Melzer, D., Rice, N., Depledge, M. H., Henley, W. E., & Galloway, T. S. (2010). Association between serum perfluorooctanoic acid (PFOA) and thyroid disease in the U.S. National Health and Nutrition Examination Survey. Environmental health perspectives. https://doi.org/10.1289/ehp.0901584
Melzer D, Rice N, Depledge MH, Henley WE, Galloway TS. Association between serum perfluorooctanoic acid (PFOA) and thyroid disease in the U.S. National Health and Nutrition Examination Survey. Environmental health perspectives. 2010. doi:10.1289/ehp.0901584
Melzer, D., et al. "Association between serum perfluorooctanoic acid (PFOA) and thyroid disease in the U.S. National Health and Nutrition Examination Survey." Environmental health perspectives, 2010.
Higher PFOA blood levels linked to thyroid disease in U.S. adults
A cross-sectional analysis of 3,974 adults in NHANES, a U.S. national health survey, found that women with the highest PFOA blood levels were more likely to report treated thyroid disease. PFOA and PFOS are long-lived industrial chemicals. Men with the highest PFOS levels also had higher odds of treated thyroid disease, a nominally significant result.
Key Findings
Survey-weighted, 16.18% of women (n = 292) and 3.06% of men (n = 69) reported any thyroid disease; current treated disease affected 9.89% of women (n = 163).
After full adjustment, women in the top PFOA quartile had higher odds of current treated thyroid disease than women in the bottom two (odds ratio 2.24; 95% CI, 1.38–3.65, p = 0.002).
Men showed a similar, near significant PFOA trend (odds ratio 2.12; 95% CI, 0.93–4.82, p = 0.073). The test for a sex difference was not significant (p for interaction = 0.152).
Men in the top PFOS quartile had higher odds of treated thyroid disease than men in the bottom two (odds ratio 2.68; 95% CI, 1.03–6.98, p = 0.043). Not significant in women.
A post hoc check of arthritis, asthma, COPD, diabetes, heart disease and liver disease found no other robust associations of higher PFOA or PFOS concentration with increased disease prevalence.
Interpretation
NHANES surveys a representative sample of U.S. civilians living outside institutions, so the results describe adults in the general population. Participants reported whether a doctor had diagnosed a thyroid problem, and the survey records no specific diagnosis. Chemical levels came from one blood sample taken when disease status was reported. The authors note that this timing makes the direction of any effect hard to attribute, and they call for longitudinal studies.
RRM Context
Restorative reproductive medicine looks for root causes across the whole endocrine system. Thyroid hormone shapes ovulation and the menstrual cycle, so chemicals that may disrupt hormones, such as PFOA and PFOS, belong in that search.
Our editorial summary of this paper, not the article's abstract.
Abstract
Background
Perfluorooctanoic 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.
Objectives
We estimated associations between serum PFOA and PFOS concentrations and thyroid disease prevalence in representative samples of the U.S. general population.
Methods
Analyses 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.
Results
The 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 >or= 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 <or= 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 >or= 36.8 ng/mL (quartile 4) versus <or= 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.
Conclusions
Higher 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.
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