ALBANY — Nearly five years after New York first looked at large-scale hydraulic fracturing for natural gas, both sides of the highly contentious shale-gas-drilling debate have finally reached common ground -- not on policy, but on a perceived lack of transparency.

With a hotly anticipated health analysis of hydrofracking being carried out exclusively behind closed doors, fracking advocates and opponents say they’re becoming increasingly frustrated with a review process that they believe has been cloaked in secrecy.

Various industry representatives, environmental groups, health organizations and state lawmakers have expressed a similar sentiment in interviews over the past week: They’re all in the dark.

“No one -- and certainly no one in industry -- has any idea of what this so-called health review is,” said Karen Moreau, executive director of the New York State Petroleum Council. “You would think that if there was some sort of comprehensive review being done by the health commissioner, they certainly would at least involve the public, the industry, the environmental groups in what they’re doing.”

Concerns about the openness of Health Commissioner Nirav Shah’s review have surrounded his work since it was first launched last September and have only intensified in recent months. Little has been publicly released on the analysis, which -- according to Cuomo -- will guide an ultimate decision on whether to allow high-volume fracking in New York.

The Department of Health did not respond over the past several days to a detailed set of questions from Gannett’s Albany Bureau on the state of its review of fracking, a gas-stimulation process that proponents say could help boost the struggling upstate economy while opponents warn of potential environmental degradation.

Last September, state Department of Environmental ConservationCommissioner Joseph Martens said he had asked Shah to “assess the (DEC’s) health impact analysis” on fracking and to “identify the most qualified outside experts to advise him in his review.”

Since then, Shah has said little about the progress of his work other than expanding the parameters in broad terms as the state blew a deadline to finalize a set of proposed fracking regulations last February. He has met in recent months with researchers at Geisinger Health System and the U.S. Environmental ProtectionAgency, both of which are studying fracking’s impacts over the next several years. But Shah has said he will complete his work before those studies are through.

Shah’s outside advisers -- Lynn Goldman of George Washington University, John Adgate of the Colorado School of Public Health and UCLA’s Richard Jackson -- completed their initial workload early in the year. But Shah said in February he would ask them to review additional information and extend their contacts, which contain a provision prohibiting them from discussing the documents they’re reviewing.

Goldman and Adgate have referred recent requests for comment to the Department of Health, while Jackson has not responded to emails. The Health Department did not respond to a request to release the extended contracts.

“This has been one of the least transparent processes I’ve ever seen,” said Katherine Nadeau, water and natural resourcesprogram director for Environmental Advocates of New York. “The administration -- while I will say we’re very pleased they’re reviewing the health impacts -- has done nothing to inform the public about what type of review is actually going on, what they are looking into, what they aren’t looking into.”

It’s also not clear how Shah’s review will differ from his agency’s previous work on the issue. While the Department of Environmental Conservation has been the driver for crafting a potential drilling framework, the Health Department has been involved in the process from the beginning.

A draft assessment written by the Health Department in early 2012, which was previously obtained by Gannett’s Albany Bureau and written at a time when the Cuomo administration was facing intense criticism for not doing more to assess health concerns, found that health impacts from fracking would be “unlikely” under a proposed set of rules from the DEC.

The Medical Society of the State of New York, the largest statewide association of doctors and medical professionals, has not been impressed with the process.

In a March meeting, the group passed a resolution calling for a comprehensive health study of fracking’s impacts to be completed by a school of public health, with shale-gas drilling kept on hold in the meantime. Shah was the keynote speaker at the meeting.

“(Shah) did not provide us with a timeframe” for his work to be completed, said Pat Clancy, the Medical Society’s vice president of public health and education. “I don’t know how long these studies take. We want a thorough study.”

Shah’s review is in its ninth month, but the state’s decision-making process has stretched on since July 2008, when it put hydrofracking on hold until more research was conducted. Speaking to reporters at Binghamton University on Thursday, Cuomo said he’s “never seen a more polarized issue” than fracking.

“We have said all along that the decision is a big one and it should be made on the science and the facts, not on the emotion or the politics,” Cuomo said. “The DEC commissioner and the Health commissioner are analyzing the data and when they have a decision, that will be the decision and the path that the state follows.”

Some supporters of hydrofracking said the lengthy delay may be a signal that the state won’t go forward with it.

Senate Energy Committee Chairman George Maziarz, R-Newfane, Niagara County, said he believes Shah’s review “is taking way too long” and that critics of fracking have “pretty much won the day on this.”

“Personally, as much as I favor (fracking) or others favor it, I think the argument is over in New York,” Maziarz said. “I just don’t think there’s the will on the part of the Health Department, the DEC, the Executive Branch, to move forward with it.”