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Chlorodifluoromethane (75-45-6). Limited evidence for carcinogenicity to experimental animals. IARC. 1986.

From: IARC (International Agency for Research on Cancer)


VOL.: 41 (1986) (p. 237)

CAS No.: 75-45-6

5. Summary of Data Reported and Evaluation

5.1 Exposure data

Chlorodifluoromethane is produced extensively for use in refrigeration and air conditioning; significant quantities are subsequently released into the atmosphere, resulting in widespread, low-level human exposure. Occupational exposure to chlorodifluoromethane occurs during its production and use.

5.2 Experimental data

Chlorodifluoromethane was tested for carcinogenicity in one experiment in rats by oral administration by gavage and in experiments in rats and mice by inhalation exposure. No increase in tumour incidence was observed in rats after oral administration. The inhalation study in mice was inconclusive for males, and negative results were obtained for females. In the inhalation study in rats, males receiving the high dose had increased incidences of fibrosarcomas and Zymbal-gland tumours; negative results were obtained for female rats.

Chlorodifluoromethane causes malformations of the eyes of fetal rats, but has no reproductive effect in male rats and does not cause prenatal toxicity in rabbits following exposure by inhalation.

Chlorodifluoromethane is mutagenic to Salmonella typhimurium in the presence and absence of an exogenous metabolic system. It does not induce mutation or gene conversion in yeast, or DNA damage or mutation in cultured mammalian cells. It does not induce chromosomal damage in bone marrow or dominant lethal mutations in mice or rats treated in vivo.

5.3 Human data

No data were available to evaluate the reproductive effects or prenatal toxicity of chlorodifluoromethane to humans.

A small study of workers exposed to a mixture of chlorofluorocarbons, including chlorodifluoromethane, was uninformative with regard to the carcinogenic hazard of this chemical.

5.4 Evaluation

There is limited evidence for the carcinogenicity of chlorodifluoromethane to experimental animals.

There is inadequate evidence for the carcinogenicity of chlorodifluoromethane to humans.

For definition of the italicized terms, see Preamble Evaluation.

Subsequent evaluations: Suppl. 7 (1987); Vol. 71 (1999)


Last updated: 13 April 1999

Note from FAN:


Fibrosarcoma: A type of soft tissue sarcoma that begins in fibrous tissue, which holds bones, muscles, and other organs in place.

Zymbal's Gland - Rats and Mice: The Zymbal's gland is made up of several lobules of modified sebaceous glands which are located at the base (anterioventral) of the external ear. A section through the base of the skull at the level of the external ear generally results in a section plane through one or more lobules of Zymbal's gland tissue. Ref: http://www.item.fraunhofer.de/reni/trimming/TR_034.HTM