Which types of fish can you still eat without hesitation?
If you eat a single freshwater fish from wild-fished waters in the U.S., you may be ingesting the same amount of hazardous chemicals as you are drinking contaminated drinking water for a month.
So-called 'forever chemicals' – also known as PFA (perfluoroalkyl and polyfluoroalkyl substances, including PFOS and PFOA) – are hazardous, non-natural substances. They have been manufactured by humans since the 1940s and are used in a number of products, including cosmetics but also, for example, in frying pans.
They decay very slowly. In mid-2022, scientists succeeded for the first time in destroying eternal chemicals in order to remove them from the cycle.
According to scientists at the Environmental Working Group (EWG) – a non-profit research organization – people who eat freshwater fish ingest very large amounts of these toxic chemicals.
Although there are currently no limit values for PFOS, PFOA or other PFAS in the EU Drinking Water Directive, the European Food Safety Authority EFSA recommends not exceeding a weekly intake of 4.4 nanograms per kilogram of body weight for the four PFASs predominant in human blood.
According to EWG, the consumption of one portion of fish corresponds to the intake of water with 48 nanograms per kilogram of PFOS for one month.
"People who consume freshwater fish, especially those who regularly catch and eat fish, are at risk of alarming PFAS concentrations in their bodies," said David Andrews, Ph.D., one of the study's lead authors.
"When I was growing up, I went fishing every week and ate this fish. But when I see fish now, all I think about is PFAS contamination."
Which fish contain 'eternal chemicals'?
The researchers analyzed data from more than 500 samples of fish fillets collected in the U.S. between 2013 and 2015.
The fish samples include 44 different species, with channel catfish, small perch, large perch, yellowfish and zander being the most frequently measured.
All of these species contained dangerous amounts of the presumably toxic substances.
The study refers to fish from US waters, but it stands to reason that European fish is also contaminated.
What are eternal chemicals?
Eternal chemicals remain in the environment for more than 1,000 years. They are made up of carbon and fluorine atoms bonded together – one of the strongest chemical bonds that exist.
Such substances are hardly degradable in the environment. But we can control what we eat. In a 2021 study, PFAs were found in rainwater in most places on Earth, while an earlier analysis detected the toxic compounds in breast milk.
Scientists have linked the chemicals to fertility problems, an increased risk of cancer, and developmental delays in children.
Are PFAs contained in all fish?
The study found that freshwater fish contain up to 280 times more chemicals than commercially caught saltwater fish.
The authors described the results as "overwhelming" and "staggering."
The high rate of contamination is also a concern for environmental justice, the researchers warned, as it primarily threatens those who cannot afford to buy commercial fish and seafood.
"Identifying the sources of PFAS exposure is an urgent public health priority," said Tasha Stoiber, one of the study's co-authors.
What can we do about PFAs?
The scientists have called for rapid regulation of PFA production.
Safety guidelines for these chemicals have been significantly tightened over the past 20 years when their toxicity was discovered – many are millions of times lower than in the early 2000s.
Last year, investors managing nearly €8 trillion in assets called on chemical companies to phase out PFAs. The growing awareness of the risks of toxic chemicals has triggered a flood of lawsuits that could cost chemical companies up to 30 billion US dollars (28.7 billion euros).
Which fish can you eat from a sustainability point of view?
In a guide to fish consumption published by the Consumer Center, herring, flounder, keta salmon and plaice from the Baltic Sea as well as bonito tuna are described as "good fish" that can still be eaten today without hesitation.
The full list of the German Consumer Advice Centre can be found here.
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