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Chromated Copper Arsenate (CCA):
Preliminary Risk Assessment for Workers Who Contact Wood Preservatives Containing Arsenic and/or Chromium and Ecological Effects Assessment: Questions and Answers

CCA Table of Contents

Current as of March 19, 2004

EPA announced the results of its preliminary assessment of potential health risks for workers, as well as ecological effects and environmental risks, associated with wood preservatives containing arsenic and/or chromium. This preliminary assessment included an evaluation of the potential risks to handlers and post-application workers from exposure to these chemicals. The assessment was a cooperative re-evaluation between the US EPA and Health Canada's Pest Management Regulatory Agency (PMRA) under NAFTA. The preliminary risk assessment is available from Regulations.gov in Docket Number EPA-HQ-OPP-2003-0250.

  1. Which wood preservatives were included in this preliminary assessment?
  2. What were the occupational exposure scenarios included in this preliminary risk assessment?
  3. What are the findings of this preliminary risk assessment?
  4. What recommendations could the Agency make for handlers?
  5. Were potential risks to children included in this preliminary risk assessment?
  6. What has been the role of Canada's Pest Management Regulatory Agency (PMRA) in the development of this preliminary risk assessment?
  1. Which wood preservatives were included in this preliminary assessment?
    The predominant inorganic arsenical preservatives used by the wood treatment industry are mixtures of "chromated copper arsenate," more commonly referred to as "CCA." Other wood preservatives covered include: ammoniacal copper arsenate (ACA), and ammoniacal copper zinc arsenate (ACZA). Acid Copper Chromate (ACC) is also a wood preservative containing arsenic and/or chromium; however, it is subject to a voluntary cancellation action and is not part of this assessment. Preservatives such as ACZA and ACA are used for specialized applications or in cases where wood penetration by CCA chemicals cannot be achieved (e.g., ACA and ACZA are used on large dimension wood products made from hard-to-treat wood species such as Douglas Fir). These chemicals are referred to as "heavy duty wood preservatives."

  2. What were the occupational exposure scenarios included in this preliminary risk assessment?
    The occupational exposure chapter addresses potential exposures and risks of chromium and arsenic to humans who may be exposed to CCA and related arsenicals and chromated wood preservatives in "occupational settings" including: (1) handlers (mixers, loaders, applicators) of CCA and related pesticide products; and (2) individuals who are exposed to CCA and related pesticides through postapplication activities. The occupational settings are characterized as wood treatment plants where wood is pressure treated. Therefore representative occupational handler exposure scenarios were developed for treatment plant workers only. Potential postapplication exposures also may occur in occupational settings such as wood pressure treatment plants where treated lumber is handled for QA/QC testing, or storage/transport, or in commercial or institutional outdoor settings where the wood is fabricated into structures and professionally installed. However, occupational postapplication exposure scenarios were developed for treatment plant workers only, since it is anticipated that handling freshly-treated wood and performing postapplication work tasks in treatment areas constitute postapplication scenarios with the potential for maximum exposures.

  3. What were the findings of the preliminary risk assessment?
    Because this is a preliminary assessment, it is premature for EPA to reach conclusions about the potential for wood preservatives containing arsenic and/or chromium to contribute to cancer risks in workers, or regarding environmental or ecological risks. While EPA has identified some potential risks of concern, the risk estimates provided in this assessment are of a preliminary nature and subject to refinement. The process that EPA uses to review chemicals through reregistration is intended to gather additional information and input from the public and stakeholders about exposure and risk that will be used to revise the risk estimates.

  4. What recommendations does the Agency make for handlers?
    The Agency is in the process of evaluating exposure and risk assessment data for workers involved with pressure treatments using inorganic arsenicals. General precautions for handling treated wood include always washing hands thoroughly after contacting treated wood, especially prior to eating and drinking, and ensuring that food does not come into direct contact with any treated wood. Workers and consumers should follow the recommendations in the Consumer Awareness Program, including wearing gloves when handling wood, wearing goggles and dust-mask when sawing and sanding, and never burning CCA-treated wood.

  5. Were potential risks to children included in this preliminary risk assessment?
    No; these potential risks are being carefully evaluated through a separate but similar process. Refer to the CCA fact sheet for information on that assessment, and the Scientific Advisory Panel's report.

  6. What has been the role of Canada's Pest Management Regulatory Agency (PMRA) in the development of this preliminary risk assessment?
    The preliminary risk assessment is a cooperative re-evaluation between the US EPA and Health Canada's PMRA under NAFTA. Both countries have contributed to the study review and peer review process. Exposure data used in the preliminary risk assessment were collected from both US and Canadian wood-treatment facilities and both countries are participating in the public comment process. As the assessments are finalized, EPA will continue to work closely with Canada since the goal of these efforts is to develop science and regulatory conclusions amenable to both agencies. More information available from the PMRA website. Exit EPA disclaimer

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