Many public water systems in the United States presently use inorganic chloramines to disinfect drinking water, however, researchers thus far had not identified what decomposition products (DP) existed in the tap water.

In a new study published in SCIENCE journal on 22 November 2024, by researchers from University of Arkansas, Institute for Biogeochemistry and Pollutant Dynamics, at ETH, Zurich and US Environmental Protection Agency, reports the discovery of what the researchers called chloronitramide anion – a decomposition product – a compound whose existence, though not identity, has been known for 30 years. They have already detected it in the tap water. Since the toxicity of chloronitramide anion (Cl–N–NO) remains untested, researchers called for its immediate toxicological evaluation.

According to the researchersm this toxic material is present in the drinking water of over 113 million of US population. A quick search shows that inorganic chloramines are used in the United Kingdom, Australia, Finland, and Spain.

Chemical disinfection kills pathogens in public water supplies effectively reducing waterborne diseases in drinking water and have been used for over a century. Inorganic chloramines such as monochloramine (NH22Cl) and dichloramine (NHCl2), have become widely used in the U.S. for this purpose and are used to treat the tap water of nearly one-third of all Americans.

However, for decades, researchers knew that chloramine decomposition products were released during disinfection. These chemical products were elusive; they included potential nitrogen-containing compounds with unknown toxicity. One such disinfection by-product, referred to simply as an “unidentified product”, remains uncharacterized despite being first identified more than 40 years ago.

Julian Fairey, Associate Professor in the Department of Civil Engineering at the University of Arkansas and other researchers combined classic synthesis methods with advanced analytical techniques such as high-resolution mass spectrometry and nuclear magnetic resonance spectroscopy and isolated and identified chloronitramide anion (Cl–N–NO2–) as a previously unidentified product of inorganic chloramine decomposition. They measured chloronitramide anion content in a range of chloraminated water systems in the U.S., detecting levels as high as ~100 micrograms per liter (μg/l), which surpasses the typical regulatory limits for many disinfection by-products (60–80 μg/liter).

Researchers found that this compound was absent in water systems that used alternative disinfectants. Although they have not yet carried out direct toxicological studies, they caution that computational analyses suggest that chloronitramide anion may not be benign thereby emphasizing the need for an immediate toxicological assessment and quantification in source waters, finished drinking waters, and wastewater effluents.

“Analysis of chloraminated United States........

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