Saturated Spring
Gary Lamberti, the Rev. Julius A. Nieuwland, C.S.C., Professor of Aquatic Science in the Department of Biological Sciences at the University of Notre Dame, has studied the ecology and environmental biology of freshwater ecosystems for more than 40 years.
He’s published more than 200 studies—and counting—that explore human impacts on stream and wetland ecosystems, the ecology and control of invasive aquatic plants and animals, and the impacts of emerging contaminants in the Great Lakes watershed.
But it was during a chance encounter with Graham Peaslee, a nuclear physicist in the Department of Physics and Astronomy, at an event hosted by Notre Dame’s Environmental Change Initiative in 2019, that Lamberti learned about a contaminant he hadn’t yet studied: per- and polyfluorinated alkyl substances (PFAS).
Peaslee is a leading expert on PFAS, a class of fluorinated compounds with exceptionally strong chemical and thermal stability, inherently repellent to oil, water, soil, and stains. The chemicals have been widely used in industrial and commercial applications ranging from nonstick cookware to firefighting foams. Peaslee had pioneered a new method to detect PFAS in consumer products including fast-food wrappers, cosmetics, textiles, plastic containers, face masks, and even drinking water.
The chemicals can migrate off surfaces onto skin, into food and dust, creating multiple pathways of exposure. We inhale them, ingest them, absorb them—and they accumulate in our bloodstream.
PFAS have been linked to several adverse health conditions including immunosuppression, hormonal dysregulation, developmental delays in children, low birth weight and accelerated puberty, high blood pressure in pregnant women, and an increased risk of some cancers, such as kidney and testicular cancer.
They do not degrade or break down, and scientists say they can persist in the environment for thousands of years, earning them another name: “forever chemicals.”
Molecular structure of PFAS
It all sounded eerily familiar to Lamberti. A toxic, persistent chemical, the use of which had contaminated lakes, wetlands, rivers—even ocean waters; saturated the soil; polluted the air; and posed a hazardous risk to all living organisms...
He’d seen this before with dichloro-diphenyl-trichloroethane, better known as DDT, a synthetic and highly persistent pesticide widely used in the 1950s and ’60s. Mounting concerns about environmental contamination and the chemical’s toxicity on wildlife and humans led to regulations and eventually a cancellation order issued by the Environmental Protection Agency in the 1970s.
“PFAS,” Lamberti said, “is the DDT of the 21st Century”.
Lamberti had more than a few ideas for PFAS studies. Research was limited when it came to PFAS contamination in Lake Michigan—familiar territory for Lamberti.
In 2020, he and Peaslee went to work on a number of proposals for grant funding and started a new study of Lake Michigan fish. Previous research had found that fish in most of the Great Lakes contained measurable amounts of PFAS. Lamberti knew that Great Lakes fish were contaminated with forever chemicals, and that the chemicals persisted in the environment and accumulated in the bloodstream—and he wondered about the potential for what he called “maternal offloading.”
Could female fish pass on PFAS to their offspring?
Officials with the Indiana Department of Natural Resources, the Michigan Department of Natural Resources, and the US Fish and Wildlife Service routinely sample fish, water, and sediment to evaluate the status and health of Lake Michigan’s fisheries, which contribute millions of dollars annually to the economies of Indiana, Michigan, Illinois, and Wisconsin, while supporting thousands of jobs in charter and commercial fishing.
Lamberti’s lab partnered with each organization to collect samples of Chinook salmon, coho salmon, and steelhead that were migrating up Lake Michigan tributaries to their spawning grounds. In all, the researchers collected 42 samples from mature male and female fish.
When the samples arrived in 2021, the Michigan Department of Environment, Great Lakes, and Energy had identified an estimated 213 PFAS hotspots throughout the state—many of them connecting via waterways to the Great Lakes.
An analysis of the male and female salmon muscle tissue, as well as eggs extracted from the female fish, showed that 85 percent contained measurable concentrations of perfluorooctane sulfonic acid (PFOS), a type of PFAS that was phased out of use in 2002, and 19 percent tested positive for perfluorooctanoic acid (PFOA), another class of PFAS phased out of use in 2015.
But the most concerning result of the study was that PFOS concentrations were 100 times higher in the eggs compared to the muscle tissue of the female salmon.
“Several different mechanisms could explain why PFAS is being passed on from mother to egg,” Lamberti explained. “It could be that the mother fish have accumulated PFAS from the lake water and they’re passing it on to the eggs during ovarian development. Another possibility is that the mother is consuming food contaminated with PFAS during development and it’s passed on nutritionally to the eggs. That’s what we still don’t know. Either way, this creates a contaminant "biotransport" issue as salmon migrate from the lake to a cleaner river.”
Lamberti’s lab is looking at the “riverine PFAS cycle,” which starts with migrating salmon whose eggs are a preferred source of food for other fish and wildlife. When consumed, the PFAS can bioaccumulate in stream fish, which is then passed on to their own eggs or the fish themselves are eaten—sometimes by humans—resulting in a never-ending cycle of contamination.
For another study, the lab measured PFAS concentrations in more than 200 predator and prey fish from Lake Michigan, including alewives, sculpins, salmon, and lake trout. The goal was to create a clearer picture of concentrations in Lake Michigan fish and to better understand the potential for biomagnification, the dietary passage of compounds from one organism to another.
The study showed PFAS were present in 98 percent of those samples. Results indicated the chemicals were passing from prey fish to predator fish, suggesting a dietary connection.
This study led to other research showing higher concentrations in the fish organs—including the heart, liver, and kidneys—and in blood taken from those samples.
“The lowest concentrations were seen in muscle tissue,” Lamberti said. “So, eating a fillet may be a lower dose of PFAS, but it’s definitely not clean.”
Previous work in the lab showed that similar fish samples also contained measurable PCBs, mercury, and other chlorinated compounds.
“We need to know more about the pathway of these chemicals,” Lamberti said. “How do they get into the fish? It’s either through diet or through the water and sediment in the environment. We’re trying to learn more about how PFAS interact with the food web. We need to know how they get from the environment into the food web and ultimately into the fish that people consume. That’s why we’re meticulously sampling water, sediment, plants, and wildlife in the lake—to trace the pathways. Because only then can you think about remediation.”
But what does remediation look like? How do you eliminate chemicals engineered to stand the test of time?
How do you clean up forever?