In the past two months more than 50,000 Washington area residents have received medically oriented advice and information on over 100 subjects ranging from abortion to mumps to viruses, simply by picking up a telephone and dialing 561-9500.

When the operator answering the 10 lines servicing that number answers "Tel-Med operator," the caller gives the operator one of more than 100 tape numbers listed on a widely distributed brochure.

If the caller asks for 402, for instance, a taped woman's voice provides a brief rundown on the latest theory of how to respond to young children's questions about sex: "Answer the question they ask and . . . give them no more and no less"

According to Timothy Bell, Greater Southeast Hospital's director of public relations, some 25,000 calls a month have come in since the hospital began the service in December.

"We've had a lot of requests for the tapes on human sexual problems," said Bell, "and a lot of requests pretty well distributed throughout the listings."

The sexually related tapes include information on venereal diseases, male and female sexual response, head and body lice, and masturbation with the masturbation tape including the reassurance for young callers that masturbation "cannot harm you" and will not cause "blindness, insanity, pimples or cancer . . ."

The information on the tapes was prepared, said Bell, by the San Bernadino, Calif., medical society, and the tapes have been screened and approved by the American Medical Association, the D.C. Medical Society and Greater Southeast's medical director.

The actual tapes are produced by a nonprofit group called Tel-Med, and the hospital purchased the system for $14,000, as a "community service primarily for our community (in Southeast Washington) which has the fewest sources of medical information of any community in the metropolitan area," said Bell.

"There are now 162 tapes," he said, "and we will be adding to the system as we evaluate the kinds of tapes that are being requested."

The brochure announcing the service and listing the subjects and tape number is being distributed in "all DHR community clinics," group hospitalization facilities, health information racks at Peoples Drug Stores and in numerous other health facilities, said Bell.

The system is capable of playing 10 tapes simultaneously, one on each of the 10 lines, said Bell. Even with the 10 lines, he said, it is not uncommon for a caller to get a busy signal when calling the Tel-Med number.

In addition to including tapes on numerous diseases and conditions, the system also contains lessons and lectures on such subjects as "Power Lawn Mower - Dangerous Tool," "Teen Years - Age of Rebellion," "Seat Belts for Safety" and "Effective Toothbrushing."