How New Jersey’s Limits on “Forever Chemicals” in Tap Water Brought Levels Down

Levels of toxic "forever chemicals" in New Jersey's public water systems dropped by as much as 55% after the state moved to limit the contaminants in drinking water, according to a Rutgers Health researcher who analyzed 19 years of monitoring data from throughout the state.

Their findings in Environment International represent one of the first formal evaluations of whether state-level regulations on per- and polyfluoroalkyl substances (PFAS) effectively reduce contamination.

PFAS are a class of thousands of synthetic chemicals used since the 1940s in nonstick cookware, waterproof clothing, firefighting foam and other products. Called forever chemicals because they resist breakdown and accumulate in the human body, PFAS have been linked to elevated cholesterol, immune dysfunction, liver damage, low birthweight and cancer. In 2024, the International Agency for Research on Cancer classified perfluorooctanoic acid (PFOA), one of the most studied PFAS, as carcinogenic to humans.

An estimated 99% of Americans have detectable PFAS in their blood, and even low concentrations in tap water can produce blood levels more than 100 times the drinking water concentration.

Although researchers have yet to establish the exact extent of the harms such levels produce, state regulators signaled plans to cap concentrations in 2015 and put the first limits in place three years later.

"We knew that these standards had been put in place, and it's now been almost 10 years," said Hari Iyer, a lead author of the study and a cancer epidemiologist in the Department of Medicine, Rutger Robert Wood Johnson Medical School and a member of the Cancer Prevention and Control Program at Rutgers Cancer Institute, New Jersey's only National Cancer Institute-designated Comprehensive Cancer Center, together with RWJBarnabas Health. "We wanted to see: was there any impact of these regulations on the actual levels in the water?"

Iyer's team analyzed about 12,000 monitoring results for three PFAS - PFOA, perfluorooctanesulfonic acid (PFOS) and perfluorononanoic acid (PFNA) - from 47 community water systems serving about 45% of the state's population. The data spanned 2006 to 2025. Using interrupted time-series analysis, the researchers compared post-regulation trends with what would have occurred without the policy change.

PFOA levels fell by 55% and PFNA levels decreased by 50% after the state's Drinking Water Quality Institute recommended maximum contaminant levels for those chemicals. The share of water samples exceeding safety limits dropped from 49% to 15% for PFOA and from 24% to 2% for PFNA. PFOS showed a more modest decline.

One of the study's more notable findings was that water systems began acting before the regulations became binding. Once the Drinking Water Quality Institute recommended the limits, utilities started shutting down contaminated wells and installing granular activated carbon filtration in anticipation of the rules. The researchers used the recommendation date rather than the later adoption date as their policy intervention point.

In Paulsboro, N.J., for example, high PFNA contamination was detected in the public water supply in 2009 but not reported to the public until 2013. Officials then shut down contaminated wells, and by 2016, the town's water system had installed treatment that reduced PFNA to undetectable levels, even though the state officially adopted maximum contaminant level limits in 2018.

Iyer said government colleagues initially questioned whether the study was necessary.

"They said, 'We know what's going to happen when you put regulations in place. The levels are going to drop. It's not rocket science," he said. "But I think people want to know if these policies are working."

New Jersey was the first state to set an enforceable PFAS drinking water standard, adopting a maximum contaminant level for PFNA in 2018 and adding limits for PFOA and PFOS in 2020.

The study has limitations. The 47 water systems analyzed were generally larger, with longer monitoring histories, and may have been more aggressive about addressing contamination. About 11% of the state's residents rely on private wells not covered by these regulations. And the researchers found evidence that levels of some unregulated PFAS increased, potentially reflecting chemical substitution by manufacturers.

Iyer's team is now working to connect water-quality data to health outcomes, using cancer registry records to model how PFAS exposure may be associated with survival and other patient outcomes. A separate study at Rutgers Cancer Institute, called REPEL, is recruiting men with prostate cancer to measure PFAS in their blood and tap water.

"There are a lot of things in the world that can harm us," Iyer said. "We want to make sure we're focusing our regulations and our energy on the things that matter most and setting limits that actually improve human health."

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