Elevated levels of unregulated chemicals found in Jordan Lake, Cary drinking water
Posted December 21, 2017 2:57 p.m. EST
Updated December 21, 2017 4:39 p.m. EST
Raleigh, N.C. — Researchers at Duke University have discovered elevated levels of several perfluorinated compounds – an unregulated family of industrial chemicals including some that can raise cancer risks – in Jordan Lake and drinking water treated by Cary.
Cary water treatment officials, who have independently confirmed the findings of Duke researchers, say the town's water is safe to drink. They also point out that the compounds detected are still below health advisory levels set by the U.S. Environmental Protection Agency.
But they are continuing to test both treated and untreated water and have enhanced their treatment process in an attempt to filter out the substances, which are often difficult to remove, as they continue to supply drinking water for about 233,000 people in Cary, Apex, Morrisville and elsewhere.
"We take the concerns of our citizens very seriously," Alexandra Jones, Cary's water systems manager, said. "We've started collecting a lot of additional data to get a better handle on what the situation is."
Although the chemicals are related to GenX, the unregulated and largely untested compound that has caused alarm in Wilmington and other communities along the Cape Fear River, Jones said researchers have not found that chemical in Jordan Lake.
"Given that we are so far below the EPA health advisory and we've never detected GenX, the water is safe to drink," Jones said. "There's not a health concern from our perspective."
Among the family of compounds researchers have examined are PFOS and PFOA, perfluorinated chemicals used in Teflon and other industrial manufacturing processes that are known to cause cancer in lab animals. Jones said the most recent tests of treated drinking water in Cary found levels of PFOA at 5.6 parts per trillion, with PFOS undetectable. That value is well below the EPA's health advisory level for the combined compounds of 70 parts per trillion.
But in Jordan Lake, tests of untreated water found concentrations of the two chemicals combined at 27 parts per trillion. While still below the EPA's health advisory, a level North Carolina relies on, it's nearly twice more conservative thresholds established by states such as New Jersey, which has a limit of 14 parts per trillion.
Heather Stapleton, a professor at Duke's Nicholas School of the Environment, originally set out in September to study levels of perfluorinated compounds in Robeson County, using water from her own tap as a comparison. But when the samples returned from testing a suite of about 10 related contaminants, she found levels elevated at her own Cary home and all but undetectable in Robeson County.
"I was a little shocked by it," Stapleton said.
The chemicals are pervasive in industrialized countries and are often detected at extremely low levels, she said. But they were high enough in her own water to prompt additional testing from other drinking water sources in Cary and in untreated water in Jordan Lake.
Her follow-ups confirmed her findings, as did additional testing by Cary, which began testing on its own last month after Stapleton shared her results.
The collection of related fluorinated compounds added up to a concentration of 100 to 200 parts per trillion in Jordan Lake, which Stapleton notes is an extremely conservative way to look at potential risks.
"We don't know that all of these have a toxic effect," she said.
Researchers aren't yet sure where the elevated levels of perfluorinated compounds in Jordan Lake are coming from. Stapleton said there's no industry source or factory dumping the chemicals, as in the case of GenX in the Cape Fear River. But she said it's possible a nearby wastewater treatment plant is concentrating the substances – which are pervasive in low levels on everything from cooking products to clothing – before discharging into the lake.
"I would imagine some of these at least are coming from residential homes," Stapleton said.
Jamie Kritzer, a spokesman for the state Department of Environmental Quality, said the agency is aware of Stapleton's research findings and is working with state health officials to support Cary if needed. DEQ also is planning to roll out additional monitoring for Jordan Lake and Falls Lake in January that will include more sampling close to areas of wastewater discharge.
Officials at the state Department of Health and Human Services, meanwhile, are providing no additional guidance to water users.
"Since all levels were below the EPA combined lifetime health advisory for PFOA and PFOS, DHHS does not recommend any restrictions on water use," DHHS spokesperson Cobey Culton said Thursday afternoon. "DHHS is continuing to monitor the situation along with DEQ and is reviewing all test results."
In addition to extra testing, Jones said Cary's water plants have been increasing the use of powder-activated carbon during the treatment process. The town's most recent lab reports show levels of several perfluorinated compounds in treated water have decreased since then, but she said they'll need to continue testing to be sure. Levels in treated water are also lower compared to untreated water from Jordan Lake.
"It does seem we were able to remove some of these compounds," Jones said. "Others, not so much."
Although she said Cary is monitoring contaminant levels carefully, she said the town's water users should remember that even the untreated water is showing extremely low concentrations.
"Parts per trillion is something on the order of a drop of water in an Olympic-sized swimming pool," Jones said. "At that level, we're not talking about something that will make you sick today or even next year. We're talking about something that may increase your risk over a lifetime – and that 'may' is important."
But when comparing these results with other water systems she's examined, Stapleton says Jordan Lake does stand out.
"Cary is higher than all of them, which to me was a little shocking," she said.
Since her work began, she's installed a reverse osmosis filtration system for her own home to reduce her risks.
"I have concerns," Stapleton said. "I have young children."