The Overlooked Role of Agricultural Runoff in PFAS Water Contamination
When the topic of per- and polyfluoroalkyl substances (PFAS) contamination arises, the conversation often turns to industrial discharge, firefighting foams, or landfill leachate. But there’s another less-discussed yet significant contributor: agricultural runoff. Yes, the very fields that produce our food may also be quietly delivering toxic « forever chemicals » into rivers, lakes, and groundwater supplies. How did this happen—and what can we do about it?
Understanding the PFAS-Agriculture Link
To grasp the connection between agriculture and PFAS contamination, it’s important to understand the pathways through which PFAS enter the farming ecosystem. While PFAS are not traditionally used in farming operations themselves, they make their way into agricultural environments through indirect but impactful means. Consider these scenarios:
- Application of biosolids: One of the most common practices in large-scale agriculture involves spreading sewage sludge—also known as biosolids—on fields as fertiliser. But what if that sludge contains PFAS from household or industrial sources?
- Irrigation with contaminated water: In regions where surface water or groundwater already contains PFAS, irrigating crops can introduce these contaminants to the soil, eventually leaching them back into the water table.
- Pesticide and fertiliser additives: Some agricultural chemicals—either unintentionally or through poor regulation—have historically included PFAS compounds as surfactants or wetting agents to improve distribution and efficacy.
These practices can accumulate PFAS in soils over time, allowing these persistent chemicals to run off during rainfall events, percolate into groundwater, or be absorbed into crops and livestock.
What the Data Says
Recent studies underscore the growing concern about PFAS in agriculture. A 2022 report from the Environmental Working Group (EWG) identified more than 19 million acres of farmland in the U.S. potentially contaminated by PFAS-laden biosolids. European countries have only begun to quantify their own exposure levels, but similar patterns are emerging.
In the UK, the Environment Agency has issued warnings about elevated PFAS concentrations in regions where biosolids have historically been applied. Soil and water sampling from these areas indicate that PFAS not only remain stable over decades but also migrate into nearby surface water and drinking water catchments.
And while PFAS mobility depends on many factors—compound type, soil composition, and rainfall intensity, among others—the evidence is building: agricultural runoff is more than just nitrogen and phosphorus. It’s harbouring long-lasting chemicals that resist degradation and bioaccumulate along the food chain.
The Problem with “Forever Chemicals” in Farmland
PFAS are notorious for their stability and resistance to natural breakdown. Once introduced into agricultural soils, they don’t simply disappear. Instead, they infiltrate downstream—literally and figuratively—via several pathways:
- Leaching into groundwater: Rainwater can carry PFAS from topsoil to aquifers, compromising drinking water sources.
- Runoff into surface waters: During heavy rainfall or irrigation, PFAS can be washed into nearby rivers and streams, where they affect aquatic life and re-enter human water supplies.
- Uptake by crops and livestock: Studies show that PFAS can be absorbed by common edible crops such as lettuce, potatoes, and corn. Livestock consuming contaminated feed or water can accumulate these compounds in meat, milk, and eggs.
Ultimately, the presence of PFAS in agricultural systems raises difficult questions about food safety, land use policies, and the long-term sustainability of current farming practices.
Real-World Case Studies
Let’s take a look at how PFAS agricultural runoff has proved problematic around the globe:
- Maine (USA): In 2021, the state shut down nearly a dozen dairy farms after dangerously high levels of PFAS were detected in milk samples. The culprit? Fields fertilised with PFAS-laden sludge decades earlier.
- Germany: A region near Baden-Württemberg reported widespread PFAS contamination in surface waters linked to fertiliser additives used in the 1990s, leading to drinking water remediation efforts impacting thousands of residents.
- UK observations: Though specific cases of PFAS-affected farms have not yet dominated headlines in the UK, pilot monitoring in areas such as Herefordshire and parts of Northern Ireland have detected PFAS in soil and water linked to past sludge applications and runoff from treated lands.
These examples underline a troubling reality: what we did on our farms 10, 20, or even 30 years ago can haunt us today through our waterways and food sources.
Why Is Regulation Playing Catch-Up?
PFAS contamination through industrial channels is now subject to increasing regulation, particularly in the EU and the United States. But the agricultural side of the story has lagged far behind. Why?
Part of the problem stems from outdated waste management policies that permitted or even encouraged biosolids use without thorough chemical screening. In the UK, until recently, PFAS were not part of routine sludge testing. That’s beginning to change, but progress is slow and met with resistance from stakeholders wary of added costs and regulatory constraints.
Complicating matters further, PFAS are not a single substance but a family of over 4,700 chemicals, each with unique properties and toxicological profiles. Tracking and regulating every one of them—especially in a diffuse context like farmland—is a monumental challenge.
What Can Be Done?
Addressing PFAS pollution from agricultural runoff will require a multifaceted approach, blending regulatory oversight, scientific monitoring, and changes in agricultural practice. Here are a few steps that experts and policymakers are beginning to consider:
- Ban or restrict PFAS in biosolids: Several countries, including the Netherlands and parts of the US, are re-evaluating the legal use of sewage sludge containing PFAS. Tighter controls could reduce the long-term burden of PFAS entering farmland.
- Expand monitoring programmes: Regular testing of soil, surface water, and crops in agriculture-intensive regions can help identify PFAS hotspots and guide remediation efforts.
- Innovate filtration and remediation techniques: Advanced technologies such as activated carbon, ion exchange, or new PFAS-binding soil amendments could be deployed to remove or immobilise PFAS in vulnerable areas.
- Educate farmers and agribusinesses: Many landowners are still unaware of PFAS risks. Outreach and training can empower them to demand cleaner waste products and adopt runoff-reducing practices like contour farming or vegetative buffer zones.
And let’s not forget the role of consumers and advocacy groups who continue to push for corporate accountability and more sustainable supply chains.
A Wake-Up Call for Sustainable Agriculture
The agricultural sector, long seen as a passive recipient of pollution, is becoming an unexpected contributor to the spread of PFAS in the environment. While farmers themselves are rarely to blame—many have unwittingly inherited contaminated fields—the implications for public health and environmental sustainability are undeniable.
Addressing the problem isn’t just about reacting to contaminated water; it’s about rethinking how we manage farm inputs, waste recycling, and chemical safety across the agricultural supply chain. Until that happens, the quiet migration of PFAS from fields to faucet will continue—largely unnoticed and insufficiently addressed.
As researchers, regulators, and citizens, we have a responsibility to challenge the status quo and prioritize safe land stewardship. Because at the end of the day, what runs off the farm doesn’t stay on the farm—it ends up in all of us.