Association between Serum Perfluorooctanoic Acid (PFOA) and Thyroid Disease in the U.S. National Health and Nutrition Examination Survey

Abstract

BackgroundPerfluorooctanoic acid (PFOA, also known as C8) and perfluorooctane sulfonate (PFOS) are stable compounds with many industrial and consumer uses. Their persistence in the environment plus toxicity in animal models has raised concern over low-level chronic exposure effects on human health.ObjectivesWe estimated associations between serum PFOA and PFOS concentrations and thyroid disease prevalence in representative samples of the U.S. general population.MethodsAnalyses of PFOA/PFOS versus disease status in the National Health and Nutrition Examination Survey (NHANES) for 1999–2000, 2003–2004, and 2005–2006 included 3,974 adults with measured concentrations for perfluorinated chemicals. Regression models were adjusted for age, sex, race/ethnicity, education, smoking status, body mass index, and alcohol intake.ResultsThe NHANES-weighted prevalence of reporting any thyroid disease was 16.18% (n = 292) in women and 3.06% (n = 69) in men; prevalence of current thyroid disease with related medication was 9.89% (n = 163) in women and 1.88% (n = 46) in men. In fully adjusted logistic models, women with PFOA ≥ 5.7 ng/mL [fourth (highest) population quartile] were more likely to report current treated thyroid disease [odds ratio (OR) = 2.24; 95% confidence interval (CI), 1.38–3.65; p = 0.002] compared with PFOA ≤ 4.0 ng/mL (quartiles 1 and 2); we found a near significant similar trend in men (OR = 2.12; 95% CI, 0.93–4.82; p = 0.073). For PFOS, in men we found a similar association for those with PFOS ≥ 36.8 ng/mL (quartile 4) versus ≤ 25.5 ng/mL (quartiles 1 and 2: OR for treated disease = 2.68; 95% CI, 1.03–6.98; p = 0.043); in women this association was not significant.ConclusionsHigher concentrations of serum PFOA and PFOS are associated with current thyroid disease in the U.S. general adult population. More work is needed to establish the mechanisms involved and to exclude confounding and pharmacokinetic explanations.

Structure–activity relations in binding of perfluoroalkyl compounds to human thyroid hormone T3 receptor

“…Several large-scale surveys of Nunavik permanent residents (Dallaire et al 2009), US. general adult population (Melzer et al 2010), and children living near a chemical plant of USA (Lopez-Espinosa et al 2012) suggested the association of increased serum PFCs with abnormal THs levels and thyroid diseases.…”

Perfluorooctane sulfonate (PFOS) affects hormone receptor activity, steroidogenesis, and expression of endocrine‐related genes in vitro and in vivo

“…Serum thyroxine (T4) and triiodothyronine (T3) were reduced by PFCs in animal studies [18,19]. A recent study on the general adult population in the United States has suggested that higher concentrations of serum PFOS are associated with thyroid disease [20]. Therefore, further characterization of the endocrine-disrupting effects of PFCs is required for assessing potential health risks.…”

Environmental Thyroid Disruptors and Human Endocrine Health

“…Human biomonitoring of the general population in various countries (Calafat et al, 2006;Kannan et al, 2004;Metzer et al, 2010). has shown that, in addition to the near ubiquitous presence of PFOS and PFOA in blood, these may also be present in breast milk, liver, seminal fluid, and umbilical cord blood (Lau et al, 2007).…”

“…Modest associations between PFOA and THs (negative for free T4 and positive for T3) were reported in 506 PFOA production workers across three production facilities (Olsen & Zobel, 2007); there were no associations between TSH or T4 and PFOA, and the free TH levels were within the normal reference range. On the other hand, Metzer et al (Metzer et al, 2010) recently determined whether increased serum PFOA or PFOS concentrations are associated with thyroid disease in a general adult US population sample (n = 3,974 individuals ≥ 20 years of age from NHANES waves 1999-2000 (n = 1,040), 2003-2004 (n = 1,454), and 2005-2006 (n = 1,480)). They found that, across all the available data from NHANES, thyroid disease associations with serum PFOA concentrations are present in women and are strongest for those currently being treated for thyroid disease (P=0.002) (Metzer et al, 2010).…”