Inorganic chloramines have been used for decades to remove pathogens from public water supplies. Though chlorine remains the most widely used disinfectant in the US and globally, chloramines have increasingly replaced it in many systems to reduce certain byproducts linked to bladder and colon cancer, low birth weight, and miscarriage.

Today, more than 113 million Americans rely on chloraminated drinking water, with the compound also in use across Canada, Asia, and Europe. “However, chloramines themselves decompose into products that are poorly characterized,” said Julian Fairey, lead author of the study published in the journal Science, during a press briefing. One such product, identified more than 40 years ago but left chemically unresolved, was simply dubbed the “unidentified product.”

Using a combination of traditional chemistry methods and modern tools like high-resolution mass spectrometry and nuclear magnetic resonance spectroscopy, they identified the compound as “chloronitramide anion.”

The compound was detected in all 40 chloraminated drinking water samples tested, with concentrations reaching up to 100 micrograms per liter – exceeding typical regulatory limits for disinfection byproducts, which range between 60 and 80 micrograms per liter. Although toxicological studies have yet to be conducted, the researchers sounded a warning.

Water utilities could consider reverting to chlorine, Fairey suggested, though this would require secondary disinfectants to neutralize the known toxic byproducts chlorine produces.

From https://phys.org/news/2024-11-previously-unknown-compound.html

The researchers have now identified chloronitramide anion, chemically expressed as Cl–N–NO2−, as an end product of inorganic chloramine decomposition. While its toxicity is not presently known, its prevalence and similarity to other toxic compounds is concerning and warrants further study to assess its public health risk. Simply identifying the compound has been a challenge and breakthrough.