The Wisconsin Department of Natural Resources on Friday issued a new fish consumption advisory for Lake Superior rainbow smelt, saying recent tests found high levels of the suspected carcinogen PFAS in the fish.

The DNR is recommending people eat no more than one meal per month of smelt because of the high levels of PFAS.

PFAS include some 5,000 so-called "forever chemicals" used for decades in numerous products, including nonstick cookware, fast-food wrappers, stain-resistant sprays and firefighting foam.

The chemicals, which don’t break down over time, have been found in groundwater and surface water near factories, airports and military bases nationwide, including at the Duluth Air National Guard base and in the Twin Cities near a 3M manufacturing plant.

But the stuff is also building up in birds and fish around the Great Lakes, and the exact source is not yet clear. The DNR warning is the first for humans in the Lake Superior region for PFAS and, the DNR said, the first PFAS-based fish consumption advisory for the Great Lakes.

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The agency said the legacy contaminants have made their way into the environment in a variety of ways, including spills of PFAS-containing materials, discharges of PFAS-containing wastewater to treatment plants and firefighting foams.

“The risk of health problems increases with the amount of contaminated fish you eat. Following this advisory will help protect you from excess PFAS exposure found in fish,’’ state officials said in a statement Friday. The advisory could change in the future as the DNR and the state Department of Health Services learn more about the health risks from eating fish caught from this area and more fish data become available.

As part of the DNR’s statewide PFAS-monitoring efforts to monitor fish tissue and water chemistry at select sites around the state, smelt were collected from two locations in Lake Superior in 2019 approximately 30 miles apart at sites near the Apostle Islands and off Port Wing. PFAS was detected in samples from both locations.

Rainbow smelt are considered tasty delicacies, sometimes caught while ice fishing but most often netted during their spring spawning runs up rivers and along sand beaches such as Minnesota and Wisconsin Points in Duluth and Superior. They are actually an invasive species that entered the Great Lakes from the Atlantic more than a century ago through the Welland Canal.

“The smelt migration run starts as spring arrives and winter ice cover dissipates, which creates a popular local tradition of harvesting smelt for fish fries,” said Brad Ray, Lake Superior Fisheries Unit supervisor for the Wisconsin DNR. “It’s important for consumers to understand the potential risks associated with this new advisory.”

Some health risks associated with PFOS, one of the thousands of PFAS compounds, include lower birth weight, possible links to increased risk of kidney and testicular cancer, harm to the immune and reproductive systems, increased cholesterol levels and altered hormone regulation and thyroid hormones.

The DNR also received sample results from bloater chub, cisco/lake herring, lake whitefish, lake trout, and siscowet lake trout in Lake Superior and crappie, yellow perch, channel catfish, carp, northern pike, walleye and musky from the St. Louis River. The PFOS levels found in those fish do not warrant a consumption advisory change at this time.

What are PFAS?

Per- polyfluoroalkyl (PFAS) are a group of chemicals that includes PFOA, PFOS, GenX and many other chemicals. PFAS — commonly associated with fire-retardant chemicals and nonstick cookware — have been manufactured and used in a variety of industries around the globe, including in the U.S., since the 1940s.

PFOA and PFOS have been the most extensively produced and studied of these chemicals. Both chemicals are very persistent in the environment and in the human body, meaning they don't break down and they can accumulate over time. There is evidence that exposure to PFAS can lead to adverse human health effects.

Studies indicate that PFOA and PFOS can cause reproductive and developmental, liver and kidney, and immunological effects in laboratory animals. Both chemicals have caused tumors in animals. The most consistent findings are increased cholesterol levels among exposed populations, with more limited findings related to low birth weights for infants, effects on the immune system, cancer and thyroid hormone disruption.

Where PFAS is found

  • Food packaged in PFAS-containing materials, processed with equipment that used PFAS, or grown in PFAS-contaminated soil or water.
  • Workplaces, including production facilities or industries, e.g., chrome plating, electronics manufacturing or oil recovery, that use PFAS.
  • Living organisms, including fish, animals and humans, where PFAS have the ability to build up and persist over time.

Source: U.S. Environmental Protection Agency