The risk of giving birth to an infant with a low birth weight decreases the farther the mother lives from a site, the study finds. Infants born to mothers living about a half to 2 miles from a site also experienced increases in the probability of low birth weight but the effect is smaller—about a half to a third of the effect within about a half mile. In contrast, the study found no evidence of impacts on infant health among babies born to mothers living farther than about 2 miles from a fracking site. These results suggest that hydraulic fracturing does have an impact on infant health, but only at a highly localized level. Out of the nearly 4 million babies born in the United States each year, about 29,000 of them are born within about a half mile of a fracking site, while another 95,500 are born about a half to 2 miles away.

“While we know proximity to hydraulic fracturing sites is associated with compromised infant health, we do not yet know the mechanism—air or water pollution, chemicals onsite, an increase in traffic, or some other channel—or whether it affects health after birth,” said co-author Katherine Meckel, an assistant professor at UCLA. “This is a critical area for future research because it can help identify ways to mitigate or even erase the health effects, without causing communities to lose out on the local economic benefits of hydraulic fracturing.”

Meckel, Greenstone and their co-author Janet Currie, the Henry Putnam Professor of Economics and Public Affairs at Princeton University and the director of Princeton's Center for Health and Wellbeing, discovered their findings by comparing infants born to mothers living near a drilling site to those living farther from a site both before and after the drilling began. As a check, the study farther refines this comparison so that it is based on siblings who were exposed to fracking with those who were not. The study relies on birth certificate data from more than 1.1 million births in Pennsylvania from 2004 to 2013.

This study of the impacts of hydraulic fracturing on infant health follows a study by Greenstone, Currie and other colleagues on its local economic benefits. That study, released last December, found the average household living near a hydraulic fracturing site benefits by about $1,900 per year. This is driven by a 7 percent increase in average income due to rises in wages and royalty payments, a 10 percent increase in employment, and a 6 percent increase in housing prices. However, the authors cautioned that new information on the local health consequences of hydraulic fracturing is likely to influence housing prices if it differs from current expectations of health effects.

“Housing prices are not fixed, they are based on many factors including how well the job market is and how safe the area is to live in,” said Currie. “As these results, and others on the health impacts from hydraulic fracturing, become mainstreamed into the consciousness of homeowners and home buyers, the local economic benefits could change.”

—This story originally appeared on the Energy Policy Institute at Chicago website