Living Near Freeway May Increase Autism
Results from the Childhood Autism Risks from Genetics and the Environment (CHARGE) Study published in Environmental Health Perspectives recently, found an association between living near a freeway and autism for subjects living in the Los Angeles area. Helen Volk who is the study’s lead author said, “the study isn’t saying exposure to air pollution causes autism. But it could be one of the factors that are contributing to its increase.” (Source: Los Angeles Times) She is a researcher at Children’s Hospital of Los Angeles.
Data for the study came from 304 autism cases and 259 control cases with healthy baby development (no autism or other developmental disorders). Mother’s addresses were recorded from birth certificates, and from a questionnaire for addresses for different trimesters during pregnancy. The addresses were geo-coded and distances to major freeways and roads were measured using ArcGIS. Near a freeway was defined by the study as 309 meters or less.
One criticism came from Gayle Windham, a research scientist from the California Department of Public Health: “They are using a proxy measure for air pollution, which is distance to a freeway. But you still don’t know how much time the women spent at home or working or commuting.” (Source: Los Angeles Times)
While the study didn’t measure the exact amount of exposure to air pollution for mothers that gave birth to autistic children, it did try to measure the potential impact from freeway air pollution, which is a major, if not the major source of air pollution in the Los Angeles area. The study was also intended to be a preliminary investigation, and not a definitive analysis, so the criticism doesn’t appear to be damaging overall. Windham’s own previous research on the same relationship found that “children with autism were about 50% more likely to have a birth residence in an area with hazardous air pollutants.” (Source: Los Angeles Times)
There have been a number of studies examining the relationship between air pollution and infant health. Last year a study found air pollution exposure during pregnancy may lower a child’s IQ. Air pollution has also been tied to low birth weights, reduced head size, childhood asthma, and premature births.
The American Lung Association has ranked Los Angeles the worst city in the country for ozone pollution, third worst for year-round air particle pollution, and fourth worst for short-term air particle pollution. Particles from burning fossil fuels get into our air, but are so tiny we can’t see or feel them. They contain hazardous chemicals often, and contribute to respiratory disease, heart disease and stroke. Pregnant women also inhale them and they can damage developing fetuses. Scientists at the California Air Resources Board say the number of deaths caused by particle pollution each year in California ranges from 5,000 to 32,000.