International Agency for Research on Cancer (IARC) - Summaries & Evaluations

(Group 3)

For definition of Groups, see Preamble Evaluation.

VOL.: 71 (1999) (p. 737)

CAS No.: 74-87-3
Chem. Abstr. Name: Chloromethane

5. Summary of Data Reported and Evaluation

5.1 Exposure data

Exposure to methyl chloride may occur in its production, and in the production of silicones and various other chemical products. Methyl chloride is produced naturally, primarily in oceans, and it is widely detected in ambient air and water.

5.2 Human carcinogenicity data

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.

5.3 Animal carcinogenicity data

No adequate data were available to the Working Group.

5.4 Other relevant data

The toxicokinetics of methyl chloride have been studied in human volunteers. It can be converted by human erythrocytes to S-methylglutathione, a metabolite also observed in animal studies; alternatively, it is metabolized by CYP2E1. 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.

5.5 Evaluation

There is inadequate evidence for the carcinogenicity of methyl chloride to humans.

There is inadequate evidence for the carcinogenicity of methyl chloride in experimental animals.

Overall evaluation

Methyl chloride is not classifiable as to its carcinogenicity to humans (Group 3).

For definition of the italicized terms, see Preamble Evaluation.

Previous evaluations: Vol. 41 (1986); Suppl. 7 (1987)


Last evaluated: 13 April 1999

    See Also:
       Toxicological Abbreviations
       Methyl chloride (ICSC)
       Methyl chloride (WHO Food Additives Series 14)
       Methyl chloride (PIM 339)
       Methyl chloride (CICADS 28, 2001)