Compounds from the family of chemicals known as PFAS can suppress the body’s ability to mount a defense against new pathogens—and the effects can last well into adulthood.
That’s one conclusion from a new Michigan State University study that looked at how people in two West Michigan communities that had PFAS-contaminated water responded to the virus that causes COVID-19.
Courtney Carignan, an environmental epidemiologist and the lead researcher for the MSU team, had already been conducting PFAS impact studies in Parchment and Cooper Township near Kalamazoo. Both communities were home to paper mills, and in 2018, state testing found that public water supplies had been historically contaminated.
Carignan said it’s well-established that PFAS chemicals are immunotoxic in children, but it’s been harder to study that impact on adults. That’s because adult immune systems have already been exposed to a number of pathogens that trained their immune systems to respond by producing antibodies, the frontline “soldiers” of immune response.
So when the COVID pandemic struck, Carignan and her team took the opportunity to look at the immune responses in adults participating in the existing research. And what they found was striking: a strong link between blood levels of a certain PFAS compound—perfluorohexanesulfonic acid, or PFHxS—and fewer defensive antibodies being produced in response to COVID exposure through vaccination.
“And so we infer then that people who have higher exposures, if they're producing less antibodies, then their bodies are less able to fight an infection,” Carignan said.
“It reinforces what we know about these contaminants—that they have been phased out of use because they're known to be harmful, that they are immunotoxic, and that these effects persist into adulthood.”
Carignan added that while some classes of PFAS have been phased out, including PFHxS, thousands more remain in use.
They’re known as “forever chemicals” because of how long they take to break down in the environment and in human bodies. In addition to immunotoxic properties, they’re also known endocrine disruptors and linked to multiple types of cancer.
PFAS are so prevalent in the environment that nearly everyone has some level of them present in their body. However, Carignan said there doesn’t appear to be a link to suppressed immune response correlated with those lower levels.
“Most of us, unfortunately, do have these chemicals in our body,” she said. “[But] at those levels, we don't really see not producing enough antibodies to be protected.”
The study comes at a time when the U.S. is still debating PFAS standards for drinking water. The U.S. Environmental Protection Agency finalized its first enforceable drinking water standards for certain PFAS chemicals in 2024, but implementation timelines and enforcement for some compounds have since been pushed back, according to Carignan. Michigan, however, has its own standards.
“I think Michiganders can know that our state is doing more than other states, and we have more protections,” Carignan said. “That's a good thing.”
