| Summary: | Over the last decades little work has been conducted on the environmental behaviour and effects of perfluorinated organochemicals (FOCs). These chemicals are commonly used as solvents, surfactants, cosmetics and are applied in fire foam extinguishers. Recent findings have shown that FOCs (with perfluorooctane sulfonic acid - PFOS - as the most important representative) are detected in organisms living in industrialized as well as in remote areas. The fact that PFOS is hardly biodegradable, clearly accumulates in the liver and blood of top predators and the fact that little information is available on the toxic properties of PFOS, makes this chemical an environmental pollutant of primary concern. In the present study we measured PFOS concentrations in seven marine mammals stranded on the Belgian, French and Dutch North Sea coast between 1994 and 2000. PFOS concentrations were measured in liver and kidney tissue using combined liquid chromatography-mass spectrometry (LC-MS/MS). Detectable PFOS concentrations (up to 820.60 ng/g) were found in harbour porpoises, white-beaked, white-sided and striped dolphins, sperm whales and harbour seals. In fin whale and hooded seal concentrations were below the detection limit of 10 ng/g. PFOS levels in female porpoise livers were significant higher than those in males. The present results show clearly the difference in accumulation pattern of PFOS compared to that of persistent organochlorine chemicals. In order to evaluate the interspecies differences, we developed PFOS-trophic level relationships based on stable nitrogen and carbon isotope ratios. Animals that display the highest trophic positions (highest d15N) have the highest PFOS levels. The different feeding ecology of these species (inshore versus offshore) also seems to contribute to differences in PFOS concentrations. Next to the presentation of PFOS concentrations in marine mammals of the North Sea, the possible toxicological effects of perfluorinated compounds are discussed.
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