Newly identified chemical in drinking water may be toxic: study

About a third of US residents have received tap water containing a previously unidentified chemical byproduct, a new study has found. Some scientists are now concerned—and actively investigating—whether that chemical might be toxic.

The newly identified substance, called “chlornitramide anion,” is produced when water is treated with chloramine, a chemical formed by mixing chlorine and ammonia. Chloramine is often used to kill viruses and bacteria in municipal water treatment systems.

Scientists said the byproduct’s existence was discovered about 40 years ago, but it was only identified now because analytical techniques have improved, finally allowing researchers to determine the chemical’s structure.

It may take years to find out if chloronitramide anion is dangerous – it has never been studied. The researchers reported their findings Thursday in the journal Sciencepartly to stimulate research to solve security problems.

The researchers said they have no hard evidence to suggest the compound represents a danger, but that it has similarities to other chemicals of concern. They believe it deserves investigation because it has been discovered so widely.

“It has similarities to other toxic molecules,” said David Wahman, one of the study’s authors and a research environmental engineer at the Environmental Protection Agency. “We looked for it in 40 samples in 10 US chlorinated drinking water systems in seven states. We found it in all the samples.”

Chloronitramide anion is produced as chloramine decays over time. It is likely to be found in all drinking water treated with this method, he said.

The fact that a byproduct with unknown risks could be so ubiquitous and elude researchers for so long renews questions about potential health effects of the chemicals used to treat tap water.

About 113 million U.S. residents receive chloramine-treated water from their faucets, according to the study. The chemical has been used for about a century to disinfect water. Today, it is often used to protect a system’s “residuals”—the water that remains in the pipes for several days after it leaves a water treatment plant.

Chloramine has been increasingly favored over chlorine because the latter also produces byproducts, some of which are linked to bladder cancer and are regulated by the EPA.

David Reckhow, a research professor of civil and environmental engineering at the University of Massachusetts, Amherst, who was not involved in the study, said the result was an important step. The ultimate goal, he said, is to understand whether the substance is a hazard; he agreed that it was probably poisonous.

“It is a fairly small molecule, and it can probably penetrate biological systems and cells for that reason. And it is still a reactive molecule,” he said. “That’s the kind of thing you worry about.”

The authors of the new study reached their findings after figuring out how to formulate high concentrations of the chemical for laboratory testing, said Julian Fairey, lead author and associate professor at the University of Arkansas.

“We don’t know the toxicity, but this study has allowed us to do that work now,” said Fairey, who studies drinking water byproducts. “Now we can get down to the hard work of trying to figure out what its toxicological relevance is in our water systems.”

He added that some previous studies have suggested a link between drinking disinfected water and increased incidence of certain cancers.

“We don’t know what’s driving these. We have no idea if this connection is in any way related to these results,” Fairey said. “But we have unexplained incidents of certain types of cancer from treated drinking water.”

But any conclusions about whether the newly identified substance is toxic are likely to be years away. Potential regulation based on these eventual findings would take even longer.

“It’s a lot — probably a decade of research once a funding source is found,” said Alan Roberson, executive director of the Association of State Drinking Water Administrators.

Reckhow said that in the meantime, water utilities should pay close attention to ongoing research and try to reduce people’s exposure.

“You do what you can to minimize,” he said. “You’re making the best judgment you can about the toxicity, and you’re running with incomplete information. That’s the world we live in, unfortunately.”

The EPA regulates only a handful of disinfectant byproducts, including several associated with the use of chlorine. Researchers said these regulations have pushed some water providers to increase their use of chloramine.

“This study really calls into question whether this disinfection process is safer from a health perspective,” said David Andrews, a senior scientist at the Environmental Working Group, an advocacy group pushing for more scrutiny of the chemicals.

He added that there are hundreds of disinfection byproducts in water systems, but that this one deserves investigation.

“Many of the other pollutants occur in lower concentrations or less frequently,” Andrews said.

Any treatment of drinking water involves some level of health risk, Roberson said. It is a trade-off: Disinfection processes have largely overcome waterborne diseases such as cholera and typhus, but research suggests that some by-products are associated with the risk of cancer and miscarriage.

“The reason you add the chloramine — you want to kill bacteria and viruses, you have a real risk-risk trade-off,” he said.

Many American water utilities state on their websites whether they treat the water they supply with chlorine or chloramine. Wahman said some studies suggest that activated carbon filters, such as those used in home water purification devices or refrigerator filters, can remove disinfectant byproducts, but that more research is needed.