A new study of asthma sufferers in Pennsylvania’s Marcellus Shale area has found that exposure to shale gas development – especially in its production phase – correlates with a higher risk of asthma attacks among the patients. According to the study, the odds of the condition flaring-up was about 1.5 to 4 times higher for patients living near active shale wells, but the researchers are not yet able to determine why.
The report “Association Between Unconventional Natural Gas Development in the Marcellus Shale and Asthma Exacerbations,”, published Monday in JAMA Internal Medicine, stopped short of claiming that there is a causative relation between proximity to shale wells and asthma attacks. The lead author of the study Sara Rasmussen, a Ph.D. candidate in environmental health sciences at Johns Hopkins Bloomberg School of Public Health, explained that other factors such as stress could also contribute to the worsening of the condition in patients.
“Ours is the first to look at asthma but we now have several studies suggesting adverse health outcomes related to the drilling of unconventional natural gas wells,” said Rasmussen. “Going forward, we need to focus on the exact reasons why these things are happening, because if we know why, we can help make the industry safer.”
The study, praised for its rigorous research methods, is the first to examine detailed medical records from the Geisinger Health System, which provides care for more than 400,000 Pennsylvania residents, encompassing 40 counties in central and northeast Pennsylvania.
“That makes working with the Geisinger data really special,” said Rasmussen. “We know the dates of emergency room visits, hospitalizations, smoking status, medications, and a family’s socio-economic status.” She says other studies relied on self-reported data.
The researchers identified 35,508 patients ages 5 to 90 with a history of asthma between 2005 and 2012, and correlated this data with cases of asthma attacks reported to Geisinger to obtain a picture of severity of the condition in patients.
The study put the reported asthma attacks into three categories: “mild” included a new asthma medication, “moderate” meant a visit to the emergency room, and “severe” correlated with hospitalization.
This data was later mapped against the level of shale activity near the homes of asthma patients who did not report asthma attacks.
The results showed that residents who lived in homes ranked among the top 25 percent for production activity were four times more likely to have a mild asthma attack, and 1.7 times more likely to suffer a severe asthma attack, than those in the bottom 25 percent. Proximity to wells in the production stage correlated with more severe symptoms, with wells that produced the most gas having the greatest effect.
Nicole Deziel, an assistant professor of epidemiology at Yale School of Public Health, who was not involved in the paper, said that the study “is an important step towards a better understanding of whether a certain aspect of the unconventional development process may be more hazardous.”
However, the Marcellus Shale Coalition, an industry group, criticized the report for ignoring air quality data gathered by the Department of Environmental Protection and Drexel University that showed lower than expected levels of air pollution from shale gas wells. The group spokeswoman Erica Clayton Wright said that the coalition welcomed “sound, accurate and fact-based research”, but she pointed to the fact that the study did not find a direct causal link between drilling and increased risk of asthma attacks.
“It’s also striking that the authors failed to provide comparative data from, say, eight years or so prior to shale development emerging in the region,” said Clayton Wright.
Meanwhile, Energy In Depth, a campaign body set up by the Independent Petroleum Association of America, contested the findings. They told BBC News that while “the researchers claim this study ‘adds to a growing body of evidence tying the fracking industry to health concerns, […] the study – and many others like it – actually doesn’t have any evidence to prove causation, while numerous studies that actually provide real evidence that fracking is reducing asthma throughout the US continue to be overlooked.”
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