Organochlorine compounds in blubber, liver and brain in neonatal grey seal pups

The present study focuses on the distribution and accumulation of persistent organochlorine compounds in different tissues and organs of grey seal (Halichoerus grypus) pups. Thus, levels of drins (aldrin, dieldrin, endrin), chlordanes (heptachlor, heptachlorepoxide, oxychlordane, transnonachlor), DDTs (p,p'-DDE, o,p'-DDD, p,p'-DDD, o,p'-DDT, p,p'-DDT) and 22 PCB congeners were determined in samples of brain, fat, and liver of 0-10 days old grey seal pups from the species' main breeding site in Norway. Whereas 10 different compounds were detected in the blubber, 8 compounds were detected in the liver. The concentrations of the two major classes of OCs (PCBs and DDTs) in liver were both about 75% of that in blubber. In cerebral tissue, only two PCB congeners were detected, and sigma PCB was only about 1% of that measured in the blubber. The distribution pattern of PCB-congeners in liver and brain differed significantly from that in blood and blubber tissue, indicating that the physico-chemical properties of the individual congeners and the lipid composition of the tissue are decisive for the tissue-specific pattern of congener distribution. A significant increase of the sigma DDT/sigma PCB-ratio as a function of blubber thickness indicates that DDT compounds are more readily accumulated in older pups.