Great Lakes fishing is a Michigan mainstay, but new research suggests that some freshwater catches are heavily contaminated – and in Detroit, the dangers are much greater. 

A study from the Environmental Working Group, a research advocacy group in Washington, D.C., found that freshwater fish across the country have high levels of per- and polyfluoroalkyl substances, or PFAS. The levels are so high that eating just one freshwater fish is equivalent to drinking PFAS contaminated water for a month, researchers found. In the Great Lakes, where fishing is a $7 billion industry, the contamination was even worse. 

“These chemicals don’t break down in the environment quickly,” said Tasha Stoiber, senior scientist at the Environmental Working Group and co-author of the study. “We’re looking at legacy chemicals that have been used for decades — some of these were phased out in the early 2000s and yet, we’re still seeing high, concerning levels in these fish.” 

Researchers noted that the risk of PFAS contamination is biggest for vulnerable populations who rely on fish for survival. In Detroit, where some residents use fish as a source of protein, the PFAS levels were more than six times as much as the national median level. 

“My concern for the Detroit River is that we do have a lot of anglers and fisher people of color. Sometimes this [fish] is their primary source of protein in their diet, and it does raise flags for environmental justice concerns on the Detroit River,” said Donna Kashian, co-founder of the Riverwalkers, a group created to advise Detroit fishers on the contamination risks of fishing in the Detroit River.

The EWG study analyzed data from 500 samples of fish collected in the country from 2013 to 2015 under the U.S. Environmental Protection Agency and found a median level of 9,500 parts per trillion of PFAS in freshwater fish, compared to 11,800 parts per trillion in Great Lakes fish. 

PFAS are a class of man-made substances that have been linked to kidney and liver disease and other health issues in laboratory animals, and are also a possible carcinogen. Commonly referred to as “forever chemicals,” PFAS stick around in the environment for long periods of time, and have been found in rainwater, soil, beef and the new research now points to the severity of the problem with freshwater fish. 

A study sample taken from a largemouth bass caught in the Detroit River had 64,200 parts per trillion of PFAS. 

“That is quite high,” said Stoiber, adding that, in general, fish from streams in urban areas had higher PFAS levels. High levels like the Detroit River or Grand River on the west side of the state, which had nearly 80,000 parts per trillion, could be indicative of direct pollution sources nearby, she said, although more research is needed. 

Contaminated fish from the Detroit River, a river historically polluted by heavy industry, has long been a problem. A previous study found that fishers who ate their catch from the Detroit River had 2.5 times more mercury and two times as much PCBs in their system, compared to the average American. 

A  2018 study found that Black fishers on the Detroit River are more disproportionately impacted by contamination than other groups that fish in the Detroit River, because they’re less likely to know about the risk of contamination, but more likely to eat the fish they catch. To mitigate this, the Riverwalkers formed more than a decade ago.

The Riverwalkers hadn’t been warning people about PFAS in fish in the Detroit River, because there hadn’t been any state advisories, said Kashian, but she suspects this will change with the new study. 

In the Great Lakes region, fishing is a way of subsistence for a number of Indigenous communities. Take the Keweenaw Bay Indian community in the upper peninsula of Michigan, where 87% of members surveyed said they rely on Lake Superior fish as a major food source, but are limited by a number of state advisories due to contamination. 

Earlier this week, Michigan officials issued an expanded advisory to limit the consumption of rainbow smelt and carp caught in lakes Michigan and Huron and five other Michigan water bodies, due to PFAS contamination. The limits are strict – for rainbow smelt caught from Lake Michigan and Lake Superior, officials advise that no more than one serving should be eaten in a month. 

“This points to something PFAS researchers have known for a long time: The effects of PFAS extend well beyond drinking water concerns and have already greatly impacted our food web,” said Colleen Linn, PhD candidate for urban anthropology at Wayne State University whose research focuses on PFAS in Michigan groundwater. 

In 2020 a study of 2,000 fish across Michigan found PFOS, a type of PFAS, in 92% of the sampled fish. 

“Freshwater fish is a vital part of Michigan’s economic and cultural heritage,” she said. “It is important for more testing and guidance to be developed in areas of the state where freshwater fish are relied upon not just for consumption but for economic subsistence, which is particularly true for Michigan’s indigenous communities.”