News Coverage
A safer way to pressure-treat wood
Wood treated with arsenic being phased out. New lumber treated with copper-based formulations
Published May 10, 2002
New types of pressure-treated wood will be showing up at lumber centers in the next year and a half as wood treated with arsenic is phased out of the market.
Starting in 2004, the EPA will ban residential use of pressure-treated lumber preserved with chromated copper arsenate, a chemical compound containing inorganic arsenic, copper and chromium. The phase-out is a result of an agreement announced in February between the U.S. Environmental Protection Agency and the treated-wood industry.
The decision was based on concerns over the safety of arsenic, which has been linked to cancer. Production of CCA-treated lumber is expected to decline up to 25 percent this year as plants retool for use of other preservatives. CCA has been the most common preservative for lumber used for outdoor residential uses, said Mel Pine, communications director for the American Wood Preservers Institute. CCA-treated wood is popular because it's cheaper than rot-resistant woods such as redwood and cedar and can last for decades.
Pine said consumers can expect to see CCA-treated wood replaced by lumber preserved with two other chemical formulations, both of them copper-based: alkaline copper quat, which is used in ACQ Preserve, Preserve Plus and NatureWood lumber brands, and copper boron azole, used in Wolmanized Natural Select lumber.
Those formulations have been in use for about 10 years, he said, although copper boron azole has been available in the United States for less than two years. Both have the same wood-protection properties and give wood about the same life span as CCA, but lumber treated with the newer formulations is about 10 to 20 percent more expensive, he said.
Lumber choices
Consumers can also choose lumber that's naturally rot-resistant, such as cedar, redwood or ipe, a tropical hardwood sold under the brand name Pau Lope. Pau Lope is five times harder than cedar and redwood and carries a 20-year warranty against fungal decay and insect infestation.
Even though CCA-treated wood is being taken off the market, the EPA stopped short of recommending homeowners tear down their decks, play sets and other structures made from it. "EPA has not concluded that CCA-treated wood poses unreasonable risks to the public for existing CCA-treated wood being used around or near their homes or from wood that remains available in stores," the agency said in a news release announcing the phase-out.
The Environmental Working Group, an environmental research organization, believes otherwise. The organization recommends people replace structures built of CCA-treated lumber if they can afford it, or at least replace handrails and other surfaces with frequent hand contact or seal the surface with an oil-based sealant.
The benefits of applying sealants aren't entirely clear. Some studies suggest that applying certain types of penetrating coatings, such as oil-based, semitransparent stains, every year or two may reduce the amount of arsenic leaching from CCA-treated wood. However, the Environmental Working Group notes that sanding during preparation and resurfacing can increase exposure to arsenic.
Common sense
The EPA recommends some common-sense precautions, such as not letting food touch the wood, washing hands before eating if you've touched treated wood or played outside, and not burning the wood. The Environmental Working Group also recommends not storing toys or tools under the deck because they might become coated with arsenic that leaches from the wood when it rains, and keeping children and pets away from the soil beneath and around arsenic-treated wood structures.
The EPA advises people who work with CCA-treated lumber to wear a dust mask, goggles and gloves; throw sawdust and scraps into the trash rather than using them in compost or mulch; wash hands and all other exposed areas before eating, drinking or using tobacco products; and launder work clothes separately from other clothing.
CCA has been used as a wood preservative since the 1940s. In making pressure-treated lumber, it is forced into the wood under high pressure so the chemicals saturate the wood. Those chemicals protect the wood from dry rot, fungi, molds, termites and other pests.