Effects of Age Factors on Accumulations of Organochlorine Compounds in Finless Porpoises(Neophocaena phocaenoides)from the Coastal Waters of Japan

摘要

Finless porpoises live in coastal areas and are known to accumulate various organochlorine compounds(OCs).However,the accumulation kinetics such as age-dependent variations of various persistent contaminants is not well known.In this study,age was determined by counting the growth layers of dentine in 41 finless porpoises that were found stranded at the coasts of Seto Inland Sea and the Pacific coast of Japan between 1998 and 2005.Concentration of OCs including dioxins and related compounds(DRCs)and organochlorine pesticides and organotin compounds(OTs)in their tissues were quantified.Positive logarithmic relation was observed between the age and body length of finless porpoises despite the wide difference in the body lengths of the specimens.PCDDs and PCDFs were found to be accumulated in an age-dependent manner,but no significant sex difference was observed.For other OCs,the concentrations increased with age in males,but in females,concentrations decreased after maturity,indicating maternal transfer of these compounds.Levels of organotins increased with age in both males and females.Age and sex determination is essential when comparing the data of these contaminants in finless porpoise.