Air Pollution Exposure during Pregnancy and Childhood Autistic Traits in Four European Population-Based Cohort Studies: The ESCAPE Project

Abstract

BACKGROUND: Prenatal exposure to air pollutants has been suggested as a possible etiologic factor for the occurrence of autism spectrum disorder. OBJECTIVES: To assess whether prenatal air pollution exposure is associated with childhood autistic traits in the general population. METHODS: Collaborative study of four European population-based birth/child cohorts -CATSS (Sweden), GENERATION R (the Netherlands), GASPII (Italy), and INMA (Spain). Nitrogen oxides (NO2, NOx) and particulate matter (PM) with diameters of <2.5 µm (PM2.5), <10 µm (PM10), and between 2.5-10 µm (PMcoarse) and PM2.5 absorbance- were estimated for birth addresses by land-use regression models based on monitoring campaigns performed between 2008 and 2011. Levels were extrapolated back in time to exact pregnancy periods. Autistic traits were assessed between four and ten years of age using quantitative assessments. Children were classified with autistic traits within the borderline/clinical range and within the clinical range using validated cut-offs. Adjusted cohort-specific effect estimates were combined using random-effects meta-analysis. RESULTS: A total of 8,079 children were included. Prenatal air pollution exposure was not associated with autistic traits within the borderline/clinical range (OR = 0.94; 95% CI: 0.81, 1.10 per each increase by 10 µg/m(3) in NO2 pregnancy levels). Similar results were observed in the different cohorts, for the other pollutants, and assessing children with autistic traits within the clinical range or children with autistic traits as a quantitative score. CONCLUSIONS: Prenatal exposure to NO2 and PM was not associated with autistic traits in children from four to ten years of age in four European population-based birth/child cohort studies.