Methyl chloride is produced naturally, primarily in oceans, and it is widely detected in ambient air and water. Two small cohort studies evaluated the mortality experience of workers employed in facilities using or producing methyl chloride. No clear mortality excess occurred, and the small size and mixed exposures of these studies limited their utility for assessing the carcinogenicity of methyl chloride. No adequate data were available to the Working Group. The toxicokinetics of methyl chloride have been studied in human volunteers.
Carbon dioxide is a major metabolite.
Methyl chloride causes toxicity in rodents in the liver, kidney and central nervous system. It may deplete glutathione in tissues. Methyl chloride is mutagenic to bacteria. It was genotoxic in a number of mammalian cell systems in vitro and gave positive results in the dominant lethal test in rats in vivo . There is inadequate evidence for the carcinogenicity of methyl chloride to humans.