Researchers suspect that chloronitramide anion might be toxic, but further study is needed.
For decades, utilities in the U.S. have used a family of disinfectants known as chloramines to disinfect drinking water. Municipalities turned to these substances as an alternative to chlorine, because chlorine's byproducts in water have been associated with possible adverse health effects such as elevated risks of colon and bladder cancer, low birth weight, and miscarriage. However, scientists have long suspected that at least one decomposition product of chloramine might also be detrimental to human health. That byproduct has at last been identified, 40 years after it was first observed, but whether it's dangerous remains an open question. The decomposition products of chloramines are difficult to isolate and identify, and this substance has proven particularly elusive. For decades, it has been referred to as simply "unidentified product." A paper published November 21 in Science appears to have solved the mystery. The paper , a small molecule with the formula ClN 2 O 2 and the structure Cl-N-NO 2 . The anion is formed when monochloramine–the most commonly used chloramine disinfectant–decomposes into dichloramine (NHCl 2 ), which then goes through a series of reactions with water, atmospheric oxygen, and other monochloramine molecules to form chloronitramide (HClN 2 O 2 ). This substance dissociates in water to produce the chloronitramide anion. Now, however, scientists need to determine whether their long-standing suspicions about potential toxicity of the formerly "unidentified product" are true. As of now, scientists do not know for sure. Daniel McCurry, author of the Perspective accompanying the study, says, "Unfortunately, we have no idea yet how toxic [the] chloronitramide ion is, or if it's toxic at…