ABSTRACT
In mg/kg: 3,040 at 10 °C, 2,375 at 20 °C, 3,182 at 30 °C (shake flask-GC, Howe et al., 1987) Vapor density: 8.51 g/L at 25 °C, 7.19 (air = 1) Vapor pressure (mmHg): 76 at 20 °C (Schwille, 1988) Environmental fate: Biological. Dibromochloromethane showed significant degradation with gradual adaptation in a static-culture flask-screening test (settled domestic wastewater inoculum) conducted at 25 °C. At concentrations of 5 and 10 mg/L, percent losses after 4 wk of incubation were 39 and 25, respectively. At a substrate concentration of 5 mg/L, 16% was lost due to volatilization after 10 d (Tabak et al., 1981). Surface Water. The estimated volatilization half-life of dibromochloromethane from rivers and streams is 45.9 h (Kaczmar et al., 1984). Photolytic. Water containing 2,000 ng/µL of dibromochloromethane and colloidal platinum catalyst was irradiated with UV light. After 20 h, dibromochloromethane degraded to 80 ng/µL bromochloromethane, 22 ng/µL methyl chloride, and 1,050 ng/µL methane. A duplicate experiment was performed but 1 g zinc was added. After about 1 h, total degradation was achieved. Presumed transformation products include methane, bromide, and chloride ions (Wang and Tan, 1988). Chemical/Physical. The estimated hydrolysis half-life in water at 25 °C and pH 7 is 274 yr (Mabey and Mill, 1978). Hydrogen gas was bubbled in an aqueous solution containing 18.8 µmol dibromochloromethane. After 24 h, only 18% of the dibromochloromethane reacted to form methane and minor traces of ethane. In the presence of colloidal platinum catalyst, the reaction proceeded at a much faster rate forming the same end products (Wang et al., 1988). At influent concentrations of 1.0, 0.1, 0.01, and 0.001 mg/L, the GAC adsorption capacities at pH 5.3 were 4.8, 2.2, 1.0, and 0.46 mg/g, respectively (Dobbs and Cohen, 1980). Toxicity: Acute oral LD50 for rats 848 mg/kg, mice 800 mg/kg (quoted, RTECS, 1985). Drinking water standard (proposed): MCL: 60 µg/L. MCLG: 80 µg/L. Total for all trihalomethanes cannot exceed a concentration of 80 µg/L. In addition, a DWEL of 700 µg/L was recommended (U.S. EPA, 2000). Uses: Manufacture of fire extinguishing agents, propellants, refrigerants, and pesticides; organic synthesis.
