A new study found that pregnant women exposed to high levels of air pollution doubles their risk of having children with autism.
In March, the U.S. Centers for Disease Control and Prevention (CDC) released the latest statistics of autism in the United States, which revealed that one in 68 children have the condition. This is double the rate compared to 2000, when the case was one in 150 children, making autism the fastest-growing developmental disorder.
Several studies were launched to determine the cause of autism, which resulted in different findings: belly bacteria, brain inflammation, genetic disease, food chemicals, iron deficiency and incorrect timing of pregnancy among many other causes. But a new study conducted by the Harvard School of Public Health (HSPH) blames it on air pollution, predominantly pregnant women being exposed to high levels of fine particulate matter during their third trimesters.
Researchers examined the data of the children of 116,000 female nurses residing in 50 different states since 1989. The data was compared to the air pollution data provided by the U.S. Environmental Protection Agency (EPA). The analysis showed that 245 children, or 14 percent, of the study participants were diagnosed with autism during the follow-up period. The mothers of these children coincidentally lived in states with high levels of air particulate matter or PM2.5.
Researchers believe that something in the air particulate matter could be interfering with the brain development of the babies while still inside of their mothers' wombs, but another study is needed to pinpoint that.
"The evidence base for a role for maternal exposure to air pollution increasing the risk of autism spectrum disorders is becoming quite strong," Marc Weisskopf, associate professor of environmental and occupational epidemiology and senior author of the study, said in a university news release. "This not only gives us important insight as we continue to pursue the origins of autism spectrum disorders, but as a modifiable exposure, opens the door to thinking about possible preventative measures."
The study is the first to examine a link between air particulate matter and autism. But Professor Frank Kelly, the director of the environmental research group at King's College London, was not surprised at the findings.
"I think if it was this study by itself I wouldn't take much notice, but it's now the fifth that has come to the same conclusion," Kelly told BBC News. "It is biologically plausible, the placenta is there to ensure the fetus has optimal supply of nutrients, but if chemicals are entering the mother's body then the fetus will have access to those too."
This study was published in the Dec. 18 issue of Environmental Health Perspectives.
