BIOACCUMULATION PROFILES OF POLYCHLORINATED-BIPHENYLS INCLUDING COPLANAR CONGENERS AND POSSIBLE TOXICOLOGICAL IMPLICATIONS IN BAIKAL SEAL (PHOCA-SIBIRICA)

Isomer specific concentrations of individual polychlorinated biphenyls (PCBs) including toxic non-ortho (IUPAC 77, 126, 169), mono-ortho (10 5, 118, 156) and di-ortho (137, 138, 153, 180) coplanar congeners were determined in the blubber of 40 Baikal seals (Phoca sibirica) and as their fish diet collected fr om Lake Baikal, Siberia. Residue levels o f total PCBs in Baikal seals were noticeably high and comparable to th ose reported for seals from the North Sea, suggesting the recent usage of this compound in the watershed of Lake Baikal, Non-, mono-, and di -ortho coplanar congeners were also detected in Baikal seals and fish. An approach to estimate bioaccumulation profiles of PCB congeners rev ealed that the non-ortho PCBs, IUPAC 77, 126 and 169 seemed to be less persistent than other congeners, Furthermore, selective biotransforma tion of PCB congeners having either meta-para vicinal H atoms or both adjacent chlorinated meta-para and ortho-meta positions has been sugge sted. Comparison of 2,3,7,8-TCDD toxic equivalents (TEQ) of non-, mono - and di-ortho coplanar congeners in Baikal seals with those for other marine mammals suggested higher enrichment of mono-ortho congeners, p articularly IUPAC 105 and 118, which contr ibuted significantly to the total TEQs in Baikal seals. Results imply that the TCDD-like toxicity is relatively serious in Baikal seals, because of the enrichment of t hese toxic PCB congeners in tissues. (C) 1997 Elsevier Science Ltd.