Traffic Smog Tied to Serious Birth Defects
California study found higher risk of spinal cord, brain disorders
Friday, March 29, 2013
The study included women who lived in California's San Joaquin Valley for at least the first eight weeks of their pregnancy. The valley is known as one of the smoggiest regions in the United States.
"We found an association between specific traffic-related air pollutants and neural tube defects, which are malformations of the brain and spine," study lead author Amy Padula, a postdoctoral scholar in pediatrics at the Stanford University School of Medicine, said in a university news release.
She and her colleagues focused on two types of neural tube defects: spina bifida, which is a malformation of the spinal column; and anencephaly, which is an underdeveloped or absent brain. The study included 806 women who had babies with birth defects between 1997 and 2006, and 849 women who delivered healthy babies.
After accounting for factors such as race/ethnicity and mothers' education levels and vitamin use, the researchers concluded that women exposed to the highest levels of traffic-related carbon monoxide pollution in early pregnancy were nearly twice as likely to have a baby with spina bifida or anencephaly as those with the lowest carbon monoxide exposure.
Exposure to traffic-related nitrogen oxide and nitrogen dioxide air pollution was also linked to increased risk for these birth defects. For example, women with the highest exposure to nitrogen oxide were nearly three times more likely to have a baby with anencephaly than those with the lowest exposure.
While the study found associations between traffic-related air pollution and serious birth defects, it did not establish a cause-and-effect relationship.
"If these associations are confirmed, this work offers an avenue for a potential intervention for reducing birth defects," Padula said.
The study was published online March 28 in the American Journal of Epidemiology.
"Birth defects affect one in every 33 babies, and about two-thirds of these defects are due to unknown causes," study senior author Gary Shaw, a professor of neonatal and developmental medicine, said in the news release. "When these babies are born, they bring into a family's life an amazing number of questions, many of which we can't answer."