A new study says drinking water with chlorine levels commonly seen in the United States is linked to an increased risk of developing cancer.
Drinking water systems throughout the United States and the European Union commonly use a process of disinfecting water with chlorine, which produces trihalomethane (THM). This process is connected to a 33% higher risk of bladder cancer and a 15% increased risk of colorectal cancer, according to the study’s authors.
One estimate said that nearly 300 million people in the U.S. have concerning levels of THM in their water.
The findings were published in the National Center for Biotechnology Information last month. The authors said that while the process leveraged in the U.S. and E.U. is “cheap, effective, and readily available,” it has a cost in terms of higher cancer risks, per The Guardian.
“What we see is alarming and we need some more high-quality studies,” said Emilie Helte, a lead author with Karolinska Institutet in Sweden.
The chlorination process dates back to the early 1900s and is credited with dramatically increasing life expectancy in the U.S. by substantially reducing microbial infections and waterborne illnesses like cholera.
However, decades later, in the 1970s, researchers began to uncover negative attributes of using chlorine. When the chemical is mixed with water and reacts with organic compounds, hundreds of potentially toxic byproducts result.
While the limit on byproducts in the United States is 80 parts per billion (ppb), evidence shows that even levels as low as 40 ppb are problematic. According to the EPA, levels typically range between 40 and 60 ppb.
Helte said alternative water treatments, such as ultraviolet light or improved filtration systems, are available, but they are expensive.
Last year, The Dallas Express reported that federal officials announced restrictions on polyfluoroalkyl substances in drinking water. These substances are part of the family of chemicals known as PFAS or “forever chemicals.” They can enter drinking water supplies from sources like landfills or industrial settings. The EPA associates PFAS with multiple conditions, including higher risks of cancer.