PCBs, DDTs and methyl sulphone metabolites in various tissues of harbour porpoises from Swedish waters

Abstract

Aryl methyl sulphones of polychlorinated biphenyls (PCBs) and 3- p,p′-DDE (MeSO 2-PCBs and 3-MeSO 2- p,p′-DDE), PCBs and ΣDDTs were analysed in five different tissues (blubber, nuchal fat, liver, muscle, brain) of adult male harbour porpoises from the west coast of Sweden. Two different methods for MeSO 2-PCBs and 3-MeSO 2- p,p′-DDE determination were used, gas chromatography–mass spectrometry and gas chromatography–atomic emission detection. Highest concentrations of ΣMeSO 2-PCBs were found in liver (0.15–0.49 μg/g lipid wt.), which corresponded to 2.0–2.8% of the ΣPCBs concentrations. Blubber and nuchal fat showed ΣMeSO 2-PCB concentrations that were three to five times lower than those in liver. Concentrations of 3-MeSO 2- p,p′-DDE in liver, muscle and brain corresponded to 0.26–4.6% of the p,p′-DDE concentrations, while in blubber and nuchal fat, 3-MeSO 2- p,p′-DDE constituted 0.033–0.21% of p,p′-DDE. The different tissues analysed showed similar levels (lipid wt.) of ΣPCBs and ΣDDTs, except for brain that had almost 10 times lower levels compared to the other tissues. Using the ΣPCBs/ΣMeSO 2-PCBs ratio to estimate MeSO 2-PCB formation and secondary metabolism capacity, the harbour porpoise showed a relatively low capacity of MeSO 2-PCB formation compared to other small toothed whales and seals. Blubber sampled from five different anatomical locations showed that concentrations of contaminants may be unevenly distributed in blubber in certain animals. This should be taken into account when choosing sampling sites on the porpoise.