Bill Eisenman has always fished.

“Growing up, we ate whatever we caught — catfish, carp, freshwater drum,” he said. “That was the only real source of fish in our diet as a family, and we ate a lot of it.”

Today, a branch of the Rouge River runs through Eisenman’s property in a suburb north of Detroit. But in recent years, he has been wary about a group of chemicals known as PFAS, also referred to as “forever chemicals,” which don’t break down quickly in the environment and accumulate in soil, water, fish, and our bodies.

The chemicals have spewed from manufacturing plants and landfills into local ecosystems, polluting surface water and groundwater, and the wildlife living there. And hundreds of military bases have been pinpointed as sources of PFAS chemicals leaching into nearby communities.

Researchers, anglers, and environmental activists nationwide worry about the staggering amount of PFAS found in freshwater fish. At least 17 states have issued PFAS-related fish consumption advisories, KFF Health News found, with some warning residents not to eat any fish caught in particular lakes or rivers because of dangerous levels of forever chemicals.

With no federal guidance, what is considered safe to eat varies significantly among states, most of which provide no regulation.