Specific accumulation and distribution of butyltin compounds in various organs and tissues of the Steller sea lion (Eumetopias jubatus): Comparison with organochlorine accumulation pattern

The present study was conducted to elucidate the specific distribution of butyltin (BT) compounds in various tissues and organs of Steller sea lions collected from coastal waters of Hokkaido, Japan. BT concentrations were an order of magnitude higher in the liver than in other tissues and organs except hair, whereas organochlorine (OC) compounds accumulated at two to three orders of magnitude higher in blubber than in other tissues. No relationship was observed between BT concentrations and the lipid content in tissues, while the levels of OCs were positively associated with the lipid content. The levels of BTs in hair (1500 ng g−1 on a wet weight basis) were the highest of all the tissues analysed. Results also suggested that 26% of the total BT burden in the body was eliminated through shedding. Selective accumulation of BTs in liver and hair is attributed to its protein-binding capacity rather than lipophilicity. The discovery of high concentrations of BTs in hair implies their excretion by shedding in piliferous animals.