A coalition of environmental groups called on state officials to release details of a health impact study for shale gas drilling and a procedure that involves blasting chemical-laden water deep into the ground.

Representatives of a dozen prominent organizations signed a letter to Health Commissioner Nirav Shah and Environmental Conservation Commissioner Joseph Martens. They asked them to make public the health impact study being evaluated by a scientific panel, and they called for public hearings and a 60-day public comment period on the health study.

Shale gas development often involves a drilling procedure called hydraulic fracturing, or fracking. Large volumes of water, along with sand and hazardous chemicals, are injected underground to break rock apart and free the oil and gas. The energy industry says the procedure has been used safely for years, but environmentalists, homeowners and other critics say it can pollute water supplies.