Last January, while plugging a projector into an apparently faulty outlet at work, Mary Moss was seriously burned and missed nearly four months from her job at the Department of Health and Human Services. But although she lost $4,000 in salary and can now work just four hours a day, Moss has yet to receive a dime from the disability program for federal workers.

"I am being sued by quite a few of my creditors," said the 36-year-old Lanham resident, who wears a neck brace and is undergoing regular physical therapy. "My mortgage is in trouble, and I've depleted my savings." But every time she calls the Labor Department, Moss said, she is either put on hold, disconnected or told that no one is available to talk to her.

Moss' experience appears to be fairly common. The Labor Department takes an average of 129 days to decide whether to pay benefits to federal employes who suffer traumatic injuries on the job, the General Accounting Office said in a report released last week. And in cases involving job-related diseases, GAO found that Labor officials don't reach a decision for an average of 270 days.

GAO said that the Labor Department's guidelines call for most such cases to be decided in five to 10 days. A Labor spokesman, however, said she was not familiar with such a deadline.

The congressional watchdog agency, after surveying disability cases at Labor's local offices in the Washington area and in three other cities, found the department was too slow in processing 98 percent of the disability claims they examined. More than 90,000 disability claims are now filed nationwide each year.

Rep. Steny Hoyer (D-Md.) said yesterday that his caseworkers have gotten the runaround from Labor's Washington-area office.

"I find this virtually criminal," Hoyer said. "People are losing their homes, losing their cars and being called into court by hospitals for nonpayment of debts because of the deplorable conduct . . . by the Labor Department."

At Hoyer's side were Moss and a wheelchair-bound federal worker, Joseph Gagliardi, 49, of Bowie, who said his medical bills for a job-related hip injury haven't been paid since last November because Labor officials lost his records and then took seven months to acknowledge it.

Labor Department spokesman Leslie Milk said she could not discuss individual claims, but added "we cannot deny there are problems" with the program. In the Washington area, she said, 87 percent of the traumatic injury claims are now resolved in 45 days, and 71 percent of cases involving diseases are processed in five months. "A year ago the figures weren't that good," she said. "We've automated our bill paying and are now automating our compensation checks."

But GAO said the Washington office failed to stamp the date on 85 of 122 claims it received for traumatic injuries, thus making it impossible to gauge the delays in those cases, and that the office has only one part-time physician to review disputed medical claims.

Many delays are caused when the employes themselves, or their agencies, fail to provide key information about their injuries, GAO said. The auditors also blamed some private physicians for submitting only the information that their patients want documented.

The number of disability claims has soared from 12,000 to over 90,000 since Congress made it easier for workers to get these tax-free benefits in 1974, and Senate investigators recently found that Labor has frequently failed to detect that some claims are questionable or fraudulent.

Hoyer acknowledged that the system may be backlogged with some questionable cases, and that a 10-day deadline may be unrealistic for claims that, for example, involve complicated questions about whether a heart attack is job-related. But he said the Labor program provides the only legal remedy for injured federal workers and should move more quickly to separate legitimate claims from frivolous ones.