Environmental Risk Factors for Autism in Israel

Principal Investigator: Marc Weisskopf, Cecil K and Phillip Drinker Professor of Environmental Epidemiology and Physiology Harvard T.H. Chan School of Public Health.

Project objective: The project aimed to explore the relationship between a mother’s exposure to air pollutants and the risk of autism spectrum disorders (ASD) in her child. We studied a large group of people and examine different pollutants, specific time periods of exposure, and vulnerable groups, such as male fetuses.

Project’s alignment with the Hoffman Program on Chemicals and Health mission: Through this research, we aimed to deepen our understanding of how air pollutants affect human health, particularly in relation to ASD. By investigating how a mother’s exposure to chemicals can impact her child’s health, we hope to gain insights into the role of chemical exposures in the development of health conditions. In addition, access to a longitudinal birth cohort provides opportunities to investigate the development of chemical sensitivities later in life.

Some key takeaways:

  • Our study found that children with certain male reproductive disorders, such as hypospadias and cryptorchidism, have an increased risk of ASD. This suggests a possible link between these disorders and ASD.
  • The results challenge the “extreme male brain” theory, which suggests that high levels of fetal testosterone increase the risk of ASD. It seems that the relationship between fetal hormone exposure and neurodevelopment is more complex than previously thought.
  • Maternal factors and exposures during pregnancy seem to play a significant role in the development of male reproductive disorders and ASD. Environmental chemicals that disrupt hormones may contribute to these conditions.

Additional scientific articles related to our research suggest that in Israel, being exposed to nitrogen dioxide after birth is associated with a higher risk of ASD. Interestingly, prenatal exposure to nitrogen dioxide appears to be associated with a lower risk, possibly due to other factors. Furthermore, we found that exposure to specific pollutants from traffic-related pollution after birth, such as nitrogen oxides (NOx) and nitrogen dioxide (NO2), and exposure to larger particles during pregnancy (PM2.5-10), are linked to an increased risk of ASD. These findings suggest that postnatal exposure to traffic-related pollution may play a causal role in ASD.

Products resulting from Hoffman Program on Chemicals and Health support:

Magen-Molho H, Weisskopf MG, Nevo D, Shtein A, Chen S, Broday D, Kloog I, Levine H, Pinto O, Raz R. Air Pollution and Autism Spectrum Disorder in Israel: A Negative Control Analysis. Epidemiology. 2021 Nov 1;32(6):773-780. doi: 10.1097/EDE.0000000000001407. PMID: 34347685; PMCID: PMC8478838.

Raz, R., Levine, H., Pinto, O., Broday, D. M., Yuval, & Weisskopf, M. G. (2018). Traffic-related air pollution and autism spectrum disorder: a population-based nested case-control study in Israel. American journal of epidemiology, 187(4), 717-725.

Rotem, R. S., Chodick, G., Davidovitch, M., Hauser, R., Coull, B. A., & Weisskopf, M. G. (2018). Congenital abnormalities of the male reproductive system and risk of autism spectrum disorders. American journal of epidemiology, 187(4), 656-663.