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Freshwater fish are filled with ‘forever chemicals’ at alarming levels, researchers find

A rainbow trout lies on the gray rocks of a river bank. A fishing pole is lying next to it in the background.
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A 2014 sample of a rainbow trout from the North Platte River in Wyoming, such as this one here, had total PFAS levels of 49,976 parts per trillion, according to researchers at Environmental Working Group.

A new study shows that eating a single serving of freshwater fish in the U.S. can be equal to drinking a month’s worth of water laced with “forever chemicals.”

Per- and polyfluoroalkyl substances, better known as PFAS, are man-made chemicals used in a variety of industrial and consumer products – from plastics to cosmetics – and have been linked with health issues like cancer and infertility. They’re known as “forever chemicals” because they don’t break down in the environment over time.

Researchers at Environmental Working Group analyzed more than 500 fish fillet samples collected by the U.S. Environmental Protection Agency from 2013 to 2015. The median level of the PFAS compound known as PFOS in the fish was 8,410 parts per trillion, or ppt. That means eating one 8-ounce serving of fish with that much PFOS, the study shows, is equivalent to drinking water containing PFOS at 48 ppt for a month – which would be 2,400 times the EPA’s recommended limit.

“People who are eating freshwater fish for subsistence as a source of protein – that’s where it really stands out as being of highest concern,” said David Andrews, a senior scientist at Environmental Working Group and lead author of the study. “Especially if those people are in or closer to urban areas, closer to where there’s development.”

As EWG’s interactive map shows, some fish pulled from Mountain West rivers and streams contained significantly higher total PFAS levels. In Colorado, channel catfish from the Yampa River had more than six times the median level (60,718 ppt). In Wyoming, rainbow trout from the North Platte River had more than five times (49,976 ppt). In New Mexico, the common carp from the Rio Grande River had more than four times (43,183 ppt).

The median total PFAS levels in the freshwater fish were nearly 300 times higher than in store-bought fish, Andrews said, citing a 2022 seafood survey by the U.S. Food and Drug Administration.

He said that’s because marine fish and farmed fish are typically farther away from industrial sources of pollution and have cleaner water supplies.

Last June, the EPA updated its lifetime drinking water health advisories for PFOS and PFOA – two of the most widely used and studied forever chemicals – to 0.02 ppt and 0.004 ppt, respectively, much lower than its previous recommended limit of 70 ppt.

This story was produced by the Mountain West News Bureau, a collaboration between Wyoming Public Media, Nevada Public Radio, Boise State Public Radio in Idaho, KUNR in Nevada, the O'Connor Center for the Rocky Mountain West in Montana, KUNC in Colorado, KUNM in New Mexico, with support from affiliate stations across the region. Funding for the Mountain West News Bureau is provided in part by the Corporation for Public Broadcasting.

Kaleb is an award-winning journalist and KUNR’s Mountain West News Bureau reporter. His reporting covers issues related to the environment, wildlife and water in Nevada and the region.
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