Nobody knows what exactly causes autism. Genetics are probably a piece of it. Vaccines are not. A new study says there’s another trigger: air pollution.
The study, published this week in Environmental Health Perspectives, tested the idea that air pollution while in utero can contribute to autism in children. It’s a hypothesis supported by past research—other studies have found a link, but only conducted their research in three states. This most recent study looked at children in all 50 states. The result: exposure to air pollutants—including diesel, lead, manganese, mercury, and methylene chloride—in utero increases the risk of autism, especially in boys.
The researchers looked at the levels of air pollutants (gathered from Environmental Protection Agency data) present at the time and place of the children of women who participated in the Nurses’ Health Study II, a long-term health study of (you guessed it) nurses. After adjusting for socioeconomic measures, year of birth, and maternal age at birth, the researchers found that air pollutants significantly increased the risk of autism.
As you might imagine, the EPA’s air pollution modeling isn’t perfect. The study explains:
The EPA air pollution prediction models provide only approximate measures of pollutant exposures, and the prediction modeling technique differed in the four assessment models. Ideally, pollution exposure would be measured individually to account for variation in exposure due to time spent outdoors, commuting, indoor exposure, seasonal fluctuation and neighborhoodlevel variations in pollutants. However, validation studies of EPA models have found them to reflect relative exposure fairly accurately.
At the very least, this study indicates that the link between autism and air pollution deserves an even closer look.