Fast Lane to Autism: Living Near Freeways

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From WebMD Health News

Fast Lane to Autism: Living Near Freeways

J. DeNoon

December 22, 2010 -- Having a mother who lived within 1,000 feet of a freeway

while pregnant doubles a child's odds of having autism.

The finding comes from a study looking at environmental factors that might play

a role in autism. University of Southern California researcher E. Volk,

PhD, MPH, and colleagues collected data from 304 California children with

confirmed autism and from 259 children who developed normally.

" It has been estimated that 11% of the U.S. population lives within 100 meters

[328 feet] of a four-lane highway, so a causal link to autism or other

neurodevelopmental disorders would have broad public health implications, " the

researchers note.

Exposure to air pollution during pregnancy is suspected of a wide range of

negative effects on the fetus. A particularly crucial period may be the third

trimester, when the brain develops rapidly.

Air pollution is particularly heavy within a thousand feet of a highway. Volk

and colleagues found that the 10% of women who lived closest to a freeway during

pregnancy were within about 1,000 feet of center line. Children born to these

women were 86% more likely to have autism than kids born to women who lived

farther from the freeway.

The relationship was stronger for women who lived within 1,000 feet of a freeway

during their third trimester. Children born to these women were 2.2 times more

likely to have autism.

Interestingly, the odds of autism remained unchanged when the researchers

controlled for factors such as child gender or ethnicity, household education,

maternal age, and maternal smoking.

It's becoming clear that a child's genetic inheritance has a lot to do with

whether that child has autism. But genes do not explain why one child develops

autism while another does not. Many researchers believe that something or a

combination of things in the environment trigger autism in genetically

susceptible kids. That exposure may come while the child is still in the womb.

But what is it about living near a freeway that might trigger autism? Is it

really air pollution? Or could it be the noise?

Volk and colleagues note that their findings should be confirmed in studies that

measure the actual air pollutants to which pregnant women living near freeways

are exposed.

The Volk study appears in the Dec. 16 online issue of Environmental Health

Perspectives, published by the U.S. National Institute of Environmental Health

Sciences.

SOURCE:

Volk, H.E. Environmental Health Perspectives, published online Dec. 16, 2010.