1,1-Dichloroethylene

CAS RN:75-35-4

Carcinogenicity Evidence

Evaluation: There is inadequate evidence in humans for the carcinogenicity of vinylidene chloride. There is limited evidence in experimental animals for the carcinogenicity of vinylidene chloride. Overall evaluation: Vinylidene chloride is not classifiable as to its carcinogenicity to humans (Group 3). /To be changed to Group 2B (Possibly carcinogenic to humans) in a volume still in progress/
Under the 1986 cancer guidelines (U.S. EPA, 1986), 1,1-DCE is assigned to Group C, possible human carcinogen. Under the draft revised guidelines for carcinogen risk assessment (U.S. EPA, 1999), EPA concludes 1,1-DCE exhibits suggestive evidence of carcinogenicity but not sufficient evidence to assess human carcinogenic potential following inhalation exposure in studies in rodents. Male mice developed kidney tumors at one exposure in a lifetime bioassay, a finding tempered by the absence of similar results in female mice or male or female rats and by the enzymatic differences (i.e., CYP2E1) between male mice and female mice, male and female rats, and human kidney cells. Limited evidence of genotoxicity has been reported in bacterial systems with metabolic activation. The data for 1,1-DCE are inadequate for an assessment of human carcinogenic potential by the oral route, based on the absence of statistically or biologically significant tumors in limited bioassays in rats and mice balanced against the suggestive evidence in male mice in a single bioassay by inhalation and the limited evidence of genotoxicity. The human epidemiological results on the carcinogenicity of 1,1-DCE are too limited to draw useful conclusions. EPA concludes that the results of kidney tumors in one sex and one exposure in a single species of rodents are too limited to support an exposure-response assessment.
A4; Not classifiable as a human carcinogen.
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