Metabolism of nine benzidine-congener-based azo dyes in rats based on gas chromatographic assays of the urine for potentially carcinogenic metabolites.
Bowman-MC; Nony-CR; Billedeau-SM; Martin-JL; Thompson-HC Jr.; Lowry-LK
J Anal Toxicol 1983 Jan; 7(1):55-60
Potential carcinogenic metabolites of benzidine congener based azo dyes were studied by gas chromatography of rat urine samples. The dyes studies were based on benzidine (92875) and its congeners 3,3'- dimethylbenzidine (119937) and 3,3'-dimethoxybenzidine (119904). Dyes were administered to male Fischer-344-rats by a single gavage dose of 2 milligrams in water at 39 degrees-C. Samples of urine were collected 0 to 12, 12 to 24, 24 to 48, and 48 to 96 hours after administration. Extracted urine samples were subjected to assays of benzidine congener free amines and their monoacetyl metabolites and alkaline hydrolyzable conjugates or for diacetyl metabolites by derivatization with heptafluorobutyryl derivatives and electron capture gas chromatography. Stability of the dyes in both rat and human urine was tested at 5 degrees for 96 hours. Six dyes liberated high amounts of benzidine congener amines when held in rat or human urine at 25 degrees for 96 hours. All dyes metabolized to yield appreciable amounts of the corresponding amine, monoacetyl, diacetyl, and alkaline hydrolyzable products. Only red-39 (6358298), direct-orange-6 (547579), and direct-red-46 (6548294) showed peak excretion amounts during the 12 to 24 hours post interval. Metabolite amounts for all dyes decreased from 24 to 48 hours post administration and by 48 to 96 hours reached pretreatment amounts. Minimum detectable amounts of all metabolites were 12 parts per billion or less. The authors conclude that the dyes are sufficiently metabolized in rats to yield urinary benzidine congener metabolites.
NIOSH-Author; Metabolites; Azo-dyes; Carcinogenicity; Urinalysis; Dyes; Comparative-toxicology; Health-hazards; Amines; Animal-studies
92-87-5; 119-93-7; 119-90-4; 6358-29-8; 547-57-9; 6548-29-4
Journal of Analytical Toxicology