Grants and Fellowships | 2014

50 Post-Doctoral Fellowships Association between Air Pollution and Incidence of Autism Spectrum Disorder in the Nurses’ Health Study II Autism spectrum disorder (ASD) is a developmental disorder with increasing incidence worldwide, yet with unclear etiology. Recent studies suggest that environmental factors in fetal development are part of the etiology. The Nurses’ Health Study II (NHS II) is a large cohort of female nurses in the United States that have been followed with biennial questionnaires since 1989. The autism project in NHS II includes participants from across the US, and utilizes a nested case control approach, eliminating many of the potential biases associated with comparisons in previous studies. The aim of the current project is to explore the association between maternal exposure to particulate matter (PM) air pollution and risk of ASD. Mother’s address at birth was geocoded and linked to ambient PM 10-2.5 and PM 2.5 estimates, using the generalized additive models of these pollutants for the continental US. These models use ambient PM data from air quality and research monitoring networks, meteorological variables from weather databases and site characteristics from GIS. Average exposure measures were calculated for the period the mother was pregnant with a case or control child in the sample, and for adjacent 9-months periods. Subjects were NHS II participants’ children born between 1990-2002 with ASD (n=245) and without ASD (n=1,522). Participants were randomly selected using frequency matching for birth years and ASD diagnosis was based on validated maternal report. We found that PM 2.5 exposure during pregnancy was associated with increased odds of ASD, with the 4th exposure quartile having an adjusted odds ratio (OR) of 1.71 (95% CI: 1.10, 2.66) compared with the 1st quartile. The association was stronger when limiting the sample to those who did not change residences around the time of pregnancy (OR=2.02, 95% CI: 1.15, 3.54). ASD associations with PM 2.5 exposure nine months before or after the pregnancy were substantially lower. During pregnancy, PM 2.5 exposure during the third trimester had the strongest association (OR=1.49 per inter-quartile range increase in PM 2.5 [4.40 µg/m 3 ], 95% CI: 1.20, 1.85) with ASD. There was no association between PM 10-2.5 and ASD. In conclusion, higher exposure to PM 2.5 during pregnancy, and especially during the third trimester, is associated with risk of ASD. Research publications (1) Raz, R., Weisskopf, M.G., Davidovitch, M., Pinto, O., & Levine, H. (2014). Differences in Autism Spectrum Disorders incidence by sub-populations in Israel 1992–2009: A total population study. Journal of Autism and Developmental Disorders . Advance online publication. doi:10.1007/s10803-014-2262-z Fellow Raanan Raz Harvard University, USA Supervisor Marc Weisskopf 2012-2014