1,1,2,2-Tetrachloroethane

CAS RN:79-34-5

Exposure Summary

1,1,2,2-Tetrachloroethane's production and use as an intermediate in the manufacture of trichloroethylene, tetrachloroethylene and other chlorinated hydrocarbons may result in its release to the environment through various waste streams. Its former uses as a solvent, in cleaning and degreasing metals, paint removers, varnishes, lacquers, photographic film, resins and waxes, and extraction of oils may have resulted in its release to the environment through various waste streams. Its former use in insecticides, as a weed killer, and fumigant resulted in its direct release to the environment. 1,1,2,2-Tetrachloroethane's current use as an approved inert ingredient in pesticides for nonfood uses will result in its direct release to the environment. If released to air, a vapor pressure of 5.74 mm Hg at 25 deg C indicates 1,1,2,2-tetrachloroethane will exist solely as a vapor in the ambient atmosphere. Vapor-phase 1,1,2,2-tetrachloroethane will be degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals; the half-life for this reaction in air is estimated to be 127 days. 1,1,2,2-Tetrachloroethane does not contain chromophores that absorb at wavelengths >290 nm and, therefore, is not expected to be susceptible to direct photolysis by sunlight. If released to soil, 1,1,2,2-tetrachloroethane is expected to have high to moderate mobility based upon a Koc range of 79 to 236. Volatilization from moist soil surfaces is expected to be an important fate process based upon a Henry's Law constant of 4.20X10-4 atm-cu m/mole. 1,1,2,2-Tetrachloroethane is expected to volatilize from dry soil surfaces based upon its vapor pressure. 1,1,2,2-Tetrachloroethane undergoes biodegradation under anaerobic conditions, but is persistent under aerobic conditions in soil and water. If released into water, 1,1,2,2-tetrachloroethane is not expected to adsorb to suspended solids and sediment based upon the Koc. Volatilization from water surfaces may be an important fate process based upon this compound's Henry's Law constant. Estimated volatilization half-lives for a model river and model lake are 6.5 hours and 6 days, respectively. One river die-away test observed 19% degradation in 24 days. A BCF range of 4.5-13.2 suggests bioconcentration in aquatic organisms is low. Data reported indicate that 1,1,2,2-tetrachloroethane is expected to hydrolyze under environmental conditions to form trichloroethylene. The rate of hydrolysis increases with increasing pH. At 25 deg C, half lives of 36 days to 102 days have been approximated under neutral pH while half lives from 6.6 hours to 1.02 days were determined under alkaline conditions at pH 9. Occupational exposure to 1,1,2,2-tetrachloroethane may occur through inhalation and dermal contact with this compound at workplaces where 1,1,2,2-tetrachloroethane is produced or used. Monitoring data indicate that the general population may be exposed to 1,1,2,2-tetrachloroethane via inhalation of ambient air, ingestion of food and drinking water, and dermal contact with this compound. (SRC)
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