Chloroform

CAS RN: 67-66-3

Exposure Summary

Chloroform's production and use in the synthesis of hydrochlorofluorocarbon 22 (HCFC-22), use as an extractant or solvent, chemical intermediate, dry cleaning agent, fumigant ingredient, synthetic rubber generation may result in its release to the environment through various waste streams. Its indirect production in the manufacture of ethylene dichloride and as a disinfection byproduct in the chlorination of drinking water, municipal sewage, cooling water in electric power generating plants will result in its direct release to the environment. Chloroform is produced during the atmospheric photodegradation of trichloroethylenes. It is produced by the tropical red algae (Asparagopsis armata) and by the red seaweed (A. taxiformis). Chloroform has been reported to be produced by micro algae in the North Sea and open ocean of the northeast Atlantic. If released to air, a vapor pressure of 197 mm Hg indicates chloroform will exist solely as a vapor in the atmosphere. Vapor-phase chloroform 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 156 days. Chloroform 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, chloroform is expected to have very high to moderate mobility based upon Koc values of 34-196. Volatilization from moist soil surfaces is expected based upon a Henry's Law constant of 3.67X10-3 atm-cu m/mole. Chloroform is expected to volatilize from dry soil surfaces based upon its vapor pressure. Utilizing the Japanese MITI test, 0% of the Theoretical BOD was reached in 2 weeks indicating that biodegradation is not an important environmental fate process. Under normal environmental conditions, chloroform is not expected to undergo biodegradation in soil. However, several studies have demonstrated that at low concentrations, chloroform can be anaerobically degraded by methanogenic bacteria in the presence of a primary substrate such as acetic acid. If released into water, chloroform is expected to adsorb to suspended solids and sediment based upon the Koc values. Reports of biodegradation of chloroform in aqueous environments have both supported and refuted anaerobic biodegradation. Volatilization from water surfaces is expected based upon this compound's Henry's Law constant. Estimated volatilization half-lives for a model river and model lake are 3.5 hours and 4.4 days, respectively. BCFs in various fish have been reported as 1.4-10.35 suggesting bioconcentration in aquatic organisms is low. Hydrolysis is not expected based on estimated hydrolysis half-lives of 3,400 and 340 years at pHs 7 and 8, respectively. Occupational exposure to chloroform may occur through inhalation and dermal contact with this compound at workplaces where chloroform is produced or used. Monitoring data indicate that the general population may be exposed to chloroform via inhalation of ambient air, ingestion of food and drinking water, and dermal contact with chlorinated pool water and other consumer products containing chloroform. (SRC)
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