Toxic chemicals known as Polychlorinated biphenyls (PCBs) are continuing to leach into oceans, causing serious physiological damage to cetacean life. PCB exposure is particularly rife in European waters. Symptoms include infertility, weakened immune systems and causing changes to brain functionality in both humans and animals. An estimated 10% of all PCBs created are currently contaminating the world’s oceans. 

PCBs were introduced into US manufacturing processes in 1927. Overall, there are 209 different types of PCB compounds, all of which have varying levels of toxicity depending on the amount of chlorine atoms (one of the main compounds, as well as hydrogen and carbon) as well as their arrangement within each PCB molecule. PCBs were first banned by the United States in 1979, in the UK from 1981 and in 1986 an international agreement was solidified to ban usages of most PCBs. PCBs were used for a wide variety of industrial processes, from electrical equipment, cement, plastic, machinery and buildings as well as being used to create inks, surface coatings and adhesives. They were considered a staple due to their chemical stability, electrical insulation abilities and fire resistance. PCBs were also found in food products. 

However, in 1968 there was an incident of mass food poisoning in Japan from consuming a brand of rice oil that had been contaminated by PCBs. After further research, it was discovered that PCBs are damaging to human health, causing a litany of illnesses such as brain and liver cancer, melanomas, reproductive deficiencies, damage to the immune system as well as pigmentation disturbances. Although PCBs have been banned in many jurisdictions, human exposure has not completely gone away. Due to continued marine life exposure to PCBs and the way in which PCBs are able to trickle across food chains, humans are still at risk from ingesting these toxic chemicals from eating dairy, salmon, shellfish and animal fat. PCBs are an airborne toxic threat to humans, although inhaling PCBs creates less chlorine exposure in comparison to ingestion. Those living near infected landfill sites or contaminated buildings are in danger of developing long-term health problems. The greenhouse gas effect also amplifies the risk of PCBs acting as a source of air pollution, especially near sites of contamination. An estimated 299 000- 585 000 tonnes of PCB was produced in Europe from 1954-1984 alone – 15% of the world’s total. Within the US, between 1930 and 1975, total production was calculated to be 635 million kg overall. 

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PCBs do not easily break down within the environment and continue to linger within landfill sites; from here, it is easy for them to leach into the ocean. They also linger by reemerging after being buried under sediment from the ocean floor by absorbing its organic matter. PCBs are able to bind tightly to soil, and in the sea it sticks to bottom sediments and organic particles.These toxic chemicals are also able to store up within the fatty tissues of fish and other animals. Higher levels of PCBs are found in odontocetes (toothed whales) because these predators are high in the food chain and consume larger concentrations of PCBs from their prey. 

A recent study conducted by the Zoological Society of London found that otherwise healthy male harbour porpoises within UK waters with high levels of PCBs displayed shrunken testes and lower sperm counts. The researchers analysed the blubber of 267 harbour porpoises (collected from 1991-2017) that had been stranded across UK coastlines, and measured the concentration of PCBs. ZSL’s lead researcher, Rosie Williams, stated her concerns: “This finding is particularly concerning in harbour porpoises because their sole mating strategy is to be as promiscuous as possible. They’re what’s known as sperm competitors in that the only way that they compete against other males is to maximise the number of times and number of females they mate with, so we think having large testes is a really important part of their mating strategy. Therefore, we believe it is likely that PCBs are causing reduced fertility in some individuals in this population of harbour porpoises.” In December 2019, ZSL also found that female harbour porpoises may transfer PCBs to their calves through feeding. This is especially toxic for the calves’ brain development

There have also been concerns about the health of dolphins within the English Channel. Researchers determined from sampling the tissue of 80 bottlenose dolphins off the south coast of France that these dolphins were afflicted with a cocktail of chemicals. High volumes of PCBs and mercury were found in their blubber. Over 91% of organic chemicals in their samples were infected with PCBs. Overall, 420 bottlenose dolphins remain in the Normanno-Breton Gulf within the English Channel. Rob Deaville, from UK Cetacean Strandings Investigation Programme stated: “As apex predators, bottlenose dolphins are at higher risk of exposure to some of the chemicals mentioned in this study – and as many of the European coastal populations of bottlenose dolphins are relatively small in size, they may therefore be under greater conservation threat.” 

Dr Krishna Das, a zoologist at the University of Liege expressed that bottlenose dolphins are not only affected by PCBs but a number of other factors within the Channel: “The bottlenose dolphins in European waters are protected by the Habitats Directive. Their conservation requires the creation of special areas of conservation and the need for strict protection. Despite this European directive, human activities are increasing in the Normanno-Breton Gulf. The potential threats include pollutants, noise pollution, disturbance by tourism activities and by-catch.” Scientists believe that dolphins’ exposure of PCBs weakens their immune systems

Another apex predator that is facing continuous threats from PCBs in British waters is the orca, which consume the most PCBs from consuming infected seals, tuna, fish and seabirds. Experts have suggested that without including other environmental threats, PCBs could wipe out 10 out of 19 orca populations within the next century. The orca population off UK coastlines has plummeted dramatically, not producing a calf in 25 years. In 2016, an orca named Lulu was found deceased on the shores of Isle of Tiree, Scotland. After tests were conducted on the body, it was discovered that Lulu was suffering from one of the most severe cases of PCBs infections within a cetacean thus far, with a staggering 957 parts per million in PCBs, only superseded by an orca found in the US with 1 300 parts per million in 2002. Head of the Scottish Marine Animal Stranding Scheme at Scotland’s Rural College, Dr Andrew Brownlow, breaks down the significance of Lulu’s PCB levels:  “The levels of PCB contamination in Lulu were incredibly high, surprisingly so. They were 20 times higher than the safe level that we would expect for cetaceans to be able to manage. That puts her as one of the most contaminated animals on the planet in terms of PCB burden, and does raise serious questions for the long-term survivability of this group (of UK killer whales).” Lulu was stuck in netting when found, and due to the animals immense PCB exposure is it possible that its brain function was altered by these chemicals as orcas seldom get caught in netting. There are only eight remaining orcas residing in UK waters. Paul Jepson of Zoological Society of London expressed his doubts about the future of the last remaining UK orca pod: “This is a population studied for many years, and there has not been a calf in all the years that this group has been studied, so that population will go extinct.” 

So why are Europeans waters considered to be PCB hotspots in comparison to the US which was the biggest producer of these chemicals? “All we have done is banned them and hoped they went away. The US produced even more PCBs but they are spending a lot of money on a clean-up and it is working,” says Paul Jepson of ZSL, breaking down how US policies have actively created deductions in PCB levels whilst European nations have yet to fully mitigate the continuous contamination: “PCB levels in the United States have slowly declined in humans and other biota such as fish for many years now, and the overall PCB mitigation is generally considered to be successful in the US. This is partly related to numerous US Environmental Protection Agency (EPA) Superfund sites, which the EPA is actively working to decontaminate. We urgently need a similar approach in Europe.” Seas that are currently considered to be PCB hotspots include: Southwestern Iberia, Strait of Gibraltar,  the Mediterranean Sea, the Gulf of Cadiz as well as the English Channel. “The Seine (a 775-kilometre-long river flowing into the English Channel) is a hotspot for PCBs, and the Normanno-Breton Gulf, which is close to the Seine estuary, is an environment with high industrial, agricultural and urban activities,” explains Dr Das, “as emphasised by my colleague Paul Jepson and Robin Law in 2016 (published in the journal Science), in 2004 the Stockholm Convention committed more than 90 signatory countries to phasing out or eliminating large stocks or other sources of persistent organic pollutants, including PCBs. Yet, PCBs continue to threaten the survival of marine predators.” 

Overall, there is still an estimated one million tonnes of PCB-contaminated material that is waiting to be disposed of in Europe alone which risks entering the ocean. However, marine life in US waters aren’t without risk to PCB exposure. Ocean Wise marine mammal toxicologist, Peter Ross, states that PCBs remain a pervasive threat to top predators throughout other orca habitats: “Based on the weight of evidence from a couple of decades of research, PCBs remain the number one pollutant of concern at the top of the food chain for wildlife in the northern hemisphere.” This includes Norway, Japan and the North east Pacific Ocean – all regions where orcas are known to frequent.”

In the early nineties, The Environmental Protection Act 1990 was introduced under UK law and was created to control pollution waste within land, air and sea. However, the UK government has admitted that there has been no significant monitoring data on PCBs levels within the Southern region of the North Sea, English Channel and South West of England, which is quite shocking considering the levels of contamination within dolphins, porpoises and other marine life within these regions. Monitoring efforts such as the UK Clean Seas Environmental Monitoring Programme and OSPAR Coordinated Environmental Monitoring Programme were created to assess threats of contamination and to protect marine life, yet areas rich in biodiversity are not receiving thorough assessments and are significantly disregarded. In 2016, the Scottish Government began creating marine protected areas in order to protect biodiversity and ecosystems within Scottish waters, protecting 225 sites considered conservation priority sites. A recent study has shown that out of 21000 old landfill sites in England and Wales, 1 287 are currently containing hazardous chemicals – including PCBs. 746 of these toxic dump sites are within 500 metres of water bodies. The severity of ingesting PCBs for animals and humans alike is a serious case for concern and more research, investigation and expert analysis is vital to raise awareness about toxicity levels within UK waters and beyond. More efforts need to be implemented to understand just how toxic UK oceans have become. The UK government has stated in their 25 Year Environment Plan that a new chemical strategy is being developed, the first objective being to minimise the risk of chemical contamination in UK waters. However, the The UK’s Department for Environment, Food and Rural Affairs has temporarily paused publishing the chemical strategy- originally due for 2022- due to staff being moved into new roles to support the government’s efforts with the pandemic. 

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