Relationships Between Urinary Phthalate Metabolite and Bisphenol A Concentrations and Vitamin D Levels in U.S. Adults: National Health and Nutrition Examination Survey (NHANES), 2005-2010.

CONTEXT: Recent research suggests that environmental exposure to endocrine-disrupting chemicals may alter circulating 25-hydroxyvitamin D [25(OH)D] levels in humans. To date, no studies have assessed the associations between phthalates and bisphenol A (BPA) and total 25(OH)D in the U.S. general population.

OBJECTIVE: To explore relationships between urinary concentrations of 11 phthalate metabolites and BPA and serum total 25(OH)D in a representative sample of U.S. adults.

DESIGN: A cross-sectional study.

SETTING: U.S. National Health and Nutrition Examination Survey, 2005-2010.

PATIENTS OR OTHER PARTICIPANTS: U.S. general adult population (aged ≥20 years).

INTERVENTIONS: None Main Outcome Measures: Serum total 25(OH)D measured by liquid chromatography-tandem mass spectrometry.

RESULTS: Metabolites of di(2-ethylhexyl) phthalate (DEHP) were consistently inversely associated with total 25(OH)D in the overall study population and in gender-stratified models. In the overall population, we detected a significant inverse relationship for the molar sum of DEHP metabolites (ΣDEHP), where an interquartile range increase in ΣDEHP was associated with a 1.90% decrease (95% confidence interval [CI], -3.64, -0.17) in total 25(OH)D. A positive association was detected for monoethyl phthalate. For BPA, we found a statistically significant inverse relationship in women, but not in men. In women, an interquartile range increase in urinary BPA was associated with a 3.71% decrease (95% CI, -6.41, -1.02) in total 25(OH)D.

CONCLUSIONS: Overall, our results provide suggestive evidence that environmental exposure to phthalates and BPA may alter circulating levels of total 25(OH)D in adults. Future human and animal studies are required to resolve the direction, temporality, and impact of these relationships.