Recent contamination of persistent chlorinated endocrine disrupters in cetaceans from the North Pacific and Asian coastal waters

To elucidate the global distribution and toxicological impacts of persisten t organochlorines (OCs) on cetaceans, the present study determined the conc entrations of organochlorine pesticides such as DDT and its metabolites (DD Ts), hexachlorocyclohexane isomers (HCHs), hexachlorobenzene (HCB), chlorda ne compounds (CHLs) and PCBs including toxic coplanar congeners in the blub ber of 10 species of adult male odontoceti cetaceans collected from several locations in the North Pacific Ocean and coastal waters of Japan, Hong Kon g, Philippines and India during 1985-1997. Concentrations of tris(4-chlorop henyl) methane (TCPMe) and tris(4-chlorophenyl)methanol (TCPMOH), which are among the newly identified contaminants, were also determined. Residue pat tern was in the order of DDTs greater than or equal to PCBs>CHLs>HCHs>HCB>T CPMOH>TCPMe. Greater DDT concentrations were found in cetaceans from the Ja pan Sea, coastal waters of Hong Kong and India, indicating serious marine p ollution in industrialized Asian nations and current usage of DDTs in tropi cal regions. In general, cetaceans inhabiting cold and temperate waters con tained relatively higher concentrations of PCBs, HCHs, CHLs and HCB as comp ared with those from tropical regions, reflecting atmospheric transport fro m the tropical sources to the northern sinks. Latitudinal distribution of T CPMe and TCPMOH in cetaceans from the North Pacific Ocean and Asian coastal waters was similar to that of DDTs, suggesting the less transportable natu re of TCPMe and TCPMOH in the marine environment. Penta- and hexa-chlorobip henyls ware the predominant PCB congeners, accounting for about 70% of the total PCBs. 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQs) of non- and mono-ortho coplanar PCBs in the blubber of cetaceans ranged from 36 (in spinner dolphin from Philippines) to 510pg/g wet wt tin humpbacked dolphin from I-long Kong). Toxic evaluation of coplanar PCBs using TEQ concept ind icates an increasing impact on cetaceans from mid-latitudes. Mono-ortho con gener IUPAC 118 or non-ortho congener IUPAC 126 was estimated to have the g reatest toxicity contribution. The estimated TEQ concentrations in the blub ber of some cetacean species exceeded the level associated with immunosuppr esion in harbour seals.