The nation's only municipal law ordering safety standards for employees using video display terminals has been thrown out by a judge who ruled that the state must regulate workplace safety.

Labor officials said they would appeal Thursday's decision by Superior Court Judge Lucy McCabe."This law filled a void," said Barbara Kellogg, spokeswoman for the Service Employees International Union, which sponsored the ordinance. "Workers now have absolutely no recourse."

The law required that all San Francisco businesses employing 15 or more workers provide VDT-using employees with adjustable chairs, glare shields, detachable keyboards, tables with sufficient leg space, special lamps to reduce vision impairment, and a 15-minute break every two hours. The law also created a committee to study the health effects of VDT use.

Workplace studies have linked constant use of VDTs to painful hand and wrist injuries caused by repetitive motion. VDTs have also been blamed for back, neck and eye strain, headaches and sleep disturbances.

The ordinance, which began a three-year phase-in period last month, was the only one in effect in the nation. The only previous measure, in Suffolk County, N.Y., was overturned in a similar ruling by an appeals court in 1989.

The San Francisco law, adopted in 1990, was challenged by two businesses.