High Levels of PFOS in Fresh Water Fish in Wisconsin

Thursday, January 19th, 2023 -- 9:12 AM

(By Danielle Kaeding, Wisconsin Public Radio) A new study found dining on one fish caught in freshwater could be the same as drinking PFOS-contaminated water for a month, with highest levels of the harmful forever chemicals observed in Great Lakes fish.

According to Danielle Kaeding with Wisconsin Public Radio, the study published in the journal Environmental Research is an analysis of government data collected by the U.S. Environmental Protection Agency.

Researchers from the Environmental Working Group and Duke University reviewed data from more than 500 fish fillet samples drawn from national rivers, streams and the Great Lakes from 2013 to 2015.

The sampling was part of the agency’s National Rivers and Streams Assessment and the Great Lakes Human Health Fish Fillet Tissue Study. Researchers say their review found eating one freshwater fish is similar to drinking water polluted with PFOS, one of the two most widely studied PFAS, at levels of 48 parts per trillion for a month.

"We found that even one or a few meals a year would likely have a significant impact on your blood levels, and so (it’s) really quite concerning in that regard that even very infrequent freshwater fish consumption could likely be a significant source of exposure," David Andrews, senior scientist with the nonprofit Environmental Working Group, said.

The analysis of 44 fish species sampled, which included walleye and largemouth bass, showed the highest PFOS levels among 152 samples collected from the Great Lakes with average concentrations of 12,350 parts per trillion.

Levels of 13 PFAS chemicals observed in Great Lakes fish averaged 11,800 parts per trillion. Andrews said it’s not yet known what’s driving higher levels in Great Lakes fish.

"I believe it's in part because the water in the Great Lakes is not continually flowing and rushing out into the ocean. I mean, it is, but on a much slower timescale," Andrews said. "So water and contamination that ends up in the Great Lakes actually sticks around a lot longer."

The study included a map showing locations of PFOS-contaminated fish. Near the city of Superior, a lake trout sampled in Lake Superior had levels of 21,000 parts per trillion while a coho salmon tested near Milwaukee in Lake Michigan had levels of 19,000 parts per trillion.

In Green Bay, a channel catfish showed levels of 5,000 parts per trillion. The findings of the peer-reviewed study come as federal regulators have updated health guidelines for PFAS chemicals in drinking water from 70 parts per trillion to levels less than zero for PFOA and PFOS.

The EPA based its updated advisory levels on research that indicates the compounds may be harmful at much lower concentrations.

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