A scientific study has found that exposure to banned polychlorinated byphenyls (PCBs) in the ocean could be negatively affecting the fertility of male harbour porpoises.

The study led by scientists from the Zoological Society of London (ZSL) found that harbour porpoises exposed to PCBs had shrunken testicles, suggesting an effect on sperm count and fertility. This study, conducted on harbour porpoises stranded on the UK coast, is the first study highlighting the impact of PCBs on the reproductive system of male cetaceans, an effect that has so far been demonstrated mostly for females. This raises serious concerns regarding the long-term impacts on harbour porpoise populations and other coastal cetaceans.

Synthetic chemicals that don’t degrade easily in the environment are known as persistent chemicals. Once released into the environment, these chemicals can remain present for centuries: as they continue to be released, their concentration only increases. Some of these chemical pollutants are hazardous to humans, wildlife, and the environment.

PCBs are an infamous example of a persistent pollutant. Multiple studies over the last 60 years have linked PCBs to reproductive problems in marine mammals. Despite being banned globally in 2001, PCBs are still emitted from old industrial sites or open-air applications (such as paint on bridges) – and due to their persistence, these pollutants unfortunately are still ubiquitous in our marine environment. The authors of the study stress that “it is imperative that more is done to reduce the input of legacy PCBs into the environment”.

Read more about this story in the BBC.

Read more on the effects of chemical pollutants on wildlife and the environment.

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