Linda Lee, distinguished professor of agronomy and environmental and ecological engineering and assistant dean of agricultural research and graduate education.
When Linda Lee received a sample of shellfish from an Alaskan reservation in 2005, she was looking for PCBs, or polychlorinated biphenyls — a group of chemicals banned in the U.S. in 1979 due to their harmful health effects.
Instead, Lee, distinguished professor of agronomy and environmental and ecological engineering and assistant dean of agricultural research and graduate education, found PFAS. PFAS, or per- and polyfluoroalkyl substances, are a group of chemicals used to make consumer products heat, water or stain resistant. (Think firefighting foam, nonstick cookware, stain-resistant carpets, fast-food packaging and even some cosmetics.)
Lee wasn’t working on that chemical group. But when a team from DuPont visited her lab asking for her help to fill in data gaps in their own research on PFAS, she used their check to buy a liquid chromatography–tandem mass spectrometer. With this highly sensitive tool, she could detect the chemical group in parts per billion to parts per trillion. She was now in the business of PFAS research, and 20 years later, her work continues expanding. The addition of three more analytical systems allows her to contribute to a wider body of research across campus.
PFAS are commonly known as “forever chemicals,” because they last in the environment for a long time and are difficult to destroy. They bioaccumulate, or build up in body, and have been detected on every continent and in the blood of most Americans. They’re also found in human urine, animals and fish, water, air and soil. Studies have linked PFAS to slowed metabolic rates, reduced fertility and fetal growth, increased cancer risk and suppression of immune responses.
They’re also frequently in the news. In April 2024, the Environmental Protection Agency (EPA) began regulating levels of six PFAS in drinking water. That same month, Indiana Attorney General Todd Rokita filed a lawsuit accusing 22 companies of polluting Indiana’s natural resources by continuing to manufacture PFAS despite possessing evidence that they harm human health.
Purdue University’s Institute for a Sustainable Future (ISF) has designated a strategic research team (SRT) for PFAS. And the recent launch of the university’s One Health strategic initiative focuses on solving just this type of complex challenge at the intersection of human, animal and plant health.
So, just as a chain of carbon and fluorine atoms distinguishes the chemicals in the PFAS family, the university hosts a chain of researchers needed to address PFAS, including detection and accurate measurement, impact on human and animal health, mitigation in the environment and alternative substances for manufacturing.
Leading the way
Marisol Sepúlveda, professor of forestry and natural resources, and Jennifer Freeman, professor of health sciences in the College of Health and Human Sciences (HHS) and assistant vice president for research development in the Office of Research, co-lead the ISF’s strategic research team on PFAS with faculty across four colleges and eight units. Both were early collaborators with Lee.
“My component of this whole chain is looking at what PFAS do once they’re released, and mostly what they do in aquatic systems,” Sepúlveda explains. As an ecotoxicologist, she studies how PFAS impact an organism’s life, including physiology, behavior and reproduction, from the ecology of an animal community down to how PFAS interact with proteins and DNA.
Marisol Sepúlveda, professor of forestry and natural resources, studies how PFAS affect aquatic systems.
She often uses small fish as models for their high genetic similarity to humans. While those similarities are useful, the differences between organisms are also revealing, she says. A chemical may have a similar impact on a cell, but how fast the impact occurs and how quickly the animal can eliminate that chemical, for example, can vary. Gills are a more efficient means to eliminate PFAS than the methods humans have: through respiration, urine, feces, hair, nails, breastmilk and so on.
Sometimes those differences also hide an important data point. In a study of the impact of PFAS exposure on half a dozen amphibian species, Sepúlveda and her colleagues found something odd: the animals were becoming obese. A typical reaction to a toxic substance would be to lose weight, but the opposite was happening. That might be good for a frog trying to compete in the wild, but this characteristic discovered by chance was eventually found in humans, too, with adverse health impacts like high cholesterol. Sepúlveda and her team are now doing further studies to determine the exact mechanism by which PFAS disrupt lipid metabolism.
Links in the research chain
The support for collaboration was key to Freeman’s decision to join Purdue’s faculty. “I really love team science, so that was one of the initial reasons I came to Purdue. It allowed me to meet people outside of my college who were doing environment-related work and to start those conversations.”
She also values “the structural support that ISF and their team bring to help us and keep us going.”
Lee agrees. “I’m at Purdue because our walls are really thin between departments and colleges. Definitely in the last decade, that interdisciplinary interaction has really been promoted and valued.”
Jennifer Freeman, professor of health sciences, studies the neurotoxicity of PFAS.
Freeman and others in the PFAS SRT cite Lee’s measurements of PFAS in water and tissue samples as key to their work. Understanding how different species absorb, metabolize and excrete PFAS helps with the translational potential, Freeman says.
That translation from zebrafish to humans is valuable to her work on the neurotoxicity of PFAS, specifically, “things that are happening in the brain during development, either during the exposure or right after the exposure. Primarily we’re looking at embryonic exposures in the first three days of the zebrafish life.”
She aligns her exposures and collaborative projects with Chongli Yuan, Charles Davidson Professor of Chemical Engineering, who maintains a human neuronal cell line, “so that work can have a direct translation between the whole animal model and the human cells, so we can compare them.”
Freeman’s team also rinses the fish after PFAS exposure, allowing them to mature to different life stages to determine the impact of PFAS on the neurological system over time, observing behavior and conducting imaging assessments of neurodegeneration or pathological features of different brain diseases that might occur.
She collaborates with HHS colleagues Jason Cannon, professor and acting head of the School of Health Sciences, to compare and contrast her research with his rodent model, and Dan Foti, professor of psychological sciences, who conducts neuropsychological assessments.
From the lab to the pond
Freeman is also lending her expertise to studies with Sepúlveda and Tyler Hoskins, research assistant professor in forestry and natural resources. “I like doing science that can help make decisions to make society better,” says Hoskins. “That’s what drew me to ecotoxicology in the first place — a fascination about all these invisible chemicals in the environment that could be having these profound effects, and we need evidence-based ways to make rules about how much of that we’re going to allow.”
Some of the projects he’s worked on with Sepúlveda use molecular tools to understand the basic mechanisms of PFAS bioaccumulation and toxicity. Hoskins and his frequent collaborator Jason Hoverman, professor of forestry and natural resources, are also interested in how to quantify those effects in the real world.
“What we’ve learned in recent decades is that the way things work in the lab aren’t necessarily the way things work out in nature, because there are a lot of other mitigating factors that you just can’t simulate in a lab environment,” Hoskins explains. Factors like temperature, precipitation, pH, dissolved carbon, and the presence of other chemicals in the water being tested all mediate the way PFAS behave. Wildlife exposed to PFAS also experience multiple stressors, like competing for food while being hunted by predators and dealing with environmental fluctuations.
Tyler Hoskins, research assistant professor of forestry and natural resources, collects Northern leopard frogs. 
Hoskins is studying PFAS levels in constructed ponds and their impact on gamefish. Hoskins is especially interested in constructed ponds, often added to new housing subdivisions and common on agricultural landscapes. While federal and state governments are empowered to monitor fish tissues for contaminants, the bodies of water officials usually sample include rivers, lakes, reservoirs and other public bodies of water. Private ponds are harder to access, but many are regularly stocked with fish that residents eat.
And that could pose a threat to human health, because many of these ponds receive runoff from agricultural lands. A recent analysis by Hoskins and others indicated that approximately 1,900 ponds in Indiana are within 100 meters of a known land application of biosolids.
His colleagues, like Lee, have been studying how the application of human and industrial biosolids used for fertilizer can introduce PFAS into the agricultural landscape — in the soil, taken up by crops or grazing animals, as runoff into streams and even your neighborhood pond.
Some of Hoskins’ preliminary, unpublished data showed surprisingly high levels of PFAS in fish tissue exposed to biosolids runoff, so he secured funding top study if those results are representative of constructed ponds in general or simply a hotspot. He’ll also examine the reproductive effects of PFAS in largemouth bass, the most commonly sought recreational gamefish in the country.
The way forward
With the presence of more than 15,000 different PFAS chemicals in our environment, what do we do now?
Lee and Hoskins agree that coordination, and not just among researchers, is the key. “We need cooperation across academia, industry and government,” Hoskins says. “All of us need to have the same goals. Let’s reduce PFAS use where we can, engineer PFAS replacement products that are not toxic as quickly as possible and work together to reduce the release of these chemicals into the environment.”
It’s helpful to think about PFAS using this “essential use concept” as a starting point. After all, Hoskins says, “PFAS have become so ubiquitous because they’re very useful to us as a society.” Heart valves involve PFAS use without a huge release of PFAS into the environment. Aqueous film-forming foams (AFFF) are one of the most effective ways to extinguish flammable liquids, so although they do release significant amounts of PFAS in the environment, you wouldn’t want to be on a naval ship without them.
A similar approach to reducing and replacing chlorofluorocarbons during the 1980s and 1990s, for example, helped repair the ozone hole in the earth’s atmosphere.
We may choose to continue using some PFAS as needed, but Lee suggests we should work to clean or pre-treat PFAS as a byproduct of manufacturing, require transparency so that manufacturers can more easily come forward when they find a new problem and encourage the EPA to be proactive about specific, annual sampling for PFAS.
Her work, which includes research on the fate and transport of PFAS in agriculture, such as soil, crops, animal production, well water and pollinators, has expanded to include engineering partners who work to filter PFAS through absorption (taking it in) or adsorption (causing PFAS to stick to the surface of another material).
Keeping drinking water safe
One collaborator is George (Zhi) Zhou, associate professor of civil and construction engineering and environmental and ecological engineering who works on water quality and treatment. His research on point-of-use water filtration systems shows that simple activated carbon filters or reverse osmosis filters installed under your kitchen sink are effective at filtering PFAS from drinking water in your home. Some ion-exchange water filters/softeners may also remove PFAS depending on the resin used to trap contaminants.
It’s important, Zhou says, to change the filter often, or it may not remove PFAS effectively.
George (Zhi) Zhou, associate professor of civil and construction engineering and environmental and ecological engineering, works on water quality and treatment.
“I see this in the larger scale, like big picture. It’s a societal issue,” Zhou says. “If you have very limited resources, would you like to treat the trace-level contaminants that may cause issues in the long run, or do you want to use these resources to buy food or pay the rent?”
I addition to Zhou’s work on filters to remove PFAS, Lee and David Warsinger, assistant professor of mechanical engineering, on ReNEW, a National Science Foundation Regional Innovation Engine in the Great Lakes to eliminate PFAS from wastewater. Using electric field assisted nanomembrane filtration, PFAS sit on the filtration membrane and an electric field is used to break them down. ReNEW will allow them to partner with companies who can help scale up the technology more rapidly.
Both Lee and Zhou caution, however, that there’s no one-size technology that fits all circumstances; treatment is a chain as well. “It’s important to evaluate and identify multiple control points to make sure the compounds are not released back to the environment when we’re done with the filter or when we discharge the wastewater,” Zhou says.
You’re a part of the chain
As researchers work to address PFAS in all parts of the environment, “People should not be fearful,” Lee says. “We should just recognize where we are and move forward. Try to be mindful.”
With much more work to be done, Sepúlveda says she never imagined that in her lifetime, she’d be in the middle of a chemical quandary akin to the studies in the 1960s of the health impacts of DDT. She’s proud the EPA cited data from her joint research on frogs to set up the aquatic PFAS limits. “As an ecotoxicologist, that’s a goal in your life: I hope my data will be used by the EPA some time. If it gets used by the federal agency that’s in charge [in the U.S.], what else can you ask?”
What can I do?
You can help mitigate the impact of PFAS in the environment and on your health, say Purdue’s experts, with a few key steps.
- First, educate yourself. Zhou recommends reading about PFAS to understand their origin and sources, as well as their potential health risks.
- He also recommends purchasing a point-of-use water filter, if you can. “Considering installing any treatment system at home, not only for PFAS, but for any other potentially regulated or unregulated compound that may pass through the drinking water system. This can help to minimize the potential health risk of emerging contaminants.”
- And, based on the current state of health research we have, Freeman says, “it’s highly recommended that, if you can, you find ways to avoid PFAS exposure.” She suggests helpful online buying guides that share questions consumers should ask and product labels to look for, including those that indicate no PFAS. Both Lee and Freeman emphasize recognizing your power as a consumer. “When you stop buying and purchasing products with PFAS, and you say, this is no longer my consumer choice, people will stop manufacturing those because nobody wants to buy them,” says Freeman.
