PCB is in the ocean – and it’s killing our orcas

PCB (polychlorinated biphenyls) is a chemical which was among others used in paints, adhesives and transformers until they got banned in the late 1970s due to its toxic and carcinogenic behaviour (The Guardian, 2018).

Although the production of the persistent PCB has stopped, it is still circulating in the atmosphere, the oceans and soil and can be transported over long distances. National Geographic (2018) argues that 80% of the global PCB accumulation is not even destroyed yet.


Why is PBC so bad?

New research has found that more than half of the world’s killer whale population is affected by the chemical and could collapse within the next 30 to 50 years. It is believed, that PCB has already led to a change in reproduction behaviour and harmed the immune system. Orcas are apex predators, which means that they are not only exposed to the chemicals surrounding them in the ocean and the air but also by eating fish, seals and other whales that carry PCB already. That leads to the stocking up of the carcinogens in the whales’ blubbers. Subsequently, mother whales pass on the PCB to their offspring through the mother’s fat-rich milk (National Geographic, 2018).

Life cycle of hazardous substances in the ocean
Figure 1: Life cycle of hazardous substances in the ocean (Aarhus University, 2018, online)

Jean-Pierre Desforges and his team from the Arctic Research Centre at Aarhus University in Denmark found in their research that 10 out of 19 killer whale populations where already declining and that the reproduction was decreasing, especially in near industrialised areas such as the UK, where the researches suggest that the population of orcas count less than ten mammals (Science, 2018). 

It is not so easy to find a solution to solve this issue, as PCB can only be destroyed by burning it at a very high temperature which means extreme costs to the economy. It remains to be seen if the governments start working towards that issue which may (hopefully) lead to a salvation of the orcas in the severely polluted areas.





Aarhus University (2018) Life cycle of hazardous substances in the ocean [online image] [accessed 01.10.2018] https://www.sciencedaily.com/releases/2018/09/180927145334.htm

Desforges, JP, Hall, A., McConnell, B., Rosing-Asvid, A., Barber, J.L., Brownlow, A., De Guise, S., Eulaers, I., Jepson, P.D., Letcher, R.J., Levin, M., Ross, P.S., Samarra, F., Vikingson, G., Sonne, C., Dietz, R. (2018) Predicting global killer whale population collapse from PCB pollution. Science 362(6409), pp. 1373-1376. [online] [accessed on 01.10.2018]

Doward, J. (2017) Race is on to rid UK waters of PCBs after toxic pollutants found in killer whale. 14th May, The Guardian [online] [accessed 01.10.2018] https://www.theguardian.com/environment/2017/may/14/race-on-rid-uk-oceans-pcbs-killer-whale-lulu

Welch, C. (2018) Half the World’s Orcas Could Soon Disappear—Here’s Why. 27th September. National Geographic [online] [accessed 01.10.2018] https://www.nationalgeographic.com/environment/2018/09/orcas-killer-whales-poisoned-pcbs-pollution/

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