July 18, 2005

Canada tightens TCE guideline for drinking water supplies

Health Canada and the Federal-Provincial-Territorial Committee on Drinking Water have agreed to a more stringent guideline for the amount of trichloroethylene (TCE) in drinking water. The new guideline has been lowered to 10% of the previous limit, from 0.05 milligrams per litre (mg/L) to 0.005 mg/L.

Health Canada and the drinking water committee have not determined any area or region where the current level of TCE exceeds the new maximum acceptable concentration of 0.005 mg/L. Where TCE has been detected in Canadian drinking water supplies, levels are generally less than 0.001 mg/L.

TCE is not a concern for most Canadians, particularly those whose drinking water comes from surface water (i.e. lakes, rivers and streams) rather than from underground water. Because surface water is exposed to air, TCE would evaporate.

While studies suggest only very low rates of health effects even at high concentrations of TCE, a possible link between long-term exposure to high levels of TCE and cancer has been observed. In addition, preliminary studies indicate a possible link between exposure to high levels of TCE and potential reproductive effects. The new Canadian guideline for TCE in drinking water is protective against both the cancer risks and potential reproductive effects.

Although monitoring for TCE is fairly extensive, there is little information available for individuals or small communities on private wells. TCE contamination of groundwater or wells could be a potential problem if a well is located near an old industrial dumpsite. Those concerned about their well water supplies should consult with local medical officers of health or local provincial, territorial or municipal environment officials.

TCE is a volatile solvent used extensively in the automotive and metal industries for degreasing and cleaning of metal parts. TCE can enter groundwater as a result of industrial effluents or spills, or leaking from old dumpsites.

Regulations under the Canadian Environmental Protection Act, designed to phase out the use and sale of TCE in Canada, came into force in July 2003.

The guideline document can be found on the Health Canada Web site at www.hc-sc.gc.ca/waterquality.

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