Early life bisphenol A exposure and neurobehavior at 8 years of age: Identifying windows of heightened vulnerability

Background: Early life BPA exposure could affect neurobehavior, but few studies have investigated whether there are developmental periods when the fetus or child is more vulnerable to these potential effects. Objectives: We explored windows of vulnerability to BPA exposure in a multiethnic cohort of 228 mothers and their children from Cincinnati, Ohio. Methods: We measured urinary BPA concentrations at up to two prenatal and six postnatal time points from the 2nd trimester of pregnancy until the child was age 8 years. At age 8 years, we administered the Behavioral Assessment System for Children-2 (BASC-2), Behavior Rating Inventory of Executive Function, and Wechsler Intelligence Scale for Children-IV. We estimated covariate-adjusted differences in composite scores from each instrument using a multiple informant model designed to identify heightened windows of vulnerability. Results: Among all children, there was not strong evidence that the associations between BPA and neurobehavior varied by the timing of exposure (Visit x BPA p-values >= 0.16). However, child sex modified the associations of repeated BPA measures with BASC-2 scores (Visit x Sex x BPA p-values = 0.02-0.23). For example, each 10-fold increase in prenatal BPA was associated with more externalizing behaviors in girls (beta = 6.2, 95% CI: 0.8, 11.6), but not boys (beta = -0.8, 95% CI: -5.0, 3.4). In contrast, a 10-fold increase in 8-year BPA was associated with more externalizing behaviors in boys (beta = 3.9, 95% CI: 0.6, 7.2), but not girls (beta = 0.3, 95% CI: -3.5, 4.1). Conclusions: We found that sex-dependent associations between BPA and child neurobehavior may depend on the timing of BPA exposure.