Bisphenol A and pthalate exposure may adversely affect thyroid function. - GreenMedInfo Summary
Relationship between Urinary Phthalate and Bisphenol A Concentrations and Serum Thyroid Measures in U.S. Adults and Adolescents from NHANES 2007-08.
Environ Health Perspect. 2011 Jul 11. Epub 2011 Jul 11. PMID: 21749963
University of Michigan.
Background: Limited animal, in vitro, and human studies have reported that exposure to phthalates or bisphenol a (BPA) may impact thyroid signaling. Objective: Explore the cross-sectional relationship between urinary concentrations of metabolites of di(2-ethylhexyl) phthalate (DEHP), dibutyl phthalate (DBP), and BPA with a panel of serum thyroid measures among a representative sample of U.S. adults and adolescents. Methods: Data on urinary biomarkers of exposure to phthalates and BPA, serum thyroid measures, and important covariates from 1346 adults (ages>= 20 years) and 329 adolescents (ages 12-19) from NHANES 2007-08 were analyzed using multivariable linear regression. Results: Among adults, there were significant inverse relationships between urinary DEHP metabolites and total T4, free T4, total T3, and thyroglobulin, and positive relationships with TSH. The strongest and most consistent relationships involved total T4, where adjusted regression coefficients for quintiles of oxidative DEHP metabolites displayed monotonic dose-dependent decreases in total T4 (p-value for trend<0.0001). Suggestive inverse relationships between urinary BPA and total T4 and TSH were also observed. Conversely, among adolescents, there were significant positive relationships between DEHP metabolites and total T3. Mono(3-carboxypropyl) phthalate (MCCP), a secondary metabolite of both DBP and di-n-octyl phthalate (DOP) was associated with several thyroid measures in both age groups, while other DBP metabolites were not associated with thyroid measures. Conclusions: These results support previous reports of associations between phthalates, and possibly BPA, and altered thyroid hormones. More detailed studies are needed to determine the temporal relationships and potential clinical and public health implications of these associations.