INTOX Home Page

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

(Group 2B)

For definition of Groups, see Preamble Evaluation.

Vol.: 71 (1999) (p. 401)

CAS No.: 56-23-5
Chem. Abstr. Name: Tetrachloromethane

5. Summary of Data Reported and Evaluation

5.1 Exposure data

Exposure to carbon tetrachloride may occur in its production, in the production of refrigerants, in laboratories and during degreasing operations. It has been detected at low levels in ambient air and water.

5.2 Human carcinogenicity data

The risk of cancer from carbon tetrachloride has been examined in five occupational populations. In three of four studies that collected information on non-Hodgkin lymphoma (two cohort investigations and one independent nested case–control study), associations with exposure to carbon tetrachloride were suggested. However, not all of these studies distinguished exposure to carbon tetrachloride specifically, and the associations were not strong statistically. In the fourth study (another cohort investigation), few men were exposed to carbon tetrachloride and the risk of non-Hodgkin lymphoma was not reported. A nested case–control study of lung cancer in a cohort of chemical workers showed no association with exposure to carbon tetrachloride.

Four population-based case–control studies have examined associations of carbon tetrachloride with chronic lymphocytic leukaemia, brain cancer, female breast cancer and intraocular melanoma. Findings were generally unremarkable. In a fifth case–control study, which examined several cancers, no association was found with non-Hodgkin lymphoma, although the power to detect an increased risk was low.

5.3 Animal carcinogenicity data

Carbon tetrachloride was tested for carcinogenicity by various routes of administration. It produced liver neoplasms in mice and rats and mammary neoplasms in rats following subcutaneous injection. In one study in mice by inhalation, an increased incidence of phaeochromocytomas was reported. In experiments involving administration of carbon tetrachloride after known carcinogens, the occurrence of tumours and/or preneoplastic lesions of the liver in mice, rats and hamsters was enhanced.

5.4 Other relevant data

Carbon tetrachloride is metabolized by CYP2 enzymes; several reactive metabolites have been postulated, including radicals and phosgene. In vitro, DNA binding of carbon tetrachloride is observed in several cellular systems; no such binding in vivo has been reported.

Carbon tetrachloride induces hepatic cell proliferation and DNA synthesis.

Carbon tetrachloride has a mutagenic effect and induces aneuploidy in several in-vitro systems.

5.5 Evaluation

There is inadequate evidence in humans for the carcinogenicity of carbon tetrachloride.

There is sufficient evidence in experimental animals for the carcinogenicity of carbon tetrachloride.

Overall evaluation

Carbon tetrachloride is possibly carcinogenic to humans (Group 2B).

For definition of the italicized terms, see Preamble Evaluation.

Previous evaluations: Vol. 1 (1972); Vol. 20 (1979); Suppl. 7 (1987)


See Also:
        Carbon tetrachloride (CHEMINFO)
        Carbon tetrachloride (EHC 208, 1999)
        Carbon tetrachloride (ICSC)