In 2015, state health officials said their drinking water was unsafe because of contamination from hexavalent chromium in their wells. Months later, top state health and environmental officials, even Gov. McCrory, assured them it was safe. Then in 2016, in a series of depositions, state health department scientists said that it wasn’t.
And now, well, the health and environmental departments are at loggerheads again.
A lack of guidance from the EPA — which is beset by its own infighting and inertia — and input from federal agencies whose credibility is suspect have set states adrift to set their own standards. Standards with high stakes for the public health. Standards whose level of scientific uncertainty for the people near Roxboro, Mayo and Belew’s Creek is nearly intolerable.
The NC Department of Environmental Quality last week outraged advocacy groups and those residents living near coal ash impoundments when it issued legally enforceable “performance standards” for levels of hexavalent chromium, also known as Chromium 6, in groundwater and drinking water.
That standard, 10 parts per billion, was set over the objection of the state health department, which has established a much lower health screening threshold of just 0.07 parts per billion. The Occupational and Environmental Epidemiology Branch will continue to use that lower threshold, which carries a one in 1 million lifetime cancer risk.
According to a draft memo from the OEEB, state environmental officials based their decision to use 10 ppb on two factors: One, the belief that those levels in drinking water are “sufficient” to protect people on wells within a half-mile of coal ash impoundments. And two, the memo said, DEQ “lacked confidence” in the EPA’s cancer risk estimates of Cr6 “because of the comments in the draft document.” OEEB, though, “has confidence in those estimates” because the science behind them was reviewed “and found to be valid,” even considering the comments.People who take heartburn drugs like Nexium could be more susceptible to effects of Cr6 Click To Tweet 
The draft document in question is a 2010 interagency review of the toxicological effects of the Cr6. A two-year federal study showed that tumors of the small intestine and mouth were more prevalent in mice and rats exposed to high levels of Cr6: 57 parts per million to 516 ppm, which is higher than North Carolina’s performance standard.
The risk of cancer appears to be related to the level of exposure and dosage. Other factors, such as stomach acidity, can also affect how the body handles Cr6. In 2013, California toxicologist Deborah Proctor told the Water Research Foundation  that people who take proton pump inhibitors such as Nexium, for heartburn, could be more susceptible to the health effects of Cr6.
The National Institutes of Health, Agency for Toxic Substances and Disease Registry and the Department of Defense were among those that commented on the EPA review. (As part of the EPA’s leadership change, this portion of the website has been archived and lacks updates.)
But two of those agencies, the Defense Department and the ATSDR, have reason to downplay the risks of Cr6. For example, the Defense Department is responsible for Cr6 contamination in the air, soil and groundwater at its military bases. The compound is a byproduct of the chrome plating process used on aircraft.
Defense Department reviewers commented to the EPA that language regarding the health effects of Cr6 should be softened. Instead of claiming relatively low concentrations of Cr6 are “likely absorbed and retained in the body,” the EPA should say those levels “possibly” are absorbed and retained.
As for the ATSDR, its reputation has been questionable for more than 20 years. A subset of the Centers for Disease Control and Prevention, the agency has long been criticized not only by environmental advocates but also by Congress for its misleading and questionable risk assessments.
In 2009, for example, US Rep. Brad Miller of North Carolina convened a hearing to examine ongoing problems at ATSDR. Miller, who chaired a science Investigations and Oversight Subcommittee, called witnesses to testify on the agency’s “scientific methods, conclusions and lack of follow-up actions.” These witnesses included a former ATSDR ombudsman, who testified about the “systematic problems at the nation’s public health agency.”Former ATSDR ombudsman testified about systematic problems at nation's public health agency Click To Tweet 
In its review of the Cr6 findings, the ATSDR acknowledged that the contaminant is “likely to cause cancer in humans” via drinking water or other ingestion. However, the agency cautioned the EPA that to claim hexavalent chromium induces stomach tumors” is “perhaps too strong.”
Without a federal drinking water standard for Cr6 — and under the Trump administration, none on the horizon — states are left to establish their own thresholds. (The EPA has set a maximum level of 100 parts per billion for total chromium, which includes Cr6 and Cr3, a relatively benign form.) In contrast, California has implemented a maximum contaminant level of 10 ppb, but has set a public health goal of 0.02 ppb.
Since the backlash, DEQ Secretary Michael Regan has announced that he would appoint a scientific and expert panel to recommend any changes to the water quality regulations to the Environmental Management Commission. The EMC has the authority to adopt new groundwater standards. After the review, DEQ will then make a final determination on performance standards.
Despite the prevalence of Cr6 — analysis of federal data by the Environmental Working Group  shows 200 million people in the US could be drinking water with some level of the contaminant — there is little concern in Washington. In February, US Rep. Al Green, a Democrat from Texas, introduced a resolution that calls on EPA to complete its ongoing assessment of Cr6’s human health risks and to set a drinking water standard. HR 147 was referred to the House Subcommittee on Health. It has no co-sponsors.