Is the pressure-treated wood used for decks, picnic tables and backyard play structures harmful to human health?
—Christy Silver, Cleveland, OH
Pressure-treated wood contains the preservative chromated copper arsenate (CCA), an arsenic derivative that is 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 structures against harsh weather and termites. But it is also on environmentalists” watch lists as a potential health hazard due to its arsenic content.
According to the US Environmental Protection Agency (EPA), arsenic, although a naturally occurring element found in the Earth’s crust, is poisonous. Prolonged exposure can cause vomiting, diarrhea and skin abnormalities. The EPA also considers arsenic to be 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, which in turn can be picked up on hands and clothing, potentially exposing family members to small but persistent doses of arsenic.
But while the EPA may classify arsenic itself as a toxin, it does not believe that periodic contact with pressure-treated wood poses any “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 around your home, applying an oil-based stain once every couple of years will help keep the CCA from seeping out. Additionally, you should keep children and pets out of under-deck areas where arsenic may be present. Also, 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 who may be starting from scratch, there are several safer alternatives to pressure treated wood. According to the Berkeley, California based Green Resource Center, yellow cypress, yew, tamarack, hemlock, white cedar and redwood are naturally rot-resistant, 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.
CONTACTS: EPA Arsenic Toxicity Assessment, www.epa.gov/ttn/atw/hlthef/arsenic.html ; Green Resource Center, (510) 845-0472, www.greenresourcecenter.org ; NatureWood, (800) 241-0240, www.osmose.com/wood/usa/preserved/naturewood/product/ ; Natural Select, (866) 789-4567, www.naturalselect.com.