Women who live near natural gas wells in rural Colorado are more likely to have babies with neural tube and congenital heart defects, according to a new study.
As natural gas extraction soars in the United States, the findings add to a growing concern by many activists and residents about the potential for health effects from the air pollutants.
Researchers from the Colorado School of Public Health analyzed birth defects among nearly 125,000 births in Colorado towns with fewer than 50,000 people between 1996 and 2009, examining how close the mothers lived to natural gas wells.
Babies born to mothers living in areas with the highest density of wells – more than 125 wells per mile – were more than twice as likely to have neural tube defects than those living with no wells within a 10-mile radius, according to the study published Tuesday. Children in those areas also had a 38 percent greater risk of congenital heart defects than those with no wells.
Both types of birth defects were fairly rare, occurring in a small percentage of births, but they can cause serious health effects. The researchers did not find a significant association between gas wells and other effects, including oral cleft defects, preterm births and low birth weight.
Neural tube defects, such as spina bifida, are permanent deformities of the spinal cord or brain. They usually occur during the first month of pregnancy, before a woman knows she is pregnant. Congenital heart defects are problems in how the heart’s valves, walls, veins or arteries developed in the womb; they can disrupt normal blood flow through the heart.
“Taken together, our results and current trends in natural gas development underscore the importance of conducting more comprehensive and rigorous research on the potential health effects of natural gas development.” –study authors For babies born to mothers in the areas with the most wells, the rate of congenital heart defects was 18 per 1,000, compared with 13 per 1,000 for those living with no wells within a 10-mile radius. For neural tube defects, the rate was 2.87 per 3,000, compared with 1.2 per 3,000 in areas with no wells.
The Colorado Oil and Gas Conservation Commission estimates that 26 percent of the more than 47,000 oil and gas wells in Colorado are located within 150 to 1,000 feet of homes.
“Taken together, our results and current trends in natural gas development underscore the importance of conducting more comprehensive and rigorous research on the potential health effects of natural gas development,” the researchers wrote in the journal Environmental Health Perspectives.
The study was limited in that the researchers didn’t have access to the mothers’ health or socioeconomic information, or their actual exposures to air pollutants. They had to assume that the address when they delivered the baby was the same as during their first trimester. They also knew only if a gas well existed in the year of the births, not how active it was.
Larry Wolk, executive director of the Colorado Department of Public Health and Environment, said no conclusions could be drawn from the study because the researchers didn’t know the status of the wells and didn’t know the mothers’ residential history and health care status.
“Overall, we feel this study highlights interesting areas for further research and investigation, but is not conclusive in itself,” Wolk said in a prepared statement.
“I would tell pregnant women and mothers who live, or who at-the-time-of-their-pregnancy lived, in proximity to a gas well not to rely on this study as an explanation of why one of their children might have had a birth defect. Many factors known to contribute to birth defects were ignored in this study,” said Wolk, who was appointed to his position by Gov. John Hickenlooper last August.
The Colorado Oil and Gas Association forwarded a request for comment to Dollis Wright, head of an environmental communication company in Colorado.
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