Associations of Pre- and Postnatal Air Pollution Exposures with Child Behavioral Problems and Cognitive Performance: A U.S. Multi-Cohort Study

Background: Population studies support the adverse associations of air pollution exposures with child behavioral functioning and cognitive performance, but few studies have used spatiotemporally resolved pollutant assessments. Objectives: We investigated these associations using more refined exposure assessments in 1,967 mother-child dyads from three U.S. pregnancy cohorts in six cities in the ECHO-PATHWAYS Consortium. Methods: Pre- and postnatal nitrogen dioxide (N[O.sub.2]) and particulate matter (PM) [less than or equal to]2.5 [micro]m in aerodynamic diameter (P[M.sub.2.5]) exposures were derived from an advanced spatiotemporal model. Child behavior was reported as Total Problems raw score using the Child Behavior Checklist at age 4-6 y. Child cognition was assessed using cohort-specific cognitive performance scales and quantified as the Full-Scale Intelligence Quotient (IQ). We fitted multivariate linear regression models that were adjusted for sociodemographic, behavioral, and psychological factors to estimate associations per 2-unit increase in pollutant in each exposure window and examined modification by child sex. Identified critical windows were further verified by distributed lag models (DLMs). Results: Mean N[O.sub.2] and P[M.sub.2.5] ranged from 8.4 to 9.0ppb and 8.4 to 9.1 [micro]g/[m.sup.3], respectively, across pre- and postnatal windows. Average child Total Problems score and IQ were 22.7 [standard deviation (SD): 18.5] and 102.6 (SD: 15.3), respectively. Children with higher prenatal N[O.sub.2] exposures were likely to have more behavioral problems [[beta]: 1.24; 95% confidence interval (CI): 0.39, 2.08; per 2 ppb N[O.sub.2]], particularly N[O.sub.2] in the first and second trimester. Each 2-[micro]g/[m.sup.3] increase in P[M.sub.2.5] at age 2-4 y was associated with a 3.59 unit (95% CI: 0.35, 6.84) higher Total Problems score and a 2.63 point (95% CI: -5.08, -0.17) lower IQ. The associations between P[M.sub.2.5] and Total Problems score were generally stronger in girls. Most predefined windows identified were not confirmed by DLMs. Discussion: Our study extends earlier findings that have raised concerns about impaired behavioral functioning and cognitive performance in children exposed to N[O.sub.2] and P[M.sub.2.5] in utero and in early life.