PFAS Found in 57 US Cities as Louisville Reports GenX at 32x Safe Limit

PFAS, used for decades in products such as nonstick cookware, rain gear, cosmetics, food wrappers and firefighting foam, have been linked to cancer, immune deficiencies, high cholesterol and developmental delays in children. They are often called forever chemicals because their strong molecular bonds allow them to persist in soil, water and the human body for decades.

At Louisville’s riverside pumping station, billions of gallons of water rush past each day as the city prepares it for taps across Kentucky. The job demands constant vigilance. Scientists test the water for pH levels, odors, microbes and heavy metals. Unlike many smaller utilities across the country, the Louisville Water Company also routinely screens for PFAS, the near indestructible industrial chemicals that have become a global concern.

Almost every American now carries some PFAS in their bloodstream.

A troubling spike in the Ohio River

One type of PFAS drawing close scrutiny in Louisville is HFPO-DA, better known by the trade name GenX. In December 2024, Louisville’s technicians recorded an unusual spike in GenX levels in the raw water drawn from the Ohio River. The concentration jumped from 3.4 parts per trillion to 52 parts per trillion in a single month, roughly a fifteenfold increase.

To illustrate the scale, Peter Goodmann, Louisville’s director of water quality and research, explained that one part per trillion is equivalent to a single second in 32,800 years or one drop in twenty Olympic swimming pools.

The number remained low by federal standards, but it raised questions for Goodmann’s team. Tracking the pollution upstream led them through Cincinnati and the Appalachian region to a Chemours facility in Parkersburg, West Virginia, roughly 400 miles away. The plant uses GenX in the production of fluoropolymers, a type of plastic vital for semiconductor manufacturing.

The site also has a long and contentious legacy. Lawyer Robert Bilott spent years exposing that DuPont, the former operator, had used another PFAS chemical, PFOA, despite knowing it was toxic. DuPont ultimately settled lawsuits but denied wrongdoing. Chemours was spun off from DuPont in 2015.

What the spike means for Louisville

Goodmann said the December spike matched publicly available discharge data submitted by Chemours. Even so, he stressed that customers were not at risk. PFAS risks are associated with lifelong exposure, and Louisville’s treated water remained below federal safety limits. Much of the public’s PFAS intake also comes from packaged foods and consumer products rather than drinking water alone, he noted.

Chemours did not comment to NPR, but in court filings related to an environmental lawsuit, the company denied that its discharges caused Louisville’s GenX spike. It also said downstream GenX levels in treated water were within safe ranges.

Louisville’s December samples did show elevated levels in untreated water, but after standard filtration the amount fell below the EPA’s new federal threshold, which is not scheduled to be enforced until 2029.

Shifting federal regulations

The EPA began regulating PFAS in drinking water for the first time in 2024. The rules covered six chemicals, requiring utilities to install treatment systems by 2029 if their levels exceeded the limits.

After Donald Trump’s return to the presidency, new EPA administrator Lee Zeldin announced that the agency would keep limits only for PFOA and PFOS, while removing restrictions on four others, including GenX. Utilities also received two additional years, until 2031, to comply with the remaining rules because of cost pressures, especially on rural systems.

A federal study has estimated that about 45 percent of American tap water contains at least one PFAS chemical. When the rules were published, the Biden administration predicted that up to 10 percent of the nation’s 66,000 public water systems would require new treatment equipment.

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A growing legal battle in West Virginia

Chemours is legally permitted to discharge certain chemicals into the Ohio River, but filings from the EPA and environmental groups say the company has repeatedly exceeded its limits.

The West Virginia Rivers Coalition sued in 2024, arguing that the company’s discharges persistently violated its permit. The EPA had already taken enforcement action in 2023, citing repeated overages of GenX and PFOA, but the coalition said regulators were moving too slowly.

Chemours declined interviews, citing the litigation, but noted that utilities downstream, including Louisville and Cincinnati, report that their finished drinking water remains within EPA limits.

In August, US District Judge Joseph Goodwin ruled that Chemours had to immediately stop discharging above its permitted levels. The company filed an appeal soon after.

“This is a victory for public health and the Ohio River,” the coalition’s deputy director, Autumn Crowe, said at the time. “The Court recognized what communities have known for years.”

The challenge of removing PFAS

Goodmann said higher GenX discharges upstream could make it harder for utilities to meet future federal standards. Louisville is already investing about 23 million dollars to redesign its powdered activated carbon system, one of the few proven methods to reduce PFAS levels.

Water advocates emphasise that treatment is far more expensive than prevention.

“Environmental permits are essentially licenses to pollute,” said Nick Hart of the Kentucky Waterways Alliance. “Safe levels represent maximum legal thresholds rather than actual safety.”

Goodmann agrees that the best defence remains keeping contaminants out of rivers in the first place.

“So what we do is manage risk, and we start that at the river,” he said. “It sounds strange, but source water protection is a big deal.”