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Chromated Copper Arsenate (CCA):
Questions & Answers:Draft Preliminary Probabilistic Risk Assessment for Children Who Contact
Chromated Copper Arsenate (CCA) Treated Playsets and Decks
CCA Table of Contents
Current as of November 13, 2003
Background
Chromated Copper Arsenate (CCA) is a wood preservative that has been registered to protect wood from dry rot, fungi, molds, termites, and other pests that can threaten the integrity of wood products. It is injected into wood by a process that uses high pressure to saturate wood products with the pesticide. CCA-treated wood is most commonly used in outdoor settings. Around the home, CCA-treated wood has been used for decks, walkways, fences, gazebos, boat docks, and playground equipment. Other common uses of CCA-treated wood include utility poles, building construction poles, posts and support timber, marine construction, and piles and plywood for highways.
On February 12, 2002, EPA announced a voluntary decision by industry to move away from using CCA to treat wood used in residential settings. This transition affects virtually all residential uses of wood treated with CCA, including wood used in play-structures, decks, picnic tables, landscaping timbers, residential fencing, patios and walkways/boardwalks. Effective December 31, 2003, no wood treater or manufacturer may treat wood with CCA for most residential uses. This decision will facilitate the transition in both the manufacturing and retail sectors to wood preservatives that do not contain arsenic, as well as other alternatives, such as naturally resistant woods and plastic wood.
- What is EPA releasing today?
- Why is EPA releasing this risk assessment prior to the SAP meeting?
- What is a probabilistic risk assessment? What new data were considered in this assessment?
- What are the limitations of the probabilistic risk assessment?
- What is the sealant study that is being conducted and how will EPA use the data from that study?
- What risks does arsenic pose to human health?
- What kind of advice do you have for consumers who have existing CCA structures?
- Does arsenic leach from treated wood products into soil?
- Is arsenic present in the environment from other sources?
- How can I tell if my deck or playset has been constructed with CCA-treated wood?
- What has been done to educate consumers about CCA-treated wood?
- What advice does EPA have for consumers who believe they have suffered an adverse reaction from CCA-treated wood?
- How should you dispose of CCA-treated wood?
- What was the recent Consumer Product Safety Commission (CPSC) announcement concerning a ban of CCA-treated playground equipment?
- Where is CCA in the reregistration eligibility decision (RED)'s process?
- Where can I get further information?
1. What is EPA releasing today?
EPA is releasing for scientific peer review its draft preliminary probabilistic risk assessment (PRA) on chromated copper arsenate (CCA) that evaluates potential exposure and risk to children from CCA-treated wood. This report entitled “A Probabilistic Risk Assessment for Children Who Contact CCA-Treated Playsets and Decks,” is available from the SAP Web site. The Agency is convening its Scientific Advisory Panel (SAP) on December 3-5 to seek expert independent scientific advice on the data and methodology used in this assessment. The Agency will, after receipt and consideration of the Panel's recommendations, make any changes necessary to the assessment before finalization. There will be an opportunity for public comment during the SAP meeting.
2. Why is EPA releasing this risk assessment prior to the SAP meeting?
EPA always makes documents publicly available that will be considered by the SAP. Additionally, EPA wants to ensure that its procedures and processes are transparent, and include ample opportunities for public involvement.
3. What is a probabilistic risk assessment? What new data were considered in this assessment?
Because of the statistical way in which a probabilistic assessment is able to analyze a wide range of data, it provides a more scientifically robust analysis. A probabilistic assessment is able to indicate a range of risks estimates based on a range of assumptions and what the likelihood is of any particular risk within the range occurring. This is the first time that EPA has used a probabilistic approach for a non-food use assessment. A deterministic assessment is only able to take into consideration specific point estimates in determining a single risk value. A probabilistic risk assessment provides for a much more accurate, advanced and robust analysis, thereby producing results that can be more closely correlated with exposure scenarios people experience in everyday life.
Among the new data considered in the risk assessment are a relative bioavailability study on wood surface residues and soil residues for CCA and a hand wipe study that provides information about CCA residues that may dislodge from wood surfaces as a result of hand contact. The Agency also developed a probabilistic model called the Stochastic Human Exposure and Dose Simulation (SHEDS)-Wood model, which simulates exposures to children from contact with wood preservative-treated playsets and decks, to use in this risk assessment. Additional data considered relate to dermal absorption and how CCA may form complexes with wood structure that may impact skin absorption and bioavailability.
Because the draft assessment is undergoing scientific peer review, it is premature for EPA to reach conclusions about the potential for CCA-treated playsets and decks to contribute to cancer risks in children. Further, EPA is specifically requesting the SAP to consider a range of risks estimates and provide advice about which estimates seem appropriate and most realistic. It is important to note that since this draft risk assessment is undergoing public and scientific review, its findings are preliminary in nature and are subject to additional analysis. It is, therefore, premature for EPA to reach conclusions about the potential for CCA-treated decks and playsets to contribute to cancer risk in children.
5. What is the sealant study that is being conducted and how will EPA use the data from that study?
EPA is interested in knowing what effects wood sealants may have on the leaching and exposure to CCA residues. EPA (Office of Research and Development and the Office of Pesticide Programs) and the Consumer Product Safety Commission are conducting a study to determine whether or not the application of different wood sealants on CCA-treated wood has an effect on the amount of CCA residues to which an individual may be exposed. The study is currently underway and final results are expected in the Spring of 2005. If you are concerned, you may want to consider the use of a coating product.
6. What risks does arsenic pose to human health?
Arsenic is a known human carcinogen and is acutely toxic at certain levels. When estimating the potential risks that a chemical may pose, one must consider two factors: toxicity and exposure. Toxicity is described as the harmful effects that the chemical may cause, which is often dependent on the amount or dose received. Exposure is the dose received, typically orally or through contact with the skin, or by inhaling, over a certain period of time. Thus, whether any risk of toxic effects exists is dependent on both toxicity and exposure. Arsenic is a naturally occurring chemical that can also occur in drinking water, food crops, and soil.
7. What kind of advice do you have for consumers who have existing CCA structures?
- EPA does not believe there is any reason to remove or replace CCA-treated structures, including decks and playground equipment.
- EPA is not recommending surrounding soils be removed or replaced.
- While available data are very limited, some studies suggest that applying certain penetrating coatings (e.g., oil-based semi-transparent stains) on a regular basis (one re-application per year or every other year depending upon wear and weathering) may reduce the migration of wood preservatives from CCA-treated wood.
- In selecting a coating, consumers should be aware that, in some cases, "film-forming" or non-penetrating stains (latex semitransparent, latex opaque, and oil-based opaque stains) on outdoor surfaces such as decks and fences are not recommended, as subsequent peeling and flaking may ultimately have an impact on durability as well as exposure to the preservatives in the wood.
- As always, parents should manage risks to their children. Always wash hands thoroughly after contact with treated wood, especially prior to eating and drinking; and, ensure that food does not come into direct contact with any treated wood.
- Consumers should follow the recommendations in the updated Consumer Awareness Program, including the same precautions that workers should take: wear gloves when handling wood, wear goggles and dust-mask when sawing and sanding, always wash hands before eating, and never burn CCA-treated wood.
8. Does arsenic leach from treated wood products into soil?
Published results of scientific studies suggest that arsenic, over time, slowly leaches from CCA-treated wood products. The amount and rate at which arsenic leaches, however, varies considerably depending on numerous factors, such as local climate, acidity of rain and soil, and how much CCA was applied. Some chemicals may also be dislodged from the surface of the wood upon contact with the skin.
9. Is arsenic present in the environment from other sources?
Arsenic is a chemical element and is a natural constituent of the earth's crust. It occurs naturally in rocks and soil, water, air, and plants and animals. When in the natural environment, arsenic usually binds to other molecules, such as those found in soils, and does not tend to travel very far. The average concentration of arsenic in soils in the United States varies considerably. Arsenic can be released into the environment through natural occurrences such as volcanic activity, erosion of rocks, and forest fires, or through human actions. Agricultural practices, mining, and smelting also contribute to arsenic releases in the environment. Approximately 90 percent of industrial arsenic in the United States is currently used as a wood preservative, but it is also used in dyes, metals, and semiconductors.
10. How can I tell if my deck or playset has been constructed with CCA-treated wood?
Freshly treated wood, if not coated, has a greenish tint, which fades over time. As a practical matter, CCA has been the principal chemical used to treat wood for decks and other outdoor uses around the home. Generally, if your deck or playset has not been constructed with redwood or cedar, then most likely the deck or playset was constructed with CCA-treated wood. Alternatively, if you know who constructed the deck or playset, you may want to call and ask. Playsets have been constructed from a variety of materials, including CCA-treated wood, but CCA-treated playsets represent a smaller percentage than CCA-treated decks.
11. What has been done to educate consumers about CCA-treated wood?
EPA has implemented a Consumer Awareness Program (CAP) for CCA, a voluntary program established by the manufacturers of CCA products to inform consumers about the proper handling, use and disposal of CCA-treated wood. Under this program, the information is disseminated to consumers upon purchasing CCA-treated wood products via Consumer Safety Information Sheets and/or tag labeling applied directly to the wood products. EPA more recently worked with the wood preservative industry, registrants, major retailers, and public interest groups to expand the program to include precautionary labeling on all pieces of CCA-treated lumber, in-store displays and additional information available to the public.
12. What advice does EPA have for consumers who believe they have suffered an adverse reaction from CCA-treated wood?
If you feel you are suffering possible adverse effects from working with CCA-treated wood, you should immediately contact your medical provider. For further information, and to report incidents to the EPA, please contact the National Pesticide Information Center at 1-800-858-7378.
13. How should you dispose of CCA-treated wood?
Homeowners should never burn CCA-treated wood or use it as compost or mulch. CCA-treated wood can be disposed of with regular municipal trash (i.e., municipal solid waste, not yard waste). Homeowners should contact riate state and local agencies for further guidance on the disposal of CCA-treated wood. For more information, contact EPA's Office of Solid Waste.
14. What was the recent Consumer Product Safety Commission (CPSC) announcement concerning a ban of CCA-treated playground equipment?
On November 4, 2003 CPSC announced that it denied a petition to ban CCA-treated playground equipment since industry had already voluntarily requested that EPA cancel the use of CCA to treat wood used in play equipment and EPA granted that request.
15. Where is CCA in the reregistration eligibility decision (RED)'s process?
The Agency is continuing to evaluate those uses not included in the voluntary cancellation under the reregistration process within the Office of Pesticide Programs (OPP). Once OPP completes the reregistration review for CCA, the reregistration eligibility decision (RED) document for chromated arsenicals will be released, planned for late summer 2006.
16. Where can I get further information?
More information on Wood Preservatives.