Protecting populations from dangers of PFAS exposure
By Jessica M. Scully
A group of manufactured chemicals known as “forever chemicals” due to their persistence in the environment and our bodies has been linked to cancer and a host of other health harms.
Jackie Goodrich, research associate professor of Environmental Health Sciences at the University of Michigan School of Public Health, studies one way the chemicals may be responsible for these harms. At relatively low levels of exposure, they cause changes in cells, including changes in mechanisms cells use to control gene expression.
PFAS—per- and polyfluoroalkyl substances—have been widely used in industrial and consumer products for decades because they repel water, resist heat and are chemically stable. They’re in everything from stain-resistant carpeting to nonstick cookware.
Their routine use and omnipresence—PFAS don’t break down for hundreds to thousands of years—means researchers and regulators have found them in many places they shouldn’t be, including soil, the air, fish and water, according to the US Environmental Protection Agency (EPA). At least 45% of the nation’s water supply is contaminated with one or more PFAS, according to the US Geological Survey, and nearly everyone in the United States has been exposed to PFAS, according to the Centers for Disease Control and Prevention’s Agency for Toxic Substances and Disease Registry.
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Firefighters face double PFAS exposure risk
Goodrich has long studied firefighters because their profession exposes them to chemicals, including PFAS, that other professions don’t encounter. PFAS are in some of their firefighting gear and in the foams firefighters have used to put out certain fires, giving them a double burden of environmental and occupational exposures, she said.
Evidence links certain PFAS to two kinds of cancer and to increases in cholesterol levels, changes in liver function, and decreased birth weight for infants, according to the Agency for Toxic Substances and Disease Registry. Some evidence suggests PFAS could be linked to hormone-related cancers, such as breast and thyroid.
“When we know something is hazardous, like PFAS, we have to provide as much evidence as we can to the people who make policies since even low doses can be dangerous,” Goodrich said.
“It shouldn’t be up to consumers and workers to have to avoid PFAS; they shouldn’t be exposed in the first place.”
Goodrich has studied PFAS exposures in firefighters and in children and their effects on the epigenome—all the chemical modifications within a cell that regulate gene expression. She measures a component called DNA methylation, which is part of how cells regulate gene expression, turning a gene off or on.
High PFAS levels linked to cancer
Understanding how certain PFAS impact cancer risk is a current research focus for Goodrich. PFAS may deactivate tumor suppressor genes while activating genes that promote cancerous processes and cell growth, she said. Additionally, PFAS can disrupt hormone signaling, harm cells and modify the immune system.
“All of those could come into play when we think about how PFAS might eventually lead to cancer,” she said.
Goodrich has observed alterations in DNA methylation in both firefighters and newborns at exposure levels near the median for the US population. Increased exposure to PFAS is linked to more severe biological effects.
All of those could come into play when we think about how PFAS might eventually lead to cancer.”
Moreover, individuals residing in heavily contaminated areas or workers exposed to PFAS on the job can have significantly higher levels—approximately 50 to 500 times greater than what Goodrich has identified in firefighters.
“In people with higher PFAS concentrations in their bodies, we see bigger, more dramatic changes,” she said.
In a 2021 article published in Epigenomics, Goodrich and her research partners analyzed blood samples from about 200 firefighters. Despite firefighters’ additional exposures, the researchers found concentrations just a little higher for some PFAS than in the general US population.
The researchers studied the concentration of nine PFAS and their effect on DNA methylation and epigenetic age, which is linked to several harmful conditions. Three PFAS were linked with increased epigenetic age, and four with altered DNA methylation at genes involved in immune function and possibly cancer risk.
The study included firefighters from the Fire Fighter Cancer Cohort Study, which Goodrich joined in 2018 and now co-leads. Currently, more than 6,000 firefighters are part of the study. But the researchers hope to eventually have 10,000 firefighters and to follow them over 30 years to better understand what effect PFAS and other exposures have on their health, including whether they develop cancer.
PFAS exposure risks begin prenatally
Goodrich began her PFAS work in children to fill what she saw as a gap in research. With so many sources of PFAS exposure, “if even low levels of exposure are impacting children, prenatally onward, that’s something we need to know to better protect against these chemicals,” she said.
For a 2023 paper in Clinical Epigenetics, Goodrich and her team tested first trimester blood samples from pregnant women and umbilical cord blood. Higher PFAS exposure levels were associated with altered DNA methylation and with decreased newborn gestational age and size.
Whether those epigenetic changes are transient or lasting isn’t known, since the study stopped at birth, Goodrich said. But as part of the nationwide ECHO consortium, she is continuing to investigate how prenatal PFAS exposures might affect children’s health over the longer term.
“These exposures during pregnancy can have subtle impacts that you can’t always see when a child is born, but PFAS can have a longer-term effect on children’s risk for developmental issues and disease later in life,” she said.
In people with higher PFAS concentrations in their bodies, we see bigger, more dramatic changes.”
Because PFAS are so prevalent in the environment and essentially indestructible, most people have an ongoing exposure source and continue to accumulate more in their bodies over time, Goodrich said.
“That gives a PFAS more time to create damage in the tissues that it’s in and to activate cell mechanisms that could eventually turn a healthy cell into a cancerous cell,” she said.
Some of the work Goodrich does may offer help to reverse this. Determining biological pathways affected by PFAS might mean those pathways could be targeted with a specific diet or other form of treatment, she said, “that reduces people’s risk of getting a disease even though they’re already exposed to these chemicals.” A folate-rich diet is currently showing promise, she said.
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EPA sets new PFAS regulations nationwide
With more and more evidence from researchers documenting the harms of PFAS, the EPA has recently taken action. In April 2024, it issued the first national, legally enforceable drinking water standard for PFAS, and classified two widely used PFAS as hazardous substances.
Goodrich says she’s glad to see the changes, though she notes that the regulation covers only seven PFAS. Depending on how a PFAS is defined, there are 14,000 total, with new ones being developed.
“For the PFAS it is protecting against, which are some of the worst ones that we know about,” she said, “I think it’s really going to help protect populations.”