Vehicle emissions could be main cause of rising rates of autism: Study

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Air pollution breathed in by women during pregnancy may be linked to a greater risk of their child developing autism, according to a new study.

Researchers found that exposure to nitric oxide (NO), which is produced when fuel is burned, “can disrupt normal brain development” and may pose a “significant risk” of a child developing autism spectrum disorder (ASD).

“‘NO is a common air pollutant produced mainly by vehicle emissions and the combustion of fossil and industrial fuels,” study authors Shashank Kumar Ojha and Haitham Amal wrote.

“Exposure to NO and its derivative NO2 (nitrogen oxides) during pregnancy and early childhood can disrupt normal brain development.”

They added: “The timing of its exposure is crucial. Exposure to these pollutants during pregnancy and early postnatal development poses a significant risk of ASD, since these periods are essential for brain development.”

The researchers noted that “individuals with a genetic predisposition to ASD may be more vulnerable to the harmful effects of NO exposure.”

The study, published on Tuesday in the journal Brain Medicine also looked at other air pollutants, like ozone, fine particles, and other emissions, and found that together, these environmental toxins increase the risk of autism.

“Benzene is a volatile organic compound commonly found in vehicle emissions, industrial processes, and tobacco smoke,” the study authors noted.

“Maternal exposure to NO2 and benzene during pregnancy can also increase the risk of ASD.”

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Their research determined that when breathed in during early childhood or in the womb, the environmental toxins can get into the bloodstream.

There, the pollutants can bypass the protective layers of the brain, causing inflammation, and can “influence the activity of brain regions involved in social and cognitive functions, which are commonly impaired in ASD.”

According to Health Canada, one in 50 Canadian children and youth were diagnosed with ASD, based on the 2019 Canadian Health Survey on Children and Youth.

They studied four different components to air pollution: NO; particulate matter (a mixture of solid particles and liquid droplets in the air that includes aerosols, smoke, fumes, dust, ash and pollen); sulfur dioxide (the sixth most common air pollutant released to the environment in Canada and precursor to smog and haze); and ozone (a colourless gas that can be good or bad for your health, depending on its location).

The researchers found that people with a genetic predisposition to autism who were exposed to air pollution in early life were more likely to develop the condition than people exposed to less air pollution.

While they acknowledged more research needs to be done on the link between autism and pollution, they theorized that when someone breathes in one of these pollutants, it can cause inflammation in nerve tissue, changing how they develop over time.

They also said that the intake of air pollution can interrupt the production of some chemicals that rule the brain, including dopamine and norepinephrine, which are crucial in brain development.

The researchers also noted that the increase in autism cases worldwide is likely in part due to an increased awareness about the disease, which leads to more diagnoses.

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