Polychlorinated biphenyls (PCBs) may induce activity of hepatic enzymes, mainly Phase I monooxygenases and conjugating Phase II enzymes, that catalyze the metabolism of PCBs leading to formation of metabolites and to potential adverse health effects. The present study investigates the concentration and pattern of PCBs, the induction of hepatic phase I and II enzymes, and the formation of hydroxy (OH) and methylsulfonyl (CH3SO2=MeSO2) PCB metabolites in two ringed seal (Phoca hispida) populations, which are contrasted by the degree of contamination exposure, that is, highly contaminated Baltic Sea (n = 31) and less contaminated Svalbard (n = 21). Phase I enzymes were measured as ethoxyresorufin-O-deethylation (EROD), benzyloxyresorufin-O-dealkylation (BROD), methoxyresorufin-O-demethylation (MROD), and pentoxyresorufin-O-dealkylation (PROD) activities, and phase II enzymes were measured as uridine diphosphophate glucuronosyl transferase (UDPGT) and glutathione-S-transferase (GST). Geographical comparison, multivariate, and correlation analysis indicated that sum-PCB had a positive impact on Phase I enzyme and GST activities leading to biotransformation of group III (vicinal ortho-meta-H atoms and <=1 ortho-chlorine (Cl)) and IV PCBs (vicinal meta-para-H atoms and <=2 ortho-Cl). The potential precursors for the main OH-PCBs detected in plasma in the Baltic seals were group III PCBs. MeSO2-PCBs detected in liver were mainly products of group IV PCB metabolism. Both CYP1A- and CYP2B-like enzymes are suggested to be involved in the PCB biotransformation in ringed seals.

Concentrations are given per gram wet weight.Sum 43-PCB: CB-47/48,-52,-66,-74,-99/113,-101,-105,-110,-114/122,-118,-128,-138,-141,-153,-156,-157,-170/190,-172/192,-174,-177,-178,-180/193,-182/187,-183,-189,-194,-195,-196/203,-197,-199,-201/204,-202,-206,-209Sum 4-OH-PCB: 4-0H-CB107, 4'-0H-CB108, 4-OH-CB163, 3'-OH-CB184Sum 17-OH-PCB: 4-0H-CB107, 4'-0H-CB108, 3-OH-CB118, 4'-OH-CB120, 4-OH-CB134, 3'-OH-CB138, 4-OH-CB146, 4-OH-CB162, 4-OH-CB163, 4'-OH-CB172, 4'-OH-CB177, 4-OH-CB178, 4-OH-CB187, 4-OH-CB193, 4'-OH-CB199, 4'-OH-CB202, 4'-OH-CB208Sum 10-MeSO2-PCB: 4-MeSO2-CB49, 4-MeSO2-CB64, 4-MeSO2-CB70, 4-MeSO2-CB87, 3-MeSO2-CB101, 4-MeSO2-CB101, 4-MeSO2-CB110, 4-MeSO2-CB132, 3-MeSO2-CB149, 4-MeSO2-CB174Data extracted in the frame of a joint ICSTI/PANGAEA IPY effort, see http://doi.pangaea.de/10.1594/PANGAEA.150150

Supplement to: Routti, Heli; Letcher, Robert J; Arukwe, Augustine; van Bavel, Bert; Yoccoz, Nigel G; Chu, Shaogang; Gabrielsen, Geir W (2008): Biotransformation of PCBs in relation to phase I and II xenobiotic-metabolizing enzyme activities in ringed seals (Phoca hispida) from Svalbard and the Baltic Sea. Environmental Science & Technology, 42(23), 8952-8958