Treated Lumber
June 4, 2002
CCA treated lumber for residential markets to be phased out
Chromated copper arsenate (CCA) as a treatment for lumber used in consumer products and the residential building market is being phased out by Dec. 31, 2003.
The U.S. Environmental Protection Agency (EPA) and the wood treating industry announced a voluntary decision in February 2002 to phase out CCA, says Tom Milton, forest products specialist with the University of Minnesota Extension Service. Milton says CCA has accounted for a huge share of pressure treated wood in the U.S., especially over the last 30 years. Over 78 percent of the 728 million cubic feet of wood treated in 1997 was treated with CCA.
"CCA is a registered pesticide," Milton says. "Considering the volume that's been used and the 70 years that it's been around, it continues to have an outstanding safety record when you follow proper handling precautions. But times have changed.
"In recent years, the public has become increasingly concerned about exposures to arsenic," Milton says. "Even though the EPA has not concluded that there is an unreasonable risk to the public from CCA-treated products, it does believe that any reduction in exposure to arsenic is desirable. When you couple the market's growing negative perception of CCA with the development of non-arsenic preservatives, it's easy to see why the industry volunteered to phase out CCA for the residential market.
"This is a huge change for the treating industry," Milton says. "We are already seeing a growing amount of non-CCA lumber at retail yards and Minnesota's treating plants are already beginning the transition to the new preservatives. The new preservatives are copper-based fungicides like CCA, but without the arsenic."
They include ACQ (Ammoniacal Copper Quat) found in the brand name products ACQ Preserve and NatureWood; and CBA (Copper Boron Azole) found in the brand name Natural Select. In place of arsenic, ACQ uses DDAC (the quat component) and copper azole uses tebuconazole to provide protection against copper tolerant fungi and insects. Both preservatives perform similar to CCA. CCA will continue to be used for a number of industrial products such as utility poles, piling and crossties.
What about replacing existing decks, playground sets or other CCA-treated material? "The EPA does not recommend replacing or removing any existing structures made with CCA-treated material, since exposure to such material has not been proven to be harmful," Milton says. However, the EPA does recommend, based on some limited studies, that potential arsenic exposures can be further reduced by applying a protective sealant such as a semi-transparent stain or water-repellent finish on an annual or semi-annual basis. Such finishes minimize moisture uptake into the wood and the leaching of preservative components out of the wood.
"Perhaps just as important is that a proper and well-maintained finish protects the appearance of wood exposed to weathering," Milton says. For more information, go to http://www.preservedwood.com or http://www.epa.gov/pesticides/citizens/cca_transition.htm. Or, you can contact Tom Milton at (612) 624-5307, tmilton@umn.edu.
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Source: Tom Milton (612) 624-5307, tmilton@umn.edu
Editor: Jack Sperbeck (612) 625-1794, sperb001@umn.edu
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