University of Wisconsin - Extension

Recent studies indicate that arsenic is leaching out of pressure-treated or green-treated wood into soil at significantly greater than established safe levels, according to a University of Wisconsin-Extension Solid and Hazardous Waste Education specialist.

"Treated wood, which resists rot and insects, is widely used in decks, playground equipment, gazebos, picnic tables, boardwalks and docks," explains Sherrie Gruder. "The wood is treated with CCA-chromated copper arsenate- a pesticide formulated with arsenic, which is also at the center of the debate over the safety of America's drinking water."

In 1996, the US wood products industry used 30 million pounds of arsenic or half of all the arsenic produced worldwide, according to a May 2001 report of the Environmental Working Group, "Poisoned Playgrounds: Arsenic in 'Pressure-Treated Wood". "When sawing treated wood, people should wear gloves and dust masks and catch the sawdust on tarps for trash disposal off site," Gruder says. "Hands should be washed after touching the wood. Scraps should not be burned because they give off toxic smoke and create toxic ash."

Arsenic is classified as a human carcinogen and has been shown to increase the risk of skin cancer and a variety of internal cancers. However, the health threat caused to people from arsenic being released slowly from pressure-treated structures is not known. The industry -- American Wood Preservers Institute -- maintains that pressure-treated wood is safe (www.preservedwood.com).

The Environmental Protection Agency (EPA) has banned most arsenical pesticides, but in 1985 designated CCA a restricted-use pesticide. However, the CCA-treated wood products are not regulated like the pesticides they contain because it is assumed that the chemicals will stay in the wood. What is at question is whether the chemicals actually are fixed in the wood permanently and whether the wood product is harmless.

According to a recent study by Stan Lebow of the U.S. Forest Products Laboratory in Madison, to help ensure that treated lumber has achieved fixation (a series of chemical reactions that bind the chemicals into the wood), it should be wrapped in tarps at the construction site. The amount of storage time varies with the temperature. For example, in 50-degree weather it should be stored for 872 hours (36 days), in 70 degrees for 285 hours (12 days), etc. At 32 degrees, no fixation occurs.

"Beginning in August, the EPA is requiring that pressure-treated wood carry warning labels with safety handling information," explains Gruder. In October, the EPA will hold a meeting with scientists to review the Agency's hazard assessment and methods for calculating children's exposure to treated wood in playground equipment. Completion of a risk assessment for CCA-treated wood has been given a high priority with EPA's Office of Pesticide Programs. Elsewhere, Switzerland, Vietnam and Indonesia have banned CCA-treated wood, while Germany, Sweden, Denmark, Japan, Australia and New Zealand restrict its use.

In Wisconsin, there is pending legislation in the state budget directing the Department of Agriculture, Trade and Consumer Protection (DATCP) and the Department of Commerce (Commerce) to review scientific evidence to determine whether CCA-treated lumber causes substantial harm to the environment and to human health, and to report the results by June 2002. It also directs the agencies to develop a comprehensive plan to keep CCA-treated wood from being used in children's playground equipment, picnic tables and park benches at K-12 schools and in municipal parks. The Governor may veto this provision.

The potential environmental impacts from CCA-treated wood relate to its disposal and its leaching into the environment. For the next 30 years, landfills will receive increasingly large amounts of CCA-treated lumber. "Most CCA-treated wood is disposed of in unlined construction and demolition landfills where, if there are significant quantities of CCA-treated lumber, arsenic may possibly leach into the groundwater", reports Gruder.

"It is difficult to distinguish treated from untreated wood after the CCA-treated wood has aged and lost its green tint. This is a problem as more recycling of construction and demolition materials is occurring. Treated wood should be kept separate from untreated if it is destined to be ground as mulch for plantings and gardens, or if it is going to a commercial boiler where it should not be burned", says Gruder.

According to research sponsored by the Florida Center for Solid and Hazardous Waste Management, the Connecticut Agricultural Experimental Station and others, leaching of arsenic into the ground or water under CCA-treated structures occurs at greater than safe levels.

The Wisconsin Department of Health and Family Services (DHFS) has a fact sheet on treated wood products, available upon request from a health official (http://www.dhfs.state.wi.us/"> http://www.dhfs.state.wi.us/ search for CCA). It states; "Children who play on CCA-treated playground equipment can be exposed to significant amounts of arsenic. To reduce the potential for this type of exposure, the U.S. Consumer Product Safety Commission recommends that playground equipment be painted or sealed with an oil-based sealer every two years." Other recommended treatments include polyurethane or other hard lacquer, spar varnish or paint, according to Gruder.

"Children should wash their hands immediately after being in contact with treated wood," DHFS advises. The fact sheet also states that a pet lying on or under a treated deck can get arsenic on its fur that will be brought inside the house.

The state of Connecticut's health department issued a warning three years ago about CCA treated wood in playgrounds, and that exposure from CCA-treated wood can be a major source of arsenic to children because its easily taken up onto hands from contact with the surface and may be swallowed with hand to mouth activity. They state that children should be prevented from playing underneath CCA-treated structures to minimize exposure to contaminated soil.

There are alternatives to using CCA-treated wood readily available in Wisconsin. "Building a patio with stone or brick rather than building a deck might be a more natural choice," says Gruder. "Recycled plastic lumber that is either a composite of plastic and wood fiber or all plastic is another alternative that is rapidly increasing in market share and is widely available." Gruder adds. Recycled plastic lumber resists rot and insects and is maintenance free as well. It doesn't require sealing annually or every two years like CCA-treated lumber does.

Lumber treated with non-arsenic preservatives is also made by US companies. ACQ Preserve Treated Lumber- treated with alkaline copper quaternary is made in Wisconsin by Northern Crossarm (http://www.crossarm.com">www.crossarm.com) and is available at about 100 retail lumberyards in our state. ACQ does not contain any arsenic.

All the alternative materials are more expensive than pressure-treated lumber. ACQ-treated lumber starts around 10 percent more with recycled plastic choices at least twice as expensive. But consumers now have the information to weigh the cost against the potential health and environmental risks.