The effect of 3,3′,4,4′-tetrachlorobiphenyl and clophen A50 on the hepatic monooxygenase system of Eider Ducklings ( Somateria mollissima) with indications for structure-related biotransformation of CB congeners

Abstract

Environmental contamination may be one cause of the high level of parasitic infections and high death rates of eiders in the Wadden Sea where, among other contaminants, high concentrations of polychlorinated biphenyls (PCBs) occur. To study this problem, four-week-old eider ducklings were exposed to single doses of 3,3′,4,4′-tetrachlorobiphenyl (CB 77; 5 or 50 mg i.p./kg) or Clophen A50 (50 or 200 mg i.p./kg). The control group was injected with corn oil only (5 ml/kg). A dose-dependent induction of the hepatic monooxygenase system was only found in ducklings treated with CB77. Clophen A50 (Clo A50) showed no effect. Comparison of CB patterns in the Clo A50-injected groups with the original mixture revealed differences associated with molecular structure: only CBs with vicinal hydrogen atoms in the meta- and para-positions had