New research published earlier this month shows declining levels of the so-called "forever chemicals" known as PFAS in Great Lakes fish, offering hope that one day, Michigan’s “do not eat” fishing warnings may be retired.
Since PFAS was first discovered in Michigan in 2010, sites across the state have been identified for potential contamination. State health officials have discouraged eating fish from bodies of water with high levels of chemical contamination, including from PFAS.
PFAS is a large group of man-made chemicals that have been used in a variety of sectors since the 1940s. The chemicals breaks down very slowly over time and have been linked to negative health and environmental effects.
The study, published this month in the Journal of Great Lakes Research, used preserved whole lake trout and walleye samples to measure how much PFAS had bioaccumulated in the fish from 1975 to 2020. Researchers tested decades worth of samples for 45 compounds. 15 of the 45 compounds were found in Great Lakes predatory fish, and eight were detected regularly.
PFAS has caused “do not eat” advisories across Michigan and a wave of new drinking water standards.
“PFAS in the Great Lakes has been of high concern to a lot of the public because PFAS builds up in fish very readily, and that's a significant way that humans can get exposed to PFAS is through eating freshwater fish,” said Sarah Balgooyen, a researcher at the Colorado School of Mines and a lead author of the study.
PFAS levels peaked in 2008 and have been declining since, according to the study. Researchers found average PFAS levels in 2020 were at their lowest level since the 1980s, with some variation across lakes.
Not degraded, just diluted
"We're not seeing the degradation of these compounds," Balgooyen said. "They're just getting diluted out into the oceans. So the Great Lakes go out the St. Lawrence Seaway and into the oceans, and the reduction of PFAS in the Great Lakes is likely just due to that turnover and not necessarily any kind of environmental degradation."
The archived fish Balgooyen and her team studied were preserved by the United States Environmental Protection Agency’s Great Lakes Fish Monitoring and Surveillance Program. Their research began at the EPA Office of Research and Development, which was disbanded in July as a part of the Trump administration’s reduction of the agency. Balgooyen and other researchers continued their study despite the changes.
Shifts in manufacturing standards may also be behind the lower PFAS levels, according to Balgooyen. Manufacturing changes and new regulations throughout the 2000s sought to further regulate PFAS production.
“It’s a really reassuring trend to see that the ecosystem responded so readily to these changes in manufacturing that we've made in the U.S., and also reassuring that we can use this technique to look at historical contamination,” she said.
Researchers weren’t originally sure studying archived fish would give a snapshot of changes in the Lakes over time, according to Balgooyen. But now that the study is completed, they are excited for further possibilities for this kind of research.
“Since we had this access to archived fish, it seemed like a good way to look at the historical trends, and it worked out really well,” Balgooyen said. “We didn't know if it was going to be possible looking at fish that was so old, but everything worked out and we got really good trends out of it.”
Lynn Sutfin, Public Information Officer at the Michigan Department of Health and Human Services, told Michigan Public the MDHHS is reviewing the article, and encourages residents to continue to refer to the state’s guidelines to make informed decisions about what fish are safe to eat.
