Grazing in Michiana
I've been writing monthly for The Farmer's Exchange long enough to know that some topics come and go, while others linger. The ones that stay with me aren't always the most technical or headline-grabbing, but they are the ones that reach across the barn aisle and land squarely in the daily decisions farmers make.
Feed. Water. Soil. Trust. That's how I felt after attending this year's Michigan Sheep Producers Assn. Shepherds Weekend in Lansing, where I sat in on a presentation by researchers from the Center for PFAS Research.
The talk, titled "PFAS in Agricultural Systems," left little doubt that these "forever chemicals" are no longer an abstract environmental concern. They are already intersecting with livestock agriculture in ways that matter right now. Per- and polyfluoroalkyl substances, commonly called PFAS, are a large class of human-made chemicals used for decades in products designed to resist heat, water, grease and stains. They are found in firefighting foams, non-stick cookware, waterproof fabrics, food packaging, industrial lubricants and, more recently, in some pesticide formulations approved for use in the United States in late 2025 by the Trump administration.
PFAS are often referred to as "forever chemicals" because their carbon-fluorine bonds are extremely strong, meaning they do not readily break down in the environment. As a result, PFAS are now widespread in soil, surface water, groundwater, wildlife and food systems across the country.
At Michigan State University, more than 80 researchers from fields including soil science, toxicology, animal health, environmental chemistry and risk communication are working together to answer a set of questions farmers increasingly ask: How do PFAS move through agricultural systems? How do they accumulate in crops and livestock? And most importantly, what practical steps can producers take to reduce risk to animals, markets and consumers?
One of the clearest findings from recent research is that PFAS move into livestock primarily through water and feed, not direct contact with soil. Animals drinking contaminated well water or consuming forage grown on affected fields gradually accumulate PFAS in their bodies. Biosolids application, irrigation with contaminated water, proximity to airports or military installations that used aqueous film-forming foams (AFFF), and certain industrial discharges have all been identified as common sources.
Scientific studies published in environmental health and agricultural chemistry journals consistently show that PFAS can bioaccumulate in animals, concentrating in blood and organs such as the liver and kidneys, and then transferring into milk, meat and eggs. This process is not uniform across all PFAS compounds or livestock species.
Some PFAS clear the body relatively quickly once exposure stops, while others persist for months or years. A widely cited example comes from a dairy operation near Clovis, N.M., where groundwater used by the herd was contaminated by PFAS linked to firefighting foam use at a nearby airbase. Testing revealed elevated PFAS levels in cow blood and milk.
Notably, the herd did not show obvious signs of poor health; milk production, reproduction and mortality rates were within normal ranges. Yet the milk was unmarketable due to contamination, illustrating a central challenge of PFAS in agriculture: the absence of visible illness does not mean the absence of risk.
Controlled feeding studies and field investigations show that PFAS accumulation varies widely by species. Ruminants such as cattle and sheep tend to store certain long-chain PFAS in blood and organs, while others pass through more quickly. Poultry exposed to PFAS in water or feed often show measurable concentrations in blood plasma and egg yolks. Swine may accumulate PFAS in muscle and fat tissues, raising concerns for pork products.
A 2023 modeling study in Environment International estimated that even relatively low PFAS concentrations in drinking water can, over time, lead to detectable residues in animal products. The key variable is duration of exposure. Chronic intake, even at low levels, allows PFAS to build up gradually. This helps explain why farms may operate for years without issue, only to discover contamination once testing becomes available or a market threshold is introduced.
Importantly, PFAS concentrations in animals are not fixed forever. Research from Maine, Michigan and Europe shows that switching livestock to clean water and uncontaminated feed can reduce PFAS levels in milk and tissues over time. However, the pace of decline depends on the specific PFAS involved, the species, and how long exposure occurred. In some severe cases, particularly where water contamination is high, animals may never clear PFAS sufficiently to reenter food markets, leading to herd depopulation and significant financial loss.
To understand how this plays out on the ground, consider a typical Midwestern operation: a cow-calf farm in northwest Ohio, a dairy near the Michigan-Indiana line, or a diversified livestock farm outside South Bend. A routine well test reveals elevated PFAS. Soil samples follow, perhaps prompted by historic biosolids application. Forage tests show low but detectable PFAS uptake. The cattle appear healthy. Yet questions quickly pile up. Can calves be sold? Will a processor accept finished animals? Does milk need to be dumped? Who pays for testing?
Maine offers a glimpse of how states are grappling with these questions. After widespread PFAS contamination linked to biosolids, the state established action levels for certain foods, including 210 parts per trillion (ppt) for PFOS in milk and 3.4 parts per billion (ppb) in beef. These are not federal standards, but guidance values intended to protect public health.
Other states, including Michigan, have focused more heavily on drinking water limits and fish consumption advisories, leaving livestock producers navigating uncertainty with limited regulatory clarity. This uncertainty affects more than farm economics. It reaches into consumer confidence.
Milk, eggs and meat are daily staples, especially for families with children. Even trace contamination can erode trust if communication is poor or information is incomplete. For farmers, transparency becomes as important as testing.
Decades of toxicological research link PFAS exposure in humans and laboratory animals to impacts on liver function, immune response, thyroid hormones and reproductive health. Epidemiological studies suggest associations with elevated cholesterol, reduced vaccine response, and certain cancers.
For livestock, however, evidence of overt disease at environmental exposure levels is limited. Most affected animals look normal, perform normally, and reproduce normally. This does not mean PFAS are harmless. Instead, it highlights the difference between acute toxicity and chronic, low-level exposure.
The primary concern today is cumulative exposure over a lifetime, especially when PFAS enters the body through multiple pathways: drinking water, food, dust and consumer products. With more than 4,000 PFAS compounds identified and only a fraction routinely measured, scientists acknowledge that current monitoring captures only part of the picture.
Testing remains one of the biggest hurdles. PFAS analysis requires specialized laboratories, costs can be high, and interpreting results without enforceable food standards is challenging.
Still, Extension specialists and researchers increasingly agree on several practical steps livestock producers can take now:
• Test water first. Drinking water is often the largest single source of PFAS exposure for livestock. Private wells near airports, industrial sites, landfills, or firefighting training areas deserve particular attention.
• Evaluate feed and forage sources. If water tests positive, forage and stored feeds should be assessed to understand ongoing exposure.
• Switch inputs where possible. Providing clean water and uncontaminated feed can significantly reduce PFAS levels over time, particularly in dairy systems.
• Work with experts. Veterinarians, extension educators, and university researchers can help interpret results and develop realistic management plans.
• Communicate early. Open conversations with processors, buyers and consumers build trust and reduce the risk of sudden market disruptions.
Farmers have faced persistent, complex problems before: nutrient runoff, pesticide resistance, soil erosion, and emerging animal diseases. PFAS represents a new chapter, but not an unfamiliar one. The tools remain the same: good science, careful management and honest communication.
Research at institutions like Michigan State University is already moving beyond problem identification toward solutions. Ongoing studies across the Midwest are measuring real-world PFAS transfer rates, evaluating mitigation strategies on working farms, and developing decision-support tools tailored to livestock producers. Farmers are not passive subjects in this work; they are partners shaping how agriculture responds.
PFAS may be invisible, but their implications are not. They affect how we steward land, care for animals, and maintain the trust that connects farms to families. Talking about them; around kitchen tables, at extension meetings, and in barns across northern Indiana and southwest Michigan is not alarmist, it's responsible.