Concentration of polychlorinated biphenyls and risk assessment in finless porpoises from the East China Sea

Polychlorinated biphenyls (PCBs) are bioaccumulative persistent organic pollutants with a great impact on cetaceans. To examine the content of PCBs and their risks to finless porpoises, this study determined the concentrations of seven typical PCB congeners in 56 tissue samples of East Asian finless porpoises (EAFPs) sampled in 2009-2012 from Ningbo (29.8835 degrees N, 122.0644 degrees E), Pingtan (25.5133 degrees N, 119.8172 degrees E) and Lvsi (32.1035 degrees N, 121.6078 degrees E). PCB138, PCB153 and PCB101 were the predominant congeners, accounting for 31.15%, 18.59% and 15.75%, respectively, of all PCBs detected. The content of PCBs increased with age in males but decreased from juveniles to adults in females due to transfer to calves by reproduction and lactation. EAFPs in Ningbo and Pingtan accumulated more PCBs than those in Lvsi Port. The trophic positions of EAFPs from Lvsi, Pingtan and Ningbo were 9.41, 8.95 and 9.43, respectively. PCB concentrations did not accumulate significantly with increasing trophic levels. The risk quotient index indicated that the risk of trichlorobiphenyl (3-PCB), tetrachlorobiphenyl (4-PCB), pentachlorobiphenyls (5-PCB), and hexachlorobiphenyls (6-PCB) to EAFPs in the East China Sea was generally low and within safe limits thus far.