HIGH ACCUMULATION OF TOXIC BUTYLTINS IN MARINE MAMMALS FROM JAPANESE COASTAL WATERS

Organotins are one of the most toxic chemicals in the aquatic environment. While contamination and toxic effects of organotin compounds in lower trophic aquatic organisms have been well-documented, no investigation has focused so far on higher aquatic organisms like marine mammals. We attempted to analyze butyltin compounds (BTCs), including mono-(MBTs), di- (DBTs), and tributyltin compounds (TBTs), in various tissues and organs of finless porpoise (Neophocaena phocaenoides) collected from Japanese coastal waters and detected these compounds in all the animals. The highest residue levels were found in the liver of a porpoise collected in the inland sea, recording more than 10 ppm BTCs on a wet weight basis. The composition of BTCs was different according to the tissues and organs with higher proportions of DBTs noticed in the liver and blood. Estimation of ETC burdens in tissues and organs indicated that muscle, liver, and blubber retained predominant portion of TBTs, DBTs, and MBTs. The occurrence of higher rates of TBTs on the whole implied the lower metabolic potential of porpoises to BTCs.