PCB and DDE methyl sulfones in mammals from Canada and Sweden

Abstract

AbstractLevels of PCB methyl sulfones (MeSO2‐CBs) and DDE methyl sulfones (MeSO2‐DDEs) have been determined in tissues from polar bear (Ursus martimus), beluga whale (Delphinapterus leucas), and false killer whale (Pseudorca crassidens) from the Canadian environment, and grey seal (Halichoerus grypus), otter (Lutra lutra), and wild mink (Mustela vison) from the Swedish environment. Up to 30 MeSO2‐CB congeners and three MeSO2‐DDE isomers were shown to be present in the analyzed tissues. The concentration of total MeSO2‐CBs ranged from 0.1 to 21 μg/g extracted lipids. 3‐MeSO2‐2,5,2′,4′,5′‐penta‐CB is the dominating MeSO2‐CB congener in all the analyzed samples, but the corresponding 4‐MeSO2‐CB also is present in high concentrations. A smaller number of MeSO2‐CBs, always dominated by the meta‐substituted MeSO2‐CBs, were present in livers of grey seal, otter, and mink than in adipose tissue or muscle. In all studied mammals the concentrations of MeSO2‐CBs were higher in liver than in blubber or muscle. Seven PCB congeners were identified as precursors of the PCB methyl sulfones: 2,4,2′,5′‐tetra‐CB (CB‐49), 2,5,3′,4′‐tetra‐CB (CB‐70), 2,4,5,2′,5′‐penta‐CB (CB‐101), 2,3,4,5,2′,5′‐penta‐CB (CB‐87), 2,3,6,2′,4′,5′‐hexa‐CB (CB‐149), 2,3,4,2′,3′,6′‐hexa‐CB (CB‐132), and 2,3,4,2′,5′‐hexa‐CB (CB‐141). All species except beluga whale contained 3‐MeSO2‐4,4′‐DDE, but at a much lower concentration in mink and otter than in the other mammals. Polar bear and grey seal liver also contained 2‐MeSO2‐4,4′‐DDE. The concentrations of 2‐ and 3‐MeSO2‐DDE ranged from 0.01 to 1.3 μg/g extracted lipids. A hitherto unknown MeSO2‐DDE isomer was determined in false killer whale blubber by GC‐MS, along with 2‐ and 3‐MeSO2‐4,4′‐DDE and several unknown MeSO2‐penta‐CBs and MeSO2‐hexa‐CBs. tris(4‐chlorophenyl)methanol was identified in the aryl methyl sulfone fraction of polar bear liver and grey seal blubber samples.