By Greg Barnes

A new Duke University study has found that the concentrations of some potentially cancerous per- and polyfluoroalkyl substances — or PFAS — are two to four times higher in the blood of Pittsboro residents than the U.S. population as a whole.

The study also found that some types of PFAS chemicals found in Pittsboro residents’ blood are “strikingly similar” to those found in the blood of Wilmington residents during an earlier study conducted by N.C. State and East Carolina universities.

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The findings suggest that two of the legacy PFAS compounds — PFOA and PFOS — and at least one newer type of the substance are coming from the Haw River and finding their way downstream into the Cape Fear River, potentially contaminating drinking water for 1 million people, or 10 percent of North Carolina’s population.

“These data suggest that any drinking water utility drawing water from the Haw or Cape Fear River between Burlington and Wilmington could have similar exposures, and that’s a lot of people,” said Heather Stapleton, a Duke University researcher in the Nicholas School of the Environment. Stapleton is the lead investigator for the study.

Communities that draw their drinking water directly from the Cape Fear or Haw rivers include Sanford, Harnett County, Fayetteville, Wilmington and Pittsboro.

Previously, many people assumed that contamination found in drinking water for New Hanover, Pender and Brunswick counties had been coming largely from the Chemours chemical plant in Bladen County, Stapleton said.

Chemours has been ordered to stop releasing GenX and other PFAS into the Cape Fear River, though some contaminants continue to leach into it from groundwater.

Stapleton said some of the PFAS showing up in Wilmington’s drinking water have no apparent connection to Chemours and are likely coming from upstream of the company’s Fayetteville Works plant.

“What this suggests to me is that the source of exposure could be the same,” she said. “If you think about the fact that the Haw River empties into the Cape Fear River then it’s likely that a lot of the PFAS that is reaching Wilmington is coming from the Haw River itself.”

Study presented to Pittsboro residents

Stapleton and other researchers presented preliminary study results Saturday at a town hall Zoom meeting for Pittsboro residents. The study had a small sample size — researchers drew blood from 49 Pittsboro residents and tested their tap water for PFAS.

While the study was underway, Duke researchers had been collecting water samples since 2018 at sites along the Haw River. Since 2019, weekly samples have been collected along the river at nine sites from Burlington to Pittsboro. At least two collection sites are on Jordan Lake, where concentrations of PFAS have been detected at lower levels. The Haw flows into the lower end of the lake, where the Cape Fear begins.

The researchers tested for 13 types of PFAS in the 49 Pittsboro participants — 18 men and 31 women between the ages of 33 and 86. The levels of PFAS detected in drinking water ranged from none — largely because those people were either drinking bottled water or used advanced filtration systems — to 452 parts per trillion (also measured as nanograms per liter.)

The legacy compounds PFOA and PFOS were found in the residents’ blood at the highest concentrations. A shorter-chain compound, called perfluorohexane sulfonic acid (PFHxS), was found at the third-highest concentration. Stapleton said the three substances made up about 90 percent of the PFAS found in residents’ blood.

“What’s in your blood today is a result of your exposure, not just in the last 24 hours or the last week, but really over a lifetime, and particularly over the last decade,” Stapleton said. “PFOA, PFOS and PFHxS in particular have very long half-lives in the body. That means once they get into our body, it is a long time before they’re lost or excreted from our body.”

a woman in rubber boots collects water from a muddy river, looking for PFAS. She's wearing a sweater, winter clothes
Emily Sutton, the Haw River riverkeeper, taking samples in the Haw River in early 2019. A sample she took in July 2018 near Pittsboro drinking water intake measured 1,076 parts per trillion of PFAS, the highest recorded in the state. Photo credit: Greg Barnes Credit: Greg Barnes

Stapleton explained that PFOS has a half-life of about 3.4 years. Without any additional exposure, she said, it would take that long for half of the substance’s concentration to leave the body, seven years for it to drop to 25 percent and 11 years before it reached 12 percent.

Another substance called perfluorodecanoic acid (PFDA) was found in the study participants at a level five times higher than the general U.S. population. It is often used as a wetting agent, which allows for water to saturate a surface. PFDA is also used as a flame retardant. The substance was not found in the blood of  Wilmington residents.

No conclusions on residents’ health

The federal Environmental Protection Agency does not regulate the estimated 5,000 types of PFAS known to exist. The only health advisory the agency has set is for PFOA and PFOS at 70 parts per trillion, either by themselves or in combination.

Pittsboro is the only community that draws its drinking water from the Haw, where total PFAS levels have been detected exceeding, at times, 1,000 parts per trillion. The highest level found in Pittsboro’s drinking water during this study was 760 parts per trillion, or nearly 11 times higher than the EPA’s health advisory for the consumption of PFOA and PFOS over a lifetime.

The study, which is still being developed, has so far drawn no conclusions on whether the health of Pittsboro residents is being harmed by the PFAS contamination.

“We are going to be collaborating with N.C. State with the hope of expanding this study and recruiting volunteers to collect more blood samples,” Stapleton said in an interview with NC Health News before the town hall meeting. “Our hope is that we can try to determine if higher levels are associated with any adverse health risks, with a focus potentially on thyroid disease or immune function.”

The study is also looking at whether high levels of PFAS in pregnant women is associated with lower birth weights in infants. Stapleton said it’s statistically hard to determine whether birth weights are lower in Pittsboro than elsewhere because of its small population of about 4,000 people.

Where is it coming from?

Drinking water is the primary source of PFAS in Pittsboro residents, but the contaminants also come from firefighting foam and many common household products, including food packaging, Teflon pans, rain-resistant clothing, stain-proof fabrics and anything that keeps food or liquid from sticking. PFAS are known as forever chemicals because they do not break down easily in the environment and accumulate in the human body.

The legacy compounds PFOA and PFOS are associated with kidney and liver disease, high cholesterol and immune suppression in humans. Although those compounds have been phased out in the U.S. in favor of what were originally thought to be safer, shorter-carbon-chain PFAS cousins, they continue to be found in high levels throughout the Cape Fear River basin.

Stapleton said the sources of PFOA and PFOS in the basin include household products that get into the rivers as waste, runoff of biosolids from farm fields and industrial byproducts that flow unfiltered through wastewater treatment plants.

Most of the other types of PFAS have not been well studied in humans, but those that have been suggest a link between an increased risk of thyroid disease, preeclampsia, higher blood cholesterol levels and blood pressure, a decrease in the body’s response to vaccines and lower infant birth weight.

Searching for sources

Researchers and the state Department of Environmental Quality don’t know the sources of most of the PFAS and 1,4 dioxane in the Cape Fear River basin, but they are trying to find out.

The DEQ last year ordered 25 municipal utilities in the basin to test for the substances at their sewer treatment plants. Of those, 19 reported total PFAS levels of more than 100 parts per trillion.

Sanford’s sewer plant recorded the highest level of PFOS at 1,000 parts per trillion. After extensive sampling, officials now believe a single, unknown discharge occurred that caused the spike. The levels measured since then have been far lower, though total PFAS was found at 399 parts per trillion at the same sewer plant in April.

The DEQ also asked 19 industries known to be using PFAS to measure their discharges into the river basin. High levels were found leaving many of them.

Meanwhile, the N.C. PFAS Network has been sampling drinking water from all public utilities in the state. Of the 320 utilities tested, nearly half had detectable levels of PFAS. The highest level measured was 846 parts per trillion in Pittsboro.

The DEQ’s investigations into discharges of 1,4 dioxane have resulted in special orders by consent against Greensboro and Reidsville, which hold the pretreatment permits for their sewer utilities. Those cities have been ordered to reduce the levels of 1,4 dioxane leaving their sewer treatment plants.

Correction: This story originally stated that perfluorodecanoic acid is a short-chained PFAS. However, PFDA has 10 carbons and is not considered short chained.  For PFCAs, carbon fewer than 7 is considered short chained.

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Greg Barnes retired in 2018 from The Fayetteville Observer, where he worked as senior reporter, editor, columnist and reporter for more than 30 years. Contact him at: gregbarnes401 at