Treated wood preservatives linked to aquatic damage, human illness, and death--a societal problem.
On February 12, 2002, the US 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 arsenate (As) by December 31, 2003, in favor of new alternative wood preservatives. Chromated copper arsenate (CCA) is a chemical mixture consisting of three pesticidal compounds (As, chromium, and copper) registered for wood preservative uses. CCA is injected into wood by a process that uses high pressure to saturate wood products with the chemical. Only people who have received the proper safety training should use CCA to treat wood products. Around the home, CCA-treated wood is commonly used for decks, walkways, fences, gazebos, boat docks, and playground equipment. Other common uses of CCA-treated wood include highway noise barriers, sign posts, utility posts, and retaining walls. As of January 1, 2004, the EPA is no longer allowing CCA products to be used to treat wood intended for any of these residential uses. This decision will facilitate the voluntary transition to new alternative wood preservatives that do not contain As in both the manufacturing and retail sectors. To its credit, the EPA has developed consumer safety information sheets, hanging signs, end signs, and bin stickers that provide comprehensive information about the dangers of CCA-treated wood, use-site, and handling precautions. The EPA has not concluded that CCA-treated wood poses any unreasonable risk to the public or the environment. Nevertheless, As is a known human carcinogen and, thus, the EPA believes that any reduction in the levels of potential exposure to As is desirable. The toxicologic manifestations have been primarily related to the effects of As exposure from drinking water sources and include the following: acute poisoning incidents, cardiovascular effects, diabetes mellitus, and cancer. Understanding the biomethylation of As is central to elucidating its action as a toxin and a carcinogen. In humans as in many other species, inorganic As is enzymatically converted to the methylated products methyl As (MAs) and dimethyl As (DMAs). The aforementioned voluntary agreement to reduce the uses of CCA-treated wood does not include a ban on the use of CCA for residential roofing. A major reason that this wood product should be banned from residential roofing is that it does not provide a Class "A" fire-rated roof system, which markedly reduce the frequency of residential roof fires.