The fate of chiral organochlorine compounds and selected metabolites in intraperitoneally exposed arctic char (Salvelinus alpinus)

The fate of chiral organochlorine compounds (OCs) and selected metabolites in exposed Arctic char (Salvelinus alpinus) was investigated. The contaminants α‐hexachlorocyclohexane (α‐HCH), cis‐chlordane, 13C4‐heptachlor, o,p′‐DDT, and the atropisomeric chlorinated biphenyls (CBs) 95, 132, 136, 149, and 174 were solved in peanut oil and injected into the peritoneal cavity. The exposed fish were sampled three times during a five‐week period, and the OC residues and detected metabolites (heptachlor‐exo‐epoxide) were quantified in muscle and liver tissues by chiral and achiral gas chromatography‐mass spectrometry and gas chromatography‐electron‐capture detection. Peak concentrations were reached after one to two weeks, and thereafter, the levels declined. At the end of the experiment, liver concentrations had decreased 76 to 92% relative to peak concentrations, whereas muscle concentrations showed a moderate decline (5–38%), with the exception of α‐HCH (91%). Hydrophobicity and steric hindrance were shown to influence the assimilation process, and a significant linear relationship between the product of the steric hindrance coefficients and the inverse of the octanol‐water partition coefficients (Kow) versus peak concentration was found for the CBs (r2 = 0.86, p = 0.02). The assimilation of the contaminants into muscle and liver tissues generally resulted in racemic mixtures, whereas elimination was enantioselective for α‐HCH, cis‐chlordane, o,p′‐DDT, CB‐132, and CB‐136. The chiral heptachlor metabolite 13C4‐heptachlor‐exo‐epoxide was formed in the fish. The enantiomeric composition of the formed metabolite indicated racemic formation, whereas the elimination process appeared to be enantioselective.