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

Aryl methyl sulphones of polychlorinated biphenyls (PCBs) and 3-p,p'-DDE (M eSO2-PCBs and 3-MeSO2-p,p'-DDE), PCBs and Sigma DDTs 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 MeSO2-PCBs and 3-MeSO2-p,p'-DDE determination were used, gas chromatograph y-mass spectrometry and gas chromatography-atomic emission detection. Highe st concentrations of Sigma MeSO2-PCBs were found in liver (0.15-0.49 mu g/g lipid wt.), which corresponded to 2.0-2.8% of the Sigma PCBs concentration s. Blubber and nuchal fat showed Sigma MeSO2-PCB concentrations that were t hree to five times lower than those in liver. Concentrations of 3-MeSO2-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-MeSO2-p,p'-DDE constitut ed 0.033-0.21% of p,p'-DDE. The different tissues analysed showed similar l evels (lipid wt.) of Sigma PCBs and Sigma DDTs, except for brain that had a lmost 10 times lower levels compared to the other tissues. Using the Sigma PCBs/Sigma MeSO2-PCBs ratio to estimate MeSO2-PCB formation and secondary m etabolism capacity, the harbour porpoise showed a relatively low capacity o f MeSO2-PCB formation compared to other small toothed whales and seals. Blu bber sampled from five different anatomical locations showed that concentra tions of contaminants may be unevenly distributed in blubber in certain ani mals. This should be taken into account when choosing sampling sites on the porpoise. (C) 2000 Published by Elsevier Science Ltd. All rights reserved.