| Abstract
| - Hepatic butyltin concentrations were determined in 63cetaceans belonging to 14 species and four pinnipedsbelonging to two species collected from North Pacificand Asian coastal waters. Butyltin compounds (BTs)includingtributyltin (TBT), dibutyltin (DBT), and monobutyltin(MBT)were detected in almost all the liver samples suggestiveof its worldwide distribution. The elevated residuesdetected in coastal species and low concentrations foundin off-shore species indicate a high degree of butyltincontamination in coastal waters than in the open sea.Mammals inhabiting waters of developed nations were foundto contain higher BT concentrations compared with thosecollected from the waters proximal to developingcountries.These observations strongly suggest serious BTcontaminationin the waters of developed countries than in developingnations at present. Among the samples collected offJapanese coastal waters, lower BT concentrations werefound in pinnipeds compared with the cetaceans, suggestive of a possible difference in degradation capacitiesand excretory moulting between these two groups ofanimals. The estimated concentration ratio of BT intheliver of killer whale fetus to its pregnant mother wasrelatively low (0.015), indicative that transplacentaltransferof BTs from the mother to her fetus is a deal less.Amongthe BT breakdown products, DBT was predominant inmost of the liver samples analyzed, followed by TBT andMBT.
|
