Aerial view of a wastewater treatment plant. Municipal wastewater plants in North Carolina cannot treat fracking wastewater. Image courtesy U.S. Environmental Protection agency

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Managers at water-treatment plants know bromides are a problem, but the science of how much bromide is needed to start forming carcinogenic byproducts is still unclear.

By Gabe Rivin

In the Dan River, in north-central North Carolina, a carcinogen precursor flowed freely through the water. The chemicals landed in two municipal drinking-water plants, temporarily causing the water to be tainted for thousands of residents.

That same precursor flowed freely in the Allegheny River, in Pittsburgh, causing the same problem for an even greater number of residents.

Power plant on the Dan River. Photo courtesy Appalachian Voices

In both cases, the chemicals, bromides, had been produced by energy industries. North Carolina’s source of bromides was Duke Energy’s Belews Creek Steam Station, a 2,240-megawatt coal-fired power plant that releases its waste into the Dan.

In Pennsylvania, the booming natural-gas industry was to blame. Drillers used hydraulic fracturing to penetrate shale – a process that may soon appear in North Carolina too. These drillers then sent their fracking wastewater to inadequate waste-treatment plants. The plants failed to remove bromides from the wastewater before releasing it into the Allegheny, Pittsburgh’s source of drinking water.

Academic researchers and state regulators are well aware of these problems. And they understand the chemical mechanisms that allow bromides to produce the cancer-causing compounds.

Yet bromides remain unregulated in state waters.

The simple question is: Why?

An investigation by N.C. Health News has found that with scarce research and monitoring, state and federal regulators have a limited ability to control bromides. Regulators can’t say with certainty when bromides may become a problem – when a river’s concentration of bromides will cause carcinogens to form in drinking-water plants.

And that means regulators have mostly been reactive, waiting to find that drinking water has been tainted rather than eliminating the bromides before they become a problem.

How bromides cause harm

Bromides are mostly benign, according to Connie Brower, a water-quality standards coordinator with the N.C. Department of Environment and Natural Resources.

“Bromide is relatively nontoxic – and I use that word cautiously – to aquatic life,” she said.

Chemical diagram of bromoform, a brominated trihalomethane. The U.S. EPA says that exposure to bromoform can cause injuries to livers, kidneys and central nervous systems, and the agency lists the chemical as a probable carcinogen. Graphic courtesy Wikimedia Commons

The problem isn’t with bromides themselves. It’s what bromides do once they’re in drinking-water plants, according to Jeff Poupart, a wastewater branch supervisor for DENR.

When bromides flow downstream, they can find their way into drinking-water plants, which draw from rivers. Once inside the plants, bromides react with organic matter and chlorine, the latter of which is used to kill harmful bacteria.

This process causes brominated trihalomethanes to form.

Chloroform, a type of trihalomethane, forms without the presence of bromides, according to Philip Singer, a professor emeritus of environmental engineering at the University of North Carolina-Chapel Hill.

But, he said, “There’s a fair amount of literature to suggest that the brominated species are the ones that we’re much more concerned about.”

The disparity in health effects between the two classes of trihalomethanes is large. The American Water Works Association estimated that dibromochloromethane, one of the brominated forms of the chemicals, is roughly 17 times more carcinogenic than chloroform.

The U.S. Environmental Protection Agency warns too that trihalomethanes, along with other byproducts of the chlorination process, can cause damage to livers, kidneys and central nervous systems.

Regulation Is challenging without data

The question isn’t whether trihalomethanes are harmful. For state and federal regulators, the search now is for the sources of bromides, and for an acceptable concentration of bromides in surface waters, such as rivers.

“The problem is that we don’t have a knowledge of [whether] that problem begins at 10 micrograms per liter or 100 milligrams per liter,” said DENR’s Brower. “It’s not a matter of understanding we need to do something; it’s having a level. We can’t do anything without ironclad science. We desperately need that.”

The EPA has begun the work to find these answers, according to Victoria Binetti, associate director of the water-protection division for the EPA’s Region 3 office.

The regional office is working with the EPA’s national science office “to see if there can be a quantitative relationship developed between the amount of bromides in a water supply – the water source – and the formation of disinfection byproducts that contain bromine,” she said.

But that research is far from complete. And even when the EPA finishes its work, the data will probably not prompt federal or state regulations, Binetti said.

Some history helps to explain why.

Permit writers limited by current regulations

In 1972, Congress passed the Clean Water Act, which created an ambitious system to clean up surface waters throughout the country.

At the heart of the law is a permitting program for polluters. The program requires polluters to gain government approval to release their wastes into waterways. The permits set limits on the release of different pollutants, and permittees are regularly monitored.

Like other federal environmental laws, the CWA allows states to run this process. Permit writers – at DENR, in North Carolina’s case – consider two sets of requirements when deciding what a polluter can release into state waters.

First is a set of effluent limitation guidelines, which the EPA issues. This sets pollution limits on an industry-by-industry basis.

Jon Devine, a senior attorney at the Natural Resources Defense Council, gave a hypothetical example: “For all widget factories nationwide, their process of laminating the widgets … has to meet x, y and z discharge standards, based on what’s technically achievable. In some cases, cost comes into it. And the kind of pollutant is also a factor in how stringent that standard is supposed to be.”

Permit writers must also consider their states’ water-quality standards.

The EPA requires states to list different uses for their surface waters. A river, for example, may be listed as a fishing spot.

Given those listings, states establish scientific measures to preserve the water’s intended use. If the state designates a river as a fishing spot, for example, it may set limits on the water’s mercury concentrations or pH. The EPA offers recommendations for each type of waterway, but states can adopt their own methods as long as they’re equally protective.

But pollutants like bromides often go unmentioned in a state’s water-quality standards. In effect, that state is legally unconcerned about a chemical’s presence in water.

That’s the case in North Carolina, where, as in other states, regulators have not established a maximum allowed concentration for bromides in state waters. This owes in part to a lack of scientific research, as Brower said. But the EPA hasn’t issued recommendations either.

Aerial view of a wastewater treatment plant. Many municipal wastewater plants in North Carolina use chlorines to treat water. But if that water contains bromides, trihalomethanes can form. Image courtesy U.S. Environmental Protection agency

Without that standard, permit writers have no defensible mechanism by which they can place a limit on the release of bromides into state waters.

“There’s not a numeric criteria for permit writers to use to establish a limit” on bromine, said DENR’s Poupart. “North Carolina has not adopted a numeric criteria for that.”

Limited enforcement

The EPA may someday offer recommendations for bromide levels in waterways. Those recommendations would figure into states’ standards. But that day is likely far off, according to the EPA’s Binetti. And even once the EPA finishes its current research, she said, “there would need to be a great deal more data” before the agency issues its recommendations to states.

Still, states are not completely toothless.

Binetti noted that in Pennsylvania, the EPA and the state’s environment department forced wastewater facilities to monitor bromide levels in their releases. In some cases, she said, “enforcement actions were taken to force wastewater systems not to accept [waste from shale drillers].”

Brower said that DENR could require polluters to monitor their releases of bromides. (That’s exactly what the state did with Duke Energy’s Belews Creek plant.) This sort of monitoring would help permit writers to set limits on bromides – if, at some point in the future, the state sets a water-quality standard for bromides, she said.

Binnetti also stressed the importance of monitoring facilities’ bromide releases, given the large uncertainties that remain about their presence in waterways.

Gabe Rivin

Gabe is our former environmental health reporter from 2014-2016. He is a former editor of The Cooperative Business Journal, and a former reporter for Inside Washington Publishers, where he covered federal...