Fracking shale for gas brings wealth, concerns

Researchers don't know if the discharges are dangerous to humans or wildlife; several studies on possible environmental effects are under way. Drilling companies are exempt from disclosing their chemical formulas.

At least 269 million gallons of wastewater went to treatment plants in Pennsylvania for river discharge in the 18 months ending Dec. 31, according to an Associated Press review of reports filed with the state's Department of Environmental Protection. Millions more gallons of wastewater went unaccounted for because of weaknesses in the state's tracking system.