Uptake, turnover and distribution of chlorinated fatty acids in aquatic biota

Sammanfattning: Chlorinated fatty acids (ClFAs) are the major contributors of extractable, organically bound chlorine in fish lipids. A known anthropogenic source of ClFAs is chlorine bleached pulp production. Additional anthropogenic sources may exist, e.g., chlorine-containing discharge from industrial and house-hold waste and they may also occur naturally. ClFAs have a wide geographic distribution. They have, for instance, been identified in fish both from Alaskan and Scandinavian waters. In toxicological studies of ClFAs, the most pronounced effects have been found in reproductive related processes. ClFAs have also been shown to disrupt cell membrane functions. The present study was carried out to further characterise the ecotoxicological properties of ClFAs and their presence in biota. To investigate the biological stability of ClFAs, two experiments were carried out using radiolabelled chlorinated and non-chlorinated fatty acids. In both experiments, ClFAs were taken up from food by fish and assimilated to lipids. From the first experiment it was concluded that the chlorinated fatty acid investigated was turned over in the fish to a lower degree than the non-chlorinated analogue. In the second experiment, the transfer of a chlorinated fatty acid was followed over several trophic levels and the chlorinated fatty acid was transferred to the highest trophic level. In samples with differing loads of persistent organic pollutants (POPs) from both fish and marine mammals, high concentrations and diversity of ClFAs were detected. This was also observed in samples with low POP concentration. Chlorohydroxy fatty acids made up a considerable portion of the ClFAs in certain samples, both from limnic fish and marine mammals. ClFAs in fish were found to be bound in complex lipids such as triacylglycerols (storage lipids) and phospholipids, as well as in acyl sterols (membrane lipids). In the marine mammals investigated, high concentrations of ClFAs were mainly bound in phospholipids. If ClFAs are assimilated like 'normal' fatty acids, are incorporated into membrane lipids, and are recalcitrant to catabolism, they may thus give rise to ecotoxicological effects when released to the environment and accumulated in biota.