A recent study published in the Marine Pollution Bulletin has found a significant increase in bisphenol concentrations in the Pearl River Estuary of the Northern South China Sea. The PRE is home to the world’s largest known population of the vulnerable Indo-Pacific humpback dolphin.

The study examines levels of six bisphenols in the estuary and gives insight into the potential risks they pose to the dolphins and the ocean ecosystem.

Bisphenols are a group of chemicals widely used in the production of polycarbonate plastics and resins, including in food packaging. Bisphenol A (BPA) is the most well-known bisphenol and has been classified in the EU as an endocrine disrupting chemical (EDC). This means that it interferes with the body’s sensitive endocrine (hormone) system, which controls key functions such as growth and brain development.

With increasing regulations on BPA and a subsequent decline in its use, alternatives such as bisphenol S (BPS) and bisphenol F (BPF) are increasingly used as replacements. However, these alternatives have a similar structure to BPA and have been shown to have similar endocrine disrupting properties. This is what is known as regrettable substitution, which CHEM Trust has written about in our Toxic Soup report.

The Pearl River Estuary is an area that has undergone rapid economic development and population growth, and it is recognised as a regional hotspot for pollution. The study finds that while levels of BPA in the seawater are declining, levels of alternative bisphenols, such as BPS, are increasing.

These pollutants could build up in marine wildlife through the food web. Smaller prey ingest the chemicals, where they make their way up the food chain, accumulating in bigger predators. The humpback dolphins are apex predators, meaning they sit at the top of the food chain and therefore ingest the largest amounts of the chemicals through their food. This is called biomagnification.

The authors of the study highlight that previous research on impacts in people shows that alternatives to BPA may have greater toxicity and pose a range of health risks, including reproductive abnormalities, increased rates of miscarriages, and infertility.

To prevent the regrettable substitution of BPA with potentially more harmful bisphenols there needs to be bans on this group of chemicals around the world. CHEM Trust has been calling for a group ban on bisphenols in the EU for many years.

Read more on bisphenols and EDCs.

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