The Duke University women’s rowing team practices at Lake Michie in spring 2016. Lake Michie is a drinking water source for Durham; recent tests show low levels of perfluorinated compounds in the water. (Photo Lisa Sorg)
In early spring, Lake Michie stirs to life, with fishers and the Duke University women’s rowing team taking to the water at dawn. The 480-acre reservoir near Bahama is not only a source of largemouth bass, but it is also a boating destination, and it provides Durham with 30 million to 35 million gallons of drinking water each day.
Testing by the City of Durham’s water department detected low levels of perfluorinated compounds in both Lake Michie and the Little River, another drinking water source, near Treyburn. The levels ranged from 2.4 parts per trillion to 7 ppt.
Treated water from the Brown plant, which flows from the thousands of taps in Durham, also had low concentrations of the compounds — PFOA, PFOS and PFB — ranging from 2.7 ppt to 4.8 ppt. (The Williams plant is offline until later this year for renovations.)
Vicki Westbrook, assistant director of water management, announced the findings last night at a GenX forum sponsored by the Sierra Club and NC Central University School of Law. The city had just received the results within the previous 24 hours.
These are not the same compounds as GenX, which has been found in public drinking water systems in New Hanover and Brunswick counties, and private wells in Bladen, Cumberland and Robeson counties. But PFOA, PFOS and PFBs are cousins to GenX; at high levels, exposure has been linked to cancer, hormone disruption, liver and immune system damage, and thyroid changes. Still, there is little scientific data on the health effects and safe levels of perfluorinated compounds.
The EPA has established a health advisory goal of 70 parts per trillion a combination of PFOS and PFAS, but there is no enforceable regulatory standard for them under the Clean Water Act or the Safe Drinking Water Act. Some states, though, have established their own legal limits for PFOAs. Vermont has set its threshold at 20 ppt for PFOA , while New Jersey has proposed limits of 14 ppt, according to the Environmental Working Group.
Westbrook said the source of the contamination is unknown. The city has surveyed all of its industrial users, she said, and none reported the use of these compounds. Nor do Lake Michie or Little River receive industrial or wastewater discharges. No biosolids or sludge are currently being applied in northern Durham and southern Person counties, she said. That leaves air emissions and atmospheric deposition as the culprits. The compounds can leave the stacks at an industrial facility, travel on the wind and fall to the ground or into water.
Of the three compounds found in Durham’s water supply, only PFB is still commercially produced. It is used in flame retardants, metal plating, pesticides and water-repellant coatings.
The Town of Cary recently tested its drinking water and found levels of PFB ranging from 3.6 ppt to 3.9 ppt; Durham’s one result was higher, at 4.8 ppt.
Eighteen utilities in Alabama, Georgia, Pennsylvania and Colorado have detected levels of PFB above EPA health advisory goals in their drinking water, according to the Environmental Working Group database.
The EPA has required companies to phase out PFOA, used to make Teflon, and PFOS, an ingredient in Scotchgard. Nonetheless, the compounds remain ubiquitous in the environment, and people can be exposed to them in numerous ways, including microwave popcorn bags.
There was little public awareness of perfluorinated compounds and GenX until last year, when the Star-News of Wilmington reported on findings in the Cape Fear River by NC State University researchers. Since then, state lawmakers have tried but failed — for political reasons — to pass substantive legislation to fund the NC Department of Environmental Quality to tackle the problem of emerging contaminants statewide.
Late last year, Duke University scientists Lee Ferguson and Heather Stapleton found a variety of perfluorinated compounds in Jordan Lake, the drinking water supply for Cary and other southern Wake County communities. Ferguson, who was on the Sierra Club panel, said the only way to “avoid being taken by surprise” by the presence of emerging contaminants is to conduct routine non-targeted monitoring — looking for chemical compounds, both known and unknown, in water.
It requires expensive high-resolution mass spectrometers, as well as staff trained on that equipment, which DEQ does not have. Ferguson said he and other academic scientists have met with DEQ, EPA and several state lawmakers to pitch a bill to fund the NC Emerging Contaminant Observatory. “It’s an early warning alarm system,” Ferguson said, similar to one in Basel, Switzerland, that would detect water contamination in real-time.
“What other perfluorinated chemicials are being used?” Ferguson said. “It’s environmental wack-a-mole.”
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