| Abstract |
Exposure-related information on methylene chloride, trichloroethylene, 1,1,1-trichloroethane, carbon tetrachloride, Freon 1132, and perchloroethylene is presented, addressing the physical and chemical properties, environmental fate and transport potential, and available environmental monitoring data for each chemical. These substances are used as solvents, degreasers and cleaners, and as components in fire extinguishers, fumigants, pesticides and inorganic chemical manufacturing. All 6 are colorless, dense, nonflammable liquids. Volatilization is the principal transport process affecting them when they are released to water or land. The volatilization rate from these is rapid, with a half-life of minutes to a few days. Oxidative degradation of methylene chloride, perchloroethylene, trichloroethane and 1,1,1-trichloroethane occurs in the troposphere; photodissociation of carbon tetrachloride and Freon 113 takes place in the stratosphere. Carbon tetrachloride and Freon 113 may persist in ground-water systems, since they are resistant to hydrolysis. A large body of monitoring data are available and summarized for trichloroethylene, 1,1,1-trichloroethane, methylene chloride and perchloroethylene; less is available for carbon tetrachloride, and very little for Freon 113. |
