Key messages:  European seas are contaminated by both legacy and currently used per- and polyfluorinated substances (PFAS). Contamination by substances such as perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) poses a risk to marine organisms and human health. PFOS concentrations in marine organisms have been found at levels up to 100 times greater than the EU Environmental Quality Standard established for fish. There are many other PFAS which have not been monitored; their effects are unknown. By including 24 PFAS in the list of priority substances, the proposed revision of the Water Framework Directive will improve our understanding of human and environmental exposure to these substances. 

Concentrations of PFOS divided by Environmental Quality Standard (EQS) in marine organisms 

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Chemical emissions to the marine environment come from both sea-based and inland human activities. This incorporates offshore productions such as oil and gas, and diffuse releases from the shoreline and inland river basin discharge — including from wastewater treatment plants and run-off water from land. Atmospheric deposition can also occur from both land- and sea-based sources including the combustion of fuel on ships, resulting in global impacts.  

Data from between 2006 and 2016 show that 80% of maritime areas assessed in the EU were designated ‘problem areas’ due to chemicals in water, marine organisms and sediments. This mainly concerns legacy substances such as polycyclic aromatic hydrocarbons. PFAS are an example of currently-used substances present in European seas, and are widespread in consumer products and industrial processes. Many are very mobile and have long-range transport potential, meaning they can pollute areas long distances away from the source of release. PFAS are very persistent in the environment; some are bioaccumulative and toxic to aquatic organisms and humans. They have been found in crustaceans, fish (including species intended for human consumption), and bottlenose dolphins in European seas. This raises concerns for ecosystem and human health given that some substances may biomagnify — grow more concentrated — across the food chain. 

Data collected by the International Council for the Exploration of the Sea (ICES) between 2001 and 2021 across EU seas shows that marine organisms contain different levels of perfluorooctane sulfonic acid (PFOS): from 0.01 to 100 times more than the environmental quality standard (EQS) level set by the EU for fish

The results show high concentrations in mammals and most seabirds. The highest concentrations were in polar bears, with a median of almost 100 times the EQS (900 µg/kg wet weight). Such exceedances may become even higher with the proposed update of the EQS; if adopted, the EC Directive proposal will replace the EQS for PFOS in biota (9.1 µg/kg ww) and lower it 100 times (0.077 µg/kg ww). This revised scale will apply to a sum of 24 PFAS, according to a potency factor.  

The data also show that PFOS is bioaccumulated over time in organisms and biomagnified, meaning that organisms at the top of the food chain contain higher concentrations than those lower down. In the European human biomonitoring initiative HBM4EU, higher levels of PFOS were associated with higher consumption of fish and seafood.  

Measurements in sea water also showed substantial PFAS contamination in the coastal regions of the North and Baltic Seas between 2005 and 2018, especially by perfluorobutane sulfonic acid (PFBS), perfluorohexane sulfonic acid (PFHxS) and PFOS, although a slight decline was observed between 2015 and 2017. In the Mediterranean Sea, perfluorooctanoic acid (PFOA) and PFOS concentrations significantly decreased between 2012 and 2018. Compared to the EQS for transitional, coastal and territorial waters, annual average concentrations of PFOS in 2018 appeared to be slightly lower than the EQS in the North Sea, about 35 times higher in the Baltic Sea, and 50% higher in the Mediterranean Sea. Thus, although some decreasing trends were observed, PFOS concentrations still appeared to be concerning in certain areas. A decreasing trend for the sum of PFOS, PFOA, perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA) and perfluoroundecanoic acid (PFUnDA) concentrations was also observed in the North Sea based on measurements in sediment layers of different depths, with a decline starting from approximately 2014.  

The decline of sea water and sediment concentrations of the above-mentioned PFAS suggests that EU regulations are having an impact on persistent organic pollutants. However, these studies only concern a small fraction of PFAS whereas the family includes about 10,000 different substances. The monitoring of some PFAS of emerging concerns such as Hexafluoropropylene oxide dimer acid (HFPO-DA, or GenX) has already shown toxic properties similar to the regulated PFOS. As a result, GenX was added to the REACH Candidate List of substances of very high concern (SVHC). Most PFAS have not been adequately tested for their eco-toxicological properties, however. This would require an extensive timeframe, during which pollution would continue. In addition, while regulatory measures support reducing emissions of some PFAS to the environment, the persistence of such substances means they can continue to pose an environmental risk long after measures are taken. This highlights the need to promote further upstream prevention of PFAS use.   

For PFAS in marine organisms, the EQSlevel set by the EU for PFOS in fish is 9.1 µg/kg wet weight. EQS levels are set to protect human health during the consumption of fishery products.   

Concentrations in marine organisms were measured in samples from the Atlantic Ocean, Biscay, Iberian coast and the Barents, Norwegian, Celtic, Greater North and Baltic Seas.  

Risk ratios are calculated by dividing the concentration of PFOS in different marine organisms by the EQS. Of the species analysed, mussels and oysters correspond to low trophic organisms, further down on the food web. No chemical concentration in mussels or oysters exceeded the EQS, and their concentrations were the lowest in the dataset. High concentrations were found in mammals and most seabirds. Low concentrations were found in eider ducks collected from Barents Sea, while EQS levels were seldom exceeded in Northern fulmar and Black guillemot from the Atlantic Ocean. The EQS level was exceeded in all oystercatchers and common terns from the Greater North Sea, and all common guillemots from the Baltic Sea. In 2021, data showed statistically significant differences between cod PFAS levels in different areas: higher in the North Sea and the Baltic Sea, lower in the Barents Sea, and the Norwegian Sea in between.   

For PFAS in sea water, the EQS (annual average value) set by the EU for PFOS in transitional, coastal and territorial waters is 1.30x10-4 µg/L

Using this EQS value and the data collected by Muir and Miaz (2021), the risk ratio was 0.7, 36.6 and 1.5 for the North Sea, Baltic Sea and Mediterranean Sea, respectively, based on annual average concentrations measured in 2018. 

References and footnotes

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