A coalition of researchers, utilities and state regulators have made progress tracking an unregulated and unwelcome contaminant in river water feeding drinking water supplies. Can they stop it?
By Catherine Clabby
When the EPA ordered drinking water systems nationwide to test their water for a long list of unregulated contaminants, North Carolina water systems scored high on tests most systems would wish to fail.
Some of the highest levels nationally of a likely cancer-causing chemical 1,4 dioxane were detected in North Carolina water systems in the Cape Fear River Basin, which supplies water to more than 120 public water systems used by 1.5 million residents.
Finding the human-made substance, used in many types of manufacturing, was unwelcome for two big reasons. Long-term exposure to 1-4 dioxane, even at very low levels, likely causes cancer, the EPA says. And conventional water treatment technologies cannot remove it.
“If you ask me about my biggest concern in drinking water in North Carolina right now, it’s 1-4 dioxane” says Tom Reeder, Assistant Secretary for the Environment at the state Department of Environmental Quality.
Welcome to the complex reality of emerging threats to surface waters, the streams, rivers and lakes that supply most of the drinking water North Carolinians consume. Research has improved our ability to understand and detect such risks.
Problem is, eliminating them is never simple.
Detective work over two years by North Carolina State University researchers, water utility managers and the DEQ has pinpointed three likely “hot spot” sources of 1,4-dioxane contamination in the Cape Fear basin. Levels of discharge into the basin have fallen. But the substance is not yet evicted.
While EPA does not regulate 1,4-dioxane, it has calculated that long-term exposure to concentrations at .35 parts per billion (ppb) could increase the risk of cancer in one out of 1 million people. North Carolina has calculated that the same concentration poses the same risk in waterways feeding water supplies.
Higher concentrations would pose higher risks.
People are most likely to be exposed to 1,4-dioxane in drinking water. That fact that most water systems don’t have the costly water treatment technologies that can successfully remove the human-made compound made finding the source in the Cape Fear River a priority.
In 2013, NC State University water quality researcher Detlef Knappe’s lab was dropping brown glass bottles in Cape Fear basin waters to collect samples and test for contaminants on the EPA list. When a water testing laboratory contact tipped the environmental engineering researcher that some North Carolina water systems were finding elevated levels of 1,4-dioxane, Knappe decided to look for that too.
Screening for tiny amounts of chemicals in the changing composition and flow levels of streams and rivers is not simple. Rainy periods can drop concentrations while dry periods can raise them; varying amounts of waste get released into streams and rivers from day to day. The first analytic approach Knappe used in surface waters — no EPA-approved method yet exists — didn’t make foolproof measurements, but it was evidence that 1,4-dioxane or something resembling it was present in open waters.
In 2014 Knappe approached drinking water utilities and the state Department of Environmental Quality with his team’s evidence that 1,4-dioxane was present in basin waterways feeding public drinking water supplies. The groups joined forces to track down the source. With fast-track grants awarded quickly by the National Science Foundation and the Urban Water Consortium, funded by North Carolina water utilities, Knappe and DEQ started systematic sampling for 1,4-dioxane in the Cape Fear River basin water.
“There was an expectation that we needed to do something instead of waiting for the state or federal government to figure out what to do. That didn’t seem like the right thing,” says Mick Noland, the chief of operations at Fayetteville’s water system where testing has turned up 1,4-dioxane levels as high as 8.8 parts per billion, 25 times higher than the EPA’s level of concern.
Knappe’s laboratory developed a faster and more sensitive testing method and focused its sampling on 40-plus sites in the Haw and Deep rivers, the upper reaches of the Cape Fear basin closer to the N.C. State campus. The DEQ water sciences program sampled 12 sites lower in the Cape Fear River, but also with overlap to make sure the measurements of 1,4-dioxane in river water were consistent.
By 2015 Knappe’s lab had pinpointed three likely 1,4-dioxane sources: wastewater released from communities near the basin’s headwaters in Reidsville, Asheboro and Greensboro. Since 1,4-dioxane is not used in wastewater treatment, it was likely that industries in these communities were discharging 1,4-dioxane into their sewer pipes.
To track down potential sources of 1,4-dioxane in their wastewater, Reidsville, Asheboro, and Greensboro water managers surveyed their commercial clients to see if they used 1,4-dioxane or sampled the wastewater lines serving such customers, looking for the highest concentrations. Each identified businesses using the chemical. With no stick of state or federal rules limiting the release of 1,4-dioxane into municipal sewers, the water systems approached the businesses with the problem.
In Asheboro sampling turned up one source: StarPet Inc., a local plant that produces food-grade plastic stock and is owned by Indorama Ventures in Thailand, which describes itself as a leading global manufacturer of Polyethylene Terephthalate (PET). StarPet has been highly cooperative about finding a way to stem the flow, says Michael Rhoney, Asheboro’s water resources director. StarPet is waiting for directions from the city on how to best pretreat its discharges, Rhoney said.
By surveying, Reidsville has identified two potential sources, Unifi, Inc., a Greensboro-based manufacturer of polyester and nylon yarns with other North Carolina plants in Madison and Yadkinville, as well as DyStar, owned by Kiri Holding Singapore and a producer of dyes and other chemicals. “They are looking at ways to remove it from their raw material so they can have their finalized products be the same,” said Kevin Eason, the city’s director of public works.
Steve Drew, director of water resources in Greensboro would not disclose the name of the company his water system has identified as a potential 1-4-dioxane emitter, saying an exemption to state public records law related to billing allows him to shield its identity.
“Right now it’s more of a ‘please’ and ‘thank you’ environment. We want to work with them to give them time to do good work without the risk of feeling villainized for not doing something they were not required to do,” Drew says.
North Carolina Health News has filed a state’s freedom of information query to obtain the company’s identity.
Keeping it going
DEQ isn’t finished assessing the scale of 1,4-dioxane contamination in North Carolina waters feeding drinking water supplies. Reeder, the assistant secretary, says DEQ intends to require water utilities discharging wastewater to monitor for the compound and report the results.
State environmental regulators are still sampling in the Cape Fear basin and are applying for nearly a quarter of a million dollars in grant money from the National Fish and Wildlife Foundation to continue testing there for the 1,4-dioxane and another chemical called bromide. They want to look for both in the Neuse and Yadkin river basins.
While DEQ has labelled waters below the Reidsville, Asheboro and Greensboro wastewater release sites 1-4-dioxane “hot spots,” that does not mean they are the only source in the Cape Fear River basin. Water samples taken downstream from one abandoned mill also found elevated levels. Groundwater polluted by 1,4-dioxane reaching stream and river water might carry the contaminant, too.
Knappe says he favors swift action to stop 1-4-dioxane discharges into North Carolina waters. While a better understanding of its health threats are recent, the compound may have been reaching Cape Fear River drinking water taps for decades, he said. UNC researchers reported detecting it in unspecified amounts in the Haw River in the 1980s. And if EPA decides to regulate it in drinking water, that could take years.
“Industry is constantly producing different chemicals,” Knappe says. “We need to go beyond what EPA is regulating to stay ahead of it.”
He is tracking water contamination by bromide, a by-product of drinking water disinfecting that can boost the supply of cancer-causing contaminants in water as well as perfluoroalkyl substances, compounds found on nonstick cookware and stain-resistant coatings, too.
Knappe says what he’d most like to see is a voluntary end to the release of the compound into waterways used for drinking water supplies. If that does not occur, an existing North Carolina law intended to limit health-threatening contamination of waterways that feed drinking water supplies should be deployed, he said.
Reeder agrees that North Carolina has the regulatory authority to limit 1,4-dioxane discharges within a statute that says toxic substance concentrations in drinking water (and fish) cannot exceed levels that protect people’s health.
Required monitoring in discharge permits is an initial step to find contamination sources. Once those are certain, DEQ could determine acceptable discharge limits that are informed by health risks, though not everyone may support the restrictions.
“I believe that the administrative code gives us the ability to regulate a potential carcinogen,” Reeder says. “There might be some people who disagree.”