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


VOL.: 29 (1982) (p. 321)

CAS No.: 16071-86-6
Chem. Abstr. Name: Cuprate (2-), (5-[(4'-((2,6-dihydroxy-3- ((2-hydroxy-5-sulfophenyl)-
azo)phenyl)azo)(1,1'-biphenyl)-4-yl)azo]-2-hydroxy benzoato(4-))-, disodium salt

5. Summary of Data Reported and Evaluation

5.1 Experimental data

Oral administration to rats of one commercial sample of Direct Brown 95 resulted in one hepatocellular carcinoma and several neoplastic nodules in females sacrificed 13 weeks after start of exposure to the highest dose at which animals survived. The study in mice was inadequate for evaluation.

No data were available to assess the mutagenicity or teratogenicity of Direct Brown 95.

5.2 Human data

Occupational exposure to Direct Brown 95 has and probably still does occur during its production and its use for the dyeing of textiles, leather and paper. Benzidine and its metabolic derivatives have been detected in the urine of workers exposed to direct azo dyes.

No data were available to assess the mutagenicity or teratogenicity of Direct Brown 95 to man.

No study of exposure to Direct Brown 95 alone was available to the Working Group. An epidemiological study of silk dyers and painters who had multiple exposure to benzidine-based and other dyes indicated that those exposures were strongly associated with the occurrence of bladder cancer. Case reports and other epidemiological studies support the existence of such a relationship.

5.3 Evaluation

The number of preneoplastic lesions in rats and the precocity of their onset indicate a carcinogenic effect similar to that of Direct Black 38. The present data, however, provide only limited evidence that commercial Direct Brown 95 is carcinogenic to rats.

Although the epidemiological data were inadequate to evaluate the carcinogenicity to man of Direct Brown 95 alone, they, together with the presence of benzidine in the urine of exposed workers, provide sufficient evidence that occupational exposure to benzidine-based dyes represents a carcinogenic risk to man.

For definition of the italicized terms, see Preamble Evaluation.

Subsequent evaluation: Suppl. 7 (1987)


Last updated: 9 April 1998

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