Prenatal PM2.5 exposure and behavioral development in children from Mexico City

Background: Childhood exposure to air pollution has been linked with maladaptive cognitive development; however, less is known about the association between prenatal fine particulate matter (PM2.5) exposure and childhood behavior. Objectives: Our aim was to assess the association between prenatal PM2.5 exposure and behavioral development 4-6 year old children residing in Mexico City. Methods: We used data from 539 mother-child pairs enrolled in a prospective birth cohort in Mexico City. We estimated daily PM2.5 exposure using a 1 km(2) satellite-based exposure model and averaged over each trimester of pregnancy. We assessed childhood behavior at 4-6 years of age using the parent-completed Behavioral Assessment Scale for Children (BASC-2) composite scores and subscales. We used linear regression models to estimate change in BASC-2 T-scores with trimester specific 5-mu g/m(3) increases in PM2.5. All models were mutually adjusted for PM2.5 exposures during the other trimesters, maternal factors including age, education, socioeconomic status, depression, and IQ, child's age at study visit, and season. We additionally assessed sex-specific effects by including an interaction term between PM2.5 and sex. Results: Higher first trimester PM2.5 exposure was associated with reduced Adaptive Skills scores (beta:-1.45, 95% CI:-2.60,-0.30). Lower scores on the Adaptive Skills composite score and subscales indicate poorer functioning. For PM2.5 exposure during the first trimester, decrements were consistent across adaptive subscale scores including Adaptability (beta:-1.51, 95% CI:-2.72,-0.30), Social Skills (beta:-1.63, 95% CI:-2.90,-0.36), and Functional Communication (beta:-1.21, 95% CI:-2.21,-0.21). The association between 1st trimester PM2.5 and depression was stronger in males than females (beta for males: 1.52, 95% CI:-0.41, 3.45; 13 for females:-0.13, 95% CI:-1.99, 1.72; p-int: 0.07). Conclusions: Exposure to PM2.5 during early pregnancy may be associated with impaired behavioral development in children, particularly for measures of adaptive skills. These results suggest that air pollution impacts behavioral domains as well as cognition, and that the timing of exposure may be critical.