Urinary concentrations of phthalate biomarkers and weight change among postmenopausal women: a prospective cohort study

BackgroundSome phthalates are endocrine disrupting chemicals used as plasticizers in consumer products, and have been associated with obesity in cross-sectional studies, yet prospective evaluations of weight change are lacking. Our objective was to evaluate associations between phthalate biomarker concentrations and weight and weight change among postmenopausal women.MethodsWe performed cross-sectional (N=997) and longitudinal analyses (N=660) among postmenopausal Women's Health Initiative participants. We measured 13 phthalate metabolites and creatinine in spot urine samples provided at baseline. Participants' weight and height measured at in-person clinic visits at baseline, year 3, and year 6 were used to calculate body mass index (BMI). We fit multivariable multinomial logistic regression models to explore cross-sectional associations between each phthalate biomarker and baseline BMI category. We evaluated longitudinal associations between each biomarker and weight change using mixed effects linear regression models.ResultsIn cross-sectional analyses, urinary concentrations of some biomarkers were positively associated with obesity prevalence (e.g. sum of di (2-ethylhexyl) phthalate metabolites [sigma DEHP] 4th vs 1st quartile OR=3.29, 95% CI 1.80-6.03 [p trend<0.001] vs normal). In longitudinal analyses, positive trends with weight gain between baseline and year 3 were observed for mono-(2-ethyl-5-oxohexyl) phthalate, monoethyl phthalate (MEP), mono-hydroxybutyl phthalate, and mono-hydroxyisobutyl phthalate (e.g. +2.32kg [95% CI 0.93-3.72] for 4th vs 1st quartile of MEP; p trend <0.001). No statistically significant associations were observed between biomarkers and weight gain over 6years.ConclusionsCertain phthalates may contribute to short-term weight gain among postmenopausal women.