A recent study entitled “Association Between Per- and Polyfluoroalkyl Substance Exposures and Thyroid Homeostasis Parameters,” published in the Journal of Clinical Endocrinology & Metabolism, has found that exposure to per- and polyfluoroalkyl substances (PFAS) — a group of synthetic chemicals used in industrial and consumer products — may alter thyroid hormone sensitivity, potentially affecting metabolism and overall endocrine health.
PFAS chemicals, often called “forever chemicals” due to their persistence in the environment and human body, are found in everyday products such as nonstick cookware, food packaging, waterproof fabrics, and firefighting foam. These chemicals can accumulate over time, leading to widespread exposure through contaminated water, food, and air. Thyroid hormones are essential for metabolism, energy regulation, and overall health. Disruptions in thyroid function have been linked to weight gain, fatigue, cardiovascular issues, and hormonal imbalances. Results from this study raises concerns that chronic exposure to PFAS — long known to be endocrine-disruptive chemicals–could have long-term effects on thyroid health and metabolism.
As regulatory agencies consider stricter limits on PFAS in drinking water and consumer products, understanding the full scope of these chemicals’ effects is crucial for public health policy and personal well-being.
Previous studies have mostly focused on the disruption effect of PFAS and individual thyroid hormones. In this study, researchers from The Second Affiliated Hospital of Air Force Medical University, Shaanxi, China used the National Health and Nutrition Examination Survey (NHANES), a program run by the U.S. Centers for Disease Control and Prevention that assesses the health and nutritional status of U.S. adults and children. The team analyzed blood serum data from 2,386 adults in NHANES across two cycles (2007-2008 and 2011-2012) to examine how exposure to six PFAS correlates with central and peripheral thyroid hormone sensitivity.
Statistical models confirmed a strong association between combined PFAS exposures and altered thyroid function. In particular, PFOA had the strongest impact among all PFAS analyzed. Additionally, the researchers found that PFAS exposure is linked to changes in peripheral thyroid hormone sensitivity but not central thyroid regulation. Higher levels of four specific PFAS chemicals — perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), perfluorononanoic acid (PFNA), and perfluorohexane sulfonic acid (PFHxS) — were associated with increases in the ratio of free triiodothyronine (FT3) to free thyroxine (FT4) and the sum activity of peripheral deiodinases (SPINA-GD). The findings suggest that PFAS exposure may interfere with how the body converts and processes thyroid hormones at the peripheral level, rather than directly affecting thyroid-stimulating hormone (TSH) regulation from the brain via the pituitary gland and hypothalamus.
While this study does not confirm a direct cause-and-effect relationship, it adds to growing concerns about PFAS chemicals and their potential impact on endocrine function, the authors write, adding that “caution should be exercised in the application of compounds as an alternative for PFAS [e.g., Cl-PFESA]” as research has found some also impact the thyroid.
This study highlights the need for further research into the long-term health effects of PFAS exposure, particularly its impact on the endocrine system. As regulatory agencies consider stricter limits on PFAS in drinking water and consumer products, understanding the full scope of these chemicals’ effects is crucial for public health policy and personal well-being. Although PFAS are widespread, individuals can take steps to minimize exposure, such as using activated carbon and reverse osmosis filters to reduce PFAS contamination in drinking water, opting for stainless steel, cast iron, or ceramic alternatives to nonstick cookware, reducing processed food consumption as PFAS can be found in food packaging materials, especially grease-resistant wrappers, and reading labels of personal care products like cosmetics, waterproof clothing and stain-resistant fabrics as some contain PFAS.
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