The Huron River at Kent Lake in Oakland County is pictured. The river is under a state “Do Not Eat” advisory for all fish species. (Photo courtesy of Ruth Thornton)

LANSING — Every fish studied recently in two Southeast Michigan watersheds contained at least one of a family of toxic and persistent health-threatening chemicals.

The chemicals – collectively known as per- and poly-fluoroalkyl substances, or PFAS – are found in some rivers, lakes, soils, drinking water, fish, cattle and crops.

Researchers at Indiana University and the Ecology Center in Ann Arbor measured the contamination of fish in the Huron and Rouge River watersheds.

The findings are sobering. “Every fish had at least one” of 14 PFAS chemicals, said Erica Bloom, the toxics campaign director at the Ecology Center.

The study in the journal Chemosphere looked not only at the amount of PFAS in the filets that people eat but also in the fishes’ liver, eggs and digestive tract to assess potential effects on wildlife that eat entire fish.

Levels in the filets were much lower than in other parts of the fish, especially the liver and eggs, which had the highest levels, said Gillian Miller, a senior scientist at the Ecology Center.

The results are “not so good for animals, which eat the fish whole,” Miller said.

Even the amounts in the filets were concerning. The study found that if people eat fish caught in the tested rivers daily they would exceed Michigan’s Eat Safe Fish recommendations.

Filets tested from the Huron River had particularly high PFAS levels. The Department of Health and Human Services has issued a Do Not Eat advisory for much of the river, which means that even one meal of these fish could lead to health problems.

Little is known about many more PFAS chemicals that have been manufactured since the 1940s. Only two – PFOS and PFOA – have been extensively studied.

The Eat Safe Fish guidelines account for only PFOS – and not the many other PFAS chemicals that may be present.

High levels of these chemicals have been implicated in human health problems, including thyroid disease, kidney and testicular cancers, increased cholesterol, liver damage, decreased immune system response to vaccinations and others, according to the Environmental Protection Agency.

The health threats of most of the other more than 10,000 PFAS chemicals are poorly understood.

“There’s a lot we don’t know” about PFAS and their effects, said Cheryl Murphy, the director of the Center for PFAS Research at Michigan State University.

“We are starting to get a handle on a little bit of it, but there’s still lots to do.”

Michigan regulates seven PFAS chemicals in drinking water.

While there is no nationwide drinking water standard for PFAS, the EPA has proposed a standard of four parts per trillion for two of the chemicals. That’s the lowest level that testing methods can pick up.

“Basically they’re saying that we shouldn’t be able to detect them,” Murphy said.

“In terms of visibility and emphasis, [PFAS is] probably the most significant group of chemicals the EPA’s ever focused on in terms of effort and interest,” said Gary Ankley, a toxicologist at the federal agency.

PFAS chemicals are used in a plethora of products such as firefighting foams, chrome plating and electronics manufacturing facilities, and many consumer products, including stain- and water-repellent products, non-stick cookware, food packaging and personal care products.

“Most of us get [PFAS] through our diet,” Murphy said.

Sources of the chemicals that can end up in people include drinking water, fish, wildlife, food grown on contaminated soil and packaging that touches food.

“A lot of these chemicals will disrupt the normal hormonal processes, the physiological process within an organism in subtle ways,” Murphy said. “You don’t see a huge effect immediately. The effects usually show up after years of chronic exposure.”

It’s difficult to study so many chemicals, but researchers say they’re making progress in doing it more quickly.

“It took us 30 years to figure out the toxicity of these two chemicals,” Murphy said. “There are over 10,000 of these chemicals and we have no idea about most of them.”

It can’t take another 30 years to find out, she said. “We have to adopt new approaches.”

To study the safety of so many potentially harmful chemicals, the EPA has been exploring a high-tech method called the Toxicity Forecaster, or ToxCast.

PFAS is the perfect test for this new method since the group of chemicals is so large, Murphy said. It also allows scientists to study mixtures of chemicals more efficiently, which more closely resembles how humans are exposed.

“It’s pretty science-fiction-like. but at its core it’s pretty simple,” Ankley said. Instead of testing chemicals on whole animals or plants, researchers study their impact on cells and tissues.

These tissues are maintained in the lab for months or years and can be exposed to hundreds or thousands of chemicals through a high-volume system using robotics.

“The responses can be measured in an automated fashion,” Ankley explained. “So you can get insights pretty quickly and efficiently.”

A more thorough analysis is then prioritized for chemicals that show negative effects at low concentrations.

“To do a full risk assessment, you have to take those data and put them in the context of a whole person or a whole fish or a whole deer,” Ankley said.

Despite many challenges, given the recent scientific advances and public awareness around PFAS, Ankley and Murphy say they are optimistic that solutions will be found to reduce exposure.

“I have a feeling we’ll be dealing with PFAS, trying to figure things out, for at least a decade,” Murphy said.

Promising recent developments such as filters to remove PFAS from drinking water could mean “that in five or 10 years we’ll have a good handle on how to reduce our exposure.”

Ankley agrees: “Frankly, I wouldn’t be working in [this field] if I thought there was no way to address these challenges. But we do have new technologies, things like ToxCast, that enable us to look at chemicals in ways that we haven’t been able to do as efficiently in the past.”

Ruth Thornton reports for Great Lakes Echo.