HMN 2026: How PFAS directly shown to alter thyroid structure and function

Per- and polyfluoroalkyl substances are used across industries, and are present in waterproof clothing, makeup, carpets, upholstery, cookware, fast-food containers, and myriad other items we encounter in our daily lives.

PFAS are known for their confirmed and potentially detrimental health effects, which are hard to avoid when PFAS, which are known as “forever chemicals” considering how long they persist in the environment and in the human body (up to decades), are found in the water supply across the globe. As a result, up to 98% of Americans have PFAS in their blood, and PFAS have been linked to a disruption in the creation and availability of thyroid hormones. Studies also suggest that PFAS exposure increases thyroid cancer risk.

A recent paper by the labs of Vivian Weiss, associate professor of pathology, microbiology, and immunology, and Ethan Lee, professor of cell and developmental biology, sought to further our understanding of the effects of PFAS on the microscopic anatomy or histology of the thyroid. The paper was published in the Journal of the Endocrine Society.

“Most PFAS studies involve short-term exposure, but we wanted to look at how long-term exposure in cell lines and mouse models could change thyroid cell behavior,” Heather Hartmann said. Hartmann, a Ph.D. student in the Weiss lab, was the first author of the study.

Digging into the effects of three major PFAS compounds, PFOA, PFOS, and GenX, the paper’s authors made three primary findings:

1. The three PFAS altered the thyroid’s cellular function and structure in mice.
2. The PFAS altered several critical signaling pathways, including several involved in cancers.
3. PFAS treatment increased the levels of thyroid-stimulating hormone, which is necessary for the regulation of our metabolism.

These results directly tie PFAS exposure to changes in the histology and functioning of thyroid tissue. They also provided mechanistic clues as to how PFAS are involved in thyroid disease.

“We hope that the results from our paper can help people who are already at risk for thyroid cancer and other cancers make better-informed choices, as consumers, to limit exposure to these chemicals,” Hartmann said. “We also hope that this will also inspire researchers to further look at clinical data and PFAS levels in patients with thyroid cancer.”

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