Prenatal particulate air pollution and neurodevelopment in urban children: Examining sensitive windows and sex-specific associations

Background: Brain growth and structural organization occurs in stages beginning prenatally. Toxicants may impact neurodevelopment differently dependent upon exposure timing and fetal sex. Objectives: We implemented innovative methodology to identify sensitive windows for the associations between prenatal particulate matter with diameter <= 2.5 mu m (PM2.5) and children's neurodevelopment Methods: We assessed 267 full-term urban children's prenatal daily PM2.5 exposure using a validated satellite based spatio-temporally resolved prediction model. Outcomes included IQ (WISC-IV), attention (omission errors [OEs], commission errors [CE5], hit reaction time [HRT], and HRT standard error [HRT-SE] on the Conners' CPT-II), and memory (general memory [GM] index and its components verbal [VEM] and visual [VIM] memory, and attention-concentration [AC] indices on the WRAML-2) assessed at age 6.5 +/- 0.98 years. To identify the role of exposure timing, we used distributed lag models to examine associations between weekly prenatal PM2.5 exposure and neurodevelopment. Sex-specific associations were also examined. Results: Mothers were primarily minorities (60% Hispanic, 25% black); 69% had 12 years of education. Adjusting for maternal age, education, race, and smoking, we found associations between higher PM2.5 levels at 31-38 weeks with lower IQ at 20-26 weeks gestation with increased OEs, at 32-36 weeks with slower HRT, and at 22-40 weeks with increased HRT-SE among boys, while significant associations were found in memory domains in girls (higher PM2.5 exposure at 18-26 weeks with reduced VIM, at 12-20 weeks with reduced GM). Conclusions: Increased PM2.5 exposure in specific prenatal windows may be associated with poorer function across memory and attention domains with variable associations based on sex. Refined determination of time window-and sex-specific associations may enhance insight into underlying mechanisms and identification of vulnerable subgroups. (C) 2015 Elsevier Ltd. All rights reserved.