Tighter guideline proposed for TCE in drinking waterHealth Canada and the federal-provincial-territorial Committee on Drinking Water have proposed a more stringent Canadian guideline for trichloroethylene (TCE) in drinking water. The proposed guideline would lower the maximum acceptable concentration (MAC) of TCE from 0.05 mg/L (or ppm, parts per million) to 0.005 mg/L. The consultation document for this proposed guideline has been posted on Health Canada's Web site, www.hc-sc.gc.ca/waterquality. (The proposal has also been posted on Ontario's Environmental Bill of Rights registry for a 108-day comment period ending April 5, 2004-see www.ene.gov.on.ca, registry reference number PA03E0005)
Recent studies suggest a possible link between long term exposure to high levels of TCE and cancer. In addition, preliminary studies are indicating a possible link between exposure to high levels of TCE and potential reproductive effects associated with fetal heart development. However, even at high concentrations of TCE, current studies show only a very low rate of reproductive health effects. Further studies are required to confirm these reproductive effects as well as their long-term significance to human health. The proposed new MAC for TCE in drinking water is considered protective against both the cancer risks and potential reproductive effects.
TCE is not a concern for the majority of Canadians, particularly those who rely on surface water, such as lakes and rivers, as their source of drinking water. TCE can be introduced into groundwater as a result of industrial discharges or spills, or leaking from old dump sites. It has been deemed a concern at a few sites, where the public has been informed and remedial action is being taken. Based on existing information, Health Canada and the committee have not singled out any other area or region where the current level of TCE exceeds the proposed guideline of 0.005 mg/L.
While monitoring for TCE is fairly extensive, information for individuals or small communities dependent on well water is often lacking. TCE contamination could be a potential problem if the wells are located near an old industrial dump site.
TCE is a volatile solvent used extensively in the automotive and metal industries for degreasing and cleaning of metal parts. The Solvent Degreasing Regulations under the Canadian Environmental Protection Act 1999, which came into force in July, 2003 are designed to significantly reduce the use and release into the environment of TCE in Canada.