Forever Chemicals: PFAS Contamination of Freshwater Fish

Our recent analysis of government data shows the alarming persistence of forever’ chemicals in our rivers, present in fish populations at levels on average more than 300x the safe limits.

Emma Brisdion



A particularly worrying type of chemical pollution found in our rivers comes in the form of per- and poly-fluorinated alkyl substances (PFAS). PFAS include thousands of industrial chemicals found in everyday products from frying pans to bike oil and even our toiletries. They pose a serious pollution risk, given they are readily released to the environment, but also because they can take over a thousand years to degrade; consequently, they are known as forever chemicals. PFAS have been used since the 1940s and are now so widely dispersed that they can be found in air, soil, water and in our bloodstream. Unfortunately, whilst we are only just beginning to understand their health impacts and environmental toxicity, the compounds that have been studied to date have been shown to cause harm to humans1 and wildlife2.

The Rivers Trust, working in collaboration with the Wildlife and Countryside LINK, have recently analysed Environment Agency (EA) data to reveal that levels of just one toxic PFAS forever chemical – Perfluorooctane sulfonic acid (PFOS) in English freshwater fish are, on average, 300 times higher than proposed new European Union safe levels for aquatic biota3.

While the small freshwater fish analysed by the EA would be unlikely to be consumed, the levels of PFAS pollution found in them are a likely indicator of wider fish pollution and highlight the urgent need to monitor levels in the fish people consume. Recent US research showed freshwater fish as a significant source of exposure to PFAS chemicals, with one fish portion equivalent to drinking PFAS contaminated water every day for a month4. This new Rivers Trust research shows a similarly worrying picture in pollution of English freshwater fish. If a portion of these freshwater fish was to be eaten every month it would be equivalent to more than the amount considered safe to consume over a whole year based on standards set by the European Food Safety Authority (EFSA).

Troublingly, the actual levels of PFAS contamination in fish could be higher still than these new findings suggest. While PFOS is banned in the UK, there are more than 10,000 other PFAS substances which are still widely used, none of which were included in the Environment Agency fish data. Moreover, PFAS substances are known to build-up (bioaccumulate) over time5, and concentrations could be higher in larger fish destined for our dinner tables. These findings are highly concerning, particularly alongside new information on PFAS levels in drinking water6, given that some PFAS are proven to have several health impacts for humans.

The levels of PFOS contamination in freshwater fish serves as a critical warning, akin to the canary in the coal mine, potentially signalling a much wider issue in our environment and food chains. Despite PFOS restrictions for over a decade, other forever chemicals with similar or heightened toxicity remain in widespread use and continue to accumulate around us. We urgently need more proactive monitoring of PFAS in our wider environment and for the Government to take immediate action to ban all but their most essential uses, to safeguard our environment, wildlife, and public health.

Use the map below to explore the locations of the top 20 exceedances of PFOS levels in fish:

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