The recent discovery of naturally formed asbestos in west-central Fairfax County has raised a thicket of difficult concerns for this fast-growing county, including worker safety, economic and legal considerations.

State and federal officials have insisted that more information must be gathered before they can reach a conclusion on the potential danger of the asbestos. But so far, no government agency has come forward to make or order such a finding.

Where that task will ultimately lie "is a good question," said Clarence Wheeling, health enforcement director of the Occupational Safety and Health Program in the Virginia Department of Labor and Industry.

Fairfax officials have sought to play down the discovery that almost 7,000 acres in a prime development corridor near Fair Oaks Mall is underlain with asbestos, refusing to release details and referring many calls to the public affairs office.

Officials have said airborne asbestos identified at two construction sites -- a public high school and an office building -- poses no health hazard because the airborne fiber content is very low, based on preliminary findings.

Work at the Fair Oaks Commerce Center and the Braddock Park High School construction sites was temporarily suspended this summer when the asbestos was identified. Some construction workers had complained of itching, county employes have said.

The asbestos is embedded in a rock formation that runs through the west-central portion of the county, where a number of commercial and residential construction projects are under way or planned, including a portion of the Little Rocky Run subdivision, according to a county soil scientist who took rock samples.

Deputy County Executive Denton Kent said pockets of fibrous asbes- tos have been identified in laboratory analysis, "but the tests were not sufficient to indicate a hazard."

Kent said more sophisticated tests to determine whether there is a threat are on hold while the county awaits guidance from the state.

The asbestos problem comes at a particularly sensitive time, during an election year that is seen by political observers as a referendum on the frenetic pace of development that has transformed this once-sleepy bedroom community into a major economic center.

"We've got to find out who has the power to do anything about it," said Supervisor Elaine McConnell (R-Springfield), who is running for reelection and in whose district much of the county's asbestos problem lies. McConnell said she intends to bring up the matter at today's board meeting.

Her opponent, Toni Carney, a former Fairfax County School Board member, said the county should take immediate steps, such as conducting more detailed air testing and requiring construction workers to wear protective clothing.

"If we don't know whether we have a problem, then we really ought to assume we do and handle it as if we did," said Carney. "It may be more expensive and more inconvenient. But in the long run, we'll be absolutely certain."

In letters mailed by the county Thursday, seeking guidance from three state environmental regulatory agencies, the county's director of the Department of Environmental Management said the asbestos problem may extend to 56 Virginia counties where the rock formation exists.

"An asbestos fiber analysis . . . indicates that the asbestos present in the natural rock is mostly crystalline form, although some forms of fibrous asbestos have been discovered," Claude Cooper wrote. "The fibrous asbestos appears to be encountered at random locations in the rock, and the fibrous asbestos is friable.

"Virginians regularly construct houses, buildings and other developments on this rock. Builders and developers do not take any specific precautions in handling or disposing of this rock. The excavated rock is transported from project to project and used where the need for fill exists."

The executive director of the State Department of Waste Management, Cynthia Bailey, expressed concern about the friability of the asbestos, its ability to crumble readily and disperse into the air.

"That's what you're trying to avoid with asbestos. The fibers are accessible to people," Bailey said. "This is something that hasn't happened, certainly not in the state and probably not in the country for a long time."

Regulations on asbestos have been aimed at schools and in building materials, but how to deal with naturally occurring asbestos seems to have fallen through the regulatory cracks.

The U.S. Environmental Protection Agency considers more than 1 percent asbestos content in building materials to be a potential health threat.

"This is a situation we have to learn from," said Michael Stahl, director of the EPA's asbestos-in-buildings program. "We have to learn if this is a hazard that requires regulatory action."

The asbestos coordinator of the State Air Pollution Control Board, Jim Lehan, said of the federal government's regulation: "You figure it out. They don't have anything, and we enforce what they don't have."

At the state Department of Labor and Industry, Wheeling said the airborne fiber count appears to be too low to be covered by federal or state regulations designed to protect people from asbestos-caused cancers.

But Wheeling said he needs more detailed air samples than the preliminary findings submitted by the county. The county has said it has no authority to take on such air quality enforcement.

Actinolite, one of six minerals called asbestos, is not usually fibrous, but the mineral in this case grows as fibers within special areas or pockets of deformed rock. The special crystal growth within the deformed rock forms asbestos, according to Malcolm Ross, a research mineralogist for the U.S. Geological Survey, a part of the Interior Department.

Discovery of the actinolite was enough to prompt contractor John Driggs to stop excavation work this summer at the Fair Oaks Commerce Center site, near Rte. 50 and Waples Mill Road.

Driggs said he no longer works there after having sought advice, which has not come from the developer and the general contractor. "I don't know anything about actinolite, and that's what we were looking for," Driggs said.