Researchers from the University of Columbia and the University of Pennsylvania wrote in a study published in PLOS ONE that those who live close to the natural oil and gas drilling sites are more likely to suffer from heart conditions, neurological illnesses, and cancer. 
The scientists analyzed 198,000 hospitalizations records over a four year period (from 2007 to 2011) in Northern Pennsylvania counties, categorized 25 medical scenarios, and then associated each case with its proximity to a fracking area. A larger number of hospitalizations were found in those areas where drilling takes place.
According to the researchers, there are 18 zip code areas with a well density higher than 0.79 wells per square kilometer. That means a person who lives in one of those zip codes has a 27 percent greater risk of suffering from one of the aforementioned conditions.