Studies have linked the explosion of hydraulic fracking as a method of drilling for gas and natural oil to increased risks

 to people's health, in addition to concerns about air and water quality near the wells. Photo by Christopher Halloran/Shutterstock

PHILADELPHIA, July 17 (UPI) -- A study by the University of Pennsylvania and Columbia University has linked hydraulic fracking to hospitalizations for heart conditions, neurological illness and other conditions.

The new study came out barely a month after the Environmental Protection Agency released its five-year study, which found fracking has not had widespread impact on drinking water. EPA researchers, though, said the report was not a statement on fracking overall and only considered the oil drilling technique's potential effect on water sources.

Unlike traditional oil drilling, fracking involves pumping chemicals into the ground at high pressures in order to jar loose oil caught in rock formations so that it can be pumped from the ground.

Researchers in the new study, published in PLOS ONE, analyzed data collected by the Pennsylvania Healthcare Cost Containment Council on about 198,000 hospitalizations between 2007 and 2011. The hospitalizations were in three counties -- Bradford, Susquehanna and Wayne -- in northeastern Pennsylvania.