An investigation published in the scientific journal Environmental Science and Technology has shown that high levels of polychlorinated biphenyls (PCB) are present in stranded whales and dolphins found in the United Kingdom’s waters.
Despite being banned nearly 20 years ago, the continued presence of PCBs shows their continuing threat to marine health. The findings also have significant implications for human health, say scientists.
PCB chemicals are highly dangerous. Once present, they do not typically degrade quickly and may linger for long periods.
The persistent nature of PCB chemicals makes them an environmental catastrophe. Indeed, the production of PCB chemicals was banned in 2004 by the Stockholm Conventions.
However, despite global bans, the effects of PCB chemicals linger. This is shown by the recent investigations into their presence in stranded marine mammals.
The investigators discovered that the animals had levels of PCBs up to 30 times the point at which health impacts are seen.
These high concentrations of PCB chemicals are one reason why European populations of whales and dolphins are facing rapid decline.
Tissue was collected from 11 species of whales and dolphins. Over 1,000 individual animals were sampled. The highest concentrations of PCB chemicals were found in species that occupied the top of the food change and have long life spans.
The species with the highest levels of PCB chemical concentration were bottle-nosed dolphins, orcas, and white-beaked dolphins.
This is due to a process known as “biomagnification” where chemical concentrations increase as they move up the food chain.
As animals at the top of the food chain consume animals lower on the food chain, the PCB buildup from the prey animal’s tissues is absorbed and stored by the predator’s body.
Not only are the investigation’s findings concerning due to health implications for marine species, but they are also raising concerns for human health.
Since the seafood humans consume comes from the same source, PCBs could also build up in human tissue.
This could lead to developmental issues for babies if foods containing high levels of PCBs are consumed by expectant mothers.
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This article by Willow Lynn was first published by One Green Planet on 2 December 2023. Image Credit :Stephen Barnes/Shutterstock.