Are PFAS Causing Thyroid Cancer? Mount Sinai Researchers Investigate

Every day, millions of people around the world are exposed to perfluoroalkyl and polyfluoroalkyl substances (PFAS) in a variety of ways from their cookware and clothing to their drinking water. Thanks to researchers such as Mount Sinai’s Maaike van Gerwen, MD, PhD, we are finally gaining insights on the health impacts of this exposure, specifically the incidence and aggressiveness of thyroid cancer.

In a new study, a team led by Dr. van Gerwen compared PFAS in blood samples from 88 thyroid cancer patients who had a sample collected prior to diagnosis with those from 88 matching noncancer controls from Mount Sinai’s BioMe™ Biobank. Of the 88 patients, 84 percent had papillary thyroid cancer, the most common type of thyroid cancer.

The team found that exposure to perfluorooctane sulfate (PFOS), among the most concerning PFAS, was associated with a 56 percent increased risk for thyroid cancer. The results were similar when including patients with papillary thyroid cancer only. A subsequent study involving a subset of 31 patients who had their blood sample collected at least one year before their cancer diagnosis confirmed the team’s findings, with similar associations observed among other PFAS such as perfluorononanoic acid (PFNA), perfluorooctylphosphonic acid (PFOPA), and perfluorohexanesulfonic acid (PFHxS). The study, “Per- and polyfluoroalkyl substances (PFAS) exposure and thyroid cancer risk,” was published in the November 2023 edition of eBioMedicine.

“Based on studies that have shown that these chemicals disrupt thyroid function, which is my interest, it was our hypothesis that these chemicals would potentially be associated with thyroid cancer,” says Dr. van Gerwen, Assistant Professor and Director of Research in the Department of Otolaryngology-Head and Neck Surgery at the Icahn School of Medicine at Mount Sinai. “The fact that we observed that in such a small sample size made it a significant discovery.”

Introduced in the 1940s, PFAS are synthetic chemicals with grease-, stain-, and water-resistant properties that are used in the manufacture of everything from carpets and food packaging to firefighting foam. They are also known as “forever chemicals” because they are resistant to degradation, which means they stay in the environment for years.

“Although companies have produced PFAS for years, it has only been in the last 20 years that we found they disrupt endocrine function,” Dr. van Gerwen says. “Given that there are thousands of these chemicals being produced and given that particles from them have been found in blood samples in countries where they are not produced, we need to know the real impact of these chemicals.”

Developing Interventions and Influencing Policies and Regulations

While Dr. van Gerwen’s study provides some degree of insight into the thyroid cancer risk associated with PFAS exposure, she stresses that further investigation is necessary. She has plans to repeat the study with researchers in Europe using a larger sample size—blood samples from more than 400 patients—to see if it yields similar results. She is also planning a nationwide study of U.S. military personnel to see whether they have higher rates of thyroid cancer from ongoing exposure to PFAS in firefighting foam.

But Dr. van Gerwen has more ambitious investigations in mind. She is consulting with Ya-Wen Chen, PhD, a pioneer in lung organoid development and Associate Professor in the Department of Otolaryngology-Head and Neck Surgery and the Department of Cell, Developmental, and Regenerative Biology, at Icahn Mount Sinai, about the possibility of growing thyroid organoids and exposing them to PFAS to identify the mechanisms involved in the development of thyroid cancer. That would open the door for interventions that could reverse or even prevent cancer from occurring. She also has plans to partner with researchers at Rutgers University to look at how PFAS levels in drinking water impact thyroid cancer rates in New Jersey. The state has the second highest incidence of thyroid cancer in the nation and a high level of PFAS production-related pollution.

“They have been monitoring that longer than any other state, which means they have a lot of data we can use to model risk of aggressive thyroid cancer associated with PFAS exposure from drinking water over time,” she says. “What we find has the potential to be impactful on a regulatory level.”

This, ultimately, is what Dr. van Gerwen hopes to achieve through her work: to go beyond effective interventions to influence policies and regulations that contribute to reduced exposure and risk or result in removal of PFAS from the environment. “That would be major,” she says. “But it really needs to be a worldwide effort because so long as these chemicals are being produced, we will still have related health issues.”