Study associates some birth defects with proximity to natural gas development

Study associates some birth defects with proximity to natural gas development



Living near hydraulic fracturing (fracking) sites may increase the risk of some birth defects, according to a new study, though the Colorado Department of Public Health and Environment has countered that the findings indicate association, not causation, and should not cause great concern. The study found that an infant born to a mother who lives in an area with a high density of wells, defined as more than 125 per mile, had increased odds of being born with a congenital heart defect or neural tube defect.


A research team led by Lisa McKenzie, with the Department of Environmental and Occupational Health at the Colorado School of Public Health, examined 124,842 births between 1996 and 2009 in rural Colorado. They focused on mothers living away from urban pollution sources such as traffic, congestion and industry and selected a time frame to pre-date the rapid expansion of fracking and directional drilling, which the authors pegged to around 2000. The study examined the most common classes of birth defects thought to result, in part, from the mother’s surrounding environment during the first trimester, including exposure to suspected teratogens, mutagens that are known to cross the placenta, raising the possibility of fetal exposure. Those teratogens include benzene, toluene, polycyclic aromatic hydrocarbons and petroleum-based solvents — air pollutants tied to natural gas wells and associated drilling processes and infrastructure, including the diesel engines used to move the gas and equipment on and off the well site. They did not find a significant association with lower birth weights, pre-term births or oral clefts.

The study, which was published in the journal Environmental Health Perspectives, cross-referenced natural gas well locations geocoded based on longitudinal information from the Colorado Oil and Gas Information System and individual birth data from the Colorado Department of Public Health and Environment.

Birth mothers in the study’s high risk category had a 30 percent greater prevalence of congenital heart defects than mothers with no wells within a 10-mile radius of their homes. Out of 1,000 births, nine babies will have some form of congenital heart disorder, according to the American Heart Association — to ease the math, that would be 180 births in 20,000. In this study, of 19,793 births to women near 126 to 1,400 wells, 355 had congenital heart defects. Congenital heart defects are malformations present at birth that can range from holes between chambers of the heart to the complete absence of one or more chambers or valves in the heart, leading to medical conditions such as arrhythmias, as well as heart failure.

Births to mothers living in the study’s high risk areas also showed a possible association with increase in incidence of neural tube defects, birth defects of the brain, spine or spinal cord. Those defects can include spina bifida, in which the spinal column doesn’t completely close, often causing at least some leg paralysis, and anencephaly, in which the brain and skull do not develop. Exposure to benzene was linked to neural tube defects in a previous study.

“We’ve just seen a growing body of science develop over the past several years in particular that raise serious concerns for this rapid expansion of drilling and fracking across the country, especially as it moves into more populated areas,” says Emily Wurth, water program director for Food and Water Watch, which has been campaigning against fracking for four years. “The technology really got way out ahead of the science and we’re seeing increasing evidence that this process is inherently a risk to public health and the environment.”

Dr. Larry Wolk, chief medical officer and executive director of the Colorado Department of Public Health and Environment, issued the following response to the study: “It is difficult to draw conclusions from this study, due to its design and limitations. We appreciate continuing research about possible public health implications that may be associated with oil and gas operations in Colorado. With regard to this particular study, people should not rush to judgment.”

Wolk goes on to say that the study has not distinguished between active and inactive wells or taken into account other risk factors for birth defects, such as smoking, drinking and the mother’s folic acid intake, and was unable to pinpoint where mothers lived at the time of conception or during the first trimester of pregnancy. Pre-term birth rates actually decreased, as did low birth-weight babies, he adds.

Contrary to Wolk’s statement, the study did, in fact, register whether birth mothers had reported smoking or consuming alcohol during pregnancy.

Wolk added that the way the risk of congenital heart disease was presented was “difficult to interpret” and that their findings indicated only association, not causation, in a state he insists has some of the most stringent oil and gas rules in the country.

He also pointed out that the authors themselves provided three pages of limitations — but among those, the researchers noted that birth defects were most likely under-counted because non-live births (babies with severe neural defects may be stillborn), terminated pregnancies and later-life diagnoses were left out.

“Overall, we feel this study highlights interesting areas for further research and investigation, but is not conclusive in itself. We agree there is public concern about the effects of oil and gas operations on health, including birth outcomes. While this paper was an attempt to address those concerns, we disagree with many of the specific associations with the occurrence of birth defects noted within the study,”

Wolk concludes. “As Chief Medical Officer, 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.”

“I am absolutely stunned that the Hickenlooper administration would launch this broad-scale attack on the medical researchers at the University of Colorado,” Gary Wockner, Colorado Program Director of Clean Water Action, said in an emailed statement. “That Hickenlooper’s appointee is telling pregnant women to disregard this study is seriously questionable.”

The study concludes that further research on specific activities and production levels near homes over the course of pregnancy would provide more refined estimates. Recent data has indicated that exposure to natural gas development is increasingly common, with the Colorado Oil and Gas Conservation Commission estimating that 26 percent of more than 47,000 wells in Colorado are within 150 to 1,000 feet of a home or other building occupied by humans.

The study concludes, “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].”


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