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

Aryl methyl sulphones of polychlorinated biphenyls (PCBs) and 3-p,p-DDE (MeSO2PCBs and 3-MeSO2-p,p-DDE), PCBs and 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-MeSO2p,p?-DDE determination were used, gas chromatography-mass spectrometry and gas chromatography-atomic emission detection. Highest concentrations of MeSO2PCBs were found in liver (0.15-0.49 g/g lipid wt.), which corresponded to 2.0-2.8% of the PCBs concentrations. Blubber and nuchal fat showed MeSO2PCB concentrations that were three 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, 3MeSO2-p,p-DDE constituted 0.033-0.21% of p,p-DDE. The different tissues A analysed showed similar levels (lipid wt.) of ?PCBs and DDTs, except for brain that had almost 10 times lower levels compared to the other tissues. Using the ?PCBs/MeSO2-PCBs ratio to estimate MeSO2-PCB formation and secondary metabolism capacity, the harbour porpoise showed a relatively low capacity of MeSO2-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.