What is PCB and why is it in our oceans?

Posted on 29th November 2017

Since David Attenborough's Blue Planet 2 launched this winter on BBC one, the effect of pollution on whales and dolphins has become a hotter topic than ever before. This is particularly raw of late after the 19th November airing of an episode which showed a pilot whale carrying its dead newborn calf. It's a distinct possibility that the calf died from consuming its mother's contaminated milk after ingesting toxic polychlorinated biphenyls (PCBs). We're delighted that this important issue is reaching a new audience and people are talking about the devastating effects of single-use plastics.

PCB's have been found across the planet in high quantities, with concentrations discovered in the Mariana Trench, Western Pacific Ocean most recently. As we're supporting ORCA, we thought we'd run through a bit more about it, and why it's such a threat to these beautiful whales.

What is PCB?

Polychlorinated biphenyls, better known as PCB, is a toxic chemical most commonly used in electrical insulators and flame retardants. It's also found in old tower blocks and buildings. PCBs have also been used in products such as surface coatings, inks, adhesives, and paints. It has been banned since 1970 due to its toxic nature and danger to human and animal life.

It's designed to resist extreme heat, so it's a very hardy material. It's also resistant to being broken down naturally, hence it's still hanging around so many decades after being banned.

Why is it in our oceans?

PCB cycles between air, water and soil as a persistent organic pollutant (POP). It comes from demolished buildings, illegal dumping, and waste oil from electrical equipment, to name but a few. It starts in our rivers, then gets into sediment where often it is agitated by dredging, storms or other physical factors in the water system. It then moves to estuaries, then the oceans, where crabs and molluscs consume it., It bioaccumulates up the food chain through fish, followed by larger fish and finally sharks and whales at the top of the food chain.

PCBs continue to enter the oceans from decomposing products that have been irresponsibly disposed of. Scientists estimate that 1-10% of all PCBs ever produced have already entered the oceans, and in Europe in particular concentrations are particularly high.

How does it affect humans and marine wildlife?

PCBs were banned due to the danger it posed to humans - it can cause liver and skin damage, infertility and cancer. For cetaceans, the toxic chemical builds up in the whales' blubber, and is very easily passed from mother to calf. Up to 90% of a mother whale's PCB can be offloaded to their calf through feeding, as demonstrated on the recent Blue Planet 2 episode. It has had a particularly devastating effect on particular populations of whales, with the UK's last pod of killer whales known to have been decimated by the effects of PCBs. In 2016 a member of this pod was found to have the highest recorded concentrations of PCBs in their body ever discovered, which is a likely explanation as to why the group have not bred for over two decades.

What is being done to stop this happening?

Eradicating PCB from the environment is certainly a long game, as it's estimated there's over 40 million tonnes in circulation worldwide currently. It can only be destroyed in high-temperature incinerators, and at a huge cost to the economy.

In the UK, strict laws govern the disposal of PCB, but this doesn't help the prevalence of it that's already in our systems and steps must be taken to both stem the flow of new PCBs and dispose of existing concentrations effectively. Many parts of Europe are not meeting their obligations under the Stockholm Convention, which banned PCBs, and governments must do more to prevent the devastating impact on our marine life these dangerous chemicals are having.

AMA Waste Management are supporting ORCA in their quest to try and undo some of the damage already done by PCBs and prevent it happening in the future. To find out more about what they're doing to help, please take a look at their website http://www.orcaweb.org.uk/