Since it began in May, a free Prince George's County telephone medical service has recieved more requests for its explicit, though clinical, sexual advice and discussions of human sexual activity than any other subject.

Called "Tel-Med," the program dispenses taped telephone information on everything from hiccups to heart attacks, gout to cankers sores and laxatives to contraception. It played most frequently last month tapes on female and male sexual responses, how to recognize pregnancy, and masturbation.

Other topics among the 10 most popular themes in September were marijuana, the female disorder of vaginitis, tension, schizophrenia and psychiatric counseling.

Also of special interest to the 61,898 callers who used the service between May and September were alcoholism, breast cancer, menopause, vasectomy and a tape called "Where Did I Come From, Mama?"

The $38,000 Tel-Med program aimed at providing elementary information on staying healthy and recognizing and adjusting to illness is jointly funded by the county health department, library system and Prince's George General Hospital and Medical Center.

The particular value of the taped information is that it is "easily accessible, anonymous, confidential, medically accurate and up-to-date," said Lynn Gorton, a health educator in charge of the program.

To use Ted-Med, a caller dials the number and asks for a specific tape number among the 248 offered. The subjects are listed in a brochure distributed at nine retail food and drug franchises across the county.

The Tel-Med material, devised by the San Bernadino County California Medical Society, has been approved for use by the Prince George's Medical Society and the Dental Society of Southern Maryland.

The county school system, which offers sex education as part of a broader health education program does not allow distribution of the informational "Tel-Med" brochures to students because of the tapes on sexuality.

Sex education is taught from kindergarten on in Prince George's public schools and reaches an estimated 30 per cent of the students who from fifth grade on need written permission from their parents for the courses, which are as explicit as the Tel-Med material. However, the school system is prohibited from providing information on contraception and human sexuality to students without written permission from their parents as the students need to take the elective sex education classes.

In the schools, parents are also invited to review the material and take a human sexuality course offered especially in anticipation of parental concerns in rearing their teen-aged children.

"We do not talk about erotic techniques or anything like that in our classes," said Floss Fenton, supervisor of health education for the county schools.

The Tel-Med program, according to Gorton has heard no such complaints to its sexuality tapes.

More frequently the stuff of sex manuals and sex therapist, some Tel-Med sexuality tapes describe generally how sexual organs are aroused and how to achieve sexual satisfaction.

A female speaker on one tape on "female sexual response notes that women usually take longer to become sexually stimulated than men and need to be "held and cuddled, lovingly spoken to and caressed" in "enjoyably sensitive areas." Men, a male voice counsels on the "male sexual response tape, "need to slow down and become more sensuous" in order to achieve greater sexual pleasure.

Masturbation called both "widespread and natural" for both sexes, can be excessive when one prefers his or her own body to others," but it does not cause "insanity, tuberculosis, sterility, impotence, pimples, blindness and cancer" as some myths have erroneously stated, another tape states.

"I think you can attribute the popularity of these tapes to the popularity of sex and mental health themes in American society," said Lynn Gorton, a community health educator who oversees the program.