This research was supported by funding from the National Institute of Environmental Health Sciences. The authors report no relevant financial disclosures. Alahmad and Khraishah report…
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New data suggest that individuals with HF are more likely to be hospitalized when exposed to greater unconventional natural gas development, or fracking activity, in particular those with more severe HF.
The study, published in the Journal of the American College of Cardiology, analyzed the association between active unconventional natural gas development activity and hospitalization in patients with HF living in Pennsylvania.
Risk for HF hospitalization was greater during specific stages of the hydraulic fracturing process, the researchers reported.
Metrics of unconventional gas development activity were categorized by phase: pad preparation, drilling, stimulation and production.
“We observed exposure-effect relations for three of the four unconventional natural gas development activity metrics and heart failure hospitalizations. The largest magnitude associations were observed for the well pad preparation, stimulation and production metrics,” Tara McAlexander, PhD, MPH, researcher at Drexel University Dornsife School of Public Health, said in a press release. “Our findings suggest that individuals living with heart failure, when exposed to greater [unconventional natural gas development] activity, are more likely to be hospitalized, particularly in those with more severe heart failure at baseline.”
Risk for HF hospitalization
The researchers identified 9,054 patients with HF (5,839 hospitalizations; mean age, 71 years; 48% women) in the Geisinger health system in Pennsylvania from 2008 to July 2015, which coincided with active unconventional natural gas development. Hydraulic fracking activity at 9,669 wells in the state was stratified by phase and evaluated 30 days before HF hospitalization.
The researchers observed an exposure-effect relationship across quartiles of unconventional natural gas development activity. When the researchers compared the highest quartile of activity with the lowest quartile, risk for HF hospitalization was as follows:
For nearly every metric of activity, risk for HF hospitalization was greater among patients with more severe HF at baseline, according to the researchers.
Results demonstrated no difference in HF hospitalization among patients with HF with reduced or preserved ejection fraction, suggesting that patients with both HF phenotypes may be equally susceptible to exposures related to unconventional natural gas development activity.
The researchers noted limitations of the current study, including the use of ICD-9 codes to identify cases of HF and lack of information on diet, physical activity and patient occupation.
More research still needed
Unconventional natural gas development energy production has grown substantially in the past 2 decades.
“There are many complex processes involved before, during and after the hydraulic fracturing … of underground gas-bearing rocks that release natural gas,” Barrak Alahmad, MBChB, MPH, PhD candidate in environmental health at Harvard T.H. Chan School of Public Health, and Haitham Khraishah, MD, of the department of medicine at Beth Israel Deaconess Medical Center at Harvard Medical School, wrote in a related editorial. “First, roads to remote drilling areas are built, and well pad lands are cleared and prepared. These pre-drilling activities involve thousands of truck trips. After preparation of the well pads, drilling starts vertically and is then often followed by drilling horizontally, which could be 10,000 feet deep in both directions. Millions of gallons of water are then injected into the wells along with proppants and chemicals to crack the rocks and release natural gas, which is then processed, compressed, stored and transported through pipelines.”
The environmental effects of fracking can include air pollution, water contamination, noise, traffic and other community impacts. Air pollutants can affect individuals across large regions, and due to the high volume of truck traffic to the unconventional natural gas development sites, the noise, vibration and diesel exhaust can be spread over a large network of roads, according to the release.
Initial reports of the adverse effects of fracking focused primarily on the respiratory system and perinatal outcomes, but there is emerging research on a variety of health outcomes, including on the heart, Alahmad and Khraishah wrote.
“These associations are plausible given environmental (eg, air pollution, water contamination, noise, traffic) and community impacts of [unconventional natural gas development],” McAlexander and colleagues wrote in the JACC study. “Understanding how people living with heart failure are susceptible to environmental exposures is especially important given the growing prevalence of heart failure and the possibility that environmental factors play a role in clinical heart failure outcomes.”
There is a need to better understand the health effects of fracking, according to the researchers and editorial authors.
“In the early 2010s, the scientific community was calling for ‘good’ epidemiological studies in order to evaluate the health effects of fracking. In this observational study, the researchers applied extensive and rigorous methods to determine specific exposure-outcome associations between fracking and heart failure hospitalizations,” Alahmad and Khraishah wrote. “Moving forward, we need to better understand the mediating effects by air and water pollutants, as well as particle radioactivity, and the existence of racial disparities in the fracking impacts. We also need a better understanding of the effects of various environmental exposures on cardiovascular health.”
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