Researchers may have discovered a link between certain per- and polyfluoroalkyl substances (PFAS)—also referred to as "forever chemicals"—and an increased risk of thyroid cancer, according to a recent study published by van Gerwen et al in eBioMedicine.
Background
PFAS are a large, complex group of synthetic chemicals that can migrate into the soil, water, and air. As a result of their strong carbon-fluorine bond, PFAS do not degrade easily in the environment and have been used in consumer products around the world since the 1940s, including in nonstick cookware; water-repellent clothing; stain-resistant fabrics; and other products that resist grease, water, and oil.
Multiple national and international institutions such as the European Parliament and the U.S. Environmental Protection Agency have declared PFAS exposure a health crisis. Although PFAS exposure has been identified as a potential contributor to an increased incidence of thyroid cancer, there have been few research efforts to investigate the correlation.
“With the substantial increase of thyroid cancer worldwide over recent decades, we wanted to dive into the potential environmental factors that could be the cause for this rise. This led us to the finding that PFAS…may at least partially explain the rise of thyroid cancer and are an area we should continue to study further,” emphasized lead study author Maaike van Gerwen, MD, PhD, Assistant Professor and Director of Research in the Department of Otolaryngology–Head and Neck Surgery at the Icahn School of Medicine at Mount Sinai. “Thyroid cancer risk from PFAS exposure is a global concern given the prevalence of PFAS exposure in our world. This study provides critical evidence to support large-scale studies further exploring the effect of PFAS exposure on the thyroid gland,” she continued.
Study Methods and Results
In this study, the researchers used the medical record–linked biobank BioMe to analyze the plasma samples of 88 patients with thyroid cancer and 88 controls matched on the basis of sex, race, ethnicity, age, body mass index, smoking status, and year of sample collection—with the goal of determining the association between plasma PFAS levels and thyroid cancer diagnoses. They noted the plasma samples were collected at and after thyroid cancer diagnosis.
The researchers used untargeted metabolomics to measure the levels of eight PFAS in the plasma samples and compared the levels of individual PFAS between those with thyroid cancer and controls using different statistical models to estimate accuracy.
They found that patients who were exposed to perfluorooctanesulfonic acid had a 56% increased risk of receiving a thyroid cancer diagnosis.
The researchers then conducted the analysis again in a subgroup of 31 patients who had at least 1 year between their enrollment in the BioMe biobank and a thyroid cancer diagnosis to take into consideration the time lag between exposure to PFAS chemicals and tumor development. From this second analysis, they observed positive associations between exposure to perfluorooctanesulfonic acid and the risk of thyroid cancer as well as exposure to a few additional PFAS chemicals—including branched perfluorooctanesulfonic acid, perfluorononanoic acid, perfluorooctylphosphonic acid, and linear perfluorohexanesulfonic acid.
Conclusions
The researchers underscored that urgent actions may needed to regulate and remove PFAS from potential exposure routes.
“The results of this study provide further confirmation for the PFAS health crisis and underline the need to reduce, and hopefully one day eliminate, PFAS exposure,” stressed senior study author Lauren Petrick, PhD, Associate Professor of Environmental Medicine and Public Health at the Icahn School of Medicine at Mount Sinai. “Today, it’s nearly impossible to avoid PFAS in our daily activities. We hope these findings bring awareness of the severity of these forever chemicals. Everyone should discuss their PFAS exposure with their treating physician to determine their risk and get screened if appropriate. In addition, we need continued industry changes to eliminate PFAS altogether,” she concluded.
Disclosure: The research in this study was funded with pilot funding through the Department of Environmental Medicine and Public Health and the Institute for Exposomic Research’s National Institute of Environmental Health Sciences–funded Center on Health and Environment Across the LifeSpan. For full disclosures of the study authors, visit thelancet.com.
