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DOCUMENT GIVEN ME BY PEST CANADA ON CCA WOOD
Frequently Asked Questions and Answers about the Health and Safety of CCA-treated Wood
CCA, Chromated Copper Arsenate, is a water-born preservative used for the long-term protection of wood against attack by fungi, insects and marine borers.
Prior to treatment, small cuts are made into the surface of the wood to improve penetration of the preservative solution. The wood is then stacked and loaded into a sealed pressurization chamber where the wood's natural moisture is removed by vacuum and replaced with the treatment solution which gives the wood a greenish tinge. The chamber is then pressurized, forcing the solution into the wood. A vacuum is used to extract any excess solution; the wood is removed from the chamber and left to dry naturally, at which time the wood preservative binds to the wood in the fixing process.
CCA-treated wood is used primarily for construction lumber and timbers, utility and construction poles, marine timbers and pilings, fence posts and wood foundation lumber.
All active ingredients registered prior to 1995 will be examined under the PMRA re-evaluation program. The heavy duty wood preservatives* were ranked as high priority.
PMRA and the U.S. EPA are actively cooperating to re-evaluate CCA and all the other heavy duty wood preservatives, according to current scientific standards. We are considering new data and are using the most recent risk assessment methods. Our assessment will include consideration of workers and special focus on sensitive sub-populations such as children who may contact treated wood.
*Heavy Duty Wood Preservatives are those that are pressure or thermally applied.
6. The U.S. EPA is developing a stronger consumer information plan on CCA treated wood, including a website, and improved stickering and labelling at the retail level. Is Health Canada doing anything similar?
As part of ongoing activities under CEPA, a multi-stakeholder (industry/governments) workgroup, which includes representatives from the wood treatment industry, retailers, government (Environment Canada, Health Canada including PMRA) and academia, is working towards implementing an information program for CCA-treated lumber similar to what is being developed in the US, as it applies to the Canadian market. This program includes end-tag labelling each piece of treated wood, in store lumber bin stickers and signs, a consumer information sheet, establishment of a toll-free number and web-site to access consumer information. This program is geared towards improving the availability of consumer information and enhancing consumer awareness regarding the use and handling of CCA-treated wood. Each of these activities will be implemented as soon as possible, some components becoming available before others, with complete implementation by next spring (2002).
The ability to dislodge depends on many factors, including wood species, treatment variables, fixation schedules, retention, age in service, and the environment in which it is installed. If the preservative is not properly fixed to the wood, there is a greater potential for the preservative to dislodge. Typical dislodging losses that may occur in various environments are currently being assessed as part of the official re-evaluation of CCA. Some studies found small amounts of copper, chromium and arsenic dislodged from CCA-treated wood used in playground structures. Any possible health risk of these levels is currently being assessed as part of the official re-evaluation of CCA.
Loss of preservatives from treated wood can be minimized when the wood is free of surface debris and is "fixed" according to a voluntary standard developed by the Canadian Standards Association.
Weather conditions do have an effect on dislodgeability. Treated wood, continually exposed to water of damp soil, will lose more preservative than that exposed to an occasional rainfall. We are considering the effects of such weathering as part of our bystander exposure assessment.
There are some data that indicate some sealants can reduce dislodgeable
residues. These data are being considered as part of our bystander exposure
Exposure to arsenic may occur through food, drinking water, soil and ambient air. Most arsenic that is absorbed into the body is converted by the liver into a less toxic form and excreted through urine. Consequently, arsenic does not tend to accumulate in the body except at high exposure levels. Health risk increases with exposure. Acute effects following ingestion of significant amounts of arsenic include gastrointestinal, dermatological and neuromuscular symptoms which may become more severe with prolonged exposure. Exposure to arsenic by inhalation and ingestion is associated with the development of respiratory cancer, skin cancer and of cancers of various internal organs.
All available toxicological and epidemiological studies for CCA are under critical review as part of our re-evaluation process.
3. Decks, fences, play structures and other wooden items are often constructed with CCA-treated wood. Is it safe for my children or pets to be in direct contact with these surfaces or the soil near these structures?
The Environmental Protection Agency in the US reviewed the use of CCA-treated wood during the 1980's and at that time concluded that CCA-treated wood did not pose unreasonable risk. A similar assessment was conducted by the US Consumer Product Safety Commission in 1990, which concluded that short and long term health effects are unlikely to occur for individuals contacting treated wood. Health Canada concurred with the overall conclusions.
It is known that small amounts of chromium and arsenic may slowly leach from treated wood used in playground structures. Any potential health risk resulting from exposure to wood treated with CCA in this way would be a result of not only the toxic properties of CCA, but the level of exposure to it. Therefore, if the level of exposure is very low, the risk is also very low.
The potential health significance of detectable levels of the preservatives in soil is currently being evaluated by Health Canada as part of our re-evaluation of CCA. The re-evaluation will examine the metal levels detected, together with the manner in which children handle and play on or around these structures.
Treated wood that is continually exposed to water or damp soil will lose more preservative than that exposed to an occasional rainfall. Therefore, CCA-treated wood should not be used in direct contact with drinking water. Although warning against this use is specified on the wood preservative labels, industry and stakeholder groups are working to enhance user awareness of proper handling and disposal of preservative treated wood products.
CCA wood preservatives are not available to the general public. These types of wood preservatives are only available to specially trained commercial or industrial users. Precautions to be taken when using and disposing of wood preservative chemicals are outlined on the product label.
Basic precautions should be taken when working with CCA-treated wood.
Working with CCA-treated wood:
No, the practice of burning CCA-treated wood is unacceptable. Burning treated wood concentrates and releases the preservative chemicals in the ash and smoke particulates. Although warning against burning treated wood is specified on the wood preservative labels, industry and stakeholder groups are working to enhance user awareness of proper handling and disposal of preservative treated wood products.
Unless you are exposed to burning treated wood which creates an inhalation
hazard, it is unlikely that working with treated wood would result in
enough exposure to cause symptoms. However, if you do suspect poisoning,
you should phone your local poison control centre or contact you doctor.
The environmental hazards of CCA/Arsenical treated wood are related to the high toxicity of copper, chromium and arsenic to non-target organisms in freshwater and marine environments. The potential risk depends on the exposure, i.e., CCA being leached from treated wood into the aquatic ecosystem, directly or indirectly.
In general, small terrestrial structures made from CCA-C treated wood which is properly treated and properly fixed in accordance with CSA standards are unlikely to cause any environmental hazard. There are some data that indicate some sealants can reduce surface dislodgeability and leachability of the preservative metals. These data are being considered as part of the re-evaluation. The environmental risk of CCA treated wood in contact with freshwater and marine environments (including wetlands) is greater than in terrestrial environments and possible aquatic usage restrictions are currently being assessed.
Canadian Environmental Protection Act, Priority Substances List: Arsenic and Its Compounds, 1993, National Health and Welfare and Department of Environment.
U.S. Consumer Product Safety Commission (Washington, D.C. CPSC, 1990). Project on Playground Equipment - Transmittal of Estimate of Risk of Skin Cancer from Dislodgeable Arsenic on Pressure Treated Wood Playground Equipment. Aug. 2, 1990.
Cooper, P.A. Leaching of Wood Preservatives from Treated Wood in Service. Public Works. Minister of Supply and Services Canada, 1991. ISBN 0-662-18870-5.
The potential hazard associated with any product is a function not only of the toxic properties of the product but of the level of exposure to it. The activity of driving an ATV down abandoned railways is anticipated to result in minimal contact with creosote. Based on the very low potential for exposure to creosote, risk associated with this activity should also be very low. In the case of using railway ties for landscaping, some of the labels for creosote preservative compounds contain specific warnings against it's use for horticultural lumber. Creosote is toxic to plants and we know that treated wood exposed to soil, particularly moist soil, is at increased risk of leaching. Health Canada has never received studies for, and cannot definitively predict, the fate of creosote residues when treated wood is used as a border for vegetable gardens. The labels for creosote preservative compounds contain specific warnings against the use of creosote where direct contact with food and/or living plants is possible. Based on these characteristics, it may be inadvisable to use creosote-treated railway ties for landscaping purposes, particularly to contain food-bearing crops such as in home gardens. The re-evaluation of creosote is ongoing as you are aware. The PMRA is conducting the review jointly with the US EPA and anticipate that the reviews will be completed in 2002.
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