SELECTIVE RETENTION OF HYDROXYLATED PCB METABOLITES IN BLOOD

Polychlorinated biphenyls (PCBs) are important environmental contamina nts, and their toxicity to wildlife and humans are of major concern. P CBs form persistent and abundant metabolites, PCB methyl sulfones, tha t accumulate in biota. We now report that certain hydroxylated PCB met abolites show a strong and selective accumulation in mammalian blood. Plasma from experimentally PCB-dosed rats and blood from environmental ly exposed grey seals (Halichoerus grypus) and humans were analyzed. A mong all possible hydroxylated metabolites of PCB that may be formed, only a few, dominated by 4-OH-2,3,5,3',4-pentachlorobiphenyl and 4-OH- 2,3,5,6,2',4',5'-heptachlorobiphenyl, were found in the blood samples. All identified compounds have a structure with the hydroxy group in a para or meta position, with chlorine atoms on vicinal carbon atoms. T he concentrations of hydroxylated PCB in the blood were almost in the same range as the most persistent PCB congeners both for seals and hum ans.