Researchers figure out one mystery behind PFAS levels in Lake Superior smelt
GRAND RAPIDS, Mich. (WOOD) — State officials believe they have solved one of the mysteries of why Lake Superior smelt are showing such high levels of PFAS contamination.
The Michigan Department of Health & Human Services first issued a consumption advisory in March of 2021 after joint testing conducted along with the Wisconsin Department of Natural Resources found elevated levels of the forever chemicals in the fish.
Rainbow smelt showed an unusually high level of perfluorooctane sulfonate (PFOS), one of the most common forms of PFAS.
“These high levels of PFOS in these little smelt raised questions for state scientists: ‘Where did this PFOS come from?’ and ‘Why was it so high in smelt?’” the Michigan Department of Environment, Great Lakes and Energy said in a statement.
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The Michigan PFAS Action Response Team helped lead the study to find those answers, working alongside other agencies from Michigan and Wisconsin, tribal governments and the U.S. Environmental Protection Agency.
The breakthrough came last year when scientists noted that fish tested in Michigan had high amounts of a subtype of PFOS that wasn’t present in other data sets. Researchers were able to determine that a naturally occurring bile acid in smelt, taurodeoxycholic acid (TDCA), was triggering false results.
“According to the EPA, TDCA/bile acids have nearly the same molecular mass as branched-PFOS in addition to containing a sulfonate group, another marker for PFOS. Because of those characteristics, the lab equipment couldn’t previously separate the bile acids from the branched-PFOS,” EGLE stated.
Researchers reanalyzed some of the past samples with a new lab method and confirmed the findings.
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The consumption advisory remains in effect for Lake Superior smelt. EGLE says any updates will be provided in the agency’s annual Eat Safe Fish Guidelines.
MPART says the collaboration between other agencies will continue as researchers try to determine why Lake Superior smelt are showing elevated levels of PFOS and what the source of the PFOS contamination may be.
PFAS — or per- and polyfluoroalkyl substances — are a large group of compounds first developed in the 1940s and incorporated into all sorts of products for waterproofing and heat resistance. Decades later, research showed that PFAS compounds take a long time to break down organically and can build up in the human body, causing serious health problems including cancer.
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