Mystery in Tap Water Found

After over forty years of investigation, scientists have finally uncovered the identity of a mysterious chemical that has been detected in the drinking water of millions of Americans. This newly identified chemical, chloronitramide anion, is a byproduct of chloramine, a compound commonly used by water treatment plants to disinfect drinking water. Published in Science on November 21, 2024, the study reveals that approximately 113 million people across the U.S. may be exposed to chloronitramide anion through their tap water.

Chloramine, formed by combining chlorine and ammonia, was introduced to water treatment systems as a safer alternative to chlorine, which produces potentially harmful byproducts known to increase the risk of cancers and other health issues. While chloramine was seen as an improvement, this research uncovers the unintended consequence of a new set of byproducts, including chloronitramide anion. The compound’s chemical properties resemble those of other toxic molecules regulated by health authorities, yet its potential health risks remain unknown.

The journey to identify chloronitramide anion spanned over 15 years, led by Dr. Julian Fairey and Dr. David Wahman, whose collaborative work uncovered this elusive compound. The key breakthrough came when Dr. Juliana Laszakovits employed an advanced combination of mass spectrometry and ion chromatography, which allowed the researchers to isolate and accurately identify the compound. Their findings were confirmed by further synthesis experiments and comparisons between U.S. and Swiss water systems, with chloronitramide anion present only in U.S. systems that use chloramine for disinfection.

Despite the breakthrough, the study authors caution that the toxicity of chloronitramide anion remains unknown. The researchers call for further toxicological research to determine whether it poses health risks, given its structural similarities to other harmful chemicals. While further studies are needed, the discovery is significant in the context of growing concerns over disinfection byproducts in drinking water. Dr. David Sedlak from UC Berkeley notes that the research may mark a turning point in how water systems across the country evaluate the safety of chemicals used for water purification.

For the moment, the study suggests that individuals concerned about the presence of chloronitramide anion in their drinking water might consider using a carbon-based filter, although its effectiveness in removing this compound has not been definitively proven.

The identification of chloronitramide anion underscores the need for continued research into the safety of drinking water, particularly as more chemicals are used for disinfection. With funding for such research in short supply, the responsibility may fall to federal agencies to investigate the potential health implications of these emerging disinfection byproducts.

Source: Fairey, J., Wahman, D., Laszakovits, J., McNeill, K., et al. (2024). “Identification of Chloronitramide Anion as a Chloramine Degradation Byproduct in Drinking Water.” Science, 366(6469), 243-247.