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

For definition of Groups, see Preamble Evaluation.

VOL.: 63 (1995) (p. 315)
CAS No.: 513-37-1
Chem. Abstr. Name: 1-Chloro-2-methyl-1-propene

5.1 Exposure data

1-Chloro-2-methylpropene occurs as an impurity in the production of 3-chloro-2-methylpropene. It has no known commercial application.

5.2 Human carcinogenicity data

No data were available to the Working Group.

5.3 Animal carcinogenicity data

1-Chloro-2-methylpropene was tested for carcinogenicity by oral administration in one experiment in mice and in one experiment in rats. It produced squamous-cell carcinomas of the preputial gland in male mice and squamous-cell carcinomas of the forestomach in animals of each sex. In rats, it produced carcinomas of the nasal cavity and papillomas and carcinomas of the oral cavity, oesophagus and forestomach in animals of each sex.

5.4 Other relevant data

No data were available on the toxicokinetics or toxic effects of 1-chloro-2-methylpropene in humans. It is rapidly absorbed and excreted after oral administration to rats and mice. In rats, more of the dose was excreted via the lungs than in the urine, whereas in mice similar proportions were excreted by the two routes. Both the unchanged compound and carbon dioxide were exhaled. The major urinary metabolite in rats and mice was formed after oxidation and glutathione conjugation.

Repeated oral administration of 1-chloro-2-methylpropene to rats resulted in tissue necrosis in a number of organs, including the small and large intestine, thymus and spleen. Repeated administration of the compound to rats by gavage induced proliferation of forestomach cells.

Gene mutation and sister chromatid exchange, but not chromosomal aberrations, were induced in cultured rodent cells in single studies. 1-Chloro-2-methylpropene induced gene and chromosomal mutation in insects (in a single study). It was mutagenic to bacteria.

5.5 Evaluation

There is inadequate evidence in humans for the carcinogenicity of 1-chloro-2-methylpropene.

There is sufficient evidence in experimental animals for the carcinogenicity of 1-chloro-2-methylpropene.

Overall evaluation

1-Chloro-2-methylpropene is possibly carcinogenic to humans (Group 2B). For definition of the italicized terms, see Preamble Evaluation.

Synonyms

• a-Chloroisobutylene
• 1-Chloroisobutylene
• Dimethylvinyl chloride
• 2,2-Dimethylvinyl chloride
• b,b-Dimethylvinyl chloride
• Isocrotyl chloride
• 2-Methyl-1-chloropropene
• 2-Methyl-1-propenyl chloride

    See Also:
       Toxicological Abbreviations