Peril of the deep – the killer poison that lingers unseen in British waters

The discovery of alarming levels of PCBs, a type of chemical banned 40 years ago, has led scientists to call for an urgent clean-up

The body of Lulu the killer whale was found on jagged rocks on the Isle of Tiree in the Inner Hebrides last year. A member of the only pod found in British waters, she died after getting entangled in fishing lines.

It was a sad discovery, especially as a postmortem revealed Lulu had never had a calf. But a recent autopsy also revealed something else that is alarming marine experts and offers a bleak, damning judgment on the state of Britain's coastal waters. Lulu's body had some of the highest levels of a particular type of manmade chemical ever recorded - more than 100 times above the level that scientists say will have biological consequences for a species.