For Ohio, a Midwestern state hit hard by recession, the promise of an energy boom driven by hydraulic fracturing, or Tracking', would seem to be a sure route to financial health. Far less certain is whether the technique has an impact on human health. Fracking uses high-pressure fluids to fracture shale formations deep below ground, releasing the natural gas trapped within. With the number of gas wells in Ohio that use fracking set to mushroom from 77 to more than 2,300 in the next three years, the state is the latest to try to regulate a rapidly growing industry while grappling with a serious knowledge gap. No one knows what substances - and at what levels - people near the gas fields are exposed to in the air and water, and what, if any, health threat they might pose.
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