| Co-Investigator(Kenkyū-buntansha) |
KUNITO Takashi Shinshu University, Faculty of Science, Associate Professor, 理学部, 助教授 (90304659)
IWATA Hisato Ehime University, Center for Marine Environmental studies, Associate Professor, 沿岸環境科学研究センター, 助教授 (10271652)
HONDA Katsuhisa Ehime University, Faculty of Agriculture, Professor, 農学部, 教授 (10314973)
NAKATA Haruhiko Kumamoto University, Graduate School of Science and Technology, Associate Professor, 大学院・自然科学研究科, 助手 (60311875)
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| Research Abstract |
The present study aimed at elucidating the contamination and toxic impacts of bioaccumulative endocrine disrupters such as PCDDs (dioxins and its related compounds), PCBs (polychlorinated biphenyls), DDTs (DDTs and its metabolites), CHLs (chlordane compounds), HCHs (hexachlorocyclohexans), HCB (hexachlorobenzene), organotins (TBT, DBT and MET) and trace elements (Hg,Cd,Pb,As etc) in higher trophic wildlife.
All the above persistent toxic substances were detected at significant levels in resident birds collected from Asian developing and developed nations. In this context, the chemicals used for industrial purposes (such as PCBs, BTs etc) were relatively highly contaminated in birds from developed and former Soviet countries, while organochlorine insecticides were predominantly found in animals from developing nations in tropical and subtropical regions.In case of migratory birds from Asian regions, it could be suggested that they are exposed to inherent toxic pollutants in southern wint
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ering grounds, and their toxic effects emerge even in northern reproductive grounds which are principally pristine and far from industrial areas. Regarding the status of pollution by PCDDs in wildlife, very high concentrations were detected in fish-eating aquatic animals such as seals and cormorants, exceeding the threshold levels of adverse toxic effects reported in native and captive animals. The toxic elements such as Hg and Cd revealed higher levels in marine higher trophic organisms than terrestrial animals, effected by species-specific detoxification. mechanism and subcellar distribution of these metals. Interestingly, significant correlations between organochlorine concentrations and CYP enzyme activity/steroid hormones were clearly observed in some cetaceans and pinnipeds, suggesting enzyme induction and possible hormonal inhibition by these contaminants. Moreover preferential hepatic accumulation of hiher toxic PCDD congeners were noted in seals and cormorants, implying AhR related toxic responses to PCDDs. Experimental studies on lymphocytes revealed that TBT and DBT could pose a serious threat to the immune functions in free-ranging marine mammals and humans.
Considering all results in this study, it can be concluded that the toxic risk of bioaccumulative endocrine disrupters seems to be higher in aquatic mammals and fish-easing birds than terrestrial animals. Less
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