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

(Group 3)

For definition of Groups, see Preamble Evaluation.

Supplement 7: (1987) (p. 260)

CAS No.: 134-32-7

A. Evidence for carcinogenicity to humans (inadequate)

An excess occurrence of bladder cancer was observed in workers who had been exposed to commercial 1-naphthylamine for five or more years who had not also been engaged in the production of 2-naphthylamine or benzidine. However, commercial 1-naphthylamine made at that time may have contained 4-10% 2-naphthylamine [ref: 1]. Among a cohort of 906 men employed for at least one year between 1922 and 1970 in a dyestuffs plant in Italy, a considerable excess of bladder cancer deaths (27 observed, 0.19 expected) was observed among 151 workers involved in the manufacture of 1- and 2-naphthylamine and benzidine [ref: 2]. A case-control study of bladder cancer in the UK showed a significant, exposure-related increased risk for dyestuffs workers. 1-Naphthylamine was plausibly concerned, but it was not possible to single out any compound from the combined exposure to arylamines [ref: 3].

In view of the contamination of the commercial product and the mixed nature of the exposures investigated, it is not possible to assess the carcinogenicity of 1-naphthylamine alone.

B. Evidence for carcinogenicity to animals (inadequate)

1-Naphthylamine was tested for carcinogenicity mice, hamsters and dogs by oral administration and in newborn mice by subcutaneous injection. No carcinogenic effect was observed following oral administration to hamsters [ref: 1] or dogs [ref: 1,4,5] or in a lung adenoma bioassay in mice [ref: 6]. Inconclusive results were obtained after oral administration to adult mice and subcutaneous injection of newborn mice [ref: 1].

C. Other relevant data

No data were available on the genetic and related effects of 1-naphthylamine in humans.

1-Naphthylamine did not induce micronuclei in bone-marrow cells of mice treated in vivo; it induced DNA strand breaks in mice, but not in rats. 1-Naphthylamine increased the incidence of chromosomal aberrations in cultured rodent cells, but the results for sister chromatid exchanges, mutation and DNA damage were inconclusive; no cell transformation was induced in Syrian hamster embryo cells. It did not induce sex-linked recessive lethal mutations in Drosophila. It induced aneuploidy but not mutation in yeast; results for mitotic recombination were conflicting. It was mutagenic to bacteria [ref: 7].

Overall evaluation

1-Naphthylamine is not classifiable as to its carcinogenicity to humans (Group 3).

For definition of the italicized terms, see Preamble Evaluation.

Also see previous evaluation: Vol. 4 (1974)


1. IARC Monographs, 4, 87-96, 1974

2. Decarli, A., Peto, J., Piolatto, G. & La Vecchia, C. (1985) Bladder cancer mortality of workers exposed to aromatic amines: analysis of models of carcinogenesis. Br. J. Cancer, 51, 707-712

3. Boyko, R.W., Cartwright, R.A. & Glashan, R.W. (1985) Bladder cancer in dye manufacturing workers. J. occup. Med., 27, 799-803

4. Radomski, J.L., Deichmann, W.B., Altman, N.H. & Radmonski, T. (1980) Failure of pure 1-naphthylamine to induce bladder tumors in dogs. Cancer Res., 40, 3537-3539

5. Purchase, I.F.H., Kalinowski, A.E., Ishmael, J., Wilson, J., Gore, C.W. & Chart, I.S. (1981) Lifetime carcinogenicity study of 1- and 2-naphthylamine in dogs. Br. J. Cancer, 44, 892-901

6. Theiss, J.C., Shimkin, M.B. & Weisburger, E.K. (1981) Pulmonary adenoma response of strain A mice to sulfonic acid derivatives of 1- and 2-naphthylamines. J. natl Cancer Inst., 67, 1299-1302

7. IARC Monographs, Suppl. 6, 406-409, 1987


Last updated: 11 March 1998

    See Also:
       Toxicological Abbreviations
       Naphthylamine, 1- (IARC Summary & Evaluation, Volume 4, 1974)