While eating locally grown produce is great for the environment, eating locally caught freshwater fish might be more dangerous for human health than we realized. A study from the Environmental Working Group (EWG) finds that freshwater fish in the United States contain dangerous levels of “forever chemicals” including one called PFOS (Perfluorooctane sulfonic acid). PFOS is part of a group of manufactured additives known as perfluoroalkyl and polyfluoroalkyl substances, or PFAS.
“PFAS are called forever chemicals because they do not break down in the environment and often bioaccumulate in people and species, like fish,” said David Andrews, a senior scientist at EWG senior scientist and one of the study’s lead authors, in an email to PopSci. “PFOS was the primary ingredient in 3M’s ScotchGard. It was also used in other products, like aqueous film forming foam used for fighting fires. PFOS is one of thousands of per- and polyfluorinated alkyl substances.”
PFOS is just one of the PFAS that have since seeped into drinking water and accumulated in the bodies of fish, livestock, dairy, and game animals. The team in this study found that eating one fish in a year is equal to drinking water with PFOS at 48 parts per trillion (ppt) for one month.
“People who consume freshwater fish, especially those who catch and eat fish regularly, are at risk of alarming levels of PFAS in their bodies,” Andrews said in a statement. “Growing up, I went fishing every week and ate those fish. But now when I see fish, all I think about is PFAS contamination.”
According to the team, the research bolsters calls for stronger regulations of these chemicals, more testing on fish, and raises environmental justice concerns for the communities who depend on eating freshwater fish, including local Native American tribes.
The study found that the median amounts of PFAS in freshwater fish were 280 times greater than the forever chemicals detected in some commercially caught and sold fish. Eating a single meal of freshwater fish could lead to similar PFAS exposure as eating store-bought fish every day for a year, according to testing data.
“These test results are breathtaking,” said Scott Faber, EWG’s senior vice president for government affairs, in a statement. “Eating one bass is equivalent to drinking PFOS-tainted water for a month.”
The team analyzed data from more than 500 samples of fish fillets collected from 2013 to 2015 under monitoring programs by the Environmental Protection Agency (EPA), the National Rivers and Streams Assessment, and the Great Lakes Human Health Fish Fillet Tissue Study.
“PFAS contaminated fish across the U.S., with higher levels in the Great Lakes and fish caught in urban areas,” said Tasha Stoiber, an EWG senior scientist and study co-author, in a statement. “PFAS do not disappear when products are thrown or flushed away. Our research shows that the most common disposal methods may end up leading to further environmental pollution.”
PFOS-contaminated fish can raise blood serum levels of PFOS in people and even infrequent consumption of freshwater fish can raise PFOS levels in the body. A report from the National Academies of Sciences, Engineering, and Medicine found that the chemicals in the PFAS family are linked to cancer, high cholesterol, various chronic diseases, and a limited antibody response to vaccines in children and adults.
“The extent that PFAS has contaminated fish is staggering”, said Nadia Barbo, a graduate student at Duke University and lead researcher on this project, in a statement. “There should be a single health protective fish consumption advisory for freshwater fish across the country.”
In the early 2000s, manufacturers agreed to voluntarily stop using long-chain PFAS in the US, but they can still be found in some imported items. The FDA phased out the use of PFOS in food packaging in 2016. Still, there could be more than 40,000 industrial polluters of PFAS in the US, according to EWG estimates.
“For decades, polluters have dumped as much PFAS as they wanted into our rivers, streams, lakes and bays with impunity. We must turn off the tap of PFAS pollution from industrial discharges, which affect more and more Americans every day,” added Faber.
Along with perfluorooctanoic acid (PFOA), PFOS is a “long-chain” PFAS, made from an 8-carbon chain. According to the CDC, over 9,000 different PFAS exist and the chemicals have been reworked to be 4- and 6-carbon chains. Some experts say that these newer versions could have many of the same dangerous health effects as the 8-chain PFAS, continuing the risk to consumers and the environment.
Avoiding PFAS is nearly impossible, with the chemicals in everything from cookware to clothing to carpeting. They were found in 52 percent of tested cosmetics in a 2021 study. The coating used on nonstick pans (polytetrafluoroethylene) has been found to be the most common additive.