Metabolism of Azo Dyes to Carcinogenic Amines.
NIOSH 1980 May:378-398
The metabolism of azo dyes to carcinogenic amines was studied in hamsters. Male Syrian golden hamsters were given a single oral dose of 100 milligrams per kilogram (mg/kg) Direct Black 38 (DB-38) containing 3.0 parts per million (ppm) benzidine (92875), 6.0ppm 4- aminobiphenyl (92671) (4-ABP), and 670ppm 2,4-diaminoazobenzene (495545). Other hamsters were given 100mg/kg of the 3,3'- dichlorobenzidine (91941) based Pigment Yellow 12 (PY-12). Urine specimens were collected for 8 days and analyzed by electron capture gas chromatography and high pressure liquid chromatography. Mutagenicity of urinary metabolites of DB-38 was tested using the Ames Salmonella test, with and without mouse liver microsomal activation. DB-38 was extensively metabolized to benzidine, the N- acetylbenzidine metabolites, and unspecified benzidine conjugates. Concentrations of metabolites peaked at 8 to 16 hours, but the major metabolite, monoacetylbenzidine (3366618), was present in measurable quantities after 7 days. The amount of excreted metabolites far exceeded the amount of benzidine and 4-ABP present as impurities in the dye. None of the DB-38 metabolites were mutagenic without activation, but all had some degree of mutagenic activity in the presence of S-9 in at least one tester strain. PY-12 produced no measurable concentrations of any metabolites. The authors conclude that exposure to DB-38 may increase the risk of cancer in humans because benzidine and 4-ABP are bladder carcinogens.
Coloring-materials; Dyes; Laboratory-animals; Mutagenesis; Carcinogenesis; Metabolism; Biochemistry;
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Proceedings of the First NCI/EPA/NIOSH Collaborative Workshop: Progress on Joint Environmental and Occupational Cancer Studies, May 6-8, 1980, Rockville, Maryland, H. F. Kraybill, I. C. Blackwood, and N. B. Freas, Eds. National Cancer Institute, Environmental Protection Agency, National Institute for Occupational Safety and Health