Drilling for oil and gas in the Arctic National Wildlife Refuge would mark a departure from more than three decades of government practice, according to a new report by the General Accounting Office, the congressional watchdog agency. The report shows that some type of energy extraction takes place in 13 percent of refuges, but that nearly all of the permits to drill were granted before the 1966 passage of the National Wildlife Refuge System Administration Act. Rep. Edward Markey (D-Mass.), a drilling opponent who requested the report, said opening up the Arctic Refuge would set a precedent that could endanger the 297 other refuges identified by the U.S. Geological Survey as possibly having oil and gas reserves.