Assessing PFAS mixture exposure and thyroid function in U.S. adolescents: insights from NHANES 2011-2012.

Area of Science:

• Environmental Health
• Endocrinology
• Toxicology

Background:

• Per- and polyfluoroalkyl substances (PFASs) are persistent endocrine-disrupting chemicals found globally in human serum.
• Epidemiological studies suggest PFAS exposure may interfere with thyroid hormone production, transport, and metabolism, but findings are inconsistent, especially regarding sex-specific effects.

Purpose of the Study:

• To investigate associations between serum PFAS mixtures and thyroid hormone levels in adolescents.
• To identify PFAS mixture patterns and explore sex-specific effects on thyroid function in a nationally representative sample.

Main Methods:

• Utilized data from NHANES 2011-2012 for adolescents aged 12-20.
• Employed Principal Component Analysis (PCA) to identify PFAS mixture patterns (Factor 1: long-chain carboxylates, Factor 2: sulfonates, Factor 3: PFHpA).
• Applied multivariable linear regression to assess associations between PFAS factors and thyroid function markers (TSH, thyroid hormones, thyroglobulin).

Main Results:

• Factor 1 (long-chain carboxylates) showed sex-specific associations: positive with free T4 in males, negative with total T4 in females.
• Factor 2 (sulfonates) exposure was linked to lower total T4 and higher TSH in males.
• Factor 3 (PFHpA) exposure was significantly associated with increased total T4 in males.
• Overall, Factors 1 and 2 were linked to lower thyroid hormones, while Factor 3 was linked to higher thyroid hormones.

Conclusions:

• PFAS mixtures, not individual compounds, are crucial for understanding thyroid disruption.
• Findings suggest significant sex-specific alterations in thyroid hormone levels due to PFAS exposure in adolescents.
• PFASs may impact thyroid hormone homeostasis through mechanisms like altered hormone clearance or feedback regulation.