Investigation into water near 3M plant led to discovery of old and new chemicals in fish

Average PFOS concentration in Lake Rebecca fish was almost 10 times the national average. 

By: - August 11, 2023 7:00 am

3M still manufactures PFAS at this plant in Cottage Grove. Photo by Chad Davis

A state and federal investigation into chemical discharges from 3M’s Cottage Grove plant led to last week’s state health advisory about fish caught in the Mississippi River from St. Paul to Hastings, as well as a popular shore fishing lake near Hastings.

Of 42 toxic manmade chemical compounds researchers looked for in fish in a 41-mile stretch of the Mississippi from St. Paul into Wisconsin, all but six were found, prompting state health officials to issue a fish advisory directed at children and pregnant and breastfeeding women. Some scientists say the health department didn’t go far enough in warning people.

The average fish tissue levels of a 3M chemical called PFOS in the Lake Rebecca fish was about 400 times the state pollution regulator’s threshold for health risks for those who eat a lot of fish they catch.

The Minnesota Pollution Control Agency and EPA have been investigating chemicals in wastewater discharges from the plant since 2020, when 3M voluntarily disclosed “compliance issues” related to the plant.

The contamination is just the latest and most local of 3M’s long and troubled history of chemical pollution, which in recent years has led to a litigation morass. 

3M spokesman Grant Thompson released a statement saying the company has already taken steps to substantially reduce the volume of wastewater generated from making PFAS at the Cottage Grove site.

3M is on track to invest more than $200 million at the Cottage Grove facility by 2025 to implement a treatment system that will continue to remediate PFAS in area groundwater even after 3M stops making the chemicals, he said.

The Maplewood-based company has made per- and polyfluoroalkyl substances (PFAS) since the 1950s. Scientists working to develop atomic weapons discovered that when fluorine bonds with carbon, the bond is almost impossible to break. (Hence the moniker, “forever chemicals.”) Some of those Manhattan Project scientists were hired by the Minnesota Mining and Manufacturing Company (3M), which bought the patent and has made the chemicals since.

Now there are tens of thousands of variations of the carbon-fluorine bond, and they’ve been used in a variety of products, such as Scotchgard, microprocessors, firefighting foam and non-stick pans.

The very reason they’re useful — they’re more stable than many rocks and can repel water, oil and stains — is also the reason they’ve spread across the planet, and can be found in nearly every living thing, including the blood of nearly all people. They’ve been linked to low fertility, birth defects, suppression of the immune system, thyroid disease and various cancers.

The company has made billions off the chemicals, but as their harmful effects on humans and the environment became clear, they’ve become a liability for 3M. Bloomberg has estimated they could cost the company up to $30 billion.

In December, 3M said it will stop making the chemicals and using them in products by the end of 2025.

As part of the MPCA investigation into discharges from the Cottage Grove plant, 3M was required to study fish in the Mississippi River near the plant. It hired environmental contractors to do the study, which was overseen by the MPCA, as is standard practice.

The June 2021 study was the most comprehensive of the upper portion of the river for PFAS compounds to date, 3M said in a nearly 10,000-page report on what they found.

The study found both new and old chemicals 3M has made in Cottage Grove since the 1950s.

Two types of chemicals that 3M phased out in the early 2000s — PFOS and PFOA — were detected in fish. The compound used in Scotchgard, PFOS, was found in all of the fish analyzed, in some cases at very high levels. And that’s despite the fact 3M phased out PFOS production in 2002 under EPA pressure.

After phasing out that long-chain chemical, 3M began making new types of short-chain chemicals it says are safer, although some environmental scientists say they’re not much better.

Among the chemical compounds found in fish in the study was HQ115, a battery electrolyte that 3M produces. It’s widely used as an additive to enhance performance in rechargeable batteries. 

But little is known about the environmental impacts of its manufacture, use and disposal, according to a Research Square article that argues the clean energy sector is an “unrecognized and growing source of global PFAS release.” 

The authors said HQ115’s “occurrence, ecotoxicity, and treatability” was comparable to PFAS “that are now prohibited and highly regulated worldwide.”

“This suggests that environmental exposure to this novel, unregulated class of PFAS will increase with time and will be relevant to the majority of the world’s population,” the authors write. “Results underscore that environmental impacts of clean energy infrastructure merit scrutiny to ensure that reduced CO2 emissions are not achieved at the expense of increasing global releases of persistent organic pollutants.”

In Lake Rebecca, chemical levels in the fish were very high: The average PFOS concentration was almost 10 times the national average found in fish by the EPA. 

PFOS levels in the Mississippi River were slightly above the national average, and in other areas of the river they were slightly below, but all exceeded the MPCA’s water quality criteria.

In addition to the high levels of PFOS, the unique mixture of a variety of chemical compounds also stood out.

An environmental scientist told the Reformer last week that she wouldn’t eat the fish in the lake, even though she’s not in any of the sensitive populations that were warned. While the MPCA enforces water quality standards, the state Health Department decides whether to issue dietary advisories.

Researchers weren’t even able to catch many fish in some areas, indicating the chemicals could be impacting the health of the fish. In Lake Rebecca, despite “high gear effort,” researchers were only able to catch three freshwater drum and one walleye, and no smallmouth bass, white bass, sauger, emerald shiner or gizzard shad.

Carly Griffith, water program director for the Minnesota Center for Environmental Advocacy, said the fact that PFOS is still showing up at high levels makes them concerned about the new chemicals being made.

 “PFOS is the compound of concern but there were many types uncovered in this report,” she said.

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Deena Winter
Deena Winter

Deena Winter has covered local and state government in four states over the past three decades, with stints at the Bismarck Tribune in North Dakota, as a correspondent for the Denver Post, city hall reporter in Lincoln, Nebraska, and regional editor for Southwest News in the western Minneapolis suburbs.