Prairie Research Institute

Examining Contaminants

Pinpointing Threats to our Health & Safety

From the atmosphere and the air we breathe to the soil and the groundwater beneath it, Prairie Research Institute units have been at the forefront of studying contaminants for more than a century. Both well-known and emerging contaminants can cause ecological and human health concerns, and PRI scientists are interested in their sources, effects, and mitigation.

PRI units like the Illinois State Water Survey (ISWS) have a long history of gathering data on our environment and resources— and helping to solve contemporary problems caused by contaminants. Walt Kelly, recently retired head of the water survey’s groundwater science section and a groundwater geochemist, said the ISWS groundwater quality database dates to the 1890s and contains tens of thousands of samples from across Illinois. In recent years, ISWS has done a number of county-wide water quality studies in several Illinois counties, gaining a regional picture of groundwater health. Data like this allows researchers to see a snapshot of water quality in an area during a certain time and to analyze trends over time, such as with chloride contamination from road salt.

Road salt, which is very soluble and can quickly infiltrate water resources, is an example of a human contaminant. This category of contaminants also includes emerging contaminants like per- and polyfluoroalkyl substances (PFAS), pharmaceuticals and personal care products (PPCPs), and microplastics, as well as contaminants related to agriculture, including nitrates, phosphorus, and pesticides. Kelly said some examples of naturally occurring contaminants in groundwater are arsenic, which is found in sand and glacial deposits throughout the state, and radium, which is found in the deep bedrock aquifers in northern Illinois. Pathogens can also contaminate water supplies.

word salt spelled in salt on asphalt with snow

Geology doesn’t just contribute to the occurrence of natural contaminants, it also plays a role in how contaminants move from their source to groundwater. Karst landscapes are vulnerable to surface contamination, Kelly explained, because of the way the water flows through the porous rocks’ crevices and conduits. Several research projects in karst areas in southern Illinois and northern Illinois, particularly in Jo Daviess County, that began in the 1990s brought together four of the five surveys housed within PRI today.

The expertise of Illinois State Geological Survey (ISGS) and ISWS scientists played an important role in Jo Daviess County in the early 2000s, when a large dairy operation was proposed in the area, and researchers continued to collaborate with local officials and stakeholders to map the county’s geology and gather data after that initial involvement. Researchers in karst areas also began looking for emerging contaminants, because if those contaminants were present, they would likely be found in a karst landscape, Kelly said. Researchers on these projects found PPCPs, microplastics, bacteria, pesticides, and other contaminants. By involving scientists from ISGS, ISWS, the Illinois Sustainable Technology Center (ISTC), and the Illinois Natural History Survey (INHS), he said their work resulted in research that sees the big picture— from understanding the geology, to sampling, to analysis, to exploring the impacts of contaminants on the flora and fauna of the area.

“It is a good example of the different surveys working together,” Kelly said. “We needed that group effort because none of us could do the entire project on our own, and having the expertise in all of these different areas made it work.”

Over time, the scientific understanding of contaminants grows, as does awareness of substances that become environmental contaminants after their use has become popular. PRI scientists have been at the forefront of contaminants research for a century— from ISWS helping to solve the mystery of a typhoid epidemic in Pana in 1916 to ISTC’s work studying environmental pollution over the past nearly four decades.


John Scott, a senior analytical chemist and associate research scientist, has been at ISTC for 23 years. ISTC research on current emerging contaminants includes those making headlines, like PFAS and microplastics, as well as PPCPs. Scott explained that he and his colleagues work to discover and study new emerging contaminants, as well as innovative ways to treat them and prevent them from entering the environment.

Their research has also looked at products that have been used over many years to study trends and understand potential health impacts. One ISTC study, published in 2014, explored the use of flame retardants in homes— used in textiles and carpeting— and found a link between the use of these chemicals and hyperthyroidism in cats. Rates of hyperthyroidism in cats began increasing in the 1970s, around the same time that flame retardants became common in textiles, carpeting, and other household items, Scott recalled. The researchers wondered if cats, who are always in the home and who clean themselves, increasing their exposure to substances present in their environment, could be sentinels for the exposure of children and adults to these chemicals.

With regard to emerging contaminants, much is still unknown. These contaminants are found in the environment, but little is understood about any consequences for human, animal, and ecosystem health. New ISTC research has tracked PFAS and microplastics through waste systems. These contaminants were detected in the water that filters through waste in landfills, landfill leachate, which in some landfills is captured and sent to wastewater treatment plants. In older landfill systems, this material can percolate directly into surrounding soil and groundwater. This study found that PFAS and microplastics contained in the landfill leachate were effectively removed by the wastewater treatment process and the effluent from these systems contained very low levels of these contaminants. However, it was also found that these contaminants were enriched in the solid residuals, biosolids, produced during the wastewater treatment process. Since these materials are commonly land-applied for fertilizer, the results warrant concern that these chemicals are being re-released in the environment.

“We care about emerging contaminants because we don’t know where this stuff is going to end up,” Scott explained. “It could end up in your water; it could end up in your food. There is this perception that if I throw something away and it goes to the landfill, it’s gone forever— but it’s not, because landfills interact with the environment.”

Microplastics floating in a current.


“One thing about plastic is the staggering amount of material,” Scott said

Around 400 million tons of plastic is produced each year, according to the United Nations Environment Programme. In the environment, plastics do not biodegrade in the ways organic material does. However, plastics do break down into smaller and smaller pieces. In addition to broken-down plastic fragments, plastics are also found in products like synthetic fabrics and exfoliating scrubs. Plastic pieces that are less than 5 millimeters in at least one dimension are considered microplastics, according to ISTC.

Researchers are interested in learning how these fragments move through the environment, how other contaminants combine with them, what their chemical makeup is, and their consequences for health and ecosystems. Scott explained that part of the problem with microplastics is that nobody knows for sure what those consequences are.

Research is still needed to understand the toxicity of microplastics, Scott notes, but they have been found throughout food webs, with negative impacts, and in human tissues. Additionally, plastics can be made using substances that are toxic to humans, leading to questions about what happens when those plastics eventually break down into their component ingredients. Also, some additive chemicals, like phthalates, have been found in food packaged in plastic.

Used fire-extinguishing foam.


PFAS make up a class of more than 5,000 compounds that are water- and oil-repellant, reduce friction, and are resistant to degradation, Scott explained. “It’s like a miracle compound.”

“It has all of these wonderful properties, but those wonderful properties are also what make it problematic,” he said, adding, “And it lives forever, too. That’s why you hear them called forever chemicals.”

PFAS have been available for a variety of uses, including in consumer products, since the 1940s, according to the U.S. Environmental Protection Agency. PFAS have also been used in manufacturing, fire-extinguishing foam, food packaging, personal care products, carpeting and upholstery, household cleaners, nonstick cookware, and paints, varnishes, and sealants.

Research into the impacts on human health from exposure to PFAS is ongoing, according to the EPA, but has found adverse effects on fertility, blood pressure in pregnant women, childhood development, the immune and endocrine systems, cholesterol levels, obesity, and cancer risk for certain types of cancers.

PFAS are water soluble, so they easily contaminate surface- and groundwaters and then move through the environment. Recent ISTC research, funded by the Illinois–Indiana Sea Grant, found that PFAS can stick to microplastics that have made their way into waterways, which could have additional implications for how the compounds make their way into food webs when ingested by fish and other animals. These compounds can also bioaccumulate in the bodies of humans and animals.

PFAS are also difficult to address once released into the environment. Current ISTC research— with funding from a nearly $1 million U.S. Department of Defense grant— aims to develop an innovative and cost-effective clean method to remove PFAS from water and completely destroy these forever chemicals.

multicolored pills on white table


These contaminants come from cosmetics, personal hygiene products, and medications used for humans and animals. There are thousands of chemicals that fall into this category, but according to ISTC, some common PPCPs are caffeine, carbamazepine, gemfibrozil, ibuprofen, naproxen, sulfamethoxazole, triclosan, and estrogens. By improper disposal and through wastewater systems, these chemicals have been found to make their way into the environment.

PPCPs have been found in ground- and surface water with negative consequences for aquatic life. Researchers are also interested in understanding whether these chemicals can be taken up by plant roots and bioaccumulate, with the potential to affect food chains.

ISTC has worked on PPCP contaminants for 15 years. ISTC researchers have completed multiple grants from state and federal agencies, investigating questions about the environmental fate and transport of veterinary pharmaceuticals and animal hormones through large animal farm waste and the removal efficacy of municipal wastewater treatment plant processes. These projects have implications for public health, from understanding the pollution of water supplies to assessing potential effects due to antibiotic-resistant bacteria.

Currently, ISTC researchers are collaborating with colleagues from ISWS to monitor PPCP contaminants related to rural sewage effluent irrigation and develop effective mitigation strategies to reduce PPCP loads to surface or groundwater. This project is funded by the U.S. Department of Agriculture’s National Institute of Food and Agriculture with the aim to diminish the negative impacts of irrigation with rural sewage effluents and improve the efficiency of agricultural water use to protect water quality, thereby increasing U.S. water and food security.


Among other agricultural chemicals studied by PRI scientists, a group of pesticides is getting a closer look from INHS researchers because of their possible link to declining macro-invertebrate numbers.

Illinois River Biological Station Director Jim Lamer said INHS’ recently revived macro-invertebrate monitoring program is doing contaminant sampling, primarily looking at neonicotinoids. The program will also test for a whole suite of contaminants that includes other pesticides and emerging contaminants.

Neonicotinoids, often used as a coating on seeds, are water soluble and can persist for a long time in the water and in soils, Lamer explained. The monitoring program is currently studying burrowing mayflies, whose larvae burrow into the soil and stay there for around a year as part of their lifecycle.

In the past dozen years, the upper Mississippi River has seen a “pretty drastic decline in burrowing Mayfly numbers,” and research out of Wisconsin and Minnesota paints “quite a bleak picture” for macro-invertebrates, Lamer noted. In addition to learning whether burrowing mayflies— a food source for other invertebrates, fish, frogs, and birds— are symptomatic of a larger problem, INHS is now positioned to continue to answer questions about the impacts of contaminants across ecosystems.

Burrowing mayfly larva.

The macro-invertebrate monitoring works with a component of the Long Term Resource Monitoring program, which brings together the work of researchers and agency partners from the states that make up the upper Mississippi River system. The Illinois River Biological Station has contributed to the program since the 1990s. It is funded by the U.S. Army Corps of Engineers and implemented by the U.S. Geological Survey to provide monitoring of natural resources in the river system.

“We’re fortunate to have that infrastructure with the Long Term Resource Monitoring program that we can do this work systemically across the entire basin, not just within our own silo,” Lamer said.

Read more PRI 15th-anniversary stories.