The Environmental Protection Agency (EPA) on Tuesday proposed what would be the first national drinking water standard for per- and poly-fluoroalkyl substances, better known as PFAS or “forever chemicals.” PFAS are a family of synthetic chemicals that linger in the environment and the human body, where they can cause serious health problems.

A study from the Centers for Disease Control and Prevention (CDC) back in 2007 found PFAS could be found in 98% of the U.S. population. According to a peer-reviewed 2020 study, as many as 200 million Americans are exposed to PFAS in their tap water.

While there are thousands of PFAS, the proposed EPA water standard rule is focused on regulating six chemicals where the science is clear regarding their impact on human health. Under the proposal, water systems would have to monitor for the chemicals, notify the public about PFAS levels and work to reduce them if levels go above the standard allowed.

“EPA’s proposal to establish a national standard for PFAS in drinking water is informed by the best available science, and would help provide states with the guidance they need to make decisions that best protect their communities,” EPA Administrator Michael Regan said in a statement. “This action has the potential to prevent tens of thousands of PFAS-related illnesses and marks a major step toward safeguarding all our communities from these dangerous contaminants.”