A common disinfectant in drinking water breaks down into a chemical compound we know almost nothing about, including whether it has any potential toxic health effects to those who drink it.
Chlorine has been used to sanitise drinking water for more than a century. However, some drinking water systems in the US, UK and Australia now use a closely related chemical disinfectant called chloramine. That is because chlorine byproducts were linked to bladder and colon cancer, low birth rates and miscarriage, says at the University of Arkansas. Now, Fairey鈥檚 work suggests chloramine may also break down into toxic byproducts.
He and his colleagues analysed drinking water samples from the US. Researchers previously knew that chloramine breaks down, but they hadn鈥檛 yet determined the chemical make-up of its byproducts. Fairey and his colleagues isolated one of these byproducts from the water samples and analysed its mass, allowing them to determine the chemical formula. They identified a compound called chloronitramide anion, which consists of one chlorine atom, two nitrogen atoms and two oxygen atoms.
Advertisement
When they tested household drinking water from seven US states, they found chloronitramide anion in all 40 samples. In tests of tap water from three households in Switzerland, which doesn鈥檛 use chlorine or chloramine-based drinking water systems, the compound didn鈥檛 show up. The researchers say this confirms it is a chloramine byproduct.
On average, US drinking water samples contained 23 micrograms of chloronitramide anion per litre, though concentrations ranged from 1 to 120 micrograms per litre across samples. For comparison, the concentration of some other chlorine byproducts is limited to between 60 and 80 micrograms per litre by the US Environmental Protection Agency (EPA). Yet we don鈥檛 know what concentration of chloronitramide anion 鈥� if any 鈥� is safe for people to drink.
Chloraminated water systems serve more than 113 million people in the US 鈥� roughly a third of the country鈥檚 population 鈥� and are also found in places such as Australia, England, Scotland and Canada. Based on these findings, at the EPA anticipates all chloraminated drinking water systems also contain chloronitramide anion.
Though it is unclear whether this compound is toxic, it does share similarities with other toxic molecules linked to colon and bladder cancer, says Wahman. 鈥淔uture research on [its] occurrence and toxicity is needed to understand potential implications of it in drinking water,鈥� he says.
While those tests are currently underway, people who are worried about the potential effects of chloronitramide anion in drinking water should be able to remove it with a carbon-based water purifier, says Wahman.
We corrected the pronouns for Julian Fairey.
Science
