Previously Unknown Compound Discovered in Tap Water

Researchers from the United States and Switzerland have discovered a previously unidentified compound in chloraminated drinking water. Inorganic chloramines are widely used to disinfect drinking water, protecting public health from cholera and typhoid fever. In the United States, over 113 million people are estimated to consume chloraminated water. The study was published in Science.

The team identified chloronitramide anion, represented chemically as Cl–N–NO₂⁻, as a decomposition product of inorganic chloramines. Although its toxicity is not yet determined, its prevalence and resemblance to other toxic substances raise concerns, necessitating further investigation to evaluate potential public health risks. Identifying the compound itself posed significant challenges, marking a critical breakthrough.

Julian Fairey, an Associate Professor of Civil Engineering at the University of Arkansas, was the first co-author. Fairey explained that the compound had been known to researchers for decades, but its identification had remained elusive. He began investigating this mystery a decade ago.

It’s a very stable chemical with a low molecular weight...It’s a very difficult chemical to find. The hardest part was identifying it and proving it was the structure we were saying it was.

Julian Fairey, Associate Professor, Civil Engineering, University of Arkansas

This effort involved successfully synthesizing the compound in Fairey’s lab, a feat not previously achieved. The synthesized samples were then sent for analysis to Juliana Laszakovits, a Postdoctoral Researcher at ETH Zurich and co-first author of the paper.

The discovery raises questions regarding the health risks associated with this compound, which could not be assessed in earlier toxicity studies.

Fairey, whose research focuses on the chemistry of drinking water disinfectants, elaborated in a prior interview: “It's well recognized that when we disinfect drinking water, there is some toxicity that's created. Chronic toxicity, really. A certain number of people may get cancer from drinking water over several decades. But we haven't identified what chemicals are driving that toxicity. A major goal of our work is to identify these chemicals and the reaction pathways through which they form.”

Identifying this compound represents a significant advancement in understanding its potential implications. Future studies by academic researchers and regulatory bodies, including the US Environmental Protection Agency, will determine whether chloronitramide anion is associated with cancers or other adverse health effects. Importantly, this discovery now enables toxicity studies to be conducted on the compound.

Even if it is not toxic, finding it can help us understand the pathways for how other compounds are formed, including toxins. If we know how something is formed, we can potentially control it.

Julian Fairey, Associate Professor, Civil Engineering, University of Arkansas

The study's co-authors include Huong Pham, Thien Do, Samuel Hodges, Kristopher McNeill, and David Wahman, alongside Fairey and Laszakovits. Pham, Do, and Hodges, former Ph.D. students at the University of Arkansas, contributed to this research during their time in Fairey’s lab.

In 2022, McNeill hosted Fairey as a visiting professor at ETH Zurich during his sabbatical, where they collaborated with Laszakovits on this study. Wahman, a research environmental engineer at the U.S. Environmental Protection Agency, has long been a collaborator with Fairey’s lab group.

Journal Reference:

Fairey, J. L., et al. (2024). Chloronitramide anion is a decomposition product of inorganic chloramines. Science. doi.org/10.1126/science.adk6749.