Maine’s U.S. senators are joining a push to set standards on certain kinds of substances in bottled water.

Republican Sen. Susan Collins and independent Sen. Angus King have joined colleagues to call for the U.S. Food and Drug Administration to set the standards for per- and polyfluoroalkyl substances.

The senators described the substances as “persistent chemicals that accumulate in people’s bodies over time.”

The substances are commonly called PFAS chemicals and they have been linked to human health problems, such as low infant birth weights.

They are used in products such as food packaging and nonstick pans.