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


VOL.: 29 (1982) (p. 239)

5. Summary of Data Reported and Evaluation

5.1 Experimental data

3,3'-Dichlorobenzidine was tested in mice, rats, hamsters and dogs by oral administration, in rats by subcutaneous administration and in mice by transplacental exposure. Following its oral administration, it produced liver-cell tumours in mice, hepatocellular carcinomas in dogs, mammary and Zymbal-gland tumours in rats and carcinomas of the urinary bladder in hamsters and dogs. Increased incidences of leukaemias were observed in rats following oral administration and in mice following transplacental exposure.

3,3'-Dichlorobenzidine is mutagenic to Salmonella typhimurium with or without metabolic activation and induces unscheduled DNA synthesis in HeLa cells.

No data were available on the teratogenicity of this compound to experimental animals.

5.2 Human data

Occupational exposure to 3,3'-dichlorobenzidine dihydrochloride has and probably still does occur during its manufacture and conversion to derived pigments. Rubber workers were formerly and may still be exposed to 3,3'-dichlorobenzidine used for curing polyurethane elastomers.

No data were available to assess the mutagenicity or teratogenicity of this compound to man.

No case report on exposure to 3,3'-dichlorobenzidine was available to the Working Group. Although three retrospective epidemiological studies of workers exposed to 3,3'-dichlorobenzidine gave no evidence for carcinogenicity, the studies were of insufficient quality or statistical power to permit confident exclusion of that possibility. Because 3,3'-dichlorobenzidine and benzidine may be made in the same plant, the possibility cannot be excluded that dichlorobenzidine has contributed to the incidence of human bladder cancer attributed to benzidine.

5.3 Evaluation

There is sufficient evidence that 3,3'-dichlorobenzidine is carcinogenic in mice, rats, hamsters and dogs.

The epidemiological data are inadequate to evaluate the carcinogenicity of 3,3'-dichlorobenzidine to man.

For definition of the italicized terms, see Preamble Evaluation.

Previous evaluation: Vol. 4 (1974)

Subsequent evaluation: Suppl. 7 (1987)

Last updated: 9 April 1998

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