What is TCE and what health effects are associated with it?
TCE, or trichloroethylene, is a colourless liquid at room temperature with a somewhat sweet odour similar to ether or chloroform. It is a manufactured chemical that is mainly used as a solvent to remove grease from metal parts in the automotive and metals industries. It is also an ingredient in adhesives, paint removers, typewriter correction fluids and spot removers. TCE is further used as a chemical building block to make other chemicals.
TCE was formerly used as a general anesthetic, an alternative to ether or chloroform; as a solvent in dry-cleaning; and to extract oils, caffeine and flavours from plants.
Though TCE is still used as a solvent to clean metal parts, its use has decreased. TCE is not manufactured in Canada, and the solvent degreasing regulations under the Canadian Environmental Protection Act of 1999, which came into force in July 2003, are designed to significantly reduce the use and release of TCE into the environment in Canada. Effective 2007, there will be a mandated 65 per cent reduction in use of TCE.
TCE evaporates readily from surface water but may be found in groundwater. It can be introduced into groundwater as a result of industrial effluents, spills or leakage from old dump sites. Canadians can be exposed to TCE through its presence in drinking water, air and food. Certain segments of the population could be exposed via contaminated soil or occupational settings.
Recent studies suggest a link between long-term exposure to high levels of TCE and cancer. Studies also indicate a possible link between exposure to TCE and potential reproductive effects associated with fetal heart development. Animal studies have shown links to kidney and testicular tumours in rats and pulmonary and liver tumours in mice. Based on both animal and human studies, TCE has been classified as probably carcinogenic to humans.
What are the standards in Canada and the rest of the world?
The maximum allowable level of TCE in drinking water is often measured in parts per billion (ppb). It is Health Canada's responsibility to set a guideline for a maximum allowable level, but it is only a guideline. Monitoring water quality is a provincial jurisdiction, unless it is on federally owned land. Following the TCE contamination in Shannon, Que., and the high levels found in some homes (1,000 ppb), the Quebec government reduced the maximum allowable level to five ppb. Health Canada also reviewed the health risks and proposed the same five ppb guideline nationally.
In July 2005, Health Canada and the Federal-Provincial-Territorial Committee on Drinking Water accepted the more stringent limit. The United States also sets its limit at five ppb, although it is lower in some states, as low as one ppb in New Jersey. The European Union sets a total limit of trichloroethylene and tetrachloroethylene at 10 ppb.
Where are the contaminated sites in Canada?
In the 1960s and 1970s, TCE was commonly dumped in landfills and occasionally spilled in industrial accidents. It's been seeping into groundwater ever since, getting into the drinking water of thousands of Canadians who rely on wells.
The most infamous site contaminated with TCE is Canadian Forces Base Valcartier in Quebec, where the chemical was used in abundance as a degreaser. Nearby Shannon, Que., north of Quebec City, has seen an unusually high number of residents fall ill with cancer. Wells in some neighbourhoods contained up to 200 times the level of TCE considered acceptable by Health Canada.
The federal government has not drawn a link between the chemical and the cases of cancer found in Shannon. However, in 2000, government officials told people to stop drinking from their taps. About 600 residents of Shannon have signed on to a class-action lawsuit over tainted water against the federal government and engineering company SNC Lavalin.
TCE has also been found in groundwater in Barrie, Ont.; Brantford, Ont.; Amherst, N.S.; Fredericton; Ville Mercier, Que.; and Rockwood, Man.
In addition to Valcartier, the federal government owns over 1,700 other contaminated sites across Canada. The sites range from abandoned mines in the North to the water off the coast of Nova Scotia. The contaminants at these sites vary as well, from heavy metals to PCBs and PAHs (polycyclic aromatic hydrocarbons).