The government's main watchdog over medical X-Ray was accused yesterday of "incredible" delay in creating guidelines to control the 130,000 doctors and technicians who give Americans 90 percent of their exposure to radiation.

The accusation was made before a House oversight subcommittee by Eleanor Walters of the Environmental Policy Institute.

Despite the fact that medical and dental X-raying far outweights all other soures of possibly harmful radiation, including radiation from nuclear plants and materials, much of it is administered by untrained or ill-trained persons, the lawmakers were told.

Witnesses, including Dr. Herbert Abrams, Harvard radiology chairman, and Daniel Donohue, president of the American Society of Radiologic Technologists, said:

Between 170,000 men and women operate the nation's 250,000 pieces of medical X-ray equipment, but only 80,000 have shown their competence in voluntary certification or state licensing examinations.

Only 10 states (California, New York, New Jersey, Delaware, Oregon, Hawaii, Arizona, Montana, Kentucky and West Virginia) require licensing of X-ray technicians. Only California requires all persons who give X-rays, whether technicians or doctors, to pass a state examination.

Some 75 percent of all X-rays given by doctors are given by MIDs other than radiologists, meaning in virtually all cases that they are untrained in keeping X-ray exposure to a minimum.

In most states any person at all - "anyone who walks off the street," machine on unsuspecting patients.

The result of all these deficiencies is much unneceesary or excessive radiation, with long-range danger of cancer or genetic damage to the subjects.

John Villforth, director of the Department of Health, Education and Welfare's Bureau of Radiological Health, said early this year that medical radiation could be cut to half its present total without losing any medical benefits.

Villforth's agency has done little to accomplish this, Walters maintained.

In July 1977, she said, HEW Secretary Joseph A. Califano Jr. said the bureau should develop standards for X-ray technicians, so more states could adopt effective licensing laws. Only in March of this year, she said, did the bureau finally publish a "notice of intent" to develop any standards.

This was the first step in a process by which the bureau hopes to publish final standards in December 1980. Walters called the delay "appalling," and said "it is inexcusable for only a handful of states" to required licensing of the persons who administer such a powerful and potentially harmful tool.

James Benson, the bureau's deputy director, agreed in an interview that "we ought to be going faster." He said the agency first tried in 1977 and 1978 to assemble a professional advisory group to write licensing standards, but "all the administrative steps" currently required to do this in the federal government would have taken even longer.

Overall, however, he said the agency has done a great deal to reduce unneeded radiation given the fact that its legal authority is mainly limited to ordering standards for X-ray and related equipment, rather than controlling the way the equipment is used.

The overuse problem, said Harvard's Abrams, is not only a problem of training. The doctor who does his own X-raying has "a profound economic incentive to perform more examinations," he said. "In fact, the non radiologist physician who owns an X-ray machine uses an average of twice as many X-rays as colleagues who refer patige of twice as many X-rays as colleagues who refer patients to radiologists."