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Autism Link to Traffic Pollution Exposure During Pregnancy

By Australian Science Media Centre

Exposure to traffic pollution during pregnancy has been linked to an increased risk of autism.

Original study published in JAMA Pediatrics (

“Many countries, including Australia, have reported a dramatic increase in the number of diagnoses of Autism Spectrum Disorder (ASD) over the past three decades. Recent estimates suggest that the prevalence of ASD is one in every 110 individuals (~1%), although some figures suggest the prevalence is even higher.

The biological pathways contributing to ASD are poorly understood. Current evidence suggests that genetic factors play a major role, but these alone cannot account for the recent increase in prevalence, suggesting environmental factors may also be important.

This research contributes to a growing number of studies that have identified a link between prenatal exposure to air pollutants, in this case specifically nitric oxide from traffic, and ASD. It is, however, important to note that the results of all previous studies have not been consistent, and also that these studies are not able to show cause and effect.

Nonetheless, this research strengthens the existing evidence, and it is particularly of concern that a link between relatively low levels of air pollution and ASD has been identified. Further research is required to develop our understanding of the full health impacts of exposure to the complex mixture of air pollutants that are found in our urban and residential environments, and to inform strategies to reduce pollutant levels and/or minimise exposure.”

Dr Anna Callan is a lecturer in the School of Medical Sciences, Faculty of Health, Engineering and Science at Edith Cowan University.

“This is a well conducted study, and certainly the largest of its kind. While it’s true that traffic pollutants can be harmful in high concentrations, many previous studies have found no association between traffic pollutants and autism.

This study’s findings must be balanced by the numerous other studies which have found no link. At most, this finding would indicate a need for further research, and families should not be alarmed.”

Andrew Whitehouse is the Angela Wright Bennett Professor of Autism Research at the Telethon Kids Institute.

“This study adds to previous research suggesting that environmental toxins are a key factor contributing to autism. This is another reason why a diet rich in antioxidants is so essential during pregnancy.

Antioxidants help to neutralise free radicals from environmental toxins, likely decreasing the chance of autism and other conditions caused by these pollutants. The best source of anti­oxidants is vegetables. It’s wise to consume a variety of different coloured vegetables during pregnancy to receive a range of different antioxidants. Just like you need a range of different players on a netball court to defend the ball against the other team, a range of different antioxidants from different vegetables will help to diffuse free radicals and hopefully minimise the risks of conditions caused by environmental toxins.”

Melanie McGrice is an Advanced Accredited Practising Dietitian, and a founding member of the Early Life Nutrition Coalition.