Autism Risk Linked to Prenatal Air Pollution Exposure: Study

A new study indicates exposure to air pollution during pregnancy may increase the unborn child’s risk of developing autism. 

In findings published this month in the medical journal JAMA Pediatrics, Canadian researchers say particulate matter 2.5 (PM 2.5), nitric oxide, and nitrogen oxide exposure increase the risk of developing an autism spectrum disorder (ASD).

The study involved an analysis of data from more than 130,000 births in Vancouver, Canada, from 2004 to 2009. Monthly average exposure levels of PM 2.5, nitric oxide, and nitrogen dioxide were taken at the mother’s residence during pregnancy. PM 2.5 is a type of particulate matter that has tiny particles of soot, dust, and dirt that are smaller than 2.5 micrometers in diameter. In comparison, one strand of human hair is 70 micrometers in diameter.

Researchers then analyzed how many children were diagnosed with autism using a standardized assessment with the Autism Diagnostic Interview-Revised and Autism Diagnostic Observation Schedule, often considered the gold-standard of diagnosis.

Overall, 1,300 children were diagnosed with autism by the age of five, roughly one percent of the children in the study.

All three environmental factors, PM 2.5, nitric oxide, and nitrogen oxide, were linked to increased risk of autism. However, nitric oxide had a higher statistical significance related to autism development. Environmental nitric oxide is a traffic related pollutant.

Past studies have linked air pollution to increased risk of health side effects, including an increased risk of stillbirth after prenatal exposure. Exposure before birth is also linked to increased likelihood of behavioral problems. Children exposed to pollution before birth had difficulty regulating emotions and were more impulsive.

Autism is a developmental disability that is characterized by difficulties with communication and social interaction.

Research has also shown pollution can negatively affect the developing brains of infants and accelerate aging in children. More than 17 million infants are exposed to toxic levels of air pollution worldwide.