What to know about a newly defined chemical byproduct found in drinking water

A chemical byproduct found in some treated drinking water in the U.S. that remained a mystery for more than 40 years may have finally been identified by scientists.

The authors of the study, published Thursday in the journal Science, have named the byproduct chloronitramide anion, and believe it is a decomposition byproduct of chloramine, which is used as a disinfectant in tap water.

The study does not suggest that tap water with the byproduct is unsafe to drink -- but does call for more research to be done. It's estimated more than 113 million people drink chloraminated processed water in the U.S.

"It's putting a name to the face of this chemical that's been in our water for many years," Dr. Stephanie Widmer, a board-certified medical toxicologist and emergency medicine physician, who was not involved in the study, told ABC News. "The reality is that no one really knows too much about this chloronitramide and its impact on human health, and more research needs to be done."

"These disinfecting chemicals have been giving us clean drinking water for decades, so no reason to fear drinking water as a result of this study," she added.

The study authors suggest, in general, adding a carbon filter to a sink or a standalone pitcher may be a good option for those concerned.

Here's what you need to know about chemicals in drinking water.

How is drinking water treated?

Historically, water systems used chlorine, a chemical element, as a disinfectant for drinking water to remove harmful bacteria, viruses and certain microorganisms.

However, some studies found that chlorine can have harmful health effects. At low levels of exposure, it can irritate the eyes, skin or airways. At high levels, it can cause chest tightness and difficulty breathing.

Chlorine is still the most commonly used disinfectant in drinking water at treatment plants in the U.S., but the Environmental Protection Agency sets legal limits on how much is allowed in drinking water and is safe for consumption.

Some water systems decided to use chloramine -- a chemical compound formed by mixing chlorine and ammonia -- as a disinfectant instead. Chloramine forms fewer byproducts than chlorine and is believed to be more stable, making it useful for water systems that deliver water over large distances.

What is this byproduct?

Although chloramine was becoming commonly used as drinking water disinfectant, scientists noticed that byproducts seemed to form as a result. While some were easy to identify, one was more difficult to recognize.

"Chloramine itself, when you add any chemical to water, which itself is another chemical, there are chemical reactions; byproducts are made," Widmer said.

Widmer explained the byproduct, chloronitramide, has been in treated drinking water for years but, because of chemical complexities, it was difficult to isolate and identify.

Performing a chemical study, the authors were able to break down the compound and identify its composition. It was synthesized in a laboratory and sent for analysis. The byproduct was then detected in 40 drinking water samples from 10 U.S. drinking water systems.

"It's not that it's a new chemical that was found, just it's been there," Widmer said.

Is tap water safe to drink?

The levels of chloronitramide anion in drinking water that could pose a risk to health are unknown.

Widmer said more research is needed on the byproduct, and on water supplies in general, but the findings show that research and surveillance of our water systems are ongoing, and scientists are continuing to collect new information.

Unless there is a boil water notice issued in a community, there is nothing to suggest that tap water in a community is unsafe to drink, she said.

"We health professionals, we encourage people to drink a certain amount of water per day," Widmer said. "Water is good for you. We shouldn't be afraid to drink our water. But it's so important that continued research and surveillance is ongoing with regards to our water."

"But, because of this study that came out, no one should be afraid to drink water," she continued. "It hasn't changed anything with regards to our water. It's just a new piece of information that we have to follow up on."

Widmer said people can use sink filters or water pitcher filters if they choose, but he recommended that people do research first on what is being filtered out of the water before making a purchase.