
%DCr Red.
98.3
95.4
99.7
99.7
98.5
99.0
99.0
99.1
74.4
85.8
89.0
68.3
81.5
78.9
96.4
94.8
80.1
78.7
66.3
29.9
69.3
84.0
82.1
80.8
96.9
92.6
99.0
98.5
97.5
98.0
94.3
Average
%DCu Red.
81.6
65.6
88.9
86.2
78.8
77.4
81.7
72.2
78.0
70.9
72.2
55.1
70.4
60.2
79.8
68.7
70.8
63.1
53.3
43.1
76.4
53.7
70.7
60.7
87.6
72.6
93.8
89.5
83.8
82.9
81.3
128
-------
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Source
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
A
C
Coating ID
11
12
12
1
1
2
2
3
3
4
4
5
5
6
6
7
7
8
8
9
9
10
10
11
11
12
12
Interval
(month)
7
7
7
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
Average
%DAs Red.
94.8
62.4
81.1
90.2
82.6
73.0
71.8
89.0
91.1
77.8
81.0
51.1
38.1
80.9
82.8
70.7
72.3
93.1
93.2
95.4
97.8
94.6
97.2
92.7
95.0
49.0
79.4
Average
%DCr Red.
95.7
58.5
74.5
85.4
73.6
66.7
64.5
92.8
87.0
70.3
66.4
44.7
13.1
82.2
82.0
66.8
73.0
93.4
92.4
97.6
99.1
95.9
97.4
93.2
92.2
48.1
66.4
Average
%DCu Red.
82.7
67.1
57.3
56.1
52.6
30.8
29.8
68.1
49.3
38.2
25.1
8.8
7.4
73.6
59.6
44.4
52.9
85.2
80.6
93.0
96.0
74.1
87.3
80.8
81.2
50.6
31.0
129
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Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
90.0-
1
0)
a
o! 40 o -
n 8 8 8
0 A
H H 1 2 o
a _
0 M
? '
• A
A
.
O
O%Red.AsT= 1
• % Red. AsT = 3
A % Red. AsT = 7
O%Red.AsT= 11
0 1 2 3 4 5 6 7 8 9 10 11 12 13
Coating ID
Figure 4-34. Arsenic Coating Efficacy for Source A Specimens Using Analysis Method 3
80.0-
D
a: 50 0 -
a. 40 0
D " S
8 s R 2 A
u 6 A
A o 5
o o
.
A
©
0%Red. AsT= 1
• %Red. AsT=3
A % Red. AsT = 7
O%Red. AsT= 11
0 1 2 3 4 5 6 7 8 9 10 11 12 13
Coating ID
130
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Figure 4-35. Arsenic Coating Efficacy for Source C Specimens Using Analysis Method
3
4.6.3.4 Method 4. Estimating Coating Efficacy Relative to Deck 13 Calculated Using the
Analysis of Variance Model That Was Used to Compare Coatings
Method 4 utilizes a more rigorous statistical model than do the other methods. As such,
the results are summarized in a somewhat different fashion than for the other methods.
Specifically, a series of tables, Tables 4-16 through 4-19, are provided, which show
results composited over all four sampling intervals. Each reported efficacy is bound by
its upper and lower univariate confidence limits (CL), at 95% confidence. Two tables,
one for each wood source, are provided for DAs reduction efficacy, while only one,
combined for both wood sources, are provided for DCr and DCu reduction efficacy.
All tables show the coatings ordered by ranking with respect to efficacy, with the best
performers at the top of the table and the poorest performers at the bottom.
131
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Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Table 4-16. Composite DAs Reduction Efficiencies for Source A, per Method 4, with 95% CL
Coating
10
9
11
8
1
3
2
6
4
7
12
5
DAs Reduction Efficacy
Lower
93.5%
92.6%
88.0%
87.4%
79.6%
77.7%
68.4%
61.7%
61.1%
59.9%
55.4%
19.3%
Mean
96.4%
95.9%
93.2%
92.9%
88.5%
87.5%
82.2%
78.5%
78.2%
77.4%
74.9%
54.6%
Upper
98.0%
97.7%
96.2%
96.0%
93.5%
92.9%
90.0%
87.9%
87.7%
87.3%
85.9%
74.4%
Table 4-17. Composite DAs Reduction Efficiencies for Source C, per Method 4, with 95% CL
Coating
10
11
9
3
8
1
6
12
4
7
2
5
DAs Reduction Efficacy
Lower
96.5%
96.4%
96.2%
94.6%
85.8%
70.6%
68.7%
64.3%
56.8%
52.8%
40.9%
-18.6%
Mean
98.1%
98.0%
97.9%
97.0%
92.2%
83.7%
82.7%
80.3%
76.1%
73.9%
67.3%
34.4%
Upper
98.9%
98.9%
98.8%
98.4%
95.7%
91.0%
90.4%
89.1%
86.8%
85.6%
81.9%
63.7%
132
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Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Table 4-18. Composite DCr Reduction Efficiencies, for Both Sources Combined, per Method
4, with 95% CL
Coating
9
10
11
3
8
1
6
7
12
4
2
5
DCr Reduction Efficacy
Lower
99.2%
97.9%
96.9%
96.3%
93.6%
77.8%
75.6%
63.8%
62.4%
62.6%
61.8%
-1.3%
Mean
99.4%
98.5%
97.8%
97.4%
95.5%
84.2%
82.8%
74.5%
73.9%
73.7%
73.4%
28.7%
Upper
99.6%
98.9%
98.4%
98.1%
96.8%
88.7%
87.9%
82.0%
81.8%
81.5%
81.5%
49.8%
Table 4-19. Composite DCu Reduction Efficiencies, for Both Sources Combined, per Method 4,
with 95% CL
Coating
9
10
8
11
3
1
6
12
4
2
7
5
DCu Reduction Efficacy
Lower
89.7%
84.6%
78.1%
78.2%
74.8%
61.7%
56.6%
51.0%
50.8%
45.2%
44.5%
14.0%
Mean
92.5%
88.4%
83.5%
83.4%
80.8%
70.8%
67.3%
63.4%
62.9%
59.1%
58.1%
35.2%
Upper
94.5%
91.2%
87.5%
87.4%
85.4%
77.8%
75.3%
72.7%
72.1%
69.4%
68.4%
51.1%
133
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
4.6.3.5 Summary and Comparison of Efficacy Calculations
Tables 4-20 (Source A) and 4-21 (Source C) summarize calculated efficacies and
rankings for each coating using the three sampling interval-specific efficacy calculation
methods (methods 1, 2, and 3) at each sampling event. The tables are sorted first by
interval, then by coating rank. Appendix Q includes three-dimensional plots showing
coating ranking, sorted by sampling event, source, and calculation method (for
methods 1, 2, and 3 only).
Table 4-20. Comparison of DAs Efficacy Calculation Methods, Methods 1, 2, and 3, Source A
Interval
Rank
Method 1
Coating
% DAs
Red.
Method 2
Coating
% DAs
Red.
Method 3
Coating
% DAs
Red.
One-month sampling event (t = 1 month)
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
3
4
5
6
7
8
9
10
11
12
13
11
10
9
3
1
8
12
7
2
6
4
5
13
99.3
99.2
99.0
97.1
96.7
95.9
95.7
94.6
93.8
93.2
92.7
88.1
64.5
11
9
10
3
1
8
12
7
4
2
6
5
13
99.4
99.2
99.2
97.2
96.7
96.0
94.8
94.7
94.4
93.9
92.0
89.0
72.7
11
9
10
3
1
8
7
4
12
2
6
5
-
98.6
97.6
97.2
92.8
91.1
89.6
86.3
84.7
83.1
82.0
78.8
74.9
-
Three-month sampling event (t = 3 month)
3
3
3
3
3
3
1
2
3
4
5
6
10
9
8
11
3
1
99.4
99.2
99.1
99.0
98.4
97.9
10
9
8
11
3
1
99.5
99.3
99.1
99.1
98.6
97.8
10
11
9
8
3
1
96.7
96.6
96.4
95.9
93.8
89.7
134
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Arsenic, Chromium, and
Copper from CCA Treated
Wood
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EPA Report EPA/600/R-05/050
9 May 2005
Interval
3
3
3
3
3
3
3
Rank
7
8
9
10
11
12
13
Method 1
Coating
2
4
6
12
7
5
13
% DAs
Red.
97.1
96.8
96.7
96.3
95.2
90.5
78.5
Method 2
Coating
2
4
6
12
7
5
13
% DAs
Red.
97.1
97.0
95.7
95.5
95.4
91.2
84.1
Method 3
Coating
4
2
6
7
12
5
-
% DAs
Red.
86.1
85.2
80.6
79.6
75.0
65.6
-
Seven-month sampling event (t = 7 month)
7
7
7
7
7
7
7
7
7
7
7
7
7
1
2
3
4
5
6
7
8
9
10
11
12
13
8
9
10
1
7
2
3
11
4
6
12
5
13
98.6
98.3
98.2
96.9
95.5
95.5
95.1
95.0
92.7
92.3
91.7
87.9
69.2
8
9
10
1
11
3
2
7
4
12
6
5
13
98.6
98.4
98.2
97.0
96.0
95.9
95.5
95.0
93.9
90.5
89.7
89.0
77.3
8
9
10
1
11
3
7
2
4
5
6
12
-
95.6
94.2
92.5
90.4
89.5
87.4
84.3
84.1
80.0
70.0
67.1
62.4
-
Eleven-month sampling event (t = 11 month)
11
11
11
11
11
11
11
1
2
3
4
5
6
7
10
9
8
11
1
3
6
97.5
96.9
95.7
94.1
93.8
92.0
86.2
9
10
8
11
1
3
6
97.6
97.6
95.8
94.7
94.1
93.1
88.5
9
10
8
11
1
3
6
95.4
94.6
93.1
92.7
90.2
89.0
80.9
135
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Interval
11
11
11
11
11
11
Rank
8
9
10
11
12
13
Method 1
Coating
4
2
7
12
5
13
% DAs
Red.
85.9
85.2
84.1
75.2
63.4
43.3
Method 2
Coating
4
2
7
12
5
13
% DAs
Red.
87.0
85.4
82.0
75.1
65.6
56.4
Method 3
Coating
4
2
7
5
12
-
% DAs
Red.
77.8
73.0
70.7
51.1
49.0
-
136
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Table 4-21. Comparison of DAs Efficacy Calculation Methods, Methods 1, 2, and 3, Source C
Interval
Rank
Method 1
Coating
% DAs
Red.
Method 2
Coating
% DAs
Red.
Method 3
Coating
% DAs
Red.
One-month sampling event (t = 1 month)
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
3
4
5
6
7
8
9
10
11
12
13
11
10
9
3
8
12
1
6
7
4
2
5
13
99.8
99.8
99.6
99.5
96.1
94.0
94.0
92.7
89.7
88.9
79.1
76.6
68.7
11
10
9
3
8
12
1
6
7
4
2
5
13
99.9
99.8
99.8
99.6
96.3
94.1
93.8
93.1
89.9
89.3
81.6
78.1
68.4
10
11
9
3
8
12
1
6
7
4
2
5
-
99.5
99.5
99.3
98.0
87.0
84.9
80.0
78.1
68.2
67.5
50.7
39.3
-
Three-month sampling event (t = 3 month)
3
3
3
3
3
3
3
3
3
3
3
3
3
1
2
3
4
5
6
7
8
9
10
11
12
13
3
11
10
9
8
6
1
12
4
2
7
5
13
99.6
99.5
99.4
99.3
98.5
97.0
96.9
96.2
93.7
93.4
92.6
85.6
74.3
3
10
11
9
8
1
6
12
4
2
7
5
13
99.7
99.6
99.6
99.6
98.4
97.1
97.1
96.3
94.7
94.1
93.6
85.7
72.9
10
9
11
3
8
1
12
6
2
4
7
5
-
98.7
98.6
98.4
98.3
93.6
89.1
89.1
89.1
81.5
81.3
76.5
53.8
-
137
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Interval
Rank
Method 1
Coating
% DAs
Red.
Method 2
Coating
% DAs
Red.
Method 3
Coating
% DAs
Red.
Seven-month sampling event (t = 7 month)
7
7
7
7
7
7
7
7
7
7
7
7
7
1
2
3
4
5
6
7
8
9
10
11
12
13
10
11
9
3
8
6
4
12
7
1
2
5
13
99.0
98.7
98.6
98.3
98.0
95.0
94.8
94.2
94.1
93.6
93.3
84.5
74.2
10
9
11
3
8
4
6
7
2
12
1
5
13
99.2
98.9
98.9
98.5
98.1
95.0
94.9
94.4
94.1
94.0
93.6
85.2
74.4
10
9
11
3
8
4
12
2
6
7
1
5
-
97.0
96.2
94.8
91.6
91.5
81.2
81.1
80.4
80.1
78.2
74.6
49.1
-
Eleven-month sampling event (t = 11 month)
11
11
11
11
11
11
11
11
11
11
11
11
11
1
2
3
4
5
6
7
8
9
10
11
12
13
9
10
11
8
3
6
1
4
12
7
2
5
13
97.6
96.7
96.1
94.9
94.6
87.6
86.5
83.1
79.5
77.6
71.9
45.2
25.4
9
10
11
8
3
1
6
4
12
7
2
5
13
98.2
97.8
96.7
95.4
95.2
87.0
86.9
84.9
80.4
78.9
74.7
46.3
23.8
9
10
11
8
3
6
1
4
12
7
2
5
-
97.8
97.2
95.0
93.2
91.1
82.8
82.6
81.0
79.4
72.3
71.8
38.1
-
138
-------
Table 4-22 provides a similar comparison, showing DA reduction efficacies for all
three CCA analytes, for all four calculation methods at the 11-month sampling event
(method 4 was reapplied to be specific to the 11-month event, rather than composited
overtime). In these calculations, results from the two sources of wood are combined.
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Table 4-22. Comparison of Efficacy Calculation Methods, for Arsenic at 11 Months, Both
Sources Combined
Coating
Method 1
% Reduction
Method 2
% Reduction
Method 3
% Reduction
Method 4
% Reduction
DAs Reduction (%)
1
2
3
4
5
6
7
8
9
10
11
12
13
90.14
78.59
93.28
84.49
54.27
86.90
80.83
95.30
97.21
97.13
95.10
77.33
34.35
90.57
80.06
94.15
85.98
55.94
87.72
80.43
95.58
97.87
97.67
95.69
77.76
40.11
86.36
72.40
90.08
79.41
44.63
81.84
71.50
93.17
96.58
95.89
93.84
64.18
-
86.31
77.62
93.83
77.33
45.59
79.32
75.35
92.81
97.53
97.32
96.31
76.69
-
DCr Reduction (%)
1
2
3
4
5
6
7
8
9
81.70
68.41
91.55
70.55
26.62
84.62
75.15
94.61
98.47
82.54
70.29
92.86
73.99
32.45
85.26
75.94
94.61
98.78
79.50
65.59
89.89
68.33
28.88
82.10
69.89
92.88
98.33
84.17
73.40
97.36
73.67
28.67
82.78
74.48
95.50
99.44
139
-------
Coating
10
11
12
13
Method 1
% Reduction
97.06
92.58
66.30
22.27
Method 2
% Reduction
97.55
93.91
68.61
28.72
Method 3
% Reduction
96.61
92.73
57.22
-
Method 4
% Reduction
98.51
97.80
73.87
-
DCu Reduction (%)
1
2
3
4
5
6
7
8
9
10
11
12
13
68.44
51.45
74.47
46.59
28.01
73.93
62.59
88.01
96.41
89.50
85.59
49.22
25.81
71.27
52.91
78.15
55.89
37.58
74.78
64.23
88.40
96.65
91.12
87.97
55.08
33.85
54.33
30.30
58.69
31.62
8.10
66.60
48.67
82.89
94.48
80.70
81.03
40.83
-
70.85
59.06
80.84
62.92
35.16
67.26
58.13
83.48
92.49
88.38
83.40
63.45
-
Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
With regards to the choice of method to use to calculate efficacy, Table 4-22 indicates
that, particularly for coatings with high efficacies (percent reductions), the variability
among calculation methods is low. For the lower performing coatings, the variability is
greater. However, these poorer performing coatings are of relatively low interest since
they do not provide acceptable levels of mitigation. As such, it appears that the specific
method used to calculate efficacy is relatively unimportant. Method 4 may be the most
useful since it is most inclusive of the factors considered potentially important in
determining coating performance.
To summarize the efficacy results, every coating mitigated DA when compared with the
positive control, although the difference between coating #5 and the positive control
(coating #13) was consistently insignificant. In general, coatings, when ranked with
140
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
respect to efficacy, can be assigned into three broad performance tiers: good
performers (high), average performers (mid), and mediocre performers (low).
The best performers were generally coatings #9, #10, and #11, and, to a somewhat
lesser extent, #3 and #8. These coatings generally reduced DAs by about 90% or greater
(depending on analytical method used to compute DAs reduction) after 11 months (see
Table 4-22). The middle tier performers included coatings #1, #4, and #6; these
generally reduced DAs by about 75% or greater at 11 months. The lower tier
performers included coatings #2, #5, #7, and #12. These generally reduced DAs by
about 75% or less at 11 months. Coating #5, the poorest performer tested, achieved only
about 50% reduction at 11 months, considerably less that other coatings in this grouping
and generally not statistically significantly different from the positive control minideck.
While the top two performers were film-forming coatings - the only two paints tested
(coatings #9 and #10) - several other, more typical deck treatment products performed
almost as well. The painted minidecks show significant weathering, with an oil-based
paint seeming to resist chipping better than a water-based paint. However, there are
significant concerns about the applicability of using paints as coatings for exposed
outdoor surfaces subject to abrasion. Weathered paints can have a noticeably poor
appearance, necessitating frequent recoating. Additionally, the chipping of paints and
surface preparation techniques for recoating, which typically include sanding, can
generate dust which may make inhalation of CCA-contaminated particles a serious
health risk.
Another film-former, an elastic vinyl product designed to encapsulate CCA wood
(coating #11), performed very well initially, but appeared to fall off slightly in
comparison to other high-performing products over time. This product additionally
exhibited significant biological growth and associated discoloration.
Within the remaining coatings, no clear trends with respect to product type or
characteristics are immediately evident. For example, tinted stains and sealants do not
appear to consistently perform significantly better than untinted ones, although it must
be pointed out that this experiment did not control specifically for pigmentation. In
other words, the same coating was not tested with and without pigmentation; rather, all
twelve products tested were different from one another. In a related study being
conducted by CPSC staff, one coating was tested with and without pigmentation and the
same coating with pigmentation performed significantly better than without (CPSC staff
2005).
141
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Evaluation of the
Effectiveness of Coatings in
Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
The best non-film-forming products were identified as coatings #1, #3, and #8.
Coating #1 is an oil-based semitransparent sealant in cedar tone. Coating #3 is a clear,
oil-based, acrylic, deep tone base stain to which no pigment had been added prior to
application. Coating #8 is a clear, water-based, acrylic, tint base, solid stain to which no
pigment had been added prior to application.
4.6.4 Coating Appearance
The coating appearance after weathering was qualitatively assessed in person and by
viewing photographs of each minideck at each sampling event, that is, precoat, after
1 month, 3 months, 7 months, and 11 months of weathering. The photos can be
viewed in Appendix R. In general, the two cedar stains and sealants (coatings #1 and
#7) retained their appearance well over the first year of service. The paints (coatings
#9 and #10) generally also held their overall appearance, though substantial chipping
is evident. Coating #11 also held its overall appearance as a smooth, semi-transparent
surface layer over the boards, though it too is showing signs of wear and chipping as
well as biological growth. Other notable observations are summarized in Table 4-23.
It is important to note again that no targeted abrasion component was included in this
study. It is likely that some, if not all, coatings - and particularly the film-formers -
would have shown more extensive wear patterns if they had been subjected to
abrasion in addition to weathering.
4.7 Abrasion and Rewipe Analysis
Statistical methods used to analyze wipe sample data for abrasion and rewipe effects
are described in Section 3.4.3. As stated there, the analysis used all of the M and BL
sample data to determine whether TTPW or NOPW had an effect on predicting DA.
The statistical analysis indicates that there are no significant trends with the time
(months) since the previous wipe (TTPW), but that there is evidence of a downward
trend with the number of previous wipes (NOPW). That is, the greater the NOPW,
the lower the DA level (data not presented). The direction of the trend is opposite
what would be expected if wiping had abraded coatings and reduced their
effectiveness (i.e., the hypothesis that more wiping would wear down the coating and
allow more CCA analytes to permeate the worn-down, thinner coating).
142
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05/050
Evaluation of the
Effectiveness of Coatings
in Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-
)
9 May 2005
Table 4-23. Summary of Visual Observations of Minidecks
#
Coating 1
Coating 2
Coating 3
Coating 4
Coating 5
Coating 6
Coating 7
Coating 8
Coating 9
Coating 10
Coating 1 1
Coating 12
Coating 13
Product Type
Sealant
Sealant
Stain
Stain
Sealant
Sealant
Stain
Stain
Paint
Paint
Other
Other
No coating
Base
Oil
Oil
Oil
Oil
Water
Water
Water
Water
Water
Oil
Cover
Semi
Clear
Clear
Clear
Clear
Clear
Semi
Clear
Opaque
Opaque
Clear
Clear
Pigmentation
"Cedar"
"Clear"
"Deep Tone Base"
(no pigment added)
"Clear Stain"
"Clear"
"Clear"
"Cedar"
"Tint base, solid" (no
pigment added)
Gray
Gray
Clear
Clear
Main Ingredients
Acrylic, alkyd,
urethane
Acrylic
Alkyd
Acrylic, alkyd
Alkyd
Acrylic
Acrylic
Alkyd,
polyurethane
Elastic vinyl
Polymer
Summary of Visual Observations
Deep red coloration. Some wear-through where wiped.
No visible signs of coating. Relatively light and bright wood appearance.
Extensive black mold or mildew on untreated boards. Varying amounts,
from slight to extensive, on treated boards. Growth appeared between 7
and 1 1 months after coating. Otherwise, no visible signs of coating,
though with fresh coating the wood appearance was significantly
darkened.
No visible signs of coating. Mold or mildew on untreated boards.
No visible signs of coating. Relatively dark (gray) wood appearance.
Slightly yellow tint to treated boards. Some wear-through where wiped.
Lighter red coloration. Wear-through where wiped.
Very slight tint on treated boards, but generally no visible signs of
coating. Relatively light and bright wood appearance.
Retained gray paint coloration, but moderate-to-extensive chipping,
especially at cracks, starting around 7 months.
Retained gray paint coloration, slight-to-moderate chipping at cracks.
Some black mold or mildew on untreated boards.
Extensive black mold or mildew on untreated boards. Varying amounts,
from none to moderate, on treated boards. Growth appeared between 7
and 1 1 months after coating. Seems to visually perform better on A
source than C source. Some limited chipping and peeling at large
cracks. General appearance is slick and waxy, with an amber coloration
that has held well on treated boards.
No visible signs of coating.
No visible signs of coating. Some mold and mildew on untreated
boards.
143
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This finding should be viewed with some skepticism. Because the experiment was
not designed explicitly for assessing abrasion and wipe frequency, there is not much
relevant information in the data, and it is difficult to claim with any certainty that the
method of analysis is the best way to use the data available for teasing out abrasion
and rewipe (from each other and from the other effects). Consequently the significant
effect associated with NOPW could be due to confounding with other effects.
Alternatively, it is possible that the amount of abrasion induced by rubbing the
coating with a pad is negligible, but that the amount of cleaning (of "built-up" DA) is
substantial. Thus the number of rewipes might be a surrogate for prior cleaning; the
greater the prior cleaning, the less the measured DA.
4.8 Miscellaneous Samples
Evaluation of the
Effectiveness of Coatings
in Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
4.8.1 Brush Washwater Samples
Two types of brushes were used to apply coatings to the minidecks. They were both
2" chip brushes with either natural bristles or polyolefin bristles. Prior to coating
application, both brush types were analyzed per the methods described in Section 2.7
in order to ensure that they did not contribute significant amounts of arsenic,
chromium, or copper to the wood surfaces.
The results of the analyses are presented in Table 4-24. It can be seen from this table
that arsenic levels are below the reporting limit (note that STL-Savannah changed
their reporting limit from 0.20 (ig/L at the beginning of the study to 0.10 (ig/L,
currently); chromium levels are also less than 1 |o,g/L. Although the copper levels are
higher than levels of the other two metals, they are lower than levels seen from blank
(untreated) boards and can therefore be considered to be insignificant.
Table 4-24. Brush Sample CCA Analyte Concentrations
Sample Number
SS-502
SS-503
SS-504
SS-505
Bristle Type
Natural
Natural
Synthetic
Synthetic
Actual Concentration (ug/L)
As
<0.20
<0.20
<0.20
<0.20
Cr
0.40
0.88
0.49
0.35
Cu
4.2
2.4
1.7
1.7
144
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4.8.2 Cross Contamination and Negative Control Deck Sample Results
A series of samples were taken from the untreated specimens on each deck which are
used to separate boards from one another, as described in Section 2.16. These were
designed to provide a control to assess whether "splash-over" of water during
precipitation events, for example, could cause cross-contamination of adjacent
samples. The most effective way to assess this was to compare the cross-contamination
results for the coating #13 minidecks (the uncoated controls) versus the results from the
blank control minideck (the minideck whose top is constructed entirely of untreated
wood). These results are summarized in Table 4-25, while the full dataset is provided
in Appendix S.
The results of all of the untreated wood wipe samples for arsenic are very low in
comparison with those from the treated wood specimens. While there appears to be
more DAs from the cross-contamination controls versus the blank minideck controls, it
is unlikely that the result is significant. Additionally, a comparison of the DCr and DCu
results between the cross-contamination and blank minideck controls are inconsistent
with those of the DAs results, which also suggests that the results may not be
significant.
The cross-contamination data for all of the coatings are summarized in Table 4-26,
while the full dataset is provided in Appendix T. Again, the results do not appear
consequential; that is, no corrections for cross-contamination need to be made, though
we would suggest that future studies also include a cross-contamination buffer board
between treated samples. It is interesting to note that there is generally an increasing
trend in DA on the control boards over time, which is particularly apparent in the
results of samples taken 11 months after coating. It could be that the climatological
conditions during or prior to this sampling event resulted in more cross-contamination
or simply more retention of DA on the wipes.
Evaluation of the
Effectiveness of Coatings
in Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
145
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Evaluation of the
Effectiveness of Coatings
in Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Table 4-25. Summary of Cross-Contamination and Blank Control Minideck Results
Arsenic
(ug/L)
(ug/cm2)
Chromium
(ug/L)
(ug/cm2)
Copper
(ug/L)
(ug/cm2)
Cross-Contamination Control Samples (Untreated Boards from coating #13 Minidecks)
1 month
3 months
7 months
11
months
Average
Std Dev
RSD
Average
Std Dev
RSD
Average
Std Dev
RSD
Average
Std Dev
RSD
9.233
5.871
63.6%
6.267
4.271
68.2%
5.933
1.595
26.9%
18.433
11.544
62.6%
0.003
0.002
-
0.002
0.001
-
0.002
0.001
-
0.006
0.004
-
13.167
7.006
53.2%
9.000
5.292
58.8%
11.100
3.851
34.7%
29.000
15.395
53.1%
0.004
0.002
-
0.003
0.002
-
0.004
0.001
-
0.009
0.005
-
57.333
12.423
21.7%
153.333
50.332
32.8%
135.333
65.767
48.6%
310.000
80.000
25.8%
0.018
0.004
-
0.049
0.016
-
0.043
0.021
-
0.099
0.025
-
Blank Control Minideck
1 month
3 months
7 months
11
months
Average
Std Dev
RSD
Average
Std Dev
RSD
Average
Std Dev
RSD
Average
Std Dev
RSD
7.133
1.680
23.6%
2.100
0.500
23.8%
2.000
0.458
22.9%
2.300
0.200
8.7%
0.002
0.001
-
0.001
0.000
-
0.001
0.000
-
0.001
0.000
-
38.333
19.348
50.5%
9.367
2.294
24.5%
5.533
1.206
21.8%
7.067
1.193
16.9%
0.012
0.006
-
0.003
0.001
-
0.002
0.000
-
0.002
0.000
-
71.333
11.504
16.1%
140.000
36.056
25.8%
62.667
13.868
22.1%
126.667
5.774
4.6%
0.023
0.004
-
0.045
0.011
-
0.020
0.004
-
0.040
0.002
-
146
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Evaluation of the
Effectiveness of Coatings
in Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Table 4-26. Summary of Cross-Contamination Data for All Coatings.
Coat.
1
2
3
4
5
6
7
8
9
10
11
av
Std Dev
RSD
av
Std Dev
RSD
av
Std Dev
RSD
av
Std Dev
RSD
av
Std Dev
RSD
av
Std Dev
RSD
av
Std Dev
RSD
av
Std Dev
RSD
av
Std Dev
RSD
av
Std Dev
RSD
av
Time = 1 month
As
(ug/L)
2.07
0.32
15.6%
3.43
1.42
41 .2%
2.07
0.60
29.2%
4.70
0.66
14.0%
3.53
0.50
14.2%
4.67
1.93
41 .3%
2.77
0.32
1 1 .6%
1.53
0.25
16.4%
1.20
0.10
8.3%
1.09
0.12
11.1%
1.60
Cr
(ug/L)
3.20
0.53
16.5%
5.90
2.14
36.2%
3.37
0.61
18.1%
7.23
1.76
24.4%
6.17
1.84
29.9%
7.20
2.80
38.9%
4.80
0.95
19.9%
2.70
0.46
17.0%
3.73
3.02
80.8%
1.93
0.45
23.3%
3.30
Cu
(ug/L)
59.33
6.03
10.2%
39.67
7.23
18.2%
67.33
3.51
5.2%
28.00
7.81
27.9%
30.67
6.66
21 .7%
33.00
2.65
8.0%
34.33
4.73
13.8%
34.67
4.04
1 1 .7%
41.33
12.58
30.4%
26.33
5.86
22.3%
56.00
Time = 3 month
As
(M9/L)
2.20
1.15
52.4%
2.37
0.32
13.6%
2.80
1.11
39.8%
3.13
0.85
27.1%
4.47
1.42
31 .7%
3.43
1.07
31.1%
3.30
1.08
32.8%
2.10
0.35
16.5%
1.18
0.20
17.1%
1.67
0.51
30.8%
3.77
Cr
(M9/L)
4.60
1.54
33.5%
6.40
2.21
34.6%
4.83
1.59
33.0%
4.87
2.24
46.0%
7.53
3.00
39.9%
4.83
1.48
30.7%
4.50
1.31
29.1%
3.73
0.95
25.3%
2.23
0.29
12.9%
3.77
0.92
24.5%
4.47
Cu
(ug/L)
143.7
54.50
37.9%
112.7
31.64
28.1%
176.7
5.77
3.3%
103.7
46.69
45.0%
113.3
15.28
13.5%
86.67
43.50
50.2%
102.7
24.68
24.0%
170.0
34.64
20.4%
107.0
14.73
13.8%
143.3
55.08
38.4%
163.3
Time = 7 month
As
(ug/L)
7.37
2.00
27.2%
5.53
0.78
14.0%
5.90
0.87
14.8%
10.27
4.27
41 .6%
10.67
2.52
23.6%
10.37
1.10
10.6%
89.67
138.9
154.9%
6.50
1.35
20.7%
4.13
2.05
49.7%
6.30
1.95
30.9%
4.97
Cr
(ug/L)
10.87
1.96
18.1%
9.80
2.31
23.5%
6.57
1.98
30.1%
15.33
3.21
21 .0%
18.33
5.03
27.5%
111
1.24
16.0%
125.6
203.0
161.7%
7.67
1.86
24.2%
4.90
2.52
51 .5%
7.10
1.67
23.5%
3.77
Cu
(ug/L)
103.0
12.12
1 1 .8%
103.0
23.52
22.8%
113.7
28.29
24.9%
111.7
51.23
45.9%
117.0
39.96
34.2%
67.67
12.01
17.8%
104.0
59.09
56.8%
82.00
11.27
13.7%
53.67
23.46
43.7%
86.33
12.34
14.3%
36.67
Time =11 month
As
(ug/L)
24.00
15.59
65.0%
11.03
1.95
17.7%
9.10
1.77
19.4%
22.67
9.07
40.0%
18.00
4.00
22.2%
48.67
10.26
21.1%
40.00
5.57
13.9%
8.83
1.20
13.6%
6.33
2.31
36.5%
5.50
3.25
59.1%
7.37
Cr
(ug/L)
20.00
11.36
56.8%
17.00
1.00
5.9%
7.87
0.42
5.3%
24.67
13.50
54.7%
26.33
6.81
25.8%
22.33
13.65
61.1%
11.33
1.53
13.5%
8.80
1.93
21 .9%
3.70
1.39
37.5%
4.17
1.46
35.1%
5.70
Cu
(ug/L)
280.0
121.6
43.4%
313.3
20.82
6.6%
153.3
40.41
26.4%
303.3
185.6
61 .2%
383.3
100.7
26.3%
170.0
26.46
15.6%
176.7
28.87
16.3%
132.0
62.39
47.3%
26.33
14.47
54.9%
66.67
32.53
48.8%
45.00
147
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Evaluation of the
Effectiveness of Coatings
in Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Coat.
12
13
Std Dev
RSD
av
Std Dev
RSD
av
Std Dev
RSD
Time = 1 month
As
(ug/L)
0.26
16.5%
4.43
4.56
102.9%
9.23
5.87
63.6%
Cr
(ug/L)
0.20
6.1%
6.10
5.98
98.0%
13.17
7.01
53.2%
Cu
(ug/L)
6.08
10.9%
35.33
12.74
36.1%
57.33
12.42
21 .7%
Time = 3 month
As
(M9/L)
1.06
28.1%
4.30
2.40
55.8%
6.27
4.27
68.2%
Cr
(M9/L)
1.72
38.4%
10.97
8.59
78.3%
9.00
5.29
58.8%
Cu
(ug/L)
83.86
51 .3%
102.3
22.50
22.0%
153.3
50.33
32.8%
Time = 7 month
As
(ug/L)
1.11
22.3%
6.97
3.74
53.8%
5.93
1.59
26.9%
Cr
(ug/L)
0.60
16.0%
8.30
2.14
25.8%
11.10
3.85
34.7%
Cu
(ug/L)
7.64
20.8%
66.67
28.01
42.0%
135.3
65.77
48.6%
Time =11 month
As
(ug/L)
1.65
22.4%
12.67
4.62
36.5%
18.43
11.54
62.6%
Cr
(ug/L)
1.37
24.1%
19.00
8.19
43.1%
29.00
15.39
53.1%
Cu
(ug/L)
13.89
30.9%
233.3
25.17
10.8%
310.0
80.00
25.8%
148
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Evaluation of the
Effectiveness of Coatings
in Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
5. Data Validation and Quality Assurance and Quality Control
5.1 Assessing DQI Goals
The critical measurements for the accelerated and natural weathering tests are total
arsenic, total chromium, and total copper concentrations. Data quality indicator
(DQI) goals for concentration in terms of accuracy, precision, and completeness, as
established in the QAPP for this project, are shown in Table 5-1.
Table 5-1. Data Quality Indicator Goals for Critical Measurements
Analyte
Arsenic (total)
Chromium (total)
Copper (total)
Method
SW-846 Method 6020 (modified)
SW-846 Method 6020 (modified)
SW-846 Method 6020 (modified)
Accuracy
(%Recovery)
90-110
90-110
90-110
Precision
(%RSD/RPD)
10
10
10
Completeness
(%)
90
90
90
After reviewing sample results, the DQI goals for precision and accuracy have been
revised for concentrations <10 (ig/L. Acceptance criteria of ±25% RPD for precision
between duplicates and 75-125% recovery for accuracy will be used for
concentrations <10 (ig/L.
5.1.1 Precision
In order to evaluate the precision of a measurement, it is necessary to make at least
duplicate measurements of a relatively unchanging parameter. Precision can then be
expressed as the relative percent difference (RPD) of the duplicated measurement.
RPD is calculated using Equation 5.1 where Yl is the concentration of the first
sample and Y2 is the concentration of the duplicate sample.
(Equation 5.1)
7
A large number of blind field duplicates (wipe samples split following extraction)
were performed and delivered to the laboratory for analysis. These duplicates were
performed at a rate of 7% of the total number of samples collected and provide an
indication of the repeatability of the analytical method. The DQI goal for precision
was set at ±10% RPD. For the majority of samples, agreement between field
149
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duplicates was very good (i.e., the RSD was small). The DQI goal of ±10% was
increased to ±25% for samples with concentrations <10 (ig/L because smaller
differences in lower concentrations have a greater effect on RPD. With the
modification, there were still some cases where the DQI goal was slightly exceeded.
In only one case was RPD >50%, this was the only sample set where the data was
qualified as estimated "J" due to the RPD between the duplicate samples. A summary
of duplicate results is shown in Table 5-2. Instances where these revised DQI goals
were not met are shown in bold. Completeness summaries for each metal using the
revised DQI goals are shown at the bottom of the table. Achieved completeness was
>80%, which did not meet the DQI goal of 90% established in the QAPP. There are
no acceptance criteria given in the analytical method for agreement between
duplicate samples. A DQI goal of ±15% RPD may be more realistic for these types
of samples.
Evaluation of the
Effectiveness of Coatings
in Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
5.1.2 Accuracy and Bias
For this project, the accuracy of the measurement is expressed in terms of recovery
of a known spike. Recovery is calculated by:
R C
Percent Bias = x 100
C
(Equation 5.2)
Spiked samples were performed by the laboratory at 3 of 4 concentration levels with
the samples from each sampling event. Those concentration levels were 10,000 (ig/L,
1,000 u.g/L, 50 u.g/L and 1 u.g/L. In addition to the laboratory spikes, ARCADIS
provided 1000 u.g/L spikes (in triplicate) and submitted these blind to the laboratory.
Spike results are summarized in Table 5-3. Results that do not meet the DQI goals of
90-110% recovery are indicated in bold (with the exception of the 1 (ig/L spikes).
The DQI recovery goal for the 1 (ig/L spike sample was increased to 75-125% as was
done for precision. Completeness was calculated separately for each spiking level
and each analyte and is shown at the end of each spike level. Bias results clearly
improve as the concentration of the spike level is increased. Not enough spikes were
performed at the 10,000 u.g/L level to be representative of the sample set.
Performance of more spikes at all levels may improve completeness results. Future
sample groups should include at least one spike per 100 samples. Spikes were not
performed at that rate for any of these tests.
150
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Evaluation of the
Effectiveness of Coatings
in Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Table 5-2. Precision of Duplicate Samples
Sample/Duplicate
(Group)
SS-859/626 (WIPE-05)
SS-860/633
SS-861/635
SS-862/647
SS-863/656
SS-864/666
SS-865/674
SS-866/687
SS-867/690
SS-868/700
SS-872/712(WIPE-06)
SS-873/714
SS-874/718
SS-875/719
SS-876/720
SS-877/721
SS-878/724
SS-879/727
SS-880/730
SS-881/734
SS-886/837 (WIPE-07)
SS-887/849
SS-888/852
SS-885/824
SS-1 274/1 071 (WIPE-08)
SS-1 275/1 084
SS-1 276/1 090
SS-1 277/1 091
SS-1 278/1 107
As (ug/L)
3.6/4.0
490/490
5.9/5.4
300/270
34/36
73/74
120/140
150/150
810/810
83/83
72/81
290/300
58/56
360/340
190/190
130/120
460/440
8.9/20
5.1/5.1
3.9/4.1
160/170
69/69
3/2.8
1.7/1.7
880/890
25/26
200/200
180/190
150/150
%RSD
10.5
0
8.8
70.5
5.7
1.4
75.4
0
0
0
11.8
3.4
3.5
5.7
0
8.0
4.4
76.8
0
5
6.1
0
6.9
0
1.1
3.9
0
5.4
0
Cr(ug/L)
5.7/5.7
690/690
10/9.2
390/370
8.1/8.8
17/18
220/260
260/260
1700/1700
120/120
120/140
410/410
27/26
110/100
210/210
140/140
150/150
2.2/5.3
5.0/5.2
4.7/4.8
300/310
46/45
8.7/8.4
2.6/2.6
1100/1100
7.3/7.6
240/250
310/320
140/140
%
RSD
0
0
8.3
5.3
8.3
5.7
16.7
0
0
0
75.4
0
3.8
9.5
0
0
0
82.7
3.9
2.1
3.3
2.2
3.5
0
0
4.0
4.1
3.2
0
Cu (ug/L)
23/23
190/190
40/37
190/180
31/33
40/40
130/150
180/180
660/660
74/73
87/98
200/200
71/69
110/110
140/150
92/89
160/150
13/31
59/59
62/64
99/100
73/71
35/33
51/53
190/190
66/71
110/110
170/180
220/230
%
RSD
0
0
7.8
5.4
6.3
0
74.3
0
0
1.4
11.9
0
2.9
0
6.9
3.3
6.5
87.8
0
3.2
1.0
2.8
5.9
3.8
0
7.3
0
5.7
4.4
151
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Evaluation of the
Effectiveness of Coatings
in Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Sample/Duplicate
(Group)
SS-1279/1116
SS-1 280/1 126
SS-1281/1131
SS-1 282/1 149
SS-1 283/1 153
SS-1 284/1 160
SS-1 285/1 161
SS-1 286/1 171
SS-1 287/1 172
SS-1 288/1 173
SS-1 289/1 179
SS-1 290/1 180
SS-1291/1181
SS-1 292/1 208
SS-1 293/1 210
SS-1 294/1 21 5
SS-1 295/1 222
SS-1 296/1 223
SS-1 297/1 230
SS-1 298/1 234
SS-1 299/1 247
SS-1 300/1 258
SS-1 587/1 324 (WIPE-10)
SS-1 588/1 333
SS-1 589/1 344
SS-1 590/1 348
SS-1 591/1 352
SS-1 592/1 371
SS-1 593/1 376
SS-1 594/1 383
As (ug/L)
6/5.3
130/130
150/150
530/530
700/680
<0.5/<0.5
35/33
8.3/7.9
2.5/2.8
2.5/2.6
210/210
<0.5/<0.5
3.7/3.6
39/37
30/30
19/19
3/3
180/190
370/350
120/110
41/44
18/17
9.2/8.0
240/240
53/48
77/72
150/140
92/91
140/140
2300/2300
%RSD
12.4
0
0
0
2.9
0
5.9
4.9
11.3
3.9
0
0
2.7
5.3
0
0
0
5.4
5.6
8.7
7.1
5.7
14.0
0
9.9
6.7
6.9
1.1
0
0
Cr(ug/L)
11/10
150/160
350/340
830/840
1100/1100
<0.5/<0.5
39/37
13/12
2.6/2.9
8.3/8.3
550/570
0.95/0.84
5.7/5.7
55/54
57/58
17/16
6.2/6.6
290/310
740/700
230/220
41/46
13/12
15/13
440/440
27/24
48/44
30/26
14/14
41/39
2700/2600
%
RSD
9.5
6.5
2.9
1.2
0
0
5.3
8.0
10.9
0
3.6
12.3
0
1.8
1.7
6.1
6.2
6.7
5.6
4.4
11.5
8.0
74.3
0
11.8
8.7
74.3
0
5.0
3.8
Cu (ug/L)
150/150
280/300
250/260
390/400
490/500
1.5/1.8
130/130
140/140
110/120
170/180
220/250
2.3/2.9
120/130
93/93
77/82
120/120
170/170
140/140
300/300
160/150
80/87
110/100
90/81
230/220
100/91
210/190
41/36
36/33
81/72
390/360
%
RSD
0
6.9
3.9
2.5
2.0
18.2
0
0
8.7
5.7
12.8
23.1
8.0
0
6.3
0
0
0
0
6.5
8.4
9.5
70.5
4.4
9.4
10.0
73.0
8.7
11.8
8.0
152
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Evaluation of the
Effectiveness of Coatings
in Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Sample/Duplicate
(Group)
SS-1 595/1 386
SS-1 596/1 407
SS-1 597/1 41 5
SS-1 598/1 479
SS-1 600/1 487
SS-1601/1495
SS-1 602/1 502
SS-1 603/1 51 2
SS-1 604/1 51 4
SS-1 605/1 51 9
SS-1 606/1 529
SS-1 607/1 531
SS-1 608/1 534
SS-1 609/1 536
SS-1 61 0/1 540
SS-1 61 1/1 566
SS-1 6 12/1 568
SS-1 6 13/1 576
SS-1 6 14/1 578
WB-278/893(WIPE-11)
WB-348/894
WB-353/895
WB-373/896
WB-383/897
WB-394/898
WB-409/899
WB-445/900
WB-445/901
WB-449/902
WB-443/903
As (ug/L)
12/11
730/700
100/98
480/490
77/73
470/480
450/490
110/110
31/29
59/65
99/100
22/23
2.6/2.4
2.2/2.1
<1.0/<1.0
7.7/7.6
130/120
280/300
56/54
8900/9400
11000/9700
6200/6000
8500/8600
8800/8600
8900/10000
600/600
5300/5500
7500/7700
2200/2300
11000/8400
%RSD
8.7
4.2
2.0
2.1
5.3
2.1
8.5
0
6.7
9.7
1.0
4.4
8.0
4.7
0
1.3
8.0
6.9
3.6
5.5
72.6
3.3
1.2
2.3
11.6
0
3.7
2.6
4.4
26.8
Cr(ug/L)
11/9.2
100/950
160/160
630/640
170/160
560/570
1100/1260
240/240
87/81
270/290
22/22
6.5/6.9
5.3/5.0
8.3/7.8
<1.0/<1.0
9.6/9.2
49/43
73/80
57/56
8800/9100
12000/9800
7100/6600
7800/8000
8500/8300
8500/9600
680/680
6700/6900
7400/7700
3000/3100
11000/8100
%
RSD
17.8
5.1
0
1.6
6.1
1.8
13.6
0
7.1
7.1
0
6.0
5.8
6.2
0
4.3
73.0
9.2
1.8
3.4
20.2
7.3
2.5
2.4
72.2
0
2.9
4.0
3.3
30.4
Cu (ug/L)
72/67
490/430
140/130
350/360
150/140
230/240
420/460
160/160
190/180
140/150
32/33
33/34
83/82
91/88
2.4/3.0
94/88
140/120
140/160
170/160
5300/5300
7500/6300
4400/4000
5500/5500
4600/4400
4900/5400
410/380
4500/4600
4500/4600
1600/1700
7400/5400
%
RSD
7.2
73.0
7.4
2.8
6.9
4.3
9.1
0
5.4
6.9
3.1
3.0
1.2
3.4
22.2
6.6
75.4
73.3
6.1
0
77.4
9.5
0
4.4
9.7
7.6
2.2
2.2
6.1
37.3
153
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Evaluation of the
Effectiveness of Coatings
in Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Sample/Duplicate
(Group)
WB-437/904
WB-260/905
WB-1 96/906
WB-1 15/907
WB-1 18/908
WB-1 49/909
WB-1 73/910
WB-239/91 1
WB-255/912
WB-1 46/920 (WIPE-1 2)
WB-1 54/921
WB-21 5/922
SS-1 884/1 842 (WIPE-1 3)
SS-1885/1713
SS-1 886/1 727
SS-1 887/1 81 5
SS-1 888/1 851
SS-1 889/1 797
SS-1 890/1 671
SS-1891/1653
SS-1 892/1 624
SS-1 893/1 772
SS-1 894/1 749
SS-1 895/1 869
SS-1 896/1 882
SS-1 897/1 641
Completeness
Using DQI of ±10%
Using DQI of ±15%
As (ug/L)
1800/1200
5400/3500
4000/4300
4900/4900
5800/5200
6600/6700
5900/6500
10000/9800
12000/11000
130/91
4200/4700
5900/5000
30/28
33/31
72/78
1300/1200
590/520
7.5/7.6
870/760
1000/940
360/3440
4000/3700
85/75
310/350
140/140
14/14
%RSD
40.0
42.7
7.2
0
10.9
1.5
9.7
2.0
8.7
35.3
11.2
16.5
6.9
6.3
8.0
8.0
72.6
1.3
13.5
6.2
5.7
7.8
72.5
72.7
0
0
99/115 = 86.0%
109/115=94.8%
Cr(ug/L)
1900/1200
6600/6500
5100/5400
4800/4700
7000/6000
8400/8400
7200/7700
11000/10000
13000/12000
140/95
4800/5500
6600/5600
14/14
30/38
120/130
2200/2100
1500/1300
7.3/7.4
1800/1700
1760/1600
420/460
5600/5200
120/110
230/250
270/290
20/21
%
RSD
45.2
1.5
5.7
2.1
75.4
0
6.7
9.5
8.0
38.3
73.6
76.4
0
20.3
8.0
4.7
74.3
1.4
5.7
9.5
9.1
7.4
8.7
8.3
7.1
4.9
96/115 = 83.4%
105/115=91.3%
Cu (ug/L)
1300/860
3600/5500
2700/2700
2800/2600
4100/3400
5200/6100
4200/4300
7000/6200
7200/6200
110/77
2900/3200
3500/3000
29/27
540/480
340/370
820/780
1300/1100
140/140
650/610
950/940
260/250
2200/2100
170/180
330/340
330/340
310/290
%
RSD
40.7
41.8
0
7.4
18.7
15.9
2.4
72.7
14.9
35.3
9.8
75.4
7.1
11.8
8.5
5.0
76.7
0
6.3
1.1
3.9
4.7
5.7
3.0
3.0
6.7
93/115 = 80.9%
104/115=90.4%
154
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Table 5-3. Spike Results
Analytical
Group
Arsenic
Obtained
%Recovery
Chromium
Obtained
%Recovery
Copper
Obtained
%Recovery
10,000 ug/L Spike Level (DQI Goal 90-110%)
WIPE-10
WIPE-13
9700
10000
Completeness
97
100
100%
10000
12000
100
720
50%
9700
10000
97
100
100%
1,000 ug/L Spike Level (DQI Goal 90-110%)
WIPE-05
WIPE-06
WIPE-07
WIPE-08
WIPE-08*
WIPE-08*
WIPE-08*
WIPE 11
WIPE-11
(duplicate)
WIPE-12
WIPE-13
1100
1000
1100
980
970
940
980
1100
1100
1100
1000
Completeness
110
100
110
98
97
94
98
110
110
110
100
100%
1000
980
1000
1000
1000
1000
1000
1000
1000
990
1100
100
98
100
100
100
100
100
100
100
99
110
100%
980
920
950
980
970
950
970
930
980
970
990
98
92
95
98
97
95
97
93
98
97
99
100%
50 ug/L Spike Level (DQI Goal 90-110%)
WIPE-05
WIPE-06
WIPE-07
WIPE-08
WIPE-10
WIPE 11
WIPE-11
(duplicate)
WIPE-12
WIPE-13
50
58
45
46
52
51
54
54
64
100
116
90
92
104
102
108
108
128
52
52
47
50
49
53
51
52
57
104
104
94
100
98
106
102
104
114
49
51
43
47
48
51
50
50
59
98
102
114
94
96
102
100
100
118
Evaluation of the
Effectiveness of Coatings
in Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
155
-------
Analytical
Group
Arsenic
Obtained
Completeness
%Recovery
77.8%
Chromium
Obtained
%Recovery
88.9%
Copper
Obtained
%Recovery
77.8%
1 ug/L Spike Level (DQI Goal 75-125%)
WIPE-05
WIPE-06
WIPE-07
WIPE-08
WIPE-10
WIPE 11
WIPE-11
(duplicate)
WIPE-12
WIPE-13
2.3
0.95
0.97
1.0
1.1
1.2
0.5
1.1
1.3
Completeness
230
95
97
100
110
120
50
110
130
66.7%
3.4
0.9
0.84
1.0
<1.0
1.1
0.5
0.96
1.0
340
90
84
100
100
110
50
96
100
77.8%
4.6
1.2
1.3
1.2
<1.0
1.2
0.5
1.3
1.0
460
120
730
120
100
120
50
730
100
55.6%
Evaluation of the
Effectiveness of Coatings
in Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
5.1.3 Completeness
The ratio of the number of valid data points taken to the total number of data points
planned is defined as data completeness. Completeness goals of >90% were not
achieved for a number of measurements. These are summarized in Tables 5-2 and
5-3. Data results suggest that the DQI goal of ±10% for precision between duplicates
may be too ambitious. There is no specific acceptance criteria given in the analytical
method for precision between duplicate samples. If the DQI goal were slightly
increased to 15% RPD, completeness goals would have been met for all metals. Also,
the analytical method cites acceptance criteria for recovery of spiked blanks as 85-
115 % which is slightly higher than the DQI goal of 90-110%. Using this criteria,
completeness of accuracy results would improve. DQI goals will be reviewed and
may be revised as needed.
5.2 Quality Control Checks
A variety of control samples were taken as described in Section 4.1-4.4 of the QAPP
(U.S. EPA 2003). Results from the checks are described in the following subsections.
156
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5.2.1 Blanks
5.2.1.1 Wipe Blank Study
A number of blank evaluations were performed early in the project to evaluate the
amounts of target compounds inherent in the extraction process and the wipes
themselves. Initially, wipes directly out of the bag were placed in clean digestion
vessels and approximately 40 mL of 10% nitric acid added. The samples were then
heated lightly in the microwave and allowed to cool and the contents transferred to a
100 mL volumetric flask. An additional 40 mL of 10% nitric was added to the vessel
and the process repeated. The vessel was then rinsed with consecutive 10 mL
aliquots of 10% nitric acid and the contents transferred, bringing the volumetric to
mark. It should be noted that the wipe remained wet and it was impossible to
completely transfer all of the liquid to the volumetric flask. Successive extractions
and rinses were used in the hopes of largely transferring all of the metals to the
volumetric flask. Blank results for arsenic and chromium are shown in Table 5-4.
Initial wipe blank analysis did not include an analysis for copper.
Evaluation of the
Effectiveness of Coatings
in Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Table 5-4. Polywipe Blank Analyses
Sample Number
AQS-54
AQS-55
As (ug/L)
1.2
1.3
Cr(ug/L)
0.8
1.1
To investigate the potential to reduce the background levels of As and Cr seen in the
wipe blanks, nine polywipes were pretreated by extracting them with 10% nitric acid
at 60 °C for 1 hr, then rinsing thoroughly with de-ionized water, and allowing them
to dry in a clean environment. Results comparing the pretreated wipe blank to the
previous results are shown in Table 5-5. The pretreated polywipes were used for the
subsequent tests and sampling events.
Table 5-5. Results from a September 2003 Wipe Comparison Study
Average
Wipe Blank (Out of Bag)
Digested Nitric Blank
Acid Wipe Blank
Ar(ug/L)
0.41
<0.10
0.2
Cr(ug/L)
0.93
<0.50
<0.50
Cu (ug/L)
2.1
0.3
1.3
157
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Results for the initial out of bag wipe blanks experiments were performed using a
whole 12" x 12" polywipe. The data collected from the September 2003 Wipe
Comparison Study were performed using half of a wipe, thus the concentrations for
the half a wipe should be lower than from a whole wipe.
5.2.1.2 Blanks During Sampling Events
During actual sampling events, two types of blank samples were submitted by
ARCADIS to the laboratory for analysis. Blind field blanks were submitted at a
frequency of one every 20 samples and consisted of the extraction fluid from a clean
wipe (i.e., not wiped across a board). Reagent blanks were also submitted at a
frequency of one per sample delivery group and consisted of an aliquot of the nitric
acid reagent used for extracting samples. The majority of results from the blind field
blank samples resulted in non-detects for each metal of interest. When there were
detects (>l(ig/L), concentrations were always < 10 (ig/L and always less than the
action levels. In some cases, samples with reported concentrations of the metals less
than the action level associated with these field blanks were qualified as not detected
and flagged "U". These results are summarized in the individual validation reports
included in Appendix U. None of the metals of interest were detected in any of the
reagent blanks submitted to the laboratory for analysis. No blank corrections were
performed on reported sample concentrations.
5.2.2 Initial Spike Study
A number of spike studies were done to ensure that the analytes of interest could be
captured with the wipes, extracted and analyzed. In the first study, three samples
were prepared by spiking known amounts of arsenic and chromium standard stock
onto a clean glass plate and allowing the liquid to evaporate. Each glass plate was
then wiped using the CPSC technique and the polywipes were extracted and
analyzed. Recovery results are shown in Table 5-6.
Evaluation of the
Effectiveness of Coatings
in Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
158
-------
Table 5-6. Results of Spiking onto Glass
Spiked Amount
Sample AQS-56
Sample AQS-57
Sample AQS-58
Average
SD
% recovery (av)
% RSD
As
50
33
41
41
38.3
4.6
77%
12%
Cr
49.75
38
46
46
43.3
4.6
87%
11%
Units
H9
H9
H9
M9
M9
M9
Evaluation of the
Effectiveness of Coatings
in Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
The recoveries from the glass plate sampling have an average of 77% recovery for
arsenic and 87% recovery for chromium. Less than 100% recovery of the metals
could be expected due to the drying of the spike solutions on the glass. A small
amount of residue was seen left on the glass after wiping with the wiping apparatus.
The residue could be removed with further cleaning which indicated that the stain
was metal salts and not etching.
In the next study, pretreated polywipes were directly spiked with 1 (ig/L, 50 (ig/L
and 1000 (ig/L of arsenic, chromium and copper standard. These samples were
extracted and analyzed by the laboratory. Results are shown in Table 5-7.
Table 5-7. Results of Spiking Wipes Directly
Sample
ID
SS-562
SS-563
SS-564
Arsenic
(ug/L)
1.0
47
1100
Recovery
(%)
100
94
110
Chromium
(ug/L)
1.0
51
1000
Recovery
(%)
100
102
100
Copper
(ug/L)
1.2
47
970
Recovery
(%)
120
94
97
In addition to liquid standards for arsenic, CPSC also provided ARCADIS with a
standard CCA Dust Material that contained a known amount of arsenic. A known
weight of this material was placed directly in to extraction vessels containing the acid
rinsed polywipes and extracted and analyzed. This spiking was done in duplicate and
recoveries for arsenic were 98% and 102%. As a result of the spike studies, it was
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determined that arsenic, chromium and copper could be adequately recovered from
wipe samples.
5.2.3 Laboratory Control Samples
A series of laboratory control samples were analyzed with each batch of samples as
defined by the analytical method (EPA Method 200.8). Internal laboratory QC
checks included laboratory reagent blanks at a frequency of one every 20 samples,
laboratory fortified blanks at a frequency of one per batch and post-digestion spikes
which were performed at a frequency of one every 10 samples. Results of laboratory
control samples were summarized in the analytical reports and also in the internal
validations performed by ARCADIS. Failure to meet acceptance criteria resulted in
data flagged as estimated "J", or non-detects, "U".
5.3 Data Validation Summary
The subcontract laboratory was required to submit calibration and QC data along
with each data package. All data packages received by ARCADIS were internally
validated by a qualified staff scientist according to the QA/QC criteria set forth in the
U.S. EPA Contract Laboratory Program National Functional Guidelines for
Inorganic Data Review, July 2002 (NFG). When parameters called out in the NFG
were different from those established in the QAPP or the analytical method (EPA
Method 200.8), the more stringent criteria were used. Validation reports were
prepared for each sample delivery group and the reported data were qualified as
appropriate. These reports are included in Appendix U.
5.4 Deviations from the QAPP
Deviations from the original QAPP and the reasons or justification for them are listed
below:
" Laboratory cites use of Method 200 .^-Determination of Trace Elements in Waters
and Wastes by Inductively Coupled Plasma/Mass Spectrometry instead of SW-846
Method 6020 as referenced in the QAPP. Method 200.8 is a more detailed and
specific method than 6020 and there are no technical differences between the two.
" Field blanks at a rate of 5 % were not included in the first two batches of samples
sent to the laboratory as stated in the QAPP Section 4.4. This was a mistake by the
sampling team. Subsequent batches contained the appropriate number (or more) of
Evaluation of the
Effectiveness of Coatings
in Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
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field blanks. Based on the results of subsequent field blanks, it is not believed that
the first batches of samples were compromised due to insufficient number for field
blanks.
" Blind spiked samples were not submitted to the laboratory at the frequency
described in Section 4.4 of the QAPP. Only one set of triplicate spikes at 1,000
(ig/L were submitted. There are a number of laboratory control samples required
by the method that are performed with each batch. It was felt that one set of blind
spiked samples was sufficient.
" The laboratory performed post-digestion spikes at a 10% frequency, but did not do
standard matrix spikes and matrix spike duplicates, since ARCADIS did the
sample extraction and digestion.
" Two brush wash water samples were taken per brush type (four total samples) and
the wash technique used was slightly different than that in the QAPP.
" Wood moisture content was not measured during each wipe event, because of
concerns about damaging and compromising coatings using the wood moisture
probe.
5.5 Audits
The ARCADIS QA Officer performed an internal technical systems audit on the
sampling portion of this project on September 10 and 11, 2003. The following
findings were reported to the ARCADIS Work Assignment (WA) Manager. All
problems found during the audit were corrected the same day.
" Sampling staff were not wearing gloves on the first day of sampling. Corrective
actions were taken and for all subsequent sampling the sampling staff used double
gloves and changed the outer pair after each sample was taken.
" Sampling apparatus was not being decontaminated after each board. Corrective
action was implemented that apparatus would be wiped down after each board
using wipes wetted with DI water.
" There were some initial problems with the wipe staying on the apparatus when
wiping boards with a rough surface. The corrective action taken was to orient the
wipe such that corners are facing board when wiping, which helps the wipe stay in
place.
Evaluation of the
Effectiveness of Coatings
in Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
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Evaluation of the
Effectiveness of Coatings
in Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
In addition to the systems audit, three blind audit samples were submitted to STL for
analysis. Results from these samples were presented in Table 5-7 and met all DQI
goals.
An audit of data quality was performed on the information contained in the database
through Sampling Event #4 (July 2004). Database data was checked for accuracy by
comparing entries with raw data sheets, project notebooks and laboratory reports.
The ARCADIS QA Officer performed this audit by randomly selecting samples
representing approximately 10% of the total number of entries contained in the
database. The following parameters were verified for 77 randomly selected
specimens:
Specimen label
Board label
Minideck label
Specimen type
Date sampled
Date analyzed
Lab sample ID
Laboratory batch number
Arsenic concentration
Chromium concentration
Copper concentration
Core wood analysis results (when applicable)
Moisture content
Baseline arsenic, chromium and copper
Coating ID
In addition to the 77 samples randomly selected, 100% of the data recorded for
coating volume and coating mass for each minideck was recalculated. Any
discrepancies were immediately reported to the ARCADIS work assignment leader
(WAL) and database manager (Krich Ratanaphruks) and corrected. An internal
report was submitted to the ARCADIS WAL. The following findings were cited:
1 Specimen A-BG-BL6 in database should actually be A-L-BL5. All other
information related to this sample is correct.
• There is no baseline data for A-BG-M4 contained in the database.
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Evaluation of the
Effectiveness of Coatings
in Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
" In the file Baseline Samples-ver5.xls for sample C-BO, there are two BL4 entries.
One should be BL5.
" The concentration in the database for C-BT-M2 is an average of BL3 and B14 and
should be an average of BL2 and BL3.
« There were discrepancies (affecting approximately 20%) in the way moisture
averages were calculated. The same logic was not applied to every specimen.
" There were numerous errors made in volume (affecting approximately 30%) and
weight (affecting approximately 15%) calculations for initial coating of minidecks.
Errors were caused by mistakes in subtraction and difficulty reading handwriting
in notebooks. For this reason, 100% of the information was recalculated using the
information documented on original data sheets and in the project notebook.
Corrected values were submitted to the Database Manager.
The majority of these findings were minor and corrected in the database
immediately. As a result of the audit findings, a new column for moisture data for
each specimen was added to the database that is an average of all measurements
made for the entire board. This method of calculating moisture eliminates having to
determine which two moisture measurements to use in the average to apply to each
specimen. No systematic corrective actions were implemented for the coating
volume and mass finding because these measurements will not be performed again
unless new minidecks are prepared. In the event new coatings are evaluated, changes
in how volumes and weights are recorded will be implemented.
An EPA audit was performed in November 2004 at the time of collection of the 15-
month samples. Results of this audit will be reported within the final data report
which will contain the results for the samples collected at the 15-month sampling
period in addition to the data from each of the other sampling events.
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6. Conclusions
The primary purpose of this study is to provide EPA with data needed to make and
support guidance to consumers regarding mitigating health risks associated with the
continued use of CCA treated wood structures, like decks. As such, the coatings that
were tested were ranked based on their performance. Upper tier performers generally
reduced dislodgeable arsenic (DAs) by about 90% or greater after 11 months, middle
tier performers generally reduced DAs by about 75% or greater at 11 months, and
lower tier performers generally reduced DAs by about 75% or less at 11 months.
While the top two performers were film-forming coatings - the only two paints tested
(coatings #9 and #10) - several other, more typical deck treatment products performed
almost as well. The painted minidecks show significant weathering, with an oil-based
paint seeming to resist chipping better than a water-based paint. However, there are
significant concerns about the applicability of using paints as coatings for exposed
outdoor surfaces subject to abrasion. Weathered paints can have a noticeably poor
appearance, necessitating frequent recoating. Additionally, the chipping of paints and
surface preparation techniques for recoating, which typically include sanding, can
generate dust which may make inhalation of CCA-contaminated particles a serious
health risk.
Another film-former, an elastic vinyl product designed to encapsulate CCA wood
(coating #11), performed very well initially, but appeared to fall off slightly in
comparison to other high-performing products overtime. This product additionally
exhibited significant biological growth and associated discoloration.
Within the remaining coatings, no clear trends with respect to product type or
characteristics are immediately evident. The best non-film-forming products were
identified as coatings #1, #3, and #8. Coating #1 is an oil-based semitransparent sealant
in cedar tone. Coating #1 additionally contains a UV blocking agent. Another coating
containing a UV blocker (coating #7) did not perform as well. Coating #3 is a clear, oil-
based, acrylic, deep tone base stain to which no pigment had been added prior to
application. Coating #8 is a clear, water-based, acrylic, tint base, solid stain to which no
pigment had been added prior to application.
Additionally, we can say that:
" Rinsing the wood surfaces reduces DA measured by wipe sampling, although it
may simply relocate the CCA chemicals to other places where exposure is possible.
Evaluation of the
Effectiveness of Coatings
in Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
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" Coating the wood surfaces further reduces DA over uncoated surfaces.
" Weathering reduces the effectiveness of coatings as seen by increases in DA.
" Some coatings perform better than others in terms of DA reduction but there are
inconsistencies between coatings within the same classification.
" Coating product trade names are not tied to specific formulations, potentially
complicating the ability to communicate results and guidance effectively with the
public.
Significant findings with regards to the test protocol, include the following:
" The protocol appears robust and could be used by the coatings industry to develop
coatings and to verify coating performance for CCA exposure mitigation.
" Cross-contamination does not appear to be a significant issue with respect to the
study design utilized for this project.
" It appears that baseline (pre-coat) DA should be determined either for each PSA (as
done in this study) or averaged over each board. Averaging over each source board
may allow more flexibility from a study design logistics perspective, without
sacrificing statistical power with respect to assessing coating performance via
efficacy calculations. We recommend devising a way to take precoat measurements
before and after doing the coating preparation (washing, rinsing, etc.) step to
determine the effect of coating preparation on DA.
« The effects of abrasion - that is, the wearing down of the coating and the liberation
of more DA - resulting from the wipe sampling method used for this study appear
to be negligible, thus avoiding potential complications, or false positive
interferences, as a result of the sampling methodology.
" As noted in other related studies, rewipe effect - that is, the reduction in DA post-
sampling - may be significant. However, in this study, no significant trends were
observed between DA and the elapsed time between sampling events, although
there was a significant relationship between DA and the number of previous wipe
samples taken. The 60-day post-sampling recovery period suggested by Stilwell
(2003a) appears to be the minimum amount of time to allow DA to recover to
presample levels. In this study, rebound to presampling levels (samples taken 1
Evaluation of the
Effectiveness of Coatings
in Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
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Evaluation of the
Effectiveness of Coatings
in Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
month after coating, for the positive control minidecks), only occurs for several PSA
samples. On average, DA reductions from the first sampling event are still observed
after 4 months of no-sampling weathering, suggesting that the recovery period may
need to be even greater than 4 months.
" There appears to be a relatively strong correlation between DAs, DCr, and DCu.
That is, wipe areas with high DA measurements for one CCA analyte generally also
have high DA measurements for the other CCA analytes.
« The method by which coating efficacies are calculated or modeled did not appear to
have a large effect on the rank order of coatings. Additional work may need to be
done to determine which of the methods provide the most useful data with respect to
the specific mitigation goals of a project (i.e., in appropriately predicting percent
reductions to use in associated risk analyses, etc.).
Finally, abrasion is considered another likely important coating performance factor.
Coating protocols for testing DA mitigation should include an abrasion component in
addition to weathering.
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7. References
Bludis, T. 2002. "CCA Sealant Literature search (Action No. ELK03, TAP 1-3-8)".
Memorandum from Traci Bludis to Cletis Mixon, dated June 21, 2002. Versar,
Inc.
CPSC staff 2003(a). "Statistical Analyses of CCA-Treated Wood Study Phases I and
II". Memorandum from Mark S. Levenson to Susan Ahmed and Russell Roegner,
dated January 10, 2003. Consumer Products Safety Commission.
CPSC staff. 2003 (b). Memorandum from David Cobb to Patricia Bittner, "CCA-
Pressure Treated Wood Analysis - Exploratory Studies Phase I and Laboratory
Studies Phase II," in the Briefing Package, "Petition to Ban Chromated Copper
Arsenate (CCA)-Treated Wood in Playground Equipment (Petition HP 01-3), U.S.
Consumer Product Safety Commission, Washington, B.C., February 4, 2003. pp
229. http://www.cpsc.gov/LIBRARY/FOIA/FOIA03/brief/briefing.html. April 27,
2005.
CPSC staff. 2005. "Evaluation of the Effectiveness of Surface Coatings in Reducing
Dislodgeable Arsenic from New Wood Pressure-Treated with Chromated Copper
Arsenate (CCA)". Consumer Products Safety Commission.
Lebow, S. 1996. "Leaching of Wood Preservative Components and Their Mobility in
the Environment. Summary of Pertinent Literature." Forest Products Laboratory,
U.S. Department of Agriculture. General Technical Report FPL-GTR-93. August
1996.
Lebow, S. 2001. "Coatings Minimize Leaching from Treated Wood". Techline
Durability. Forest Products Laboratory, U.S. Department of Agriculture. Issued
11/01.
Miller, D. 2001. "Evaluation of sealants for and alternatives to the use of CCA-treated
picnic tables". Memorandum from Denise Miller to Bill Hinkly and Charles
Savering, dated June 4, 2001. Florida Department of Environmental Protection.
Steel, R.G.D., J. H. Torrie, D. A. Dickey. 1997. "Principles and Procedures of
Statistics: a Biometrical Approach," McGraw-Hill, New York.
Stilwell, D., M. Toner, B. Sawhney. 2003. "Dislodgeable Copper, Chromium and
Arsenic from CCA-Treated Wood Surfaces." The Science of the Total
Environment. 312 (2003). 123-131.
Evaluation of the
Effectiveness of Coatings
in Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
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Evaluation of the
Effectiveness of Coatings
in Reducing Dislodgeable
Arsenic, Chromium, and
Copper from CCA Treated
Wood
Interim Data Report
EPA Report EPA/600/R-05/050
9 May 2005
Stilwell, D. 2003(a). "Arsenic Dislodged from CCA Surfaces". PowerPoint
Presentation. Personal Communication.
Stilwell, D. 2003(b). "Arsenic Dislodged from CCA Surfaces - Effects of Coatings".
PowerPoint Presentation. Personal Communication.
U.S. EPA. 2003. "Evaluation of the Effectiveness of Coatings in Reducing
Dislodgeable Arsenic, Chromium, and Copper from CCA Treated Wood. Revision
6." U.S. EPA, Research Triangle Park, NC, September 24, 2003.
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