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Mulch matters

Mulch made from recycled construction and demolition wood can release arsenic into the environment, a study finds.

Outdoor structures such as decks typically contain wood treated with chromated copper arsenate (CCA) to make it resistant to termites and other pests. Since the end of 2003, the Environmental Protection Agency has banned this wood in residential structures over concerns that CCA exposure could cause cancer (SN: 1/31/04, p. 74: Danger on Deck?).

Some of the treated wood ends up at recycling facilities and gets shredded into mulch, says Helena M. Solo-Gabriele of the University of Miami in Coral Gables, Fla. She and her colleagues measured how much arsenic the mulch releases. They also investigated whether the arsenic-binding dye iron oxide affects the rate of release.

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