Prevalence of autism by children has been covered in diaries at BooMan before, in recent years the number of studies has increased to indicate exposure to a toxic environment may be a leading risk factor. Link here, here and diaries by joelado.

Traffic pollution tied to autism risk: study

NEW YORK (Reuters Health) – – Babies who are exposed to lots of traffic-related air pollution in the womb and during their first year of life are more likely to become autistic, suggests a new study. The findings support previous research linking how close children live to freeways with their risk of autism, according to the study’s lead author.

“We’re not saying traffic pollution causes autism, but it may be a risk factor for it,” said Heather Volk, an assistant professor at the Keck School of Medicine of the University of Southern California in Los Angeles.

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Autism is a spectrum of disorders ranging from a profound inability to communicate and mental retardation to milder symptoms seen in Asperger’s syndrome. The prevalence of autism has grown over the past few years. It’s now estimated that the disorder affects one in every 88 children born in the United States, which is a 25 percent increase from a 2006 estimate (see Reuters article of March 29, 2012, reut.rs/TZnRci).


Volk’s new study is one of a series of looks into how environmental factors may be linked to a child’s risk of being autistic, done over the past few years (see Reuters article of July 5, 2011, reut.rs/TZntdS). “I think it’s definitely an area that’s been understudied until recently,” Volk told Reuters Health.

Unlike their last study, which used how close a child lived to a freeway as a substitute for pollution exposure, for the new analysis Volk and her colleagues looked at measures of air quality around kids’ homes.

Compared to 245 California children who were not autistic, the researchers found that 279 autistic children were almost twice as likely to have been exposed to the highest levels of pollution while in the womb, and about three times as likely to have been exposed to that level during their first year of life.

They found that children exposed to the highest amount of “particulate matter” – a mixture of acids, metals, soil and dust – had about a two-fold increase in autism risk. That type of regional pollution is tracked by the Environmental Protection Agency.

Volk and her colleagues also saw a similar link between autism and nitrogen dioxide, which is in car, truck and other vehicle emissions. “This is a risk factor that we can modify and potentially reduce the risk for autism,” wrote Dawson in an email to Reuters Health.

The researchers said certain pollutants could play a role in brain development – but that doesn’t prove being exposed to air pollution makes kids autistic. They warned that there may be other factors that explain the association, including indoor pollution and second-hand smoke exposure.

Findings appear in the November 2012 issue of the Archives of General Psychiatry and can be found online here.

Study debunks autism as primarily genetic disorder