FREQUENTLY-ASKED QUESTIONS ABOUT CCA-TREATED LUMBER AND WOOD PRODUCTS
Larry Jahn, Wood Products Extension (Retired), Dept. of Wood and Paper Science, NCSU
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On February 12, 2002, the Environmental Protection Agency (EPA) announced a voluntary decision by industry to move consumer use of treated lumber products away from a variety of pressure treated wood that contains arsenic by December 31, 2003, in favor of new alternative wood preservatives. This transition affects virtually all residential uses of wood treated with chromated copper arsenate, also known as CCA, including wood used in playground equipment, decks, picnic tables, landscaping timbers, residential fencing, patios, and walkways/boardwalks. By January 2004, EPA will not allow CCA products for any of these residential uses. This decision will facilitate the voluntary transition to new alternative wood preservatives that do not contain arsenic in both the manufacturing and retail sectors. Although the Agency has not concluded that there is unreasonable risk to the public from these products, they do believe that any reduction in exposure to arsenic is desirable. This action comes years ahead of completing the Agency's regulatory and scientific assessment of CCA and will result in substantial reductions in potential exposure to CCA. Here, in a brief form, are some of the questions you may have about pressure treated wood used in residential settings during this transition period.
2. Does CCA pressure treated
wood present any health risks to me or my family?
To address this question, researchers at the Forest Products Lab (FPL) recently evaluated the ability of three common coatings to reduce leaching from CCA pressure treated wood. Replicate matched specimens of pressure treated 2 by 6 lumber were given one of the following coatings: (1) latex primer followed by one coat of outdoor latex paint, (2) oil-based primer followed by one coat of oil-based paint or (3) two coats of a penetrating oil semi-transparent deck stain. The specimens were then exposed to 30 inches of artificial rainfall for three weeks. The water running off the specimens was collected and analyzed for preservative components.
The results were very promising. All three coatings reduced leaching of arsenic pentoxide, chromium trioxide, and copper oxide by over 99% in comparison to uncoated specimens. None of the water collected from the specimens coated with latex or oil-based paint contained any detectable copper, chromium or arsenic. In some cases, water collected from the specimens that were coated with the penetrating oil stain did contain detectable levels, but the highest level of arsenic detected in these samples was still well below the EPAs drinking water standard. This study suggests that the application of these common coatings is an excellent recommendation for consumers who are worried about chemical exposure from CCA pressure treated wood. For more detailed information on this study contact Stan Lebow, Wood Preservation and Fire Research Work Unit, Forest Products Lab at 608.231.9411 (voice), 608.231.9592 (fax), firstname.lastname@example.org (e-mail).
It should be pointed out, however, that this test did not address how well these coatings stood up to wear and tear. Previous research on this issue has resulted in the following recommendations when considering the maintenance of a deck. A water repellent preservative (WRP) is the easiest to maintain on a deck. Since WRPs are considered a penetrating finish, they let the wood breathe and do not peel. They usually last one year. The next best finish is a semi-transparent oil-based stain also considered a penetrating finish. The expected service life of semi-transparent stains is two to three years. Film forming finishes such as paints are prone to fail by peeling and are not recommended for decks due to the issue of higher maintenance. The service life of paints will depend on its abrasion resistance. Although water repellents require more frequent application than other kinds of finishes, the ease of refinishing compensates for the increased frequency of application.
3. What steps can one take
to reduce their potential exposure to CCA?
4. Should I replace my CCA
pressure treated deck or playground equipment?
5. How can I tell if my
deck has been constructed with CCA pressure treated wood?
6. What alternatives to
CCA pressure treated wood will be available?
7. Where can I obtain additional
information on CCA pressure treated lumber?
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