From the Editors of E/The Environmental Magazine
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The Pros and Cons of Pressure-Treated
Is pressure-treated wood harmful to human health?
Pressure-treated wood contains the preservative chromated copper arsenate (CCA), an arsenic derivative used to protect the wood and prolong its life. Also used commercially as a pesticide, CCA is regarded by many homeowners and construction professionals as a godsend for preserving outdoor wood against harsh weather and termites. But it is also on environmentalists’ watch lists as a potential health hazard due to its arsenic content.
Though arsenic is a naturally occurring element, it is poisonous. Prolonged exposure can cause vomiting, diarrhea and skin abnormalities, according to the U.S. Environmental Protection Agency. The EPA considers arsenic a human carcinogen, with long-term exposure increasing the risk of skin cancer and tumors of the bladder, kidney, liver and lung.
Recent studies have shown that rainwater can release arsenic-laden CCA from the treated wood, potentially contaminating any soil or groundwater below. Also, especially after a heavy rain, a fine coating of CCA residue can build up directly on the wood’s surface, where it can be picked up on hands and clothing, potentially exposing family members to small but persistent doses of arsenic.
The EPA may classify arsenic itself as a toxin, but it says that periodic contact with pressure-treated wood poses no “ unreasonable” risk. The agency has, however, issued new safeguards for protecting workers who come into contact with CCA on a daily basis. Even the nation’s largest producer of pressure-treated wood, Arch Wood Protection Inc., advises taking precautions when working with, using and cleaning up its products, acknowledging that “exposure to CCA may present certain hazards.”
If you already have pressure-treated wood, applying an oil-based stain once every couple of years will help keep the CCA from seeping out. Additionally, keep children and pets out of under-deck areas where arsenic may be present. Don’t grow edible plants near any pressure-treated wood structures, and always follow safe-handling guidelines (including the use of gloves and dust masks) when using it in building projects.
For those starting from scratch, there are several safer alternatives to pressure-treated wood. Yellow cypress, yew, tamarack, hemlock, white cedar and redwood are naturally rot-resistant, according to the Berkeley, California-based Green Resource Center, as are plastic and wood-plastic composite building materials. Meanwhile, wood boards that are treated with alternative techniques that don’t use CCA are free of the arsenic problem. Alkaline Copper Quartenary, sold under the trade name NatureWood, is one safer option, as is Copper Azole, which is sold under the trade name Natural Select.
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