Chromated Copper Arsenate (CCA)

CCA, 22 percent pure arsenic combined with chromium and copper, is injected into wood at high pressure to prevent rot and insect damage. The arsenic migrates to the surface of treated wood, where it can be picked up on hands and then ingested. (This is a particular concern with children playing on playgrounds, where CCA treated wood is common.) Arsenic can also contaminate the soil under and surrounding treated wood. CCA was the most common wood preservative and pesticide used in the United States. Fortunately, as a result of consumer pressure to review its safety, the EPA and the treated wood industry agreed to a ban on CCA in outdoor wood intended for consumer use by the end of 2003.