Accumulation, Elimination, and Metabolism of Dichlorobenzidine in the Bluegill Sunfish

The bioconcentration, elimination, and metabolism of 3, 3 ^'-dichlorobenzidine (DCB), a suspected human carcinogen, were investigated in bluegill sunfish. [¹⁴C]DCB was rapidly accumulated by the fish from water containing 5 ppb or 0.1 ppm of the chemical. Based on total ¹⁴C residues, bioconcentration factors of 495 to 507 were observed in the whole fish with equilibria achieved in 96 to 168 h. The ¹⁴C residues were distributed in both the edible and nonedible portions. [¹⁴C]DCB or its metabolites were not completely eliminated upon transfer of the fish to water free of dichlorobenzidine. The only metabolite detected in the fish was an acid-labile conjugate of DCB, which appears to be an N-glucuronide. The ability of DCB to concentrate in aquatic organisms may present a direct hazard to human health through consumption of contaminated fish.