Priority Substances List Assessment Report for 1,1,2,2-Tetrachloroethane

Synopsis

1,1,2,2-Tetrachloroethane is not produced in, or imported into, Canada. 1,1,2,2-Tetrachloroethane enters the Canadian environment as a by-product in wastes generated during production of both vinyl chloride monomer and ethylene dichloride, in air emissions and leachates from waste disposal sites, and as a result of long-range atmospheric transport from other countries.

The highest concentrations of 1,1,2,2-tetrachloroethane that have been found in Canadian ambient surface waters are at least 180 times less than the estimated effects threshold for flagfish, the most sensitive aquatic species identified in long-term studies. Given the large difference between the estimated effects threshold and ambient water concentrations, no adverse effects are expected to result from exposure of freshwater organisms to 1,1,2,2-tetrachloroethane. However, as most 1,1,2,2-tetrachloroethane is released to the atmosphere and reliable data on effects to terrestrial organisms are unavailable, it is not possible to conclude whether current concentrations of 1,1,2,2-tetrachloroethane in air will adversely affect terrestrial biota in Canada.

Because of the low rate of release of 1,1,2,2-tetrachloroethane to the atmosphere, the low atmospheric concentration, and a calculated ozone depletion potential of much less than 0.001 relative to chlorofluorocarbon-l 1 (CFC-l 1), 1,1,2,2-tetrachloroethane is not expected to contribute significantly to stratospheric ozone depletion or to global warming.

Based on estimation of the total daily intake from ambient and indoor air and drinking water for various age groups of the general population, air appears to be the most significant source of human exposure to 1,1,2,2-tetrachloroethane. However, data from available studies in exposed human populations and experimental animals are considered inadequate to estimate a Tolerable Daily Intake, i.e., the daily intake to which it is believed that a person may be exposed over a lifetime without deleterious effects. As a result, it is not possible to determine if current concentrations of this substance in the environment are likely to have adverse effects on human life or health in Canada.

Based on these considerations, the Minister of the Environment and the Minister of National Health and Welfare have concluded that the concentrations of 1,1,2,2-tetrachloroethane present in the Canadian environment do not constitute a danger to the environment on which human life depends. Therefore, 1,1,2,2-tetrachloroethane is not considered to be "toxic" as defined under Paragraph 11 (b) of the Canadian Environmental Protection Act. The Ministers have determined that available data are inadequate to conclude whether 1,1,2,2-tetrachloroethane constitutes a danger in Canada to the environment or to human life or health as defined under Paragraphs 11 (a) and 11 (c) of the Canadian Environmental Protection Act.