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

(Group 4)

For definition of Groups, see Preamble Evaluation.

VOL.: 71 (1999) (p. 383)

CAS No.: 105-60-2
Chem. Abstr. Name: Hexahydro-2H-azepin-2-one

5. Summary of Data Reported and Evaluation

5.1 Exposure data

Exposure to caprolactam, a monomer used in high volume, can occur in its manufacture and the manufacture of nylon 6. It has been detected in surface water, groundwater and drinking-water.

5.2 Human carcinogenicity data

No data were available to the Working Group.

5.3 Animal carcinogenicity data

Caprolactam was tested for carcinogenicity by oral administration in the diet of mice and rats. No increase in the incidence of tumours was observed. Caprolactam was also tested for promoting effects in two multistage studies in male rats. In one, oral administration of caprolactam in the diet after treatment with several carcinogens showed no modifying effect on carcinogenicity in any organ or on glutathione S-transferase (placental form) (GST-P)-positive foci of the liver. In the other study, oral administration of caprolactam in the diet with a two-thirds partial hepatectomy after treatment with N-nitrosodiethylamine did not increase the numbers or areas of GST-P-positive foci in the liver.

5.4 Other relevant data

Caprolactam is metabolized in rats to a number of metabolites including 4-hydroxy caprolactam. In rats, it exhibits some hepatotoxicity at high doses.

Caprolactam was not mutagenic to rodents in vivo. It induced chromosomal aberrations and aneuploidy in human lymphocytes in vitro, but no other evidence of mutagenicity has been found in a variety of tests with rodent cell cultures. Results for morphological transformation in mammalian cells were inconclusive. Caprolactam was mutagenic in somatic and to a lesser degree to germ cells in Drosophila melanogaster. Caprolactam was not genotoxic in bacteria.

5.5 Evaluation

No epidemiological data relevant to the carcinogenicity of caprolactam were available.

There is evidence suggesting a lack of carcinogenicity of caprolactam in experimental animals.

Overall evaluation

Caprolactam is probably not carcinogenic to humans (Group 4).

For definition of the italicized terms, see Preamble Evaluation.

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


Last updated: 8 April 1999

    See Also:
       Toxicological Abbreviations
       Caprolactam (ICSC)