Debate has raged over the causes of the huge surge in children with autism. And now a large study involving more than 22,000 women and their babies has found what seems to be a powerful factor in this epidemic.
The researchers found that living in an area with high levels of air pollution may double the risk of a baby having autism.
The scientists analyzed data from Nurses’ Health Study II, a long-term study based at Brigham and Women’s Hospital in Boston that has been recording health information from 116,430 nurses since 1989. Within the group, the researchers studied 325 women who had a child with autism and 22,000 women who had a child without the disorder. When they looked at associations between autism and levels of pollutants at the time and place of birth, they found that women who lived in the 20 percent of locations with the highest levels of diesel particulates or mercury in the air were twice as likely to have a child with autism as those who lived in the 20 percent of areas with the lowest levels.
Other varieties of air pollution, including lead, manganese, methylene chloride and combined metal exposure, were also were associated with higher autism risk. Women who lived in the 20 percent of places with the highest levels of these pollutants were about 50 percent more likely to have a child with autism than those who lived in the 20 percent of areas with the lowest concentrations.
“Our results suggest that new studies should begin the process of measuring metals and other pollutants in the blood of pregnant women or newborn children to provide stronger evidence that specific pollutants increase risk of autism. A better understanding of this can help to develop interventions to reduce pregnant women’s exposure to these pollutants,” says researcher Marc Weisskopf.