Environmental Health Perspectives, a journal published by the National Institute of Environmental Health Sciences, posted an article on Residential Proximity to Freeways and Autism in the CHARGE Study (CHildhood Autism Risks from Genetics and the Environment). In the article, researchers took a survey of parents who had children with Autism, and worked out their location during pregnancy.
It was found that the odds ratio would be 1.86, or a parent would be 1.86 times more likely to have a child with Autism if they lived within 309 meters (or less than 1,014 feet) away from a freeway. From this the conclusion was drawn that it's possible (not certain) that car exhaust could be a cause of Autism, and NEEDS MORE STUDY.
So, does this mean we need to stop driving vehicles, and walk or bike to work to keep our kids from getting Autism? Well, we should be walking and biking if we can anyway, but let's look at the data before we slap the "Cause For Autism" label on freeways.
- Living near any other major road found no significant relationship to Autism in the same survey.
- Genetic data was not taken into account in this survey, just location.
- No medical association has been made to show a direct correlation between traffic-related air pollution and Autism (though the pollutants have been found to have adverse prenatal effects, those effects are still largely unknown and require additional study).
- A similar study by the University of California Davis made in 2009 showed a census of children with Autism to more likely live with parents who are highly educated.
- The chances are that you would be 1.86 times more likely to have a child with autism if you lived near a freeway at all during the pregnancy, or 2.22 times more likely if you lived near a freeway during the third trimester, according to the study.
- Near is defined as nearly one fifth of a mile away from a freeway.
Now, looking at the two surveys together, it seems likely that higher educated parents would want to live near a freeway for access to their job. Parents with a genetic disposition for Autism would most likely also want to live near a freeway. So this survey could be a pretty high coincidence, and merely pointing out the living habits of those parents who are genetically likely to have children with Autism.
Does this mean that freeway exhaust is not bad? Of course not! Just like using excessive amounts of glutamate in food, exhaust can have documented damaging effects to children by causing respiratory illnesses (like asthma). But, as the study did point out, THIS CORRELATION NEEDS MORE RESEARCH. It's not a foregone conclusion that freeway exhaust causes Autism, anymore than it is that vaccines cause Autism, or monosodium glutamate, or watching TV, or playing on an iPad, or anything else that has happened within the past 50 years as a sign of progress.
Yes, pollution is bad. Yes, it needs to be eliminated. Yes, we need to think about air quality and our children's health. But before you start a protest movement or condemning air quality as the cause, get the facts. And to get the facts, we need research. So in the mean time, if you can walk, give it a try. If you want to live farther away from the freeway, then by all means do so. But don't make the claim that it's to stop Autism, because there is more genetic research that shows a correlation, and it seems to be more accurate because there is actual medical research done, instead of just a survey.