Associations between bone mineral density and urinary phthalate metabolites among post-menopausal women: a cross-sectional study of NHANES data 2005-2010.

Bone mineral density (BMD) decreases with age, especially among post-menopausal women. Exposures to endocrine disruptors, such as phthalate diesters, could alter BMD through a variety of unidentified mechanisms. A hypothesis-generating study investigated associations between urinary phthalate metabolites and BMD at the femoral neck and spine in post-menopausal women (n = 480) participating in the National Health and Nutrition Examination Survey, from 2005 to 2010. Mono-ethyl phthalate (MEP), molar sum of low molecular weight metabolites (mono-n-butyl phthalate (MNBP), mono-isobutyl phthalate (MIBP), MEP), molar sum of estrogenic metabolites (MNBP, MIBP, MEP, mono-benzyl phthalate (MBZP)), and an estrogenic equivalency factor were negatively associated with spinal BMD. Some associations were modified by age or BMI. The cross-sectional study design, uncertainty regarding the critical time window of exposure, the potential for exposure misclassification, and residual confounding limit our abilities to draw causal conclusions regarding phthalate metabolites and BMD in post-menopausal women. Future studies should address these limitations.