Water "phantom" spotted
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For decades, a “phantom chemical” has lurked in drinking water, unknown but widely consumed.
The compound, chloronitramide anion, was pinpointed by researchers using advanced techniques that have only recently become available.
This newly characterised chemical is a by-product of inorganic chloramine, a disinfectant commonly used in the United States and Australia to treat tap water.
While effective at killing pathogens, chloramine’s decomposition has long been known to produce unidentified compounds.
The discovery raises fresh questions about the safety of such water treatment methods, though experts stress that its toxicity remains untested.
Chloronitramide anion’s presence was first suspected over 40 years ago, when researchers noticed a gap in the chemical balance of treated water. A chemical was present, but its identity could not be determined.
Led by Julian Fairey, the team employed high-resolution mass spectrometry and nuclear magnetic resonance (NMR) spectroscopy to finally isolate and define the compound.
The compound has been found in US water systems at concentrations of up to 100 micrograms per litre (μg/L). This level exceeds regulatory limits set for many disinfection by-products, typically capped between 60 and 80 μg/L.
Importantly, no traces of chloronitramide were detected in water systems that used alternative disinfectants like chlorine alone.
While the compound’s discovery is a significant scientific milestone, its health implications are not yet understood.
Fairey and his colleagues urge toxicological assessments to determine whether chloronitramide poses any risks to human health.
“This research provides us with a little more of the full picture of disinfection by-products formed following chloramine disinfection of drinking water,” says Professor Stuart Khan from the University of Sydney.
“Knowing the identity is helpful since it will enable future research aimed at minimising or controlling the formation of disinfection by-products.”
Professor Oliver Jones from RMIT University has cautioned against undue alarm.
“The presence of a compound does not automatically mean it is causing harm,” he said.
“The question is whether the substance is toxic at the amount we are exposed to. I think here the answer is probably not.”
Researcher Daniel McCurry says the discovery might spark a reassessment of chloramine’s role in water treatment:
“Regardless of whether chloronitramide anion is found to be toxic or not, its discovery warrants a moment of reflection for water researchers and engineers,” he said.
