DETECTION OF BUTYLTIN COMPOUND RESIDUES IN THE BLUBBER OF MARINE MAMMALS

The blubber samples of eight species (12 specimens) of marine mammals caught between 1981 and 1993 in seas surrounding Japan and in the Indian, North Pacific and Antarctic Oceans, were analysed for butyltin compounds (BTCs). The column chromatography using dry florisil and acetonitrile enabled isolation of BTCs from lipids in fatty tissues like blubber, and led to the reliable analysis with efficient recoveries for these contaminants. BTCs were detected in all the animals except a minke whale from the Antarctic Ocean. The highest residue levels were found in a finless porpoise from the Seto-inland Sea, Japan with a BTC concentration of 770 ng g-1 on wet wt basis. Geographical distribution of the BTC concentrations in marine mammals showed a decreasing trend from the coastal to the open seas, indicating the presence of larger pollution sources nearby the coastal regions. Compositions of the BTCs in the blubber of finless porpoises seemed to be different from those found in aquatic organisms of lower trophic levels. Lower contributions of dibutyltins to the total BTCs in the blubber suggest the presence of their specific metabolic pathways. To our knowledge, this is the first report on the detection of BTCs in marine mammals.