Researchers Identify Hidden Source of Massive PFAS Contamination in North Carolina’s Water System

For years, North Carolina residents and scientists have been puzzled by the stubbornly high levels of PFAS, often called forever chemicals, showing up in water sources across the Piedmont region. A new scientific investigation has finally traced the source of this widespread contamination—and the answer turned out to be something no one was expecting.

This discovery, led by environmental chemists at Duke University, reveals that a local textile manufacturing plant had been unknowingly releasing enormous quantities of nanoparticle PFAS precursors into the Burlington, North Carolina sewer system. These precursors were not the typical PFAS chemicals regulated or screened for by routine tests, which is why the pollution remained undetected for so long. Instead, the plant was discharging solid, insoluble colloidal nanoparticles made of side-chain fluorinated polymers, a form of PFAS precursor that can break down into harmful PFAS once they enter wastewater systems or soil.

According to the research team, the concentrations found in the plant’s wastewater reached up to 12 million parts per trillion, which is roughly 3 million times higher than the U.S. Environmental Protection Agency’s new drinking-water limits for certain PFAS compounds. Because these precursors were invisible to standard monitoring, they had been passing straight through the wastewater system for years.

How Researchers Traced the Source

The investigation began when a statewide PFAS testing network—run collaboratively by Duke University, North Carolina State University, and the University of North Carolina at Chapel Hill—found unusually high PFAS levels in certain drinking-water supplies. One of the most concerning hotspots was Pittsboro, a town that relies on the Haw River. Since Burlington’s wastewater treatment plant discharges upstream of Pittsboro, scientists turned their attention there.

However, their initial results were baffling. The amount of PFAS leaving the Burlington treatment plant was significantly higher than what was entering it. This imbalance suggested that some kind of PFAS precursor was slipping past routine detection and being converted into measurable PFAS during treatment.

One major clue came from Burlington’s use of a specialized treatment technology produced by Zimpro. This method applies intense heat and pressure to break down organic materials. Unfortunately, it also accelerated the conversion of PFAS precursors into the more dangerous forms that researchers could detect. Once this treatment step was discontinued, PFAS levels in the discharged water dropped sharply—but precursors were still entering the sewer system and accumulating in sludge.

To figure out where the precursors were coming from, the research team collected raw sewage and wastewater samples from dozens of points across the city. Early tests showed only small amounts of known PFAS precursors—far too low to explain the contamination. The breakthrough came when the researchers used a process designed to replicate the Zimpro treatment. By converting all potential precursors into detectable PFAS, they discovered that wastewater from one textile manufacturer showed increases of 50,000 to 80,000 percent after oxidation.

The levels were so extreme that the lab’s instruments became contaminated for over a week.

Discovery of Nanoparticle PFAS Precursors

After months of analyzing samples, filtering solids, and running advanced mass spectrometry techniques, the researchers uncovered something new: nanoparticles composed of side-chain fluorinated polymers, suspended in wastewater rather than dissolved like most PFAS chemicals.

These particles had never been documented in an environmental sample before. When the team compared them with a commercial fabric treatment product used in textile manufacturing, the match was nearly identical.

Armed with this information, Burlington officials worked directly with the textile company, using the city’s pretreatment authority under the Clean Water Act. After process changes were implemented at the plant, the amount of PFAS precursors entering Burlington’s wastewater system dropped by orders of magnitude. As a result, every downstream water system began to show significant decreases in PFAS contamination.

Long-Term Environmental Concerns

Even though the immediate source has been controlled, the contamination problem is far from over. For years, Burlington’s wastewater treatment plant had been concentrating these nanoparticle precursors into sewage sludge—biosolids that were then applied as agricultural fertilizer across large areas of eastern North Carolina.

These biosolids now function as a slow-release reservoir of PFAS. As the nanoparticle precursors break down in soil, they gradually transform into regulated PFAS compounds that can migrate into waterways and drinking water sources. This may help explain persistent elevated PFAS levels in places like Chapel Hill’s raw drinking water, even though traditional pollution sources were not present.

Researchers emphasize that no one yet knows how long these nanoparticles take to degrade or how widely they may have spread. They warn that communities all over the country could be dealing with similar issues without realizing it, since current testing methods are not designed to detect polymeric PFAS precursors.

Understanding PFAS and Why They Matter

PFAS—short for per- and polyfluoroalkyl substances—are a large class of synthetic chemicals used since the 1940s in products like nonstick cookware, waterproof fabrics, stain-resistant carpets, cosmetics, and firefighting foams. They are called forever chemicals because they do not naturally break down and can persist in soil, water, and the human body for decades.

Certain PFAS compounds have been linked to a variety of health problems, including:

Increased cancer risk
Immune system suppression
Hormonal disruptions
Liver and kidney effects
Developmental problems in children

What makes the North Carolina discovery especially important is that many types of PFAS precursors—especially polymeric ones like the nanoparticles found in this study—are still unregulated and poorly understood. They often convert into harmful PFAS after environmental exposure, meaning the true scale of PFAS pollution may be far larger than what standard tests reveal.

Why Standard PFAS Testing Often Misses the Problem

Monitoring programs typically focus on a limited list of known PFAS compounds, such as PFOA, PFOS, and GenX. But industries use hundreds of PFAS-related chemicals and polymers that do not show up in targeted testing. Many of these precursors only show their true impact after they degrade.

The Burlington case demonstrates that:

Advanced testing methods are essential for identifying hidden sources.
Wastewater treatment processes can unintentionally convert benign-looking precursors into harmful PFAS.
Biosolid application can turn agricultural lands into long-term PFAS release sites.
Industrial pretreatment is often more effective than downstream fixes.

What This Means for Other Communities

The breakthrough in North Carolina is likely to influence PFAS investigations worldwide. Textile manufacturing is only one of several industries that use side-chain fluorinated polymers; others include outdoor gear, upholstery, carpets, and packaging. Because these polymers can hide inside wastewater as nanoparticles, conventional monitoring may overlook major contamination sources.

Environmental agencies may now need to adopt broader PFAS surveillance strategies, including screening for precursors and polymeric particles. The study also raises new questions about agricultural practices involving biosolids and the need for stricter oversight of industrial wastewater.

Research Paper Reference

Colloidal Side-Chain Fluorinated Polymer Nanoparticles Are a Significant Source of Polyfluoroalkyl Substance Contamination in Textile Wastewater
https://doi.org/10.1021/acs.estlett.5c01014