Proposed revisions to Pennsylvania's oil and gas law will force drillers to disclose for the first time the names and amounts of chemicals they inject underground to coax oil and gas from rock.

But the final revision of those rules - earlier versions of which had been applauded by citizens and environmental groups as a step forward for public health and safety - contain provisions that will limit the amount of information drillers have to disclose.

The new rules are meant to provide citizens and regulators with information about the specific chemicals that are used to hydraulically fracture gas wells drilled next to homes and water supplies.

The process, which the industry contends has never polluted drinking water, has been criticized because companies have been reluctant to reveal the chemicals they use - making it difficult to prove contamination is caused by gas drilling.

Unlike earlier drafts of the regulations that were open for public review and comment, the final draft describes in detail the information drillers will have to disclose about each well, including the name and percent by volume of each chemical additive, as well as the names, unique identifying numbers and amounts of hazardous chemicals that make up those additives.

The final draft also describes the limits of that disclosure, including for the first time a provision that allows drillers to designate parts of the record as containing trade secrets that will be kept from the public, and another provision requiring drillers to disclose only the chemicals listed on federal safety documents - called material safety data sheets - instead of every toxic or nontoxic chemical injected into a well.

The changes were motivated by a comment letter submitted by Halliburton, the energy services giant, questioning the need for disclosure beyond what is contained in material safety data sheets and saying the draft regulations created "serious risks" to its trade secrets, including the identity of "specific proprietary chemicals."

Halliburton "believes that any requirement that service companies routinely disclose information concerning the chemical constituents of frac fluid additives ... would be inappropriate because it would require the disclosure of trade secret information when it is not needed and would serve as a disincentive to future frac fluid and technical innovation," the company wrote.

The Department of Environmental Protection, which developed the revised regulations, said it struck an appropriate balance between public disclosure and protecting confidential information.

But critics of the final revisions look at similar rules adopted by the state of Wyoming this year and see Pennsylvania's proposed standard as a step backward.

"I think it's sad that when you're writing new regulations you are actually doing less than what is state-of-the-art," said Deborah Goldberg, managing attorney of the eastern regional office of Earthjustice. "There are better regulations out there; you know what they look like; they are already in effect; they haven't shut down the industry; and you still don't do the best for your citizens. That's a shame."

The Wyoming rules - the first in the nation to require well-by-well disclosure of the chemicals used in hydraulic fracturing - require drillers to disclose all chemicals used in the process, not just those listed on material safety data sheets. That matters, Ms. Goldberg said, because many lesser-studied chemicals are not included on the safety sheets, even if they are known or suspected to be toxic. And nontoxic chemicals not on the sheets may combine with other chemicals to become toxic.

"MSDS sheets are widely known to be insufficient to really give people the information they need to protect themselves," she said.

And although Wyoming also allows companies to invoke trade secrets claims, regulators there have committed to scrutinizing those claims as they are submitted and have routinely rejected drillers' reports that incompletely identify the chemical constituents.

Under Pennsylvania's Right-to-Know Law, companies are allowed to designate information as a trade secret and the validity of that claim is only scrutinized once someone requests to see the record.

Scott Perry, the director of DEP's Oil and Gas Bureau, said the agency is restricted in what it can ask drillers to disclose because of the trade secrets standard set in the state's Right-to-Know Law.

"We don't have the same statutory authority as Wyoming does to be requesting all of this other information," he said.

"I think we've drawn an appropriate line that addresses the public's right to know what's being used at these sites without drifting into areas where, quite frankly, we would be in litigation."

Legal challenges might have held up the full suite of oil and gas revisions, which include stronger casing and cementing standards, stricter provisions requiring drillers to respond when they impact drinking water supplies and greater use of well blowout prevention equipment, he said.

The rules face reviews by the House and Senate environmental resources committees and a vote this month by the Independent Regulatory Review Commission before they take effect next year.

Contact the writer: llegere@timesshamrock.com