ALBANY, N.Y. (AP) - Environmental groups praised state regulators for delaying a decision on shale gas development until a more in-depth health study is finished, but landowners eager to reap profits from their mineral resources were frustrated at another delay in a rulemaking process that has kept drilling on hold for 4 1/2 years. "We're glad to hear that they're not putting an artificial deadline on completion of the regulations, and giving the scientists time to do the science," said Deborah Goldberg, an attorney for Earthjustice. Nick Schoonover, a landowner in southern New York who organized a coalition of landowners five years ago to pursue gas leases, said Tuesday the delay is "irresponsible. That's all there is to it. The Department of Environmental Conservation had faced a deadline Wednesday to complete its comprehensive environmental impact study of drilling for gas using high-volume hydraulic fracturing, or fracking. DEC Commissioner Joe Martens said Tuesday that the deadline will be missed, meaning regulations due to be released Feb. 27 will be delayed. Martens said he expected Health Commissioner Nirav Shah's review to be done in a few weeks. But Martens said issuing of permits for shale gas drilling could begin even while regulations are being finished, if the Health Department's review finds the Environmental Conservation Department's impact study adequately addresses health concerns. But if the Department of Health review "finds that there is a public health concern that has not been assessed in the (environmental impact study) or properly mitigated, we would not proceed, as I have stated in the past," Martens said. Goldberg said it would be illegal for the state to issue permits before the regulations were finished. "If they try to proceed without rules, we'll be suing them in court," she said. Shah said he needed more time to review recent studies. He said his review focuses in particular on the relationship of fracking to the health impacts of drinking water, as well as other areas such as air quality and community impacts. "Commissioner Shah is correct that the state needs to take the time to do a comprehensive study of the health effects of fracking to protect the public health," said biologist Sandra Steingraber, a leader of the anti-fracking movement. We are confident that such a review will show that the costs of fracking in terms of public health are unacceptable. A coalition of landowners is considering a lawsuit over the state's repeated delays in completing regulations and issuing drilling permits. "We're incredibly disappointed that our state could not get this done," said Scott Kurkoski, a lawyer representing a large coalition of landowners in the southern part of New York near the Pennsylvania border where gas drilling is most likely to start. We've been at this for 4 1/2 years. Ohio was able to accomplish their revision to regulations in eight months. Karen Moreau, executive director of the New York State Petroleum Council, said industry best practices and state regulations "have proven effective in the safe use of the hydraulic fracturing process for more than 60 years and in over a million wells." Shah noted several studies that have been initiated or published by the scientific community: an EPA study on potential impacts of fracking activities on drinking water, due to be completed in 2014; a Geisinger Health Systems study in Pennsylvania, which is analyzing health records in areas where shale gas is being developed; and a study recently announced by researchers from the University of Pennsylvania in collaboration with scientists from Columbia, Johns Hopkins and the University of North Carolina. "As we have been reviewing the scope of these studies, I have determined - and prudence dictates - that the DOH Public Health Review will require additional time to complete based on the complexity of the issues," Shah said. He said he and his team will be in Pennsylvania and Washington in coming days for briefings on the studies. He said he has also extended the terms of outside researchers assisting in his review.