Link Between PFAS Exposure and Thyroid Function Indicators in US Adults

Overview

This study analyzed data from 2,386 US adults to investigate associations between exposure to per- and polyfluoroalkyl substances (PFAS) and thyroid homeostasis parameters. Results demonstrated that PFAS exposure was positively associated with peripheral thyroid hormone sensitivity indices, specifically the FT3/FT4 ratio and SPINA-GD, but showed no significant association with central thyroid sensitivity parameters.

Background

Thyroid diseases have been increasing globally, with risk factors including chemical exposures such as endocrine-disrupting chemicals (EDCs). PFAS are persistent environmental pollutants widely used in consumer products and have been implicated in disrupting thyroid function. While prior studies focused on individual thyroid hormones, the impact of PFAS on overall thyroid homeostasis, including central and peripheral hormone sensitivity, remains unclear. Understanding these associations is critical given the role of thyroid hormones in metabolism and health.

Data Highlights

Key Findings

• PFAS exposure was positively associated with peripheral thyroid hormone sensitivity indices: FT3/FT4 ratio and SPINA-GD.
• No significant associations were found between PFAS exposure and central thyroid sensitivity parameters (TT4RI, TSHI, TFQI, PTFQI).
• Weighted quantile sum (WQS) and quantile g-computation (QGC) models confirmed positive associations of PFAS mixtures with FT3/FT4 and SPINA-GD.
• PFOA contributed the highest weight to the observed associations in mixture models.
• The study included 2,386 adults from NHANES 2007-2008 and 2011-2012 cycles, excluding those with thyroid disease or on thyroid medications.

Clinical Implications

Clinicians should be aware that environmental exposure to PFAS may alter peripheral thyroid hormone metabolism, potentially affecting thyroid hormone bioavailability without altering central regulatory mechanisms. Monitoring thyroid function in populations with high PFAS exposure might require assessment beyond standard thyroid hormone levels to include peripheral sensitivity indices. These findings highlight the need for further research on PFAS exposure and thyroid-related health outcomes.

Conclusion

This study provides evidence that PFAS exposure is associated with increased peripheral thyroid hormone sensitivity in US adults, enhancing understanding of PFAS-related thyroid disruption. These findings underscore the importance of considering environmental chemical exposures in thyroid health assessments.

References

1. NHANES Study 2007-2012 -- Link Between Exposure to Per- and Polyfluoroalkyl Substances and Thyroid Function Indicators