Six million people in the US drink contaminated water, according to researchers from Harvard T.H. Chan School of Public Health and Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS). Their investigation found that polyfluoroalkyl and perfluoroalkyl substances (PFASs), chemicals linked with cancer, are present in public drinking water supplies.

“For many years, chemicals with unknown toxicities, such as PFASs, were allowed to be used and released to the environment, and we now have to face the severe consequences,” claims the study’s lead author Xindi Hu, a doctoral student in the Department of Environmental Health at Harvard Chan School and Environmental Science and Engineering at SEAS. “In addition, the actual number of people exposed may be even higher than our study found, because government data for levels of these compounds in drinking water is lacking for almost a third of the U.S. population — about 100 million people.”

As stated in the study published in the journal Environmental Science & Technology Letters, PFASs have been linked with obesity, high cholesterol, hormone imbalance and cancer. Although their use has been discontinued, people are still constantly exposed to the chemicals.


Wastewater treatment plant. Credit: Wikimedia/SuSanA Secretariat

The research team analyzed over 36,000 water samples collected by the US Environmental Protection Agency (EPA) across the country between 2013 and 2015. The team also investigated other wastewater treatment sites, industrial sites for the chemicals, as well as military fire training sites and civilian airports.

The researchers found that 66 of the public water supplies have levels of these chemicals above the EPA safety limit or about 70 parts per trillion (ng/L) for two types of PFASs. The concentration for perfluorooctanesulfonic acid (PFOS) was as high as 1,800 ng/L while it was 349 ng/L for perfluorooctanoic acid (PFOA).

The sites with the highest levels were watersheds close to military bases, wastewater treatment plants and industrial sites. The team urges that the chemical levels be brought lower than the provisional guidelines established by EPA.