Hydroxylated and methylsulfone-containing metabolites of polychlorinated biphenyls in the plasma and blubber of bowhead whales (Balaena mysticetus)

Abstract

Bowhead whale (Balaena mysticetus) blubber (n = 20) and plasma (n = 19) samples were collected during the 1997 to 2000 Inuit subsistence harvests in Barrow, Alaska, USA, to quantify the concentrations of methylsulfone (MeSO2)-containing and hydroxylated (OH) polychlorinated biphenyl (PCB) metabolites in this cetacean. The distribution of MeSO2-PCBs in blubber was dominated by 4-MeSO2-substituted congeners, the most abundant being 4-MeSO2-CB-70, 3'-MeSO2-CB-132, and 4-MeSO2-CB-64. Mean (+/- 1 standard error) sum (sigma) MeSO2-PCBs concentrations in blubber were low (6.23 +/- 0.81 ng g(-1) lipid normalized) compared to concentrations previously reported in other marine mammals. However, similar ratios of MeSO2-PCB metabolites to parent PCB congeners among marine mammals suggest that cytochrome P450 2B-like biotransformation and other necessary enzyme-mediated processes and mechanisms that influence the formation and clearance of MeSO2-PCBs exist in the bowhead whale. Pentachlorophenol was the most abundant halogenated phenolic compound quantified in bowhead plasma (1.55 +/- 0.19 ng g(-1) wet wt). Despite indirect evidence for arene epoxidation of the biphenyl moiety inferred from MeSO2-PCB formation, sumOH-PCB concentrations in bowhead plasma were low (1.52 +/- 0.31 ng g(-1) wet wt) compared to humans and marine mammals and were comprised of only two detectable OH-PCB congeners (4'-OH-CB-130 and 4-OH-CB-187). Further research is required to elucidate the toxicokinetics and distribution of OH-PCBs in this cetacean.