After years of foot dragging, and led by the US Environmental Protection Agency (EPA), the Canadian government finally admitted in 2002 that yes, there was, maybe, a problem with Chromated Copper Arsenate (CCA) treated wood.
The problem, admitted the government, was especially important for applications where children are exposed to the run off or even surface deposits, such as playgrounds, decks and picnic tables. In the US, the manufacturers had agreed to label the CCA treated wood, and take the product off the consumer market, after remaining stocks were sold in 2003.
Accordingly, Environment Canada and Health Canada, specifically the Pesticide Management Regulatory Agency (PMRA), decided to institute a labelling program for each piece of treated lumber. Fortunately, in April 2002, the manufacturers of CCA informed the PMRA that they would voluntarily cancel their Canadian registrations for residential uses of CCA-treated wood. Since 2003, wood for playground equipment, decks, fences, walkways and landscape timbers cannot be treated with CCA.
In January 2004 the Pesticide Regulatory Management Agency announced that it was nearing completion of a further risk assessment on CCA treated lumber, based on the US EPA assessment. Since the ingredients are especially toxic to aquatic life, restrictions on its use near water have been under consideration since 2001.
What is it?
CCA is a water-borne preservative containing arsenic, chromium and copper. It is used for the long-term protection of wood against attack by fungi, insects and marine borers. Applying wood preservatives extends the productive life of wood. CCA-treated wood is used primarily for structures intended for outdoor settings, such as construction lumber, utility and construction poles, marine timbers and pilings, and fences. It has also been used extensively for picnic tables, playground structures and residential decks.
The solution is not available at the retail level, and is applied to vacuum-dried lumber under pressurized conditions in commercial treatment plants.
Is CCA-treated wood a health concern?
The risk of immediate illness from short-term exposure to chemicals from CCA-treated wood is low. Although arsenic can be poisonous at very high doses, the amounts measured on CCA treated wood are a thousand times less than a lethal dose. The other two elements in CCA, copper and chromium, are relatively less toxic to humans.
– City of Toronto Fact Sheet
The fact sheet acknowledges that, while small amounts of arsenic may not be harmful to health in the short-term, it is best to avoid unnecessary exposure because arsenic is a known human carcinogen. It concludes that “it is not yet known whether long-term exposure to arsenic leaching from CCA-treated wood is sufficient to increase the risk of cancer or other health effects.”
However, in 2002 the Canadian Medical Association Journal (CMAJ) noted that a Connecticut study (Bulletin of Environmental Contamination and Toxicology 1997;58:22-9) found that soil samples taken from beneath CCA-wood decks contained, on average, 20 times more arsenic, 76 mg/kg, than control soil, a level nearly twice as high as the US Environmental Protection Agency’s regulatory guideline of 41 mg/kg.
The CMAJ noted that “High levels of ingested inorganic arsenic can be fatal, it may also damage nerves, stomach, intestine and skin, and is a known carcinogen, increasing the risk of skin cancer and tumors of the bladder, kidney, liver and lungs.”
The amount of arsenate emitted from the wood can vary over time depending on whether the wood is in heavy rain or water or continuously damp soil, the type of wood, and whether the lumber was properly dried before treatment. In July 2003, calling for an immediate ban on sale and production of CCA-treated lumber for residential and playground uses, the Sierra Club of Canada cited a study from Ottawa which showed that while levels in the jack pine used for a deck were normal, dangerously high levels of arsenic and chromium were found in resin from the wood which had leached and pooled under the deck.
What to Do with It?
Disposal of old treated lumber is one of those familiar embarrassing predicaments of modern life. Most of the government pamphlets say to dispose of it in an acceptable “responsible manner,” without specifying what that manner is.
CCA treated wood should never be burned, indoors or outside, because it releases toxic metals. Nor should it be used as a chip mulch or put in compost due to the likelihood of arsenic compounds leaching into garden soil.
Brock McDonald of the BC Recycling Hotline advises homeowners to either store the old wood for future use in smaller items, or send it to a properly-constructed landfill with a liner. He says people should check with their municipal or regional government because the policy varies from place to place. There is no federal or provincial help for small scale disposal of this toxic waste.
What should I do if I have an existing structure made of CCA-treated wood?
If you have an existing structure (e.g. deck or playground equipment) made of CCA-treated wood, the Canadian government advises that it is not necessary to remove the structure, although the Healthy Building Network says that is the optimal solution, especially for high exposure areas such as handrails.
To minimize exposure, use a penetrating oil-based (NOT water based) wood-finishing sealant on the structure. Re-apply sealant every one or two years, depending on wear and weathering. (The Healthy Building Network suggests the sealant should be refreshed every six months and also cautions that the wood should never be sanded.) Sealants can reduce the amount of arsenic released by as much as 90%. Do not use deck washing products. Consult your local hardware or building store for appropriate products.
Children and pets should never be allowed to play on or under treated decks or stairs. Children are especially vulnerable because they put their hands in their mouths more often, and because they tend to eat more dirt than adults.
Food and water should not be exposed to the lumber. This lumber is totally unsuitable for water storage.
Elevated arsenic levels may exist in the soil or sand beneath structures made of CCA-treated wood. If there is only bare soil or sand under the structure, fence or screen off areas underneath decks to prevent access by children and pets, and plant a dense ground cover (e.g. grass) to provide a barrier between the soil and human/animal contact.
If you are exposed to soil or sand beneath the wood, remove shoes or wipe feet before entering the house.
Testing
The Healthy Building Network offers a Home Arsenic Testing kit for $20 US, which will either provide a test of how much arsenic wipes off the wood’s surface, or will identify arsenic contamination in soil. http://www.healthybuilding.net/arsenic/index.html
When working with CCA-treated wood
Health Canada advises these basic precautions:
- Only purchase CCA-treated wood that is visibly clean and free of excess surface residues of the preservative, as these may contain dislodgeable toxic chemicals.
- Wear gloves and long sleeves when handling treated wood. Wear a dust mask, eye protection, gloves and long sleeves when sawing, sanding, shaping or otherwise machining treated wood to avoid skin contact with or inhalation of sawdust.
- Wherever possible, cut or otherwise work with treated wood outdoors.
- Wash hands and other exposed skin after contact, and before eating, drinking or smoking. Wash clothes before re-wearing. Wash separately from other clothing.
- After construction, all end cuts, sawdust and construction debris should be cleaned up and disposed of in accordance with local regulations.
Alternatives when building
Look for alternatives to CCA-treated wood such as cedar, redwood, metal, and plastic. Consult your local hardware or building store for wood treated with non-arsenic containing preservatives. Rubber can be used for loading docks and plastic wood made from recycled plastic is a long-lasting excellent (although expensive) alternative for outdoor furniture and fencing.
BC Hydro has a much bigger disposal problem when their old hydro poles must be replaced. Hydro owns about 1.2 million poles and replaces at least 6,000 to 7,000 a year. CCA is the main treatment still used on Hydro poles. The old poles are sent to BC Wood Recycling which separates the treated wood from the good lumber remaining in the poles. In 2003, BC Wood Recycling salvaged 630 tonnes of lumber, sending 400 tonnes of treated pole remains to the landfill.
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Sources: City of Toronto Fact Sheet, Health Canada: Fact Sheet on Chomated Copper Arsenate (CCA) Treated Wood, Healthy Building Network, Sierra Club of Canada, Canadian Medical Association Journal, No CCA Wood, http://www.noccawood.ca, Fact sheet from the US Consumer Product Safety Commission: Chromated Copper Arsenate (CCA) -Treated Wood Used in Playground Equipment.
