PITTSBORO — Duke University researchers presented their findings from a study of PFAS contamination in Pittsboro’s drinking supply at a virtual town hall meeting on Saturday.
Their conclusion: PFAS levels are trending the wrong way, but more research is still needed.
The research group, led by Duke University Nicholas School of the Environment professor Heather Stapleton, launched its investigation into Pittsboro’s water supply after disconcerting results came back from an earlier study of PFAS levels around the greater Triangle region.
“The reason we got into this study was based on some work we were doing in 2018,” Stapleton said. “We were collecting tap water samples from different communities in research triangle park… For Pittsboro, the average concentration was 95 nanograms per liter, and this was higher than the concentrations we measured in the other areas.”
The figure surprised and worried the researchers. PFAS — a family of per- and polyfluoroalkyl substances — have appeared regularly since the 1950s in consumer products such as Scotchgard, non-stick pans and fast-food containers. The chemicals are incomparable as water, grease and stain repellents.
But they are also notorious health hazards.
“There have been a number of studies investigating health effects from exposure to PFAS,” Stapleton said, “and we know based on these studies — laboratory studies and human epidemiological studies — that higher exposure to PFAS is associated with risks for thyroid disease, increased blood cholesterol levels, reduction in our bodies’ abilities to fight off viruses, reduction in our response to vaccines — so, implicating our immune systems — and implications for reproduction and birth outcomes.”
Their prevalence in drinking water is especially insidious. PFAS in consumer products are not readily ingested into the body and they can be thrown away and replaced with safer alternatives. Water, on the other hand, is inescapable.
“(They have) high persistence in the environment and it’s the reason why they’re called ‘forever chemicals,’” Stapleton said. “They’re very difficult to break down. Because of this persistence, they’re found very often in the environment and they’re commonly detected in people’s blood and they do accumulate in our bodies over time.”
The two most common PFAS are PFOS and PFOA. They have been rising steadily enough in water supplies around the country to earn a federal health advisory from the Environmental Protection Agency.
“The EPA has established a health advisory for drinking water for just PFOA and PFOS and that advisory is 70 ng/L,” Stapleton said. The figure represents a recommended maximum allowable contamination level. “This is not enforceable as just a health advisory but there are efforts under way to consider and establish an enforceable standard for drinking water, a maximum contaminant level or MCL.”
The researchers’ preliminary measurements returned contamination levels much higher than the recommended maximum, but only in Pittsboro.
“So, we wanted to understand why?” Stapleton said. “Why are there PFAS in (Pittsboro’s) drinking water and where are they coming from? Well the answer is because they’re in the Haw River.”
Pittsboro is the Triangle’s only municipality that draws its drinking water from the Haw — and the river is teeming with PFAS.
After sampling the water at several locations upstream of Pittsboro’s water intake, Stapleton’s team concluded the contaminants are likely derived from factory effluents in Burlington.
“So, this led us, then, to wonder and question what this would mean for the residents of Pittsboro in terms of their actual exposure and their blood levels,” Stapleton said.
To find out, the team recruited 49 participants from Pittsboro — 18 men and 31 women — for a follow-up study “with the goal of trying to understand if levels in this population were higher than the general U.S. population,” Stapleton said.
The volunteers, whose ages ranged from 33 to 86 with a median of 60, provided samples on two occasions approximately two months apart.
Both sets of collected data — PFAS levels in the participants’ drinking water and from their blood — painted a worrisome picture.
PFAS concentrations in drinking water ranged from about 50 ng/L to as high as 452 ng/L. A handful of participants submitted bottled water as representative of what they drink most often; their samples returned no PFAS contamination.
Blood samples showed much less variability.
“PFAS was detected in all the blood samples, and there was very little difference in PFAS measured at the two different time points,” Stapleton said, emphasizing the duration of PFAS retention within the human body.
The results confirmed what the town’s residents have been hearing for two years: PFAS contamination in Pittsboro is much worse than elsewhere in the country — specifically, two to four times worse.
Some chemicals within the PFAS family, such as PFHxA, are not even measurable in other state’s water supplies, but their concentrations are rising in the Haw.
“PFHxA, a PFAS that was detected in all the blood samples from Pittsboro … is very abundant in the water,” Stapleton said. “Back in 2018, the concentrations were almost 300 ng/L … The exposure and concentrations of this PFAS have been increasing over time.”
But there is good news. Concentrations of some PFAS, such as PFOS, have decreased precipitously in the last 15 years.
“If you look back to what the levels have been in the past,” Stapleton said, “… the measurement of PFOA measured in samples that were collected from the Haw River in 2006 was 200 ng/L. A follow-up study in 2013 collected samples from the Haw River and measured concentrations around 34 ng/L. So, this does suggest that the PFOA levels in the Haw have been coming down.”
Still, the sum total of PFAS in Pittsboro’s water continues to rise, a fact the EPA has neglected to recognize, Stapleton said. Their advisory applies only to individual chemicals within the PFAS family. But PFAS come in clusters.
“They’re often found in mixtures,” Stapleton said. “You’re not going to find one without the other.”
The EPA’s 70 ng/L health advisory only applies to PFOS and PFOA, taken separately. In Pittsboro’s water, there were on average 48 and 15 ng/L of PFOA and PFOS, respectively.
“So, the drinking water utilities have every right to say that the water is in compliance with all federal and state standards,” Stapleton said. “It’s not above the health advisory.”
The sum of just five common PFAS in Pittsboro’s water, however, totals 224 ng/L — well above healthy levels.
Recognizing the folly inherent to the EPA’s policy, many states have imposed their own PFAS regulations. New Jersey restricts PFOA levels to 14 ng/L. PFOS and PFNA may be no higher than 13 ng/L. Michigan is even stricter limiting PFOA to 8 ng/L and PFNA to 6 ng/L.
“Some states are taking an even more progressive approach like Vermont and Massachusetts,” Stapleton said, “… they came to the conclusion that we should really be thinking about the sum total of PFAS in the drinking water, and so they developed an MCL of 20 ng/L for the sum total.”
Stapleton hopes North Carolina will consider similar measures and that local leaders will take steps to stymie PFAS contamination in Pittsboro’s water before levels reach critical concentration. Several government officials were present at the town hall including Representative Robert Reives II (N.C. House, Dist. 54) and Pittsboro Town Manager Chris Kennedy, whose own water quality task force recently concluded an investigation into Pittsboro’s PFAS problem. You can read the highlights of their report in this edition.
Stapleton’s research has made considerable progress toward understanding the scope of Pittsboro’s PFAS crisis, but it will take more effort to enact any significant change.
“We really need more information to understand how the levels here are associated with any health outcomes, particularly cancer,” Stapleton said. “…This is not the end by any means. Hopefully, this is just the beginning.”
Reporter D. Lars Dolder can be reached at dldolder@chathamnr.com