The green-tinged wood used on decks, railings and children's play grounds - pressure treated wood - may be treated with chromated copper arsenate (CCA), a chemical wood preservative and essentially a pesticide. It contains arsenic, a known human carcinogen. In humans, chronic exposure can cause cancer, toxic effects in the nervous and cardiovascular systems, and skin lesions (including skin cancer); in experimental animals, arsenic is known to cause immune system toxicity. A voluntary phase-out of pressure-treated wood for residential use began in Canada in January, 2004. Though industrial use continues, CCA-treated wood is now banned for non-industrial uses in Canada. Tests show that arsenic can be available on the surface of this wood and can build up in soil immediately below it. Alternative treated wood products are also green-tinted. Precautionary steps should be taken to avoid arsenic exposure from CCA-treated wood purchased before January 2004.
It is important to wash children's hands after contact with CCA-treated wood. Cover picnic tables made from CCA-treated wood. Never burn CCA-treated wood - this releases toxic chemicals. Saw, sand and machine CCA-treated wood outdoors. Wear a dusk mask, goggles and gloves. Do not mulch or compost the sawdust or wood chips. Removal or replacement of CCA-treated structures is generally not recommended by regulatory agencies. Coating the surface with a penetrating wood sealant (not paint) has been shown to reduce available arsenic. Regular reapplication of the sealant is necessary. Despite the CCA phase-out, remember that pressure-treated wood still contains a pesticide. Similar precautions are necessary. For product-specific safety information, see www.ptw-safetyinfo.ca
The following list of resources contain extensive information about CCA-treated wood ranging from fact sheets to comprehensive reports.