A previously unidentified chemical byproduct, named "chloronitramide anion," has been found in the tap water of about a third of U.S. residents, according to a new study. The existence of the byproduct was discovered about 40 years ago, but it was only identified recently due to improved analysis techniques.

The chemical is produced when water is treated with chloramine, a disinfectant formed by mixing chlorine and ammonia. While there is currently no evidence to suggest that the compound is dangerous, its similarity to other toxic molecules has raised concerns among scientists.

"Its toxicity is currently unknown," Dr. Julian Fairey, one of the study's co-authors, told CNN. "Its presence is expected, quite honestly, in all chlorinated drinking waters to some extent because of the chemistry, and it has similarity to other toxic molecules. Therefore, future research on chloronitramide anion is needed to understand its potential implications in drinking water."

The study, published in the journal Science, aims to spur research to address safety concerns. It could take years to determine whether chloronitramide anion is dangerous, and potential regulation based on those eventual findings would take even longer.

Chloramine has been used for about a century to disinfect water and is often used to protect a system's "residual" — the water that remains in pipes for several days after it leaves a water treatment plant. According to the study, some 113 million U.S. residents receive chloramine-treated water from their taps.

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