Urban air pollution linked to birth defects for first time in US studies

These findings show that there are more health problems caused by air pollution than solely asthma and other respiratory illnesses.

Exposure to two common air pollutants may increase the chance that a pregnant woman will give birth to a child with certain heart defects, according to a UCLA study that provides the first compelling evidence that air pollution may play a role in causing some birth defects.

According to a study published in the January 1 edition of the American Journal of Epidemiology, pregnant Los Angeles-area women, living in regions with higher levels of ozone and carbon monoxide pollution, were as much as three times as likely to give birth to children who suffered from serious heart defects.

Carbon monoxide is primarily released in tailpipe emissions, while ozone pollution is formed in the atmosphere from pollutants released by both vehicles and industrial sources.

Researchers from the UCLA School of Public Health and the California Birth Defects Monitoring Program found the risk for birth defects increased among women exposed to elevated amounts of the pollutants in the second month of their pregnancy, a period when the heart and other organs begin developing.

"The greater a woman's exposure to one of these two pollutants in the critical second month of pregnancy, the greater the chance that her child would have one of these serious cardiac birth defects," said Beate Ritz, a UCLA epidemiologist who headed the study. "More research needs to be done, but these results present the first compelling evidence that air pollution may play a role in causing some birth defects."

Researchers conducted the study by matching extensive air pollution monitoring information collected by regional air-quality officials with information from the California Birth Defects Monitoring Program, a program funded by the state Department of Health Services that collects comprehensive information about structural birth defects, in partnership with the March of Dimes Birth Defects Foundation.

According to John A. Harris, chief of the California Birth Defects Monitoring Program: "One in 33 babies in the United States is born with a serious birth defect -- the leading cause of infant death. This kind of research is not a luxury. Studies like this one on air pollution give us critical leads to follow up with further research."

Ritz said she was surprised that the study found an effect at the pollution levels researchers studied. "These findings show that there are more health problems caused by air pollution than solely asthma and other respiratory illnesses," Ritz said. "There seems to be something in the air that can harm developing fetuses." The study also suggests that despite a significant decrease in urban air pollution nationally, there may be pollution problems that are not yet understood.

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