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

(Group 2B)

For definition of Groups, see Preamble Evaluation.

Supplement 7: (1987) (p. 198)

CAS No.: 119-90-4

A. Evidence for carcinogenicity to humans (inadequate)

3,3'-Dimethoxybenzidine (together with 3,3'-dichlorobenzidine and ortho-toluidine) has been prepared in the same plants as benzidine and may therefore have contributed to the bladder cancer risk associated with benzidine [ref: 1]. No case is on record in the USSR of an occupational urinary bladder neoplasm produced solely by this compound [ref: 2].

B. Evidence for carcinogenicity to animals (sufficient)

Following its oral administration, 3,3'-dimethoxybenzidine produced tumours in rats at various sites, including the bladder, intestine, skin and Zymbal gland; it produced forestomach papillomas in hamsters [ref: 3].

C. Other relevant data

3,3'-Dimethoxybenzidine has been found in the urine of workers exposed to it [ref: 3].

No data were available on the genetic and related effects of 3,3'-dimethoxybenzidine in humans. It induced sister chromatid exchanges in Chinese hamster cells in vitro and unscheduled DNA synthesis in human cells and rat hepatocytes in vitro. It was mutagenic to bacteria [ref: 4].

Overall evaluation

3,3'-Dimethoxybenzidine is possibly carcinogenic to humans (Group 2B).

For definition of the italicized terms, see Preamble Evaluation.

Also see previous evaluation: Vol. 4 (1974)


1. Clayson, D.B. (1976) Occupational bladder cancer. Prev. Med., 5, 228-244

2. Genin, V.A. (1974) Hygienic assessment of dianisidine-sulphate production from standpoint of carcinogenous hazard for workers (Russ.). Gig. Tr. prof. Zabol., 6, 18-22

3. IARC Monographs, 4, 41-47, 1974

4. IARC Monographs, Suppl. 6, 262-263, 1987


Last updated: 2 March 1998

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