Study of the Distribution of Tetrachloroethylene and Trichloroethylene in Groundwater Throughout Canada Using SPANS-GIS

Head of the project: Dr. William Bajjali

Groundwater samples from 700 sites from different aquifers throughout Canada are represented in th study. The data mainly deals with the concentration of trichloroethylene (TCE) and tetrachloroethylene (PCE).

This data was collected from 1986 to 1995 in different provinces of Canada. The survey focused on two contaminants (TCE and PCE) in the groundwater used as household water supplies for populated areas. There are approximately 618 Canadian municipalities (over a thousand in population) relying on groundwater or a combination of groundwater and surface water (MUH, 1994 survey). Overall, there are 2,735 communities throughout the country with a distribution network, 1,078 of them relying totally or partially on groundwater (EHD, 1991). In general, about 26 % of the population of Canada uses groundwater for domestic purposes (Hess, 1986).

Health Canada has been concerned about the persistent presence of PCE/TCE in the groundwater. The PCE/TCE are a source of volatile organic compounds emission which can increase the ground level ozone concentration. In addition they can contaminate the groundwater. The PCE/TCE are chlorinated hydrocarbon and have densities that are greater than water (Dense Non Aqueous Phase Liquids or DNAPLs).

Humans can be exposed to TCE/PCE from consumer products or environmental and occupational sources mainly by inhaling its vapors or drinking contaminated water. The Environmental Protection Agency (EPA) in the U.S. set a drinking water standard of 5 ppb for the TCE and 5 ppm for PCE as Maximum Acceptable Concentration (MAC). The MAC for TCE in the Guideline for Canadian Drinking Water Quality is 50 ppb. Furthermore, the guideline is currently under review for addition to, or possible changes to, the current values of PCE/TCE. The health effects of breathing air or drinking water that have low levels of PCE/TCE are not known. Exposure to high level of these two substances can cause harm to human health, mostly to the nervous system, the liver and kidneys or even death.

The purpose of this study is to investigate the distribution of the TCE and PCE in groundwater and their effect in the communities using this groundwater through the use of a Geographic Information System (GIS).

The figure above shows the distribution of the TCE/PCE in groundwater without any comments due to the confidentiality of this project. For further information please contact Health Canada

Dr. Roderick Raphael, Chief
Monitoring and Criteria Division
Bureau of chemical Hazards
Environmental Health Directorate
Health Protection Branch
Ottawa, Ontario,
Tunney's Pasture K1A 0L2
Tel. (613) 954-0164