The Characteristic Accumulation of Hydroxylated Polychlorinated Biphenyls (HO-PCBs) in Blood, Liver and Gallbladder in Great Cormorant (Phalacrocorax carbo)

Abstract

Hydroxylated PCBs (HO-PCBs) are known to occur as metabolites of PCBs in organisms. It has been reported that certain HO-PCBs are present in human blood, and wildlife such as marine mammals. Previous analytical studies have been performed mainly for higher chlorinated (5Cl<) HO-PCBs, but little is known for lower chlorinated (<4Cl) HO-PCBs. HO-PCBs are complex mixtures of congeners, total number of congeners being 837, has the different toxicity by congeners. The purpose of this study was to develop the analytical methods for lower chlorinated HO-PCBs in addition to higher chlorinated ones together with PCBs, and applied to the determination in blood, liver and gallbladder of great cormorant (Phalacrocorax carbo). HO-PCBs and PCBs were detected in all samples analyzed. It was found that the highest concentration was determined in the gallbladder samples and the second in blood samples. In blood and gallbladder, the concentrations of HO-PCBs were found 1.7 and 2.1 times higher than the concentrations of PCBs, respectively. It is interesting that the composition patterns of HO-PCB congeners are completely different between blood and gallbladder samples. The residue pattern of HO-PCB congeners in great cormorant was also different between blood and gallbladder, probably reflecting metabolic pathway of PCBs and HO-PCBs. One explanation is like that; PCBs are metabolized in liver, and the product HO-PCBs are excreted into bile, the HO-PCB congeners as PCB metabolites being appeared in high concentration in gallbladder. A part of HO-PCBs excreted into bile was reabsorbed in gastrointestinal tract and appears in blood, which has high affinity with blood protein being remaining at higher concentration. Ratios of unidentified HO-PCBs/total HO-PCBs were 54% and 94%, respectively, in blood and gallbladder. It seems to be important to understand the chemical structures and behavior of unidentified congeners in order to evaluate toxicological and environmental meaning for HO-PCBs.