Processed or pressure-treated wood is frequently used as a construction material for playgrounds and outdoor furniture or decking. To prevent pest infestation and rotting, the wood is impregnated with chemicals. For many years, the chemical most widely used for this purpose was chromated copper arsenate, or “CCA.”

The three chemicals that make up CCA are arsenic, hexavalent chromium (chromium VI … remember Erin Brokovich?) and copper. Scientific studies show that these chemicals readily leach into the soil and can be transferred to hands by touching the wood.

The Environmental Protection Agency (EPA) classifies both arsenic and chromium (VI) as known human carcinogens. Arsenic has been linked to nervous system damage and birth defects. Children in particular are at greatest risk for exposure because they spend so much time on and around playground equipment and frequently put their hands in their mouths.

The home improvement industry agreed to a two-year phase-out of CCA in February of 2002, but existing structures and furniture will continue to present a risk. If the wood cannot be removed or replaced, it should be sealed annually with several coats of water-based latex paint or oil-based sealant to slow the rate of leaching, although tests show that some leaching continues despite such efforts.

Resources

Wood Preservatives – This article by Beyond Pesticides identifies the heavy-duty wood preservatives, specifically the inorganic arsenicals, that are considered some of the most deadly chemicals on the market.