Arsenic-Treated Wood: Background and Overview

Arsenic-Treated Wood: Background and Overview

Order Code RL32412
CRS Report for Congress
Received through the CRS Web
Arsenic-Treated Wood:
Background and Overview
Updated September 9, 2005
Michael Simpson
Specialist in Life Sciences
Resources, Science, and Industry Division
Congressional Research Service ˜ The Library of Congress

Arsenic-Treated Wood: Background and Overview
Summary
Arsenic is a known human carcinogen. A preservative using chromated copper
arsenate (CCA) has been the principal way to protect most commercially harvested
wood from decay. Such wood has been used to build play structures, picnic tables,
decks, gazebos, fences, and walkways. Arsenic and chromium can be released from
the preserved wood. Since December 12, 2001, the Federal Insecticide, Fungicide,
and Rodenticide Act (FIFRA) Scientific Advisory Panel (SAP), a group designed to
provide balanced expert assessment of pesticide-related issues to the Administrator
of the U.S. Environmental Protection Agency (EPA) has recommended inter alia
that CCA-treated wood be coated and recoated annually to reduce release of and
exposure to arsenic, and that a biomonitoring study of children normally exposed to
CCA-treated wood should be conducted. However, EPA does not believe there is
any reason to remove or replace CCA-treated structures. On February 13, 2004, the
SAP released its final report on EPA’s draft preliminary probabilistic risk assessment
of the potential risks to children associating with CCA-treated playsets and decks.
The agency says it will carefully consider the SAP recommendations and revise the
draft risk assessment as appropriate. On March 19, 2004, EPA announced in the
Federal Register the availability of the Preliminary Risk Assessment for the
Reregistration Eligibility Decision. This notice covered both occupational and
environmental assessments. On May 27, 2005, EPA released preliminary results
from studies that showed that all of the 12 commercially available sealants tested
reduced dislodgeable arsenic from CCA-treated wood for up to 12 months of natural
weathering. While sealing can reduce the amount of arsenic getting into children’s
skin, the EPA study results do not reveal the magnitude of that reduction. EPA has
announced a timeline of major pending actions, including making available the final
report of the sealant study (end of 2005), the CCA Probabilistic Risk Assessment
(end of June 2006), and the CCA Reregistration Eligibility Decision (end of
September 2006).
The wood treating industry, by January 1, 2004, voluntarily converted to
nonarsenical preservatives for residential uses, including copper boron azole (CBA)
and ammonia copper quaternary ammonia (ACQ), whose availabilities and costs are
approximately those of CCA in the past. Labeling had been on all CCA products
stating that no use of CCA would be allowed for the affected residential uses after
December 31, 2003. Wood treated prior to that date can still be used in residential
settings, and CCA-treated wood in extant built structures is not affected.
Disposal of extant CCA-treated wood, export and possible import of CCA-
treated wood and wood products, determination of the best ways to reduce arsenic
exposure from extant wood, and possible adverse effects from nonarsenic wood
preservatives are continuing concerns.
Three bills (S. 337, H.R. 688, and H.R. 3629) were introduced in the 108th
Congress prohibiting other uses of or studying alternatives to CCA-treated wood.
There are no bills on arsenic-treated wood in the 109th Congress. This report will be
updated as events warrant.

Contents
Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Health Effects of CCA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Wood Preservatives: Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Recommendations of an Independent Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Scientific Peer Review of Draft Risk Assessment . . . . . . . . . . . . . . . . . . . . . . . . . 6
Disposal Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Legislative Proposals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Arsenic-Treated Wood:
Background and Overview
Background
Beginning on January 1, 2004, the EPA no longer allowed use of chromated
copper arsenate (CCA) to preserve wood intended for most residential uses: play
structures, decks, picnic tables, landscaping timbers, residential fencing, gazebos,
patios, and walkways. Wood treated prior to that date may still be used in residential
settings, and CCA-treated wood in extant built structures is not affected. Meanwhile,
the wood preservative industry has voluntarily converted to preservatives for
residential wood uses that do not contain arsenic. While the EPA “does not believe
there is any reason to remove or replace CCA-treated structures,”1 arsenic is a known
carcinogen in humans and any reduction in the levels of potential exposure to arsenic
is desirable; the agency is continuing study of the entire range of CCA uses.
Disposal of extant CCA-treated wood, export and possible import of CCA-
treated wood and wood products, determination of the best ways to reduce arsenic
exposure from extant wood, and possible adverse effects from nonarsenic wood
preservatives are continuing concerns.
Health Effects of CCA
High pressure was used to inject CCA into wood. While some people (such as
construction workers, wood treaters, or firefighters) might touch, inhale, or ingest
CCA itself or CCA-treated sawdust or smoke from fires, the largest concern was
possible exposure of children to CCA, which slowly leaches from CCA-treated
wood.2
Copper, an essential nutrient of relatively low toxicity, is the component in CCA
causing the lowest level of concerns about safety or health. As such, EPA did not
conduct an exposure or risk assessment for copper.
Chromium leaches from CCA-treated wood mostly as chromium III (CR(III)),
one of a few forms of the element. There may be trace amounts of chromium VI
1 “Draft Preliminary Probabilistic Risk Assessment for Children Who Contact Chromated
Copper Arsenate (CCA) Treated Playsets and Decks,” which can be found at [http://www.
epa.gov/pesticides/factsheets/chemicals/draft_cca_qa.htm].
2 The amount and rate of leaching varies greatly, depending on many factors, such as local
climate, acidity of precipitation and soil, age of the wood, concentration of CCA, amount
of contact with skin, and degree of protective coating.

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(CR(VI)), a more toxic form of the element. The rarity of CR(VI) in CCA leachate
led EPA to conclude that the toxicity of CR(III) was the most appropriate toxicity
endpoint. The low toxicity of CR(III) led EPA to conclude that it was unnecessary
to present short-term, intermediate-term, or lifetime risks of exposure to CR(III).
Arsenic is a known human carcinogen and is acutely toxic. The degree of
carcinogenicity and toxicity depends highly on degree and route of exposure. EPA
has over several years been trying to assess the risk of exposure to arsenic from CCA-
treated wood.
Wood Preservatives: Overview
Untreated lumber cut from most commercially harvested tree species is subject
to attack by insects and marine organisms, or decay caused by fungi and bacteria.
Decay or insect hazard generally is greatest where the wood is subjected to moisture,
especially in hot and humid climates, or aquatic environments.
To protect untreated wood, the lumber is placed in cylinders filled with the
preservative solution, and the preservative is pressurized until it penetrates the wood.
Most commonly, copper (usually derived from recycled sources) from the
preservative deposited in the wood renders it useless as a food source for termites and
fungi. The American Wood Preservers Institute estimates that CCA increases the life
of wood products exposed to the environment from 7 to 12 times, which is about 20
to 50 years (representing a significant reduction in need for replacement wood). By
enabling wood to last longer, CCA-treated wood is better positioned to compete with
stone, concrete, brick, or other long-lived building materials, expanding the market
for wood.
The most common pressure-treated wood preservative has been CCA. More
recently, copper boron azole (CBA) has been used. CBA was introduced in 1982 and
does not contain arsenic. Introduced very recently, ammonia copper quaternary
ammonia (ACQ), like CBA, provides arsenic-free protection to wood.3 In the past,
CCA was prevalent and low-cost. With the voluntary industry transition to
nonarsenical wood preservatives, CBA and ACQ have become more widely available
at a cost approaching that of CCA in the past. The industry saw a decline during
2002 in production of CCA products for residential uses of 25%, with a
corresponding shift to alternatives. Labeling was required on all CCA products
stating that no use of CCA would be allowed for the affected residential uses after
December 31, 2003.
Cedar, redwood, plastics, metals, and concrete continue to be available as
construction materials that do not require the use of wood preservatives. These wood
and nonwood alternatives generally cost more than pressure-treated woods (up to
twice the cost of pressure-treated woods).
3 Azole also is used as an antifungal drug in humans, e.g., fluconazole (Diflucan is
a brand name for this compound) and ketoconazole (Nizoral is a brand name).
Concern has been raised by some about the potential for azole compounds losing
antifungal potency in humans because of its use in the environment.

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As a way of recognizing the presence of CCA, while new and bare (i.e.,
unpainted or uncoated) CCA wood tended to have a green tint (caused by chemical
reactions that took place between the wood and the preservative’s ingredients), as a
practical matter virtually all pressure-treated wood before 2004 was treated with
CCA. There has been some interest in requiring labeling or banning of CCA wood
already in use: Beyond Pesticides (a national environmental group) petitioned EPA
in December 2001 to ban all residential uses of CCA; CPSC was petitioned in May
2001 by the Environmental Working Group and the Healthy Building Network to ban
CCA wood for play structures.4 On November 4, 2003, CPSC announced that it had
denied the petition, noting that CCA manufacturers and EPA had previously agreed
to phase out CCA treatment of wood for most consumer uses by the end of 2003.5
For regulatory purposes, wood preservatives are considered pesticides, and are
regulated under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA).
Establishing maximum levels of pesticides in or on food, and regulating the sale,
distribution, and use of pesticides in the United States, are the responsibilities of EPA
under FIFRA. The agency also is responsible for ensuring that older pesticides
continue to meet current science and regulatory standards. To this end, EPA
reassesses the science and uses of older pesticides in a reregistration program, and
determines whether changes are needed to ensure the safety of continued use of older
pesticides (those initially registered before November 1, 1984). The agency presently
is reassessing CCA under the reregistration program. In preparation, EPA is
conducting two risk assessments: one focuses on workers (an occupational risk
assessment), and the other focuses on children. A draft probabilistic risk assessment
for children was released in November 2003 for scientific peer review.
On February 12, 2002, EPA announced a voluntary decision by industry to move
away from CCA as a preservative of wood for consumer use, with the regulatory
requirement of having only non-CCA pressure-treated wood manufactured for
consumer use after December 31, 2003.
The agency describes its reregistration review process as having three major
parts:
! Reliance on Sound Science. EPA reports that it is conducting a
review of CCA-related public health and environmental studies, is
consulting with other federal entities, and will use external peer
review in its ongoing risk assessment.
4 EPA, the wood preservative industry, various consumer groups, and others agree that
consumers should be informed of the presence of CCA wood preservative, especially so that
steps are taken to limit exposure to CCA. Such steps include coating the wood, not burning
the wood, not using the wood for kitchen countertops or where it may become a component
of food, and properly disposing of sawdust and scraps. Some others hold that an outright
ban is needed.
5 CPSC Denies Petition to Ban CCA Pressure-Treated Wood Playground Equipment, News
from CPSC, November 4, 2003. This notice can be found at CPSC’s website: [http://www.
cpsc.gov/CPSCPUB/PREREL/prhtml04/04026.html].

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! Involvement of Stakeholders. The agency reports working closely
with wood treaters, CCA product registrants, retailers, other federal
entities, trade associations, and public interest groups, and
consulting with foreign and state governments6 that have taken
regulatory actions on CCA to understand their scientific assessments
and reasons for their regulatory standards.
! Participation by the Public. EPA reports that by making its
assessments public, opening comment periods, and conducting
public meetings, it seeks to maintain open dialogue with the public,
toward the goal of comprehensive and balanced regulatory decisions.
The agency reports that it was especially concerned about two major issues
relating to CCA-treated wood: making CCA safety and health information readily
available to consumers, and determining the potential risks to children from play
structures treated with CCA. EPA started an assessment early in 2001 focused on the
potential exposure of children to CCA-treated wood play structures.
By early 2001, the agency was concerned that its consumer awareness program,
which was started in 1986, was not informing the public as well as intended. EPA
therefore met in summer 2001 with representatives of the wood preservative industry,
registrants (makers or users of CCA registered with EPA), major retailers, and public
interest groups to expand the CCA consumer awareness program, which included
labeling on all pieces of CCA-treated lumber, in-store displays, and additional
information packets available to the public.
By May 30, 2001, EPA’s Office of Pesticide Programs (OPP) had developed an
internal draft assessment of risks associated with CCA-treated wood. The Scientific
Advisory Panel met in October 2001 to discuss issues related to children’s exposure
to CCA from wood, and on February 12, 2002, the agency announced the voluntary
action by industry to move away from CCA preservatives.
Recommendations of an Independent Panel
FIFRA, as amended by the Food Quality Protection Act of 1996, provides for
the establishment of the FIFRA Scientific Advisory Panel (SAP) to provide advice,
information, and recommendations to EPA’s Administrator regarding the impact on
health and the environment of pesticide-related regulatory actions. The SAP
provides scientific peer review of the EPA Office of Pesticide Programs, and is
designed to provide balanced expert assessment of pesticide-related issues. SAP
6 Differences exist among some state and foreign governments in the ways they regulate use
and disposal of CCA wood. California, for example, requires that all CCA-treated public
play structures be coated. And while most states allow CCA-treated wood to be handled
similarly to other discarded wood products, Minnesota does not. Switzerland, Vietnam, and
Indonesia have banned arsenic-treated wood, while Japan, Denmark, Sweden, Germany,
Australia, and New Zealand have either restricted it or proposed restrictions. Differences
also exist as to what types of products may be made of CCA-treated wood.

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members were chosen because of their expertise. Following an open meeting in
October 2001, the SAP reported recommendations in a memorandum in December
2001 to the Director of EPA’s Office of Pesticide Programs. The SAP’s report was
not reviewed for approval by EPA, and does not necessarily represent the views of
the agency, or of any other agencies in the federal government. EPA received the
recommendations and has reported that it has considered them. The panel offered
several conclusions and recommendations, including the following.7
! While the SAP noted the need for additional studies (especially of
performance of different types and brands of coatings), the panel
found the evidence already sufficiently strong to recommend that
EPA should inform the public that certain coatings can substantially
reduce the amount of CCA that can be leached or dislodged from
wood. Reductions of 70% to 95% in dislodgeable arsenic were seen
in CCA wood with coatings such as polyurethane, and subjected to
natural weathering.
! The SAP found no evidence that water repellents added directly to
the CCA treatment solution reduced the amount of leachable or
dislodgeable CCA.
! While the panel to that point found no evidence that any particular
coating was clearly superior or inferior to any other, confidence was
highest for polyurethane, as it resulted in 70% to 95% reduction in
dislodgeable arsenic in a well-controlled field study, a “real-world”
application allowing for effects of use, and a short-term controlled
laboratory study.
! The SAP recommended a reapplication of a coating every year,
although polyurethane still provided up to 95% reduction after two
years of exposure.
! A biomonitoring study of children normally exposed to CCA-treated
play structures should be conducted, with the goals of clarifying the
magnitude of exposure of children to arsenic and possibly chromium
from play structures, and to help support development of a
probabilistic exposure assessment.
7 FIFRA Scientific Advisory Panel Meeting, October 23-25, 2001, held at the Sheraton
Crystal City Hotel, Arlington, Virginia, “Preliminary Evaluation of the Non-dietary Hazard
and Exposure to Children from Contact with Chromated Copper Arsenate (CCA)-treated
Wood Playground Structures and CCA-contaminated Soil,” SAP Report No. 2001-12.
Available at [http://www.epa.gov/oscpmont/sap/meetingindex.htm].

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Scientific Peer Review of Draft Risk Assessment
On November 13, 2003, EPA released its draft preliminary probabilistic risk
assessment for children exposed to CCA-treated wood. The agency released the draft
for scientific peer review. EPA convened its SAP on December 3-5, 2003, to seek
expert independent scientific advice on the data and methodology used in the draft
risk assessment. Public comments were made during the SAP meeting.8 The agency
on February 12, 2004, announced the availability of the SAP’s report on the draft
preliminary probabilistic risk assessment. EPA said it “will carefully consider the
SAP recommendations9 and revise the draft risk assessment as appropriate.”10 On
March 19, 2004, EPA announced in the Federal Register the availability, for
comments, of the Preliminary Risk Assessment for the Reregistration Eligibility
Decision. This notice covered both the occupational and environmental assessments.
On May 27, 2005, EPA released preliminary results from studies which showed that
all of the 12 commercially available sealants tested reduced dislodgeable arsenic
from CCA-treated wood for up to 12 months of natural weathering.11 Michael
Shannon, M.D., chair of the American Academy of Pediatrics’ Committee on
Environmental Health, agreed that “a sealant can cut down on the arsenic that gets
into children’s skin, but no one knows by how much.”12
EPA announced on its website the following timeline of major pending CCA
actions:13
! December 31, 2005 — announce availability of sealant study final
report.
! June 30, 2006 — announce availability of the CCA Probabilistic
Risk Assessment.
8 FIFRA Scientific Advisory Panel Previous Meetings, available at [http://www.epa.gov/
oscpmont/sap/meetingindex.htm].
9 The recommendations relate to the completeness, clarity, assumptions, mathematical
manipulations, and documentation of computer models used in the assessment, and to a
proposed biomonitoring pilot study. SAP Meeting Minutes No. 2003-04, FIFRA SAP
Meeting, December 3-5 2003, A Set of Scientific Issues Being Considered by the
Environmental Protection Agency Regarding Draft Preliminary Probabilistic Exposure and
Risk Assessment for Children Who Contact CCA-Treated Wood On Playsets and Decks And
CCA-Containing Soil Around These Structures.
10 See [http://www.epa.gov/oscpmont/sap/2003/index.htm].
11 Questions and Answers on CCA-Treated Wood Sealant Studies (Interim Results), United
States Environmental Protection Agency. This is available at EPA’s website: [http://www.
epa.gov/oppad001/reregistration/cca/timeline.htm].
12 Poison on the Playground? Arsenic-Treated Wood Structures Raise Concerns, MedPage
Today, August 9, 2005. This is available at MedPage Today’s website: [http://www.
medpagetoday.com/PublicHealthPolicy/EnvironmentalHealth/tb/1509].
13 Chromated Copper Arsenate (CCA): Timeline of Major CCA Actions, U.S. Environmental
Protection Agency, May 27, 2005. This information is available at EPA’s website:
[http://www.epa.gov/oppad001/reregistration/cca/timeline.htm].

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! September 30, 2006 — announce availability of the CCA
Reregistration Eligibility Decision.
Disposal Issues
The Resource Conservation and Recovery Act (RCRA) inter alia requires
certain solid wastes (hazardous wastes) to be managed more stringently, owing to
potential risks to human and environmental health. According to the group Beyond
Pesticides, some CCA wood fails EPA’s Toxicity Characteristic Leaching Procedure,
which simulates conditions in a landfill.14 Further, some CCA wood leaches arsenic
“many times above the U.S. primary drinking water standard” under EPA’s Synthetic
Precipitation Leaching Procedure, which simulates leaching by rainwater.15
While research is ongoing to more fully characterize leaching under more
conditions, Beyond Pesticides petitioned EPA on July 22, 2002, to require that CCA
wood be considered hazardous and disposed only in landfills with hazardous waste
management permits. A hazardous waste landfill has a double liner, leachate and gas
collection systems, and piping of leachate to a wastewater treatment plant. In 1980
EPA exempted CCA wood from hazardous waste status. As such, unless a state says
otherwise,16 CCA wood may be disposed like other wood waste — for example, it
may be put into construction and demolition landfills, or burned in waste-to-energy
facilities, or made into mulch.
If the wood were now to be reclassified as hazardous, especially with the
projected growth in disposal of CCA wood, concerns would exist regarding increased
costs, availability of sufficient hazardous waste management facilities, and illegal
dumping.
While EPA continues to exempt CCA wood from hazardous waste status, the
agency says that treated wood should never be burned in open fires, fireplaces, or
stoves, food should not come into direct contact with the wood, hands should be
thoroughly washed after contact with wood, wood should be coated on a regular
basis, nonarsenical alternatives be considered, and EPA’s Consumer Safety
Information Sheet precautions should be followed.17
Legislative Proposals
The following bills relating to arsenic in wood were introduced in the 108th
Congress.
14 See [http://www.beyondpesticides.org/wood/media/rcra_petition_7_22_02.htm].
15 “Good Wood Gone Bad,” Waste Age, August 2001, p. 42, at [http://www.wasteage.com].
16 Minnesota has not adopted the exemption. Waste Age, ibid.
17 See [http://www.epa.gov/oppad001/reregistration/cca/cca_consumer_safety.htm].

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! S. 337, the Arsenic-Treated Residential-Use Wood Prohibition Act,
would, inter alia, amend FIFRA to prohibit the use of arsenic-treated
lumber as mulch or compost. This bill was referred to the
Committee on Environment and Public Works on February 10,
2003.
! H.R. 688, the Wood Preservation Safety Act of 2003, would direct
the Secretary of Agriculture to conduct a study of the effectiveness
of silver-based biocides as an alternative treatment to preserve wood.
This bill was referred to the Committee on Agriculture, and to the
Committee on Resources, on February 11, 2003. Executive
Comment was requested from the Department of Interior and from
the United States Department of Agriculture.
! H.R. 3629, the Arsenic-Treated Wood Prohibition Act, is similar to
S. 337. This bill was referred both to the Subcommittee on
Conservation, Credit, Rural Development and Research of the
Agriculture Committee, and to the Subcommittee on Environment
and Hazardous Materials of the Energy and Commerce Committee,
on November 21, 2003.
There are no bills on arsenic-treated wood in the 109th Congress.