Research press release


Scientific Reports

Ecology: Toxic levels of PCB found in European marine mammals



今回、Paul Jepsonの研究グループは、ヨーロッパの4種の海洋哺乳類(ネズミイルカ、スジイルカ、バンドウイルカ、シャチ)の座礁した個体や生検された個体(合計1,081頭)の脂肪中PCB濃度のメタ解析を行った。その結果、バンドウイルカ、スジイルカ、シャチの平均PCB濃度が、海洋哺乳類にとっての毒性閾値を超えていることが判明した。また、これらの海洋哺乳類にとって、地中海西部と中部、イベリア半島の南西沖、カディス湾、ジブラルタル海峡が世界的なPCBの「ホットスポット(汚染海域)」であることも明らかになった。


Concentrations of polychlorinated biphenyl (PCB) in the blubber of striped and bottlenose dolphins, and killer whales in European waters, are among the highest recorded globally for whales and dolphins, according to research published in Scientific Reports. The study suggests that these concentrations are likely to cause populations to decline and suppress their recovery.

PCB is a synthetic chemical compound that was used in electrical components until it was banned in 1979 in the USA and 1981 in the UK. However, their use was not phased out until 1987 in European countries that border the Mediterranean Sea. Blubber concentrations of PCB initially declined following a ban by the EU, but have since stabilised in UK harbour porpoises and striped dolphins in the western Mediterranean Sea.

Paul Jepson and colleagues performed a meta-analysis of blubber PCB concentrations in 1,081 stranded or biopsied European marine mammals from four species: harbour porpoise, striped dolphin, bottlenose dolphin and killer whale. The authors found that in bottlenose and striped dolphins, and killer whales, mean PCB levels exceeded toxicity thresholds for marine mammals. They also found that areas of the western and central Mediterranean Sea, SW Iberia, the Gulf of Cadiz and the Strait of Gibraltar were global PCB ‘hotspots’ for these mammals.

The authors argue that blubber PCB concentrations are still very high, despite a ban on their use and manufacture, because they may have reached a ‘steady state’ between environmental input and degradation. They suggest that the high levels of PCB in these species are likely to suppress reproduction and will continue to drive population declines.

doi: 10.1038/srep18573


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