SCRANTON, Pa. -- Sen. Bob Casey said Thursday that Pennsylvania's emerging natural gas industry has the potential to create jobs and wealth, but also carries environmental risks that must be addressed.

The Pennsylvania Democrat said at a forum in Scranton that the "gas rush" taking place in the Marcellus Shale region of Pennsylvania "can create a great economic boost" in a state where nearly 600,000 people are unemployed. But he added: "We must not fail to protect our people, our land, our water and our future."

Casey is sponsoring the FRAC Act, stalled legislation that calls for federal regulation of the drilling process known as hydraulic fracturing or "fracking." Drillers inject millions of gallons of chemical-laden water deep underground to break up the shale and let natural gas escape, leaving much of the water below ground.

Because the process was exempted from federal laws by 2005 energy legislation, regulation has been left to various states.

Opponents contend fracking not only threatens the quality of groundwater but the quantity, since it requires so much water be withdrawn from area rivers.

The industry says fracking has a long track record and that it is safe, with no confirmation that the process has ever contaminated water supplies, and that other kinds of energy production use much more water.

Casey on Thursday pushed for full disclosure of all chemicals used in fracking, one of the provisions of the FRAC Act. The industry says it now does disclose those chemicals, some of which are known carcinogens, after years of claiming the chemical formulas were proprietary.

"Pennsylvanians have a right to know what is being injected into the ground at thousands of sites across the commonwealth," he said. If fracking chemicals do not pose a threat to groundwater, drinking water or human health, he asked, "then why can't we shine the light of full disclosure on that process?"

Industry official Kathryn Klaber, who appeared with Casey at the forum, said drillers have nothing to hide and do not object to additional types of disclosure to make the public more comfortable.

"There's no reason not to have that data available, and clearly the public sees it as a top priority," said Klaber, head of the Marcellus Shale Coalition.

Thursday's forum at Marywood University examined the short- and long-term impacts of natural gas development in the Marcellus Shale, a giant gas field underlying much of New York, Pennsylvania, Ohio and West Virginia. Some experts believe the Marcellus Shale, with as much as 500 trillion cubic feet of gas reserves, could become the nation's most productive. It would supply natural gas to supply the East Coast for 50 years.

The U.S. Environmental Protection Agency has conducted hearings around the country this summer, seeking input as it prepares to study the environmental issues of fracking over the next two years. While Casey has been able to attach the disclosure provisions of the FRAC Act to another energy bill that the Senate could take up this fall, legislative action on the regulatory issue is unlikely this year.

Opponents of the gas drilling process complain the industry has taken environmental and safety shortcuts in their zeal to reap the vast gas stores. Drilling companies tallied more than 1,400 violations of state laws since January 2008, according to an environmental advocacy group's recent analysis of state data.

John Hanger, secretary of Pennsylvania's Department of Environmental Protection, expressed frustration with the industry in a newspaper interview on Thursday, vowing to stop issuing permits to frequent violators.

"The only sanction left to government and the people is to tell a company it can't do business here any longer," Hanger told the Pittsburgh Tribune-Review. "We're now to the point of really sorting through these violations and identifying companies that don't seem yet to have gotten the message.

Hanger called out three companies in particular: Chief Oil & Gas of Dallas, Citrus Energy of Colorado and EOG Resources, the Houston-based company that had a blowout at a Clearfield County well in June.

Klaber said the industry shares Hanger's concern and is working to reduce violations.

"We've go to do this right," she said. "We need to be at a place where there are no violations, and we need to be doing that consistently to earn ... trust."