Urinary phthalate metabolite concentrations and hot flashes in women from an urban convenience sample of midlife women

Context: Phthalate exposure is associated with altered reproductive function, but little is known about associations of phthalate exposure with risk of hot flashes. Objective: To investigate associations of urinary phthalate metabolite levels with four hot flash outcomes in midlife women. Design: A cross-sectional study of the first year of a prospective cohort of midlife women, the Midlife Women's Health Study (2006–2015), a convenience sample from an urban setting. Participants: 728 multi-racial/ethnic pre- and perimenopausal women aged 45–54 years. Outcome measures: Women completed questionnaires about hot flash experience and provided 1–4 urine samples over four consecutive weeks that were pooled for analysis. Phthalate metabolites were assessed individually and as molar sums representative of common compounds (all phthalates: ƩPhthalates; DEHP: ƩDEHP), exposure sources (plastics: ƩPlastic; personal care products: ƩPCP), and modes of action (anti-androgenic: ƩAA). Covariate-adjusted logistic regression models were used to assess associations of continuous natural log-transformed phthalate metabolite concentrations with hot flash outcomes. Analyses were conducted to explore whether associations differed by menopause status, body mass index (BMI), race/ethnicity, and depressive symptoms. Results: Overall, 45% of women reported a history of hot flashes. Compared to women who never experienced hot flashes, every two-fold increase in ƩPlastic was associated with 18% (OR: 1.18; 95%CI: 0.98, 1.43) and 38% (OR: 1.38; 95%CI: 1.11, 1.70) higher odds of experiencing hot flashes in the past 30 days and experiencing daily/weekly hot flashes, respectively. Some associations of phthalates with certain hot flash outcomes differed by menopause status, BMI, race/ethnicity, and depressive symptoms. Conclusions: This study suggests that phthalates are associated with hot flash experience and may impact hot flash risk in women who are susceptible to experiencing hot flashes.