Variability and Predictors of Urinary Bisphenol A Concentrations during Pregnancy

Background: Prenatal bisphenol A (BPA) exposure may be associated with developmental toxicity, but few studies have examined the variability and predictors of urinary BPA concentrations during pregnancy. Objective: Our goal was to estimate the variability and predictors of serial urinary BPA concentrations taken during pregnancy. Methods: We measured BPA concentrations during pregnancy and at birth in three spot urine samples from 389 women. We calculated the intraclass correlation coefficient (ICC) to assess BPA variability and estimated associations between log(10)-transformed urinary BPA concentrations and demographic, occupational, dietary, and environmental factors, using mixed models. Results: Geometric mean (GM) creatinine-standardized concentrations (micrograms per gram) were 1.7 (16 weeks), 2.0 (26 weeks), and 2.0 (birth). Creatinine-standardized BPA concentrations exhibited low reproducibility (ICC = 0.11). By occupation, cashiers had the highest BPA concentrations (GM: 2.8 mu g/g). Consuming canned vegetables at least once a day was associated with higher BPA concentrations (GM = 2.3 mu g/g) compared with those consuming no canned vegetables (GM = 1.6 mu g/g). BPA concentrations did not vary by consumption of fresh fruits and vegetables, canned fruit, or store-bought fresh and frozen fish. Urinary high-molecular-weight phthalate and serum tobacco smoke metabolite concentrations were positively associated with BPA concentrations. Conclusions: These results suggest numerous sources of BPA exposure during pregnancy. Etiological studies may need to measure urinary BPA concentrations more than once during pregnancy and adjust for phthalates and tobacco smoke exposures.