Is hydraulic fracking for natural gas safe? That's one of the big questions surrounding America's fracking boom. Homeowners with these gas wells literally in their backyards have complained of contaminated drinking water wells and noxious fumes. The natural gas industry has said that except for the occasional accident, fracking is not to blame. The American Petroleum Institute, the trade group for the natural gas industry, says fracking is safe and there's no proof that the practice causes significant damage to the environment or human health. In our series, NPR decided to investigate the evidence the industry bases its safety claim on, and we found something astonishing. Despite some 200,000 fracked wells, very little data have been collected and few rigorous studies have been done to show whether fracking is safe, or whether it is dangerous. Not by local officials, state officials, universities or federal agencies. Essentially there is a data void on this issue. The type of scientific work that tied lead, tobacco smoke and smog to health problems, or that exonerated vaccines as the cause of autism, has not been done. With its safety claim, the industry is actively misleading the public into believing its practices have been solidly vetted and found untarnished. As we show in our seven part series, this is far from the truth.