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

(Group 3)

For definition of Groups, see Preamble Evaluation.

VOL.: 71 (1999) (p. 1163)

CAS No.: 75-35-4
Chem. Abstr. Name: 1,1-Dichloroethene

5. Summary of Data Reported and Evaluation

N.B. - Summary (but not the evaluation) prepared by the Secretariat after the meeting.

5.1 Exposure data

Exposure to vinylidene chloride may occur during its production and in the production of copolymers. It has been detected in wastewater.

5.2 Human carcinogenicity data

Two cohort studies were performed in workers exposed to vinylidene chloride. Both studies have major limitations and do not allow evaluation of the carcinogenicity of the compound.

No specific association was found between exposure to vinylidene chloride and an excess of lung cancer observed in a synthetic chemical plant in the United States.

5.3 Animal carcinogenicity data

Vinylidene chloride was tested for carcinogenicity in mice and rats by oral administration and inhalation exposure, in mice by subcutaneous administration and topical application and in hamsters by inhalation. Studies in mice and rats by oral administration gave negative results. In inhalation studies, no treatment-related neoplasm was observed in rats or hamsters. In mice, treatment-related increases in the incidence of kidney adenocarcinomas were observed in male mice, as were increases in mammary carcinomas in females and pulmonary adenomas in male and female mice. In skin-painting studies in female mice, vinylidene chloride showed activity as an initiator, but in a study of repeated skin application, no skin tumour occurred. No tumour at the injection site was seen in mice given repeated subcutaneous administration.

5.4 Other relevant data

Vinylidene chloride is oxidized principally by CYP2E1, the activity of this cytochrome P450 being higher in those tissues (particularly mouse Clara cells and male mouse kidney) that are targets for toxicity of vinylidene chloride. Glutathione levels and conjugation are important in its inactivation and protect against covalent binding. It causes gene mutations in microorganisms, but its genetic activity has not been extensively studied in mammalian cells.

5.5 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.

For definition of the italicized terms, see Preamble Evaluation.

Overall evaluation

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

Previous evaluations: Vol. 19 (1979); Vol. 39 (1986); Suppl. 7 (1987)


Last updated: 13 April 1999

    See Also:
       Toxicological Abbreviations
       Vinylidene chloride (EHC 100, 1990)
       Vinylidene chloride (HSG 36, 1989)
       Vinylidene chloride (ICSC)