Appearance and reappearance of mutagens in urine from rats after oral administration of direct brown 95, due to coprophagy

Rats treated orally with direct brown 95, a benzidine-based dye, widely used in dyeing of textiles, plastics, paper and other Materials, showed 2 peaks of excretion of mutagenic products in urine, one between 6 h and 18 h after administration and one about 30 h later. Prevention of coprophagy by fitting neck collars resulted in the disappearance of the second peak. Oral administration of carminic acid resulted in a biphasic excretion of this dye in the feces, due to coprophagy. The excretion pattern of mutagens in urine after administration of direct brown 95 corresponds with the excretion pattern in the feces of orally administered carminic acid.