People in Pennsylvania with asthma who live near bigger or larger numbers of unconventional natural gas development (UNGD) sites are up to 4 times more likely to have an asthma attack than those living farther away, according to a study that analyzed electronic health record (EHR) data over 8 years.
Sara G. Rasmussen, MHS, from the Johns Hopkins Bloomberg School of Public Health in Baltimore, Maryland, and colleagues, looked separately at the four steps of UNGD from 2005 to 2013 — well pad preparation, drilling, fracking (hydraulic fracturing of rock), and gas production — and separated asthma outcomes into three categories: mild, moderate, and severe.
The researchers identified 35,508 patients with asthma, aged 5 to 90 years, from the 400,000 primary care patients at the Geisinger Clinic, which services about 40 counties in central and northern Pennsylvania. About 20 of those counties have UNGD, coauthor Brian S. Schwartz, MD, MS, said in an audio interview with the JAMA Network.
The investigators categorized the exacerbations: 20,749 mild (patients with a new oral corticosteroid order); 1870 moderate (those who required an emergency department visit), and 4782 severe (those hospitalized for asthma). They compared these patients to matched controls without exacerbations.
They used metrics, including distance from the wells, duration of the phase of development, and type of well, to analyze associations.
All Four Phases Had Higher Risk
All four of the phases were associated with an increased risk for all three levels of asthma exacerbations, and some of the magnitudes of these associations were substantial.
Odds ratios (ORs) ranged, for example, from 1.5 (95% confidence interval [CI], 1.2 - 1.7) for the association of the pad metric with severe exacerbations to 4.4 (95% CI, 3.8 - 5.2) for the link between the production metric with mild flare-ups.
Findings were published online July 18 in JAMA Internal Medicine.
The findings were not causal, and the study could not establish how patients would have fared under conventional methods of gas extraction.
Dr Schwartz said, however, "We think the findings are biologically plausible. There's a lot of ways that unconventional natural gas development can impact communities — through light and noise and vibration and truck traffic and air quality impact. … What's needed next are studies that look at the potential mechanism of these associations."
Rachel L. Miller, MD, professor of medicine (in pediatrics) and environmental health sciences and chief of the Division of Pediatric Allergy, Immunology, and Rheumatology at Columbia University Medical Center in New York City, agrees that the results are plausible and that more studies are warranted and necessary to make recommendations.
She told Medscape Medical News the study was well designed.
"It's a large, population-based, case-controlled study. Patients with or without asthma were well-defined. Exposure to fracking was determined in a scientifically acceptable way."
Adding to the strength of the study, she said, was that the findings were consistent with various levels of exposure. "Everything's in the same direction…which reads as very solid."
"When I think of what's happening in these gas wells, it very well could be a risk factor for asthma exacerbations," she said.
She said risk for respiratory diseases beyond asthma would be speculation without knowing whether the risk is coming from the trucks, the noise, or the chemicals.
Study Spotlights Production Phase
David Brown, ScD, is the public health toxicologist and director of public health toxicology for the nonprofit Southwest Pennsylvania Environmental Health Project.
He told Medscape Medical News that given the number of people who have asthma (more than 24 million children and adults in the United States), these results indicate "a public health crisis."
"These sites are very close to schools and other sites where children need inhalers to get through the day. This study clearly shows that something coming off of those gas wells is increasing their asthma attacks. And it's not a minor increase."
He said an important finding from the study is that effects were most notable in the production phase.
"The odds ratio during production is really high," he said. Results showed that during high production, the ORs were 1.74 (95% CI, 1.45 - 2.09) for hospitalization, 2.19 (95% CI, 1.47 - 3.25) for emergency department visits, and 4.43 (95% CI, 3.75 - 5.22) for new orders of oral corticosteroid medication.
"That suggests that the problem is involved with shale gas coming back from the well itself. We've been focusing on the fracking and drilling problem…and this clearly shows the production phase is involved. This is the first time someone has shown a link to the exacerbation of asthma attacks."
He said the findings build on what his and other projects have found. "We know that particulate matter and irritants are released from the wells and from the gas itself and those things would be asthma triggers," he said.
Pennsylvania Activity High
Pennsylvania is one of the nation's fracking hotspots. Between 2005 and 2012, drilling began at 6253 UNGD wells on 2710 pads, 4728 wells were fracked, and 3706 were in production, according to the study. In contrast, New York and Maryland, also in the Marcellus shale, have moratoria on UNGD.
Devon C. Payne-Sturges, DrPH, assistant professor with the Maryland Institute for Applied Environmental Health at the University of Maryland (UMD), College Park, told Medscape Medical News that Maryland is considering allowing UNGD in the western part of the state when the ban lifts, which adds to the importance of these findings by Schwartz et al.
Dr Payne-Sturges and her colleagues at UMD School Public Health published an article on assessing potential public health impacts of UNGD in western Maryland.
"We noted at the time of that assessment there was limited information on the relationship between exposure to air pollution associated with UNGD and health outcomes. This study by researchers at Hopkins fills a critical gap and adds to the concerns about UNGD."
Guidance for Patients
Without knowing the mechanism, it's hard to give specific guidance on what precautions patients should take, Dr Schwartz said, but he added: "Patients who get shortness of breath, cough, or wheezing who live in these areas should be very cognizant of this, call their doctors…and be aware of the risks we have identified."
As to whether health impact studies will need to be done in each region where this activity is happening or proposed, Dr Schwartz said delays could put the public at risk.
Fracking proponents will argue that weather, depth, ambient temperature, and geology are different in each area and more studies need to be done, Dr Schwartz said. However, he continued, many studies have outlined other health concerns, and waiting for "the perfect study" in each region could be harmful.
"The public health may suffer a lot before we do anything about it," he said.
Study limitations include the fact that EHRs did not list patients' occupations and provided only patients' most recent address.
This study was funded by the National Institute of Environmental Health Sciences. Additional support was provided by the Degenstein Foundation, the Robert Wood Johnson Foundation and the National Science Foundation. Dr Schwartz is a fellow of the Post Carbon Institute (PCI), serving as an informal adviser on climate, energy, and health issues. He receives no payment for this role. His research is independent of PCI and is not reviewed or funded by PCI. Dr Brown, Dr Miller, and Dr Payne-Sturges have disclosed no relevant financial relationships.
JAMA Intern Med. Published online July 18, 2016. Full text
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Cite this: Fracking Linked to Asthma Flare-ups - Medscape - Jul 19, 2016.
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