Arsenic was labeled a known human carcinogen in 1980 and the US stopped producing it in 1985. It was still being imported into the country at a high rate and was used as a wood preservative for “pressure-treated” decking, landscaping, walkways, picnic tables and playground equipment through the early 2000s. Since that time, under pressure from Congress, the FDA, and consumers, the lumber industry agreed to stop using arsenic-based products to preserve wood. In 2003 the EPA also moved to ban arsenic in pesticides, but the proposition has not yet passed. Many outdoor wooden structures still contain arsenic including playsets, picnic tables, and decking. Children can be especially susceptible to the deleterious effects of arsenic.
Arsenic exposure has been linked to skin, bladder, liver, lung and prostate cancers.
Sources: EWG and Environmental Health News