Association between serum perfluorinated chemicals and thyroid function in U.S. Adults: The national health and nutrition examination survey 2007-2010

Context: Perfluorinated chemicals (PFCs) have been widely used in a variety of products worldwide for years. The relationship between serum PFCs and thyroid function has never been addressed in a nationally representative survey. Objectives: The study examined the association between serum PFCs and thyroid function in the general U.S. population. Design and Participants: We selected 1181 subjects (aged 20 years) from a National Health and NutritionExaminationSurvey(NHANES) in2007through2008and2009through2010todeterminethe relationship between serum PFCs and thyroid function. Data were adjusted for confounding variables. Results: The geometricmeansand95%confidence interval (CI) concentrations of perfluorooctanoate (PFOA), perfluorooctane sulfonate, perfluorononanoic acid, and perfluorohexane sulfonate (PFHxS) were 4.15 (4.02- 4.29), 14.2 (13.59 -14.86), 1.54 (1.48 -1.59), and 2.00 (1.89 -2.11) ng/mL, respectively. After weighting for sampling strategy, we determined a 1-U increase in natural log-serumPFOAincreased serum total T3 concentration by 6.628 ng/dL (95% CI0.545-12.712, P .035) in women. A 1-U increase in natural log-PFHxS was associated with an increase of total T4 by 0.26 g/mL (95% CI 0.108-0.413, P .002) and total T3 by 4.074 ng/dL (95% CI 2.232-5.916, P.001) inwomenanda decrease of natural log-free T4 by 0.016 (ng/dL)(95%CI0.029 to 0.003, P .019) in men. Conclusion: Higher serum concentrations of PFOA and PFHxS are associated with total T3, total T4, and free T4 in the U.S. general population. More studies are warranted to clarify the causal relationship between PFCs and thyroid function. Copyright ? 2013 by The Endocrine Society.