Asthma sufferers who live near wells in which hydraulic fracturing is used to extract natural gas are up to four times more likely to have an asthma attack than those who live farther away, according to new research from the Johns Hopkins University.
The findings are the latest in a string of studies that have linked health problems to proximity to such wells, and come as Maryland prepares to lift a moratorium next year and issue permits for the controversial method of extraction known as "fracking."
"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 Sara G. Rasmussen, a study leader and doctoral candidate in the department of environmental health sciences at Hopkins' Bloomberg School of Public Health.
"Going forward, we need to focus on the exact reasons why these things are happening," she said, "because if we know why, we can help make the industry safer."
Hydraulic fracturing involves drilling deep wells and injecting water, sand and chemicals at high pressure to break up rock and release natural gas.
The method is needed to access natural gas in the Marcellus shale rock formation, which extends from New York through Allegany and Garrett counties to Ohio and West Virginia and is believed to be the largest onshore reserve of natural gas in the United States.
Under then-Gov. Martin O'Malley, a Democrat, Maryland imposed a moratorium on fracking in 2011 out of concerns about possible groundwater contamination, air pollution and earthquake activity. Under Gov. Larry Hogan, a Republican, the state recently released draft rules for use when the moratorium expires in the fall of 2017.
Critics call the rules insufficient to protect air and water quality, while supporters say they are among the nation's most stringent.
While New York has banned high-volume wells using the process, other states have active industries, including Pennsylvania, where the Hopkins study was conducted between 2005 and 2012.
Fracking proponents deny that the wells cause health problems, and point to various measures of air quality, which the Hopkins study did not assess.
Rasmussen and other investigators agree that more study is needed to determine the cause of the negative health outcomes. Other research has connected proximity to the wells to pre-term births and lower birth weights, respiratory and skin irritation, and increased hospitalizations in neurology, oncology and urology.
The Hopkins study looked at the health records of 35,000 asthma patients in the Geisinger Health System and found there were more mild attacks requiring inhalers, more moderate attacks requiring an emergency room visit and more severe attacks requiring hospitalization.
The attacks occurred during most points in development and operation of the wells, though researchers found the risk was greater during the production phase, which can last many years.
Other factors that can worsen asthma, including proximity to major roads, family history, smoking and socioeconomics were accounted for in the study, published in July in the Journal of the American Medical Association Internal Medicine.
Rasmussen said air pollution and stress from added noise, vibrations and truck traffic could explain the risk. She said asthma complications manifest quickly after exposure to triggers, making the disease a good bellwether for potential health effects.
A recent analysis of more than 685 published peer-reviewed health and environmental studies involving fracking found that most concluded that there were potential problems.
More studies are planned to assess whether fracking is responsible for the observed health problem, said Seth Shonkoff, executive director of PSE Healthy Energy, an energy science and policy organization that produced the analysis.
"We're in kind of dot-connecting time in this field," said Shonkoff, also a visiting scholar in the University of California, Berkeley's department of environmental science, policy and management. "But there is a strong indication that the current, now sizable body of independent peer-reviewed scientific literature indicates there is harm and there are risks with this kind of oil and gas development."
Industry representatives characterize the studies as inconclusive or directly contradicted by other studies, including some conducted by government analysts.
"Numerous studies that have actually measured emissions directly on well pads have shown that development is protective of public health," said Seth Whitehead, researcher for an outreach campaign by the Independent Petroleum Association of America, which represents oil and gas producers. "It's curious that studies funded, written or peer-reviewed by activists — as the Pennsylvania asthma study clearly was — never seem to include direct air measurements."
Whitehead was referring to the Hopkins' study's senior author, Dr. Brian S. Schwartz, a Hopkins professor and unpaid, informal adviser to the Post Carbon Institute, a renewable energy think tank. The asthma study was independent of that work and was funded by the National Institutes of Health and several foundations, according to Hopkins.
Whitehead also pointed to Pennsylvania Health Department data showing that asthma hospitalization decreased statewide roughly at the same time the asthma study was conducted.
Rasmussen said better treatment or reduced energy demand likely pushed down statewide hospitalizations for asthma even as attacks remain higher near wells.
Nicole Deziel, a fracking researcher at the Yale School of Public Health, called the Hopkins study well designed and an "important advancement in how to capture exposure" to the drilling method because it accounted for the number of gas wells and how close they were to people's homes and considered the types of activities from construction to production.
"This adds rigor to the approach and is an important step toward a better understanding of whether a certain aspect of the unconventional development process may be more hazardous," said Deziel, an assistant professor in the department of environmental health sciences.
"This study provides evidence of an association between unconventional natural gas activity and asthma exacerbations," she said. "More health studies like this are needed to see if similar results are observed in other settings."
The data from various studies has been enough to raise concerns among health care professionals. The American Medical Association has called for disclosure of chemicals used during fracking and monitoring of human exposure.
A group of activist medical organizations called Concerned Health Professionals of Maryland formed to oppose fracking.
Asthma is a serious lung disease affecting 25 million Americans, said Katie Huffling, a nurse and director of programs for the Alliance of Nurses for Healthy Environments, one of the member groups. Attacks can cause wheezing, coughing and shortness of breath, and can be fatal if untreated. She said the latest study combined with other research should push state lawmakers to extend the fracking moratorium or ban the practice.
She said fracking is still relatively new, having only taken off in the past 10 to 15 years, which is not enough time to see the full scope of health and environmental consequences. But she said the studies show an association.
"Researchers are going in and looking afterward to see if it's impacting people living nearby, and unfortunately we are seeing potential," she said. "The Hopkins study adds to a growing body of knowledge showing, yes, for people living around the hydraulic fracturing sites there are negative health impacts."