(WTVO) — Eating freshwater fish might be harmful for people’s health.

A new study shows that eating just one serving of freshwater fish per year, found in certain areas, can be equal to a month of drinking water contaminated with the harmful chemical PFOS, commonly known as “forever chemicals.”

Researchers analyzed data from more than 500 samples of fillets collected in the U.S. from 2013-2015. PFAs have been linked to reproductive and developmental problems, suppressed immune systems and increased risk of some cancers.

“A lot of this contamination is expected to come from industrial releases into the environment, so chemical pollution, but these products were widely used and, so it may actually be leaching from landfills, wastewater treatment plants and a whole range of different potential sources,” said Dr. David Andrews, senior scientist at Enviornmental Working Group. “But, what we do know is that this contamination extends across the country.”

The EWG is calling for immediate action to eliminate contamination and clean up waterways. It said that concentrations from some testing are going down, but not fast enough.