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A gulf separates two numbers that North Carolina regulators and the Chemours Co. have proposed for assessing the health risks posed by GenX, a key ingredient in Teflon the company makes at its plant near Fayetteville.
GenX turned up in the Cape Fear River in 2012 and 2013, then in public water systems downstream in 2014.
The state began investigating following news reports in June 2017, finding contamination in groundwater at the plant site, hundreds of private wells around it, the air, the rain, fish and a farmer’s jar of honey.
When it comes to gauging GenX’s potential danger to humans, North Carolina’s number is 140. That’s the highest concentration, in parts per trillion (ppt), according to the state, at which the most vulnerable people healthwise may safely consume water over a lifetime.
The N.C. Department of Health and Human Services settled on that level on July 14, 2017, after suggesting a number 500 times higher about a month earlier.
Chemours’ number is far larger: 70,000 ppt, just shy of the state’s initial advisory of 71,000.
The company contends the state’s health goal rests on bogus science. More than that, Chemours suggested in a recent legal filing that key parts of DHHS’ methodology lack support from the EPA.
On Aug. 20, the state’s Secretaries’ Science Advisory Board will consider a draft report assessing whether any changes to DHHS’ health goal should be considered. By September, EPA is expected to release its own GenX health advisory, which, like the state’s, would serve as a guideline but would not legally be enforceable.
Chemours has submitted documents to the EPA to make its case for the 70,000 ppt level.
Absent regulations specific to GenX, 140 ppt has been the yardstick by which the N.C. Department of Environmental Quality and others assess whether GenX pollution warrants regulatory scrutiny or concentrations in public water systems are safe.
Getting from 140 to 70,000
The state’s announcement of the 140 ppt health goal surprised many people, including Damian Shea, a professor of environmental chemistry and toxicology at N.C. State University. Shea has spent decades working with state and federal regulators and with the industries those regulators are supposed to watch over.
He led an EPA committee examining the role bioaccumulation of chemicals should play in deriving water-quality criteria. BP hired him as an expert witness in a federal trial regarding environmental damage resulting from the 2010 Deepwater Horizon disaster. Recently, he signed on to consult for Chemours.
“It was last summer and last fall that I initially voiced concern, albeit informally, over the way the state had generated their provisional health goal and then the revised one,” Shea said in an interview.
“That piqued my interest. I looked into what they had done, not at a deep level, but what the basis was. The proper use of scientific data and procedures for the regulation of chemicals is something that I’ve been involved in for more than 30 years. And, it (the GenX contamination issue) is in my backyard, so that makes it interesting as well.
“It was six months later that Chemours approached me and asked me if I’d be willing to do an independent analysis of the data.”
Researchers have yet to directly examine the effects of GenX on humans, so they look at what happens with animals.
For the 140 ppt health goal, the state chose two studies on rodents exposed to different amounts of GenX over 28 days. For each, the level at which no ill health effects were seen, called a no observed adverse effect level, or NOAEL, was 0.1 milligram per kilogram of body weight per day.
DHHS translated that to the equivalent for a human infant and assumed that 20 percent of exposure would come from drinking water.
Of course, humans and animals may react differently, and some groups of people might be more susceptible than others. To account for this potential variation, regulators use uncertainty factors, margins of safety that reduce the recommended safe level.
Crucially, the state’s calculation required another uncertainty factor: The health advisory relates to lifetime consumption, but the studies on which it is based examined short-term effects. Incorporating that difference reduced the health goal by a factor of 10.
Shea’s criticisms, expressed in letters to the science advisory board and to state regulators, focus on DHHS’ choice of studies and use of infant body weight and water consumption.
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“There are a few essential, critical scientific mistakes they made,” he said, “Even though a chronic, gold-standard, lifetime-exposure study was available, they decided not to use it and substituted the 28-day sub-acute study, which is not what you do if you’re trying to look at lifetime exposure. That’s the main scientific error.
“They compounded the error by basically saying, ‘Since we’re using a study that’s not as appropriate as it should be, we’re going to use a 10-fold safety factor,’ when the appropriate study was available,” he said.
“The other scientific error was they used the body weight of a drinking water intake of an infant. Obviously, an infant is only an infant for a short period of time. For lifetime exposure you want to use a body weight and drinking water intake for an adult.”
To see how Shea’s criteria would affect the health goal, start with the state’s number: 140. Targeting an adult instead of an infant multiplies that by five, giving 700.
The lifetime-exposure study Shea pointed to reported a NOAEL 10 times higher than those of the 28-day studies, increasing the number to 7,000.
Finally, toss out the state’s 10-fold uncertainty factor required to use the short-term study. That results in 70,000, the number, in parts per trillion, that Shea and Chemours believe is safe in drinking water.
Protecting the most-susceptible
A number of other scientists have defended DHHS’ work. Jamie DeWitt, a professor in the department of pharmacology and toxicology at East Carolina University, was a peer reviewer on a recently released federal report detailing how many fluorochemicals may pose health risks at levels much lower than official guidelines.
She also is on a research team examining blood and urine from about 340 New Hanover County residents who consumed water contaminated with GenX and related substances.
“I can’t say I’m 100 percent certain because I was not involved in that decision-making process,” DeWitt said of DHHS’ health goal.
“I can only base my opinion on what I have read. I support their science because they followed standard methods.
“They didn’t do anything particularly unusual. They followed standard methods that are employed by the United States Environmental Protection Agency. Scientific judgment is a huge component of these (EPA) guidelines. Scientific judgment gives different entities the freedom to make decisions based on the best available science that they have. There is nothing that says you must select a chronic study if there is one available.
“Given the amount of data that they had,” Dewitt said, “they chose an appropriate study and appropriate endpoint that is supported by additional studies and endpoints. It appears as if they made the appropriate decision.”
As for targeting infants versus adults, DeWitt said: “The goal in coming up with these values is to ensure that susceptible subpopulations are protected. Susceptible subpopulations may be infants. They may be children. They may be the elderly. Maybe individuals have specific genetic differences that make them more susceptible to the toxicological effect.
“So you would use the parameters relevant to that most susceptible subpopulation to establish your exposure level and then make the assumption that if those individuals are protected, then anybody else exposed over the duration of their lifetimes to that concentration or lower also would be protected.”
‘EPA did not voice positive opinion’
Since announcing the 140 ppt health goal, the state has consistently said its work was done “in consultation” with EPA.
In a June court filing, though, Chemours questioned the strength of EPA’s backing.
The company pointed to documents it obtained from DHHS, which the agency said its staff prepared while researching the health goal.
One document includes the handwritten notation “EPA did not voice positive opinion on this” on a bullet point discussing the uncertainty factor from using the short-term study.
On another, someone noted that “they didn’t agree” near a portion describing an EPA default practice of assuming 20 percent of exposure comes from a source such as drinking water when information about other routes is unavailable.
Company attorneys wrote that “the state’s public explanation sought to create the impression that the reduction to 140 ppt was at the behest of the U.S. Environmental Protection Agency. … Here again, though, the limited internal state documents produced thus far tell a different story and indicate that EPA did not agree with at least some, and perhaps all, of the reduction.”
DHHS and EPA were asked whether EPA concurred with and supported the methodology behind the 140 ppt health goal.
DHHS spokesman Cobey Culton said: “The EPA did provide expertise and consultation on the updated drinking water health goal, and their input was very helpful in arriving at the current provisional drinking water health goal.”
An EPA source who only agreed to discuss the issue on background, described its involvement as “technical expertise and consultation.”
What impact Chemours’ assertions or Shea’s criticisms may have remains unclear. Shea said the state had not contacted him.
State science board Chairman Jamie Bartram, a professor at UNC Chapel Hill, has seen Shea’s work but said he was unfamiliar with the documents relating to EPA’s involvement.
The board, which meets Aug. 20, will consider a draft report of its work on the state’s health goal.
“I cannot predict whether that will lead to adoption of the report or to further work,” Bartram said, “but it represents a step in that direction.”
‘I believe we haven’t harmed anybody’
Chemours has long maintained that the amounts of GenX found in drinking water pose no health risks.
In a July interview at Chemours’ Fayetteville Works site, plant manager Brian D. Long said: “We have probably a decade of toxicity and toxicological studies on GenX, and that body of work and the tests and the studies indicate that at low levels, at the parts-per-trillion count levels that we see of GenX, or C3 dimer acid (another name for GenX), that there shouldn’t be a health effect on anybody in the community. So we just don’t believe that there is.
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“I really believe that we haven’t harmed anybody,” Long said.
“But I’ll also say that I understand that people have varying opinions about what the data means to them personally, so I’m never going to tell anybody, ‘You shouldn’t feel that way.’ Your safety or how you feel about something, that’s a very personal decision.”
Despite such confidence that it has caused no harm, Chemours has embarked on a $100 million pollution-reduction program it aims to complete by the end of 2019. Once in place, Chemours has said, the new technology will reduce emissions — not just GenX but also other fluorochemicals, including byproducts of its Nafion production process — by 99 percent or more compared with 2017 levels.
Regardless of whether the health goal changes, Long and other Chemours officials said the company will stand by those plans and its promises to help owners of private wells where GenX has been detected above 140 ppt.
“Brian Long’s statement regarding any change to the health goal encompasses Chemours’ overall environmental leadership commitment and approach, including the $100 million investment on emissions reduction here at our Fayetteville Works site,” the company wrote in response to emailed questions.
“For residents within the resident sampling area whose wells used for drinking water have tested at or above the North Carolina Department of Health and Human Services’ recommended provisional state health goal for GenX of 140 parts per trillion, we are committed to offering granular activated carbon (GAC) systems at no charge, and maintaining these systems as long as they are needed by the residents receiving the offer.”
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