There is growing evidence that the materials used to preserve wood can cause harm to humans and the natural environment.  Of particular note is Chromated Copper Arsenate (CCA) pressure treated wood, but also creosote, pentachlorophenol, tributyl tin oxide and finishes containing pesticide should not be used for playgrounds in particular.  When new the products are of particular concern, however over time the preservatives have been found to continue to leach out of the wood.  Arsenic is a known carcinogen linked to skin, bladder, lung, liver and kidney cancers, but also to immune diseases, cardiovascular disease and diabetes.(1) There is also evidence that even very low levels of arsenic can change hormone functions.(2) 

Arsenic can rub off onto children's hands and skin while they play on playground equipment.  It has been estimated that a child ingests 24 to 630 micrograms of arsenic from playing just once on CCA treated playground equipment. (3)

Since the late 1970's the US EPA has been aware of possible risks from CCA.  Arsenic treated wood has been banned or restricted by countries including Denmark, Sweden, Switzerland, Indonesia, Viet Nam, Japan, Australia and Germany, yet it is still widely used in Canada and the united States.(4)  In 1984, chemical companies were given the opportunity to voluntarily warn North American consumers of the risks from CCA wood use.  According
to the CCA Pressure Treated Wood Information Site (www3.sympatico.ca/pbarrie/), that effort failed.  However, new labelling rules were put into place. CCA pressure treated
wood will be phased out of use in Canada as of December 31, 2003.  There will be no recall, however.  Whatever is in stock in lumber yards will be sold until supplies are gone.

There is already much awareness of the tendency for materials to leach out of treated wood.  The US Consumer Product Safety Commission's (CPSC) Handbook for Public Playground Safety recommends regular inspections of playgrounds (According to
the US Department of Education ERIC Clearinghouse EDO-SP: 92-5, each year 200,000 children are treated at hospital emergency rooms for injuries occurring on playgrounds) but also recommends that "All paints and other similar finishes must meet the current CPSC regulation for lead paint.  Regardless of the material or treatment process, the manufacturer should ensure that the users of playground equipment cannot ingest, inhale, or absorb potentially hazardous amounts of substances as a result of contact with equipment.  Creosote, pentachlorophenol and tributyl tin oxide are too toxic or irritating and should not be used as preservatives for playground equipment wood.  Pesticide
containing finishes should also not be used."

Such products as these and CCA should not be used in places where there is an opportunity for skin contact or for the poisons to leach into soil or water. This includes playground equipment, garden decks, wharfs and garden borders. Breathing sawdust
containing CCA and other toxins is also a serious hazard. It should definitely not be burned in stoves or other fires or disposed of in incinerators because the toxins enter the air and have been known to severely harm those who breathe in the fumes.  Our sources advise that care should also be exercised in the safe disposal of treated wood in double-lined waste disposal sites. Our sources also advise sealing existing playground equipment with a non-toxic barrier sealant and to re-seal every two years.

What are the alternatives to treated wood?  The website www.healthytomorrow.org suggests naturally resistant alternatives such as metal, concrete and naturally rot and insect resistant woods such as larch, cedar, redwood and black locust.  Some advise
treating these woods with linseed oil to extend their lifespan.  However, there are alternative less-toxic treatments as well.  Boron-based wood treatments work well for objects that are not continually wet or damp. Alkaline Copper Quaternary (ACQ)
treatment appears less toxic as it contains no carcinogens and no EPA-listed compounds.  Copper Boron Axole (CBA) is used in Europe and Japan but not much in North America yet.  It apparently has low toxicity to mammals and does not cause mutations.  Check www.healthytomorrow.org  for other alternatives.

For more information on pressure treated wood consult www3.sympatico.ca/pbarrie/   and   www.environmentalhealth.ca

Numbered References:
1. National Research Council 1999.  Arsenic in Drinking Water.  National Academy of Sciences.  Washington, DC.

2. Kaltrieder RC, et.al.  Arsenic alters the function of glucocorticoid receptor as a transcription factor.  Environmental Health Perspectives 109(3):245-251.

3. California Department of Health Services. Evaluation of the hazards posed by wood preservatives on playground equipment.  Office of Environmental Health Hazard Assessment.  Report to Legislature. 1987.

4.  www.healthytomorrow.org