The study's results, which were published last Thursday in Environmental Perspectives, specifically cite exposure to particulates given off by fires, cars, trucks and other vehicles, as well as industrial smokestacks as being behind the autism risk. While this isn't entirely new news (a 2010 study found a similar autism link for moms-to-be who lived near a freeway), this is the first time a study has examined the autism-pollution link across the U.S., and found additional support for it.
According to study leader and Harvard epidemiologist Marc Weisskopf, evidence to support the link between mom's exposure to pollution and autism "is becoming quite strong" the more researchers look into the connection. While the disorder is largely considered to be rooted in genetics, scientists have been unable to ignore the strong links to environmental causes, too—particularly now, as autism rates continue to rise.
The Harvard study dug into the health records of 116,430 women in the Nurses' Health Study II of 1989, during which researchers collected data on their children as well as where the women lived and the levels of air pollution they were exposed to at the time. From there, they compared the prenatal histories of 245 children with autism spectrum disorder to 1,522 children without it, who were all born between the years 1990 and 2002.
In the end, researchers determined that there were no links between the autism rates and a mom's exposure to air pollution before her pregnancy, early in pregnancy, or right after her baby was born. The link was only found when she had high exposure in her third trimester.
So what can be done? Study author Marc Weisskopf does note that the Environmental Protection Agency has tightened air quality standards in the last year, which might help some of the problem over time. In that case, the standards were changed to help lower rates of asthma, lung cancer and cardiovascular disease. But here's the caveat: All 50 states have until 2020 to actually meet the new standards, so it will be some time until we start reaping the benefits.