A report published today shows that 50% of Orca populations around the world are at risk of collapse in just 100 years, due to the effects of Polychlorinated Biphenyls (PCBs).
But what are PCBs? They’re a type of chemical known as Persistent Organic Pollutants (POPs) that were used widely in building materials, paints and sealants before being banned almost 30 years ago. However, they are still silently poisoning our rivers and seas, as Governments fail to tackle the 14 million tonnes of contaminated material around the world. From buildings, landfills and sediments, the PCBs filter into our rivers and end up in our seas. Due to the persistent nature of PCBs they then build up through the food chain, with the highest volumes and worst effects seen in top predators, like dolphins, sharks and killer whales.
The report published today provides clear evidence of the direct impact of PCBs on marine life. Firstly, PCBs interfere with the immune systems of marine mammals and increase the risk of cancer. By impairing the immune system, PCBs weaken the individual and make them more susceptible to other diseases and stressors in the marine environment.
Secondly, their ability to reproduce is affected. This can be seen in killer whale populations around the globe. A recent example that tugged on heart strings comes from Canada where a mother killer whale carried her dead calf with her for 17 days, travelling 1000 miles. This could have been due to toxic milk from the mother killing the baby, a story that was also featured in Blue Planet II. Closer to home, a Scottish pod of orcas now number just 8 individuals, with no births recorded for 25 years.
A member of the Scottish pod, Lulu, washed up on the Isle of Tiree in 2016 and was found to have PCB levels 20 times greater than cetaceans are known to withstand. Though Lulus cause of death can’t be solely contributed to PCBs, nor can that of the Canadian whale, it shows the accumulative effect they are having on the health of marine mammals. When their immune system is weakened and they are unable to successfully reproduce, they are more susceptible to the myriad of threats in the oceans, such as ship strike, entanglement in fishing nets and noise pollution.
A global ban on PCBs is already in place through the Stockholm Convention. All signatories, the UK included, have signed up to safely dispose of (incinerate) their PCB stocks by 2028, but this agreement is not legally binding. In fact, an estimated 80% of existing PCB stocks are still to be destroyed and few countries keep up to date records of their existing stocks. This needs to change. We call on Michael Gove to push for a legal compliance mechanism to be put in place at the 2019 Stockholm Convention meeting and include this same target in a new Environment Act. This would stop new sources of PCBs reaching the ocean, but existing sources also need attention.
To tackle the pollution already in our seas, we should follow the example of the United States of America. The USA has undertaken a number of clean up programmes including in San Francisco Bay and the Hudson River. These were costly, but marine species have begun returning to the once polluted sites so the efforts have been worthwhile.
Though this is a global issue, with the current public and Government focus on marine issues at an all-time high, we need the UK Government to show global leadership and clear up this man-made mess.
The opinions expressed in this blog are the author's and not necessarily those of the wider Link membership.
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