Tetrachloroethylene Environmental Exposures
Tetrachloroethylene Environmental Exposures
The most important routes of exposure to tetrachloroethylene for the general public are ingesting contaminated water and inhaling ambient air. Improper disposal and releases from dry cleaning facilities and landfills can lead to groundwater contamination and potential environmental exposures.
Between 1994 and 2007, several provinces monitored water supplies for PERC; it was detected in no more than 4% of samples, and only one sample from all provinces contained concentrations greater than 10 micrograms/L. Tetrachloroethylene has also been found in samples of Canadian drinking water. CAREX Canada’s environmental estimates indicate that PERC concentrations in Canadian drinking water do not result in an increased cancer risk (moderate data quality).
The general public may be exposed to PERC by frequenting or living near dry cleaning businesses or via contact with freshly dry cleaned clothing. There is evidence to suggest that family members of workers employed at dry cleaning facilities are more exposed to PERC than the general population. CAREX Canada estimates that PERC levels in outdoor air do not result in an increased risk of cancer (high data quality). However, our estimates indicate that PERC concentrations in indoor air do result in an increased risk of cancer (low to moderate data quality).
PERC has been detected in dairy products, meats, oils and fats, beverages, fruits and vegetables, bread, fish, shellfish, and marine mammals. CAREX Canada estimates that PERC levels in food and beverages do not result in an increased risk of cancer in Canada (very low data quality).
Searches of Environment Canada’s National Pollutant Release Inventory (NPRI) and the US Household Products Database yielded the following results on current potential for exposure to PERC in Canada:
NPRI and US Household Products Database
|Substance name: ‘Tetrachloroethylene’|
|Released into Environment||115 t||plastic product manufacturing,
other chemical product manufacturing,
waste treatment and disposal,
textile and fabric finishing and
fabric coating (28 facilities)
|Disposed of||133 t|
|Sent to off-site recycling||125 t|
|US Household Products 2015|
|Search Term||Quantity||Product Type|
|‘Tetrachloroethylene’||37||Auto brake cleaners (17), adhesives (8), lubricants (4),
auto degreaser (3), auto cooling cleaner (1),engine dryer (1),
silver polish (1), carpet stain removers (1), fabric protectant (1)
t = tonne
This map shows predicted levels of tetrachloroethylene in outdoor air at residential locations by health region in Canada as of 2011. The average (median) concentration of tetrachloroethylene within the health regions measured in outdoor air for 2011 was 0.113 µg/m3, but concentrations of tetrachloroethylene can be higher or lower than average in many locations. Concentrations should be compared to the applicable jurisdictional guidelines and standards for ambient air quality based on chronic, carcinogenic effects (or non-carcinogenic effects, if cancer is not the point of interest).
Predicted annual average tetrachloroethylene concentrations in outdoor air at residential locations by health region, 2011
*Measured at the National Air Pollution Surveillance (NAPS) monitors in 2011
Cancer risk estimates
Potential lifetime excess cancer risk (LECR) is an indicator of Canadians’ exposure to known or suspected carcinogens in the environment. When potential LECR is more than 1 per million in a single pathway, a more detailed risk assessment may be useful for confirming the need to reduce individual exposure. If measured levels of tetrachloroethylene in relevant exposure pathways (outdoor air, indoor air, indoor dust, drinking water, and food and beverages) decrease, the risk will also decrease.
Potential LECR is calculated by multiplying lifetime average daily intake (the amount inhaled or ingested) by a cancer potency factor or unit risk factor. More than one cancer potency factor may be available, because agencies interpret the underlying health studies differently, or use a more precautionary approach. Our results use cancer potency factors from Health Canada, the US Environmental Protection Agency (US EPA), and/or the California Office of Environmental Health Hazard Assessment (OEHHA).
The calculated lifetime daily intake and LECR results for tetrachloroethylene are provided in the tables below. For more information on supporting data and sources, click on the Methods and Data tab below.
Calculated lifetime daily intake
Lifetime excess cancer risk (per million people)
*LECR based on average intake x cancer potency factor from each agency
Compare substances: Canadianpotential lifetime excess cance risk, 2011
The data in this table are based on average intake and Health Canada’s cancer potency factor, assuming no change in measured levels. When Health Canada values are not available, United States Environmental Protection Agency values are used.
Click the second tab to view LECR data.
**Exposure not applicable: For indicated pathways, substance not present, not carcinogenic, or exposure is negligible
**Gap in data: No cancer potency factor or unit risk factor, or no data available
IARC Group 1 = Carcinogenic to humans, IARC Group 2A = Probably carcinogenic to humans, IARC Group 2B = Possibly carcinogenic to humans
NOTE: Chromium (hexavalent) estimates assume that 5% of total chromium measured in outdoor air is hexavalent and 8% total chromium measured in indoor dust is hexavalent.
Potential LECR assumes exposure occurs at the same level, 24 hours per day, for 70 years. This is rarely true for any single individual, but using a standard set of assumptions allows us to provide a relative ranking for known and suspected carcinogens across different exposure routes. While ongoing research continually provides new evidence about cancer potency and whether there is a safe threshold of exposure, our approach assumes there are no safe exposure levels.
Methods and Data
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