Chlorine creates previously unidentified toxic by-products in the very drinking water it’s meant to disinfect, according to a new study.

“There’s no doubt that chlorine is beneficial,” said Carsten Prasse, an assistant professor of Environmental Health and Engineering at Johns Hopkins and the paper’s lead author. “Chlorination has saved millions of lives worldwide from diseases such as typhoid and cholera since its arrival in the early 20th century.”

“But that process of killing potentially fatal bacteria and viruses comes with unintended consequences,” Prasse added. “The discovery of these previously unknown, highly toxic by-products raises the question of how much chlorination is really necessary.”

Phenols, chemical compounds that occur naturally in the environment and are abundant in personal care products and pharmaceuticals, are also commonly found in drinking water. When these phenols mix with chlorine, the process creates a large number of by-products. Current analytical chemistry methods, however, are unable to detect and identify all of these by-products, some which may be harmful and can cause long-term health consequences, said Prasse.

Prasse stressed that this is a lab-based study and the presence of these novel by-products in real drinking water has not been evaluated.

“In other countries, especially in Europe, chlorination is not used as frequently, and the water is still safe from waterborne illnesses,” Prasse said. “In my opinion, we need to evaluate when chlorination is really necessary for the protection of human health and when alternative approaches might be better.”

“Our study also clearly emphasizes the need for the development of new analytical techniques that allow us to evaluate the formation of toxic disinfection by-products when chlorine or other disinfectants are being used,” added Prasse. “One reason regulators and utilities are not monitoring these compounds is that they don’t have the tools to find them.”

The researchers’ findings were published in the journal Environmental Science & Technology.


Please enter your name here
Please enter your comment!