According to a March 2023 study by the U.S. Geological Survey, nearly half of all tap water in the U.S. is contaminated with “forever chemicals,” also known as per- and polyfluorinated alkyl substances (PFAS). It’s a troubling problem, according to a University of Notre Dame PFAS researcher.

“I think that we should try our best to work on how to clean this up,” Dr. Graham Peaslee, a professor in the Department of Physics and Astronomy and concurrent professor of chemistry and biochemistry, told CNN. “My fear is that this is, global warming aside, this is probably the most expensive environmental problem we’re ever going to face. There’s nothing that will magically fix it. It’s fairly expensive to clean this up. And it’s a recurring cost, and there’s no permanent solutions to it for any particular utility. It looks frightening.”

PFAS are dangerous to human health and, while there are over 12,000 different kinds, the U.S. Geological Survey’s recent study only screened for a few dozen of them. That means the country’s’ tap water may be even more contaminated than the survey’s initial findings suggest.

“To fully understand exposure and adequately determine risk to human-health, continued emphasis should be placed on 1) integrating geospatial datasets with PFAS data broadly to identify vulnerable regions/subpopulations, 2) expanding monitoring to include rural small–system and private–well dependent communities, and 3) expanding target and non-target analysis methods particularly in drinking-water monitoring programs in the US and globally,” the study reported.

PFAS are linked to cancer, obesity, decreased fertility, liver damage and many other health problems.

“It’s really insidious, this poison,” Peaslee said. “We are going to have to get inventive on how to filter it out for all of our days.”

The U.S. Geological Survey detected at least one PFAS in roughly 45% of U.S. drinking water samples.