Huron River at Kent Lake, Oakland County, which is under a state Do Not Eat Advisory for all fish species. Image: Ruth Thornton.
By Ruth Thornton
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 polyfluoroalkyl substances or PFAS – are found in some rivers, lakes, soils, drinking water, fish, cattle and crops. The study by researchers at Indiana University and the Ecology Center in Ann Arbor measured the contamination of fish in Michigan’s Huron and Rouge River watersheds.
The findings are sobering. “Every fish had at least one” of 14 PFAS chemicals, said Erica Bloom, toxics campaign director at the Ecology Center.
The study, published in the journal Chemosphere last December, looked not only at the amount of PFAS in the filets that people eat, but also in the liver, eggs and digestive tract to assess potential effects on wildlife that eat entire fish.
Levels they found 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 PFAS 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.
In the Huron River the tested filets had particularly high PFAS levels. The Michigan Department of Health and Human Services has issued a Do Not Eat advisory for much of the Huron River, which means that even one meal of these fish could lead to health problems.
PFAS levels in southeast Michigan fish, in parts per billion. Image: Ecology Center
And little is known about many more PFAS chemicals that have been manufactured since the 1940s. Only two – known as PFOS and PFOA – have been extensively studied. Michigan’s Eat Safe Fish guidelines account for only PFOS – and not the many other PFAS chemicals that may also be present.
High levels of these chemicals have been implicated in multiple health problems in humans, 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.
Cheryl Murphy, director of the Center for PFAS Research at Michigan State University. Image: MSU
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, 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 is 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 some 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 soils 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 is difficult to study so many chemicals but researchers say they are 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. It is adapted from the pharmaceutical industry’s methods for testing drugs before performing expensive clinical trials.
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.
EPA Toxicologist Gary Ankley. Image: EPA
“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 the chemicals’ impact on cells and tissues.
These tissues are maintained in the lab for months or years and can be exposed to hundreds or even 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 the 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 are optimistic that solutions will be found to reduce exposure to them.
“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 to it.”
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.”