A potentially cancerous chemical has been discovered in drinking water consumed by tens of millions of Americans.
Known as chloronitramide anion, the compound is released when a popular disinfectant called chloramine (a mix of chlorine and ammonia) naturally decomposes.
Around a third of homes in the US are supplied with chloramine-treated water, which is the equivalent of about 113m people.
It's not clear what effect the new compound has on humans but researchers said its similarity to other toxic chemicals 'warrants further study to assess its public health risk.'
Julian Fairey, lead author of the study and a professor at the University of Arkansas, said: 'It's well recognized that when we disinfect drinking water, there is some toxicity that's created. Chronic toxicity, really.
'A certain number of people may get cancer from drinking water over several decades. But we haven't identified what chemicals are driving that toxicity.
'A major goal of our work is to identify these chemicals and the reaction pathways through which they form.'
A potentially cancerous chemical has been discovered in drinking water consumed by tens of millions of Americans
If people are concerned about exposure to chloronitramide anion, Fairey told DailyMail.com that 'a home filter (i.e., a Brita filter or fridge filter) will help remove it, although we don't know this for sure.'
But he warns that boiling drinking water could in fact increase the concentration of chloronitramide anion and it 'is not alive like bacteria that could be killed by boiling.'
Water utilities often use a series of water treatment steps, with filtration and disinfection being the final processes before the water is stored in tanks or reservoirs.
Common types of chemical disinfectants include chlorine, chloramine, or chlorine dioxide.
Chloramine is favored in many parts of the world for its properties.
It less volatile than chlorine, meaning it stays in water longer and provides longer-lasting protection.
It also has a less distinct taste and odor to chlorine, which can have a bleach-like smell and taste in water.
One downside of water treated with chloramine is that it has more of a corrosive effect on pipes and plumbing.
According to American Water, chloramine has been used to treat water in many states for decades and Denver, Colorado, for instance, has used chloramines since 1917.
Other countries with chloraminated drinking water include Scotland, Australia and Canada.
Chloramine is added to water by introducing ammonia into water that already contains chlorine, causing a chemical reaction between the two substances to form chloramine; this process is known as 'chloramination.'
The U.S. Environmental Protection Agency (EPA) says that water with chloramine levels up to 4 milligrams per liter is safe for drinking, cooking, bathing, and other household uses.
Fairey noted that researchers have known about the new compound for decades but have been unable to identify it.
He himself began trying to unravel the mystery 10 years ago.
'It's a very stable chemical with a low molecular weight,' Fairey said.
'It's a very difficult chemical to find. The hardest part was identifying it and proving it was the structure we were saying it was.'
Whether chloronitramide anion will be linked to any cancers or has other adverse health risks will be assessed in future work by academics and regulatory agencies, such as the U.S. Environmental Protection Agency.
The EPA has not yet commented on the recent findings.
'Even if it is not toxic,' Fairey explained, 'finding it can help us understand the pathways for how other compounds are formed, including toxins. If we know how something is formed, we can potentially control it.'
Whether chloronitramide anion will be linked to any cancers or has other adverse health risks will be assessed in future work by academics and regulatory agencies
A study published this fall, also delved into the toxicity of drinking water.
Researchers from SimpleLab in California analyzed drinking water from the San Francisco Bay area - including 100 bottled water samples, 603 tap water samples and 111 samples from treated household water (water that has been filtered at home using a Brita filter).
These included bottles labeled as spring, artesian, mineral, well and purified water and were purchased in July 2022. They did not specify which brands of water were purchased, but they said they were representative of choices in California.
The houses tested were those that purchased a water quality testing kit from SimpleLab.
They analyzed it for contaminants and results of the study were published in the journal The Public Library of Science Water.
The team found in about 53 percent of bottled waters, 61 percent of home treated tap water and 98 percent of untreated tap water tested was linked to at least one health concern.
The most common pollutive agent they found were the byproducts of chlorine used to disinfect water- called trihalomethanes. These were found in all three water sources - but it was highest in tap water.
Consuming trihalomethanes in high amounts has been linked to developmental delays, reproductive effects, liver damage and an increased risk of cancer.
Other pollutants the researchers found in the water tested included heavy metals like lead.
Lead most commonly gets into water supply through aging pipes or infrastructure. It was detected in 30 percent of household treated tap water and 51 percent of tap water samples.
Frequent exposure to lead can cause neurological, developmental, learning and behavioral problems - most commonly in children.
Climate change, aging infrastructure and pollution all contribute to the current struggles people have in securing pristine drinking water, but this has been mostly studied in tap water.
In response, Americans have turned to bottled water. The total amounts used have gone from 28 gallons per person per year in 2010 to 45 gallons per person per year in 2020.
If you are served by a public water system, the CDC notes that it is possible to find annual water quality reports online which show the kind of disinfectant used, the levels present, and disinfection byproducts if levels were not within a safe range.