Michigan triples waters with 'Do Not Eat' warning for PFAS in fish

LANSING, MI — The state of Michigan has tripled the list of lakes and rivers where high concentrations of toxic ‘forever chemicals’ make the fish unsafe to eat.

This spring, the Michigan Department of Health and Human Services (DHHS) lowered the screening values it uses to calculate the risk of eating fish meat contaminated by a compound called PFOS, which is part of the PFAS chemical group.

As result, the number of Michigan water bodies with a blanket “Do Not Eat” advisory for at least one species due to PFOS contamination has risen from 33 to 98.

Many more include a warning to limit consumption. Overall, there are now 782 fish advisories caused by PFOS across multiple different species and water bodies in Michigan.

The advisories are in the new 2025 Eat Safe Fish guidebook, which is separated by region. The southern lower peninsula accounts for most of the PFOS advisories.

The new guidebook updates the last version, published in 2023. The changes reflect an increased number of tested water bodies and new studies which show that PFAS exposure is a greater health threat than previously thought, the agency said.

The state previously issued a consumption advisory when PFOS in fish tissue samples hit 9-parts-per-billion (ppb). A blanket “Do Not Eat” species advisory was issued at 300-ppb.

Those safety levels were developed in 2014 before PFAS was widely discovered in Michigan and the long-term health risks weren’t as well studied or understood.

The new thresholds have dropped to 1.5-ppb and 50-ppb.

“Michigan families can use these guidelines to help make healthy choices about the fish they eat,” said Natasha Bagdasarian, chief DHHS medical executive.

Advocates for stricter controls on PFAS contamination praised the reduction in screening levels and said Michigan now has the fourth most protective guidance in the nation behind the states of New Jersey, Washington and Connecticut.

However, they criticized the department for not mandating warning signage at lakes and rivers. The agency said it will provide signs if requested by local health departments.

“There should be a uniform approach statewide,” said Tony Spaniola, a metro Detroit attorney and PFAS regulation advocate who co-chairs the Great Lakes PFAS Action Network. “It shouldn’t be left to a local health department to make a different determination than another local health department.”

“It’s good what they’re doing, but that needs to be improved.”

Spaniola, who owns a home in Oscoda on Van Etten Lake, which is contaminated by PFAS from the former Wurtsmith Air Force Base, said it’s important for people to recognize the exposure threat posed by eating fish with high PFAS levels.

In Michigan, fish advisories in the state’s guidebook are based on a complicated and confusing analysis. The state tests fish for a variety of different contaminants and issues a servings-per-month recommendation based on whichever individual contaminant is most elevated per species in each water body. Often, the controlling pollutant is mercury, dioxin or PCBs.

Many people are likely familiar with PFAS safety thresholds for drinking water, which are communicated in parts-per-trillion (ppt), whereas fish consumption thresholds are communicated in parts-per-billion (ppb). Due to the orders of magnitude change, that means eating a serving of fish with a PFOS tissue concentration of 1-ppb would be roughly equivalent to drinking a serving of water contaminated at 1,000-ppt.

However, toxicologists calculate risk differently for chemicals ingested with food versus water. Because most people are not, generally, consuming fish or other specific foods at the same daily rate as water, larger doses are considered safer to ingest with a lower risk of developing health problems.

Nonetheless, as fish tissue concentrations increase, “stack that up against folks who eat more than one serving, right? It can really start to accumulate,” said Spaniola.

“People in Michigan, particularly in fishing communities, tend to eat a lot of fish,” he said.

The increase pushes PFOS above PCBs as the second largest driver of fish consumption advisories in Michigan behind mercury, said DHHS toxicology section manager Marcus Waslivech.

The state’s PFOS update is partly based on findings of an exposure assessment in Kent County, which studied the blood concentrations of those exposed to pollution caused by shoemaker Wolverine Worldwide. A “statistically significant” link was found between frequency of fish consumption and higher PFAS levels in people’s blood serum

Additionally, “the update of the PFOS toxicity value … reflects the evolution downward in toxicity values that has occurred since 2014, both nationally and globally,” DHHS toxicologists wrote in an April assessment. “This downward trajectory has been based on replicated findings from the toxicological literature that show health effects of PFOS exposure occur at lower concentrations than those previously known.”

PFAS are often called “forever chemicals” because they do not readily break down in the environment or in humans. They’ve been used to make products resistant to water, grease, oil and stains, and are found in foams used to fight hydrocarbon fires.

The family of chemicals are the subject of intense health study and exposure has already been linked to certain cancers, thyroid and liver disease, pregnancy complications, low birthweight and reduced vaccine effectiveness, among other conditions.

The chemicals have been widely detected in freshwater fish across the U.S., prompting warnings from advocacy groups and calls for tighter pollution controls.

In Michigan, advisories notably remain for some rainbow smelt despite initial mistakes in analyzing smelt tissue that previously caused artificially high results.

Related stories:

Trump EPA to partly rescind PFAS rules in drinking water

Rainbow smelt PFAS levels were artificially high

Filters cut PFAS exposure near Wolverine dumps

PFAS widely detectible in U.S. freshwater fish

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