Over the past decade, the number of children diagnosed with autism in the U.S. has surged. Back in 2002, the Centers for Disease Control and Prevention (CDC) estimated that autism affected about one in every 150 children. By 2012, this estimate had changed dramatically to one in 50. Although part of this increase can be attributed to better awareness and improved testing methods, researchers are still puzzled by the underlying causes of this rise.
Recent research from the Harvard School of Public Health has uncovered a potential factor contributing to the increase in autism rates. The study suggests that pregnant women who live in heavily polluted areas might be twice as likely to have a child with autism compared to those in cleaner environments.
It’s important to note that the study didn’t establish a direct cause-and-effect relationship between air pollution and autism. However, there was a significant correlation indicating that pollution could play a role in the increasing autism rates. The findings were published in the journal Environmental Health Perspectives.
The Danger of Pollution
To gather their data, researchers compared the pollution exposure of 325 women who had children with autism to 22,000 women who had children without the condition. These women were part of the Nurses’ Health Study II, which has been tracking the health of around 117,000 women since 1989.
The study assessed each woman’s exposure to various pollutants, including methylene chloride, mercury, manganese, lead, diesel particulate matter, and overall metal exposure. Between 20 to 60 percent of the participating women lived in highly polluted areas at different points in time. Those in places with the highest levels of mercury or diesel particulates had double the risk of having a child with autism compared to women in the least polluted areas.
In addition, exposure to high levels of methylene chloride, manganese, lead, and combined metals increased the risk of having a child with autism by 50 percent. These findings remained consistent even after accounting for other known risk factors, such as education, income, and smoking during pregnancy. The study also found that boys were more likely to be affected than girls.
Growing Concerns
This groundbreaking study reinforces the idea that the air a pregnant woman breathes can significantly impact her child’s development. Previous studies have indicated that women living near freeways have an increased risk of having children with autism, but those studies were limited to specific regions. This new research uses data from across the country.
While the exact mechanisms by which pollution affects fetal development are not fully understood, it’s clear from this study that environmental factors do play a role, even if it’s a small one, in the rising number of autism cases. The results underscore the complex nature of autism, suggesting it is influenced by both genetic and environmental factors.