Trans-1,2-dichloroethylene (alias of E-12-Dichloroethene)

CAS RN:156-60-5

Exposure Summary

trans-1,2-Dichloroethylene's production and use as a solvent may result in its release to the environment through various waste streams. Under anaerobic conditions, that may exist in landfills or sediment, trans-1,2-dichloroethylene may be formed by reductive dehalogenation of trichloroethylene facilitated by microorganisms. If released to air, a vapor pressure of 331 mm Hg at 25 deg C indicates trans-1,2-dichloroethylene will exist solely as a vapor in the atmosphere. Vapor-phase trans-1,2-dichloroethylene will be degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals, ozone and nitrate radicals; the half-lives for these reactions in air are estimated to be 6.6, 5.7 and 310 days, respectively. trans-1,2-Dichloroethylene 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, trans-1,2-dichloroethylene is expected to have high mobility based upon a reported Koc of 59. Volatilization from moist soil surfaces is expected to be an important fate process based upon a Henry's Law constant of 9.38X10-3 atm-cu m/mole. trans-1,2-Dichloroethylene may volatilize from dry soil surfaces based upon its vapor pressure. Utilizing the Japanese MITI test, 0% of the theoretical BOD was reached in 4 weeks indicating that aerobic biodegradation may not be an important environmental fate process in soil. However, trans-1,2-dichloroethylene exhibited soil field biodegradation rates of 0.229 and 0.215/week. If released into water, trans-1,2-dichloroethylene is not expected to adsorb to suspended solids and sediment based upon the Koc. No biodegradation occurred in a river die-away test. However, under anoxic conditions using uncontaminated organic sediment from the Everglades, 73% of the chemical was lost in 6 months, suggesting that anaerobic biodegradation is an important environmental fate process in water. trans-1,2-Dichloroethylene had aquatic field biodegradation rates of 0.182 and 0.185/week. Volatilization from water surfaces is expected to 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 3 hours and 4 days, respectively. An estimated BCF of 11 suggests the potential for bioconcentration in aquatic organisms is low. Hydrolysis is not expected to be an important environmental fate process since this compound lacks functional groups that hydrolyze under environmental conditions. Occupational exposure to trans-1,2-dichloroethylene may occur through inhalation and dermal contact with this compound at workplaces where trans-1,2-dichloroethylene is produced or used. Monitoring data indicate that the general population may be exposed to trans-1,2-dichloroethylene via ingestion of drinking water. (SRC)
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