Urinary bisphenol A, phthalate metabolites, and obesity: do gender and menopausal status matter?

Previous studies of urinary bisphenol A (BPA), phthalate metabolites, and obesity risk have shown inconsistent results. Menopausal status is one of the main factors that affect hormone secretion change in women. In this study, we examined whether urinary BPA and phthalate metabolite levels are associated with obesity and whether the associations differ by sex and menopausal status in a sample of Korean adult populations. We recruited participants at three branches (Yeouido, Gangnam, and Gwanghwamun) of the Korea Medical Institute, a nationwide health check-up center, from 2015 to 2016. Urinary BPA level was measured by high-performance liquid chromatography-tandem mass spectrometry (Agilent 6490 Triple Quad LC-MS/MS; Agilent Technologies, CA, USA). Urinary six phthalate metabolites were analyzed with ultra-high-performance liquid chromatography-tandem mass spectrometry (TSQ Quantum Access Mass; Thermo Fisher Scientific, MA, USA). Participants with body mass index ≥ 25 kg/m2 were defined as general obesity group. Men with waist circumference (WC) ≥ 90 cm and women with WC ≥ 85 cm were defined as abdominal obesity group. Age, sex, alcohol intake, smoking, and exercise were considered in multivariate logistic regression models. Among the total of 702 participants, 211 participants were classified into the general obesity group, and 131 participants were classified into the abdominal obesity group. Urinary phthalate metabolite levels were not associated with general and abdominal obesity in men and women. However, in women, urinary BPA concentration was positively associated with abdominal obesity (OR = 1.50, 95% CI 1.00-2.26). Also, the association was stronger in postmenopausal women (OR = 2.23, 1.01-4.92), while it was weak in premenopausal women (OR = 1.31, 0.78-2.20). In this study, urinary BPA concentration was associated with abdominal obesity in women, especially postmenopausal women. Future studies should consider sex and menopausal status when investigating associations between urinary BPA, phthalate metabolites levels, and obesity.