In America, says Nobel laureate Dr. Rosalyn Yalow, there is a "mindset" against anything nuclear -- including valuable technology in the new field of nuclear medicine.

"It has been generated," she told a symposium in Baltimore last week, "by the association of radiation and radioactivity with nuclear explosion and nuclear war." As a result, "there are few areas in which more confusion exists than in the popular conception of the hazards of exposure to low-level radiation and low-level radioactive wastes."

It is so pervasive, she said, that "the new medical imaging modality, nuclear magnetic resonance, or NMR, has been renamed magnetic resonance imaging, or MRI, to avoid the bad word 'nuclear.' "

Yalow, a nuclear physicist, won the 1977 Nobel prize in medicine for developing the radioimmuneassay, a process by which minute protein substances in the blood can be identified. She is currently a medical investigator at the Bronx Veterans Administration Hospital and a professor at the Albert Einstein Medical Center of Yeshiva University.

She spoke at a day-long symposium on "Women and Radiation" sponsored by the Center for the Advancement of Radiation Education and Research (CARER) of the Johns Hopkins School of Hygiene and Public Health. CARER is financed by some 30 Baltimore hospitals involved in nuclear medicine and in small part by power industry groups like the Atomic Industrial Forum Inc.

In general, the conference did not focus solely on women, but also examined the effects of radiation -- primarily low-level, background radiation -- on the general population. Although there was some information regarding the importance of mammograms and the development of lower-radiation imaging, the emphasis was more on the putative national nuclear phobia, holding that, in general, all things nuclear were linked to war and devastation in the public mind.

In an interview before the symposium, Yalow said the widespread publicity surrounding potential cancer-causing effects of radon gases are indications of that phobia -- producing an unwarranted "mass hysteria."

Radon is the naturally occurring gas that is given off by uranium deposits, which, said Yalow, "have been here since before people." It has been linked to lung cancers in uranium miners and is currently the subject of concern because energy-conserving sealed houses in some parts of the country have permitted a buildup of indoor radon that is believed by many scientists to pose a major cancer hazard.

Yalow, however, believes that estimates attributing an average of 15,000 lung cancers a year to radon "is clearly an exaggeration."

"What scientists making these estimates have done has been to look at the incidence of lung cancer among uranium miners who are exposed to radon. They forget that there are other things in those mines, like metals and dust and all sorts of stuff like that."

They are not, she said, "looking back to what lung cancer was like before people started to smoke, for example, which is a much fairer way of examining the general kind of exposure. After all, in our houses we do not have all the other things you find in a mine."

She urged agencies like the Environmental Protection Agency, the Centers for Disease Control and the National Council on Radiation Protection to "reexamine the basis on which they are giving these numbers that could end up costing the country tens and hundreds of millions of dollars unnecessarily, to clean up something that is probably not nearly as hazardous as they think it is."

In Pennsylvania, which includes areas with especially high radon emissions and homes in which they tend to build up because they have no outlet, public officials have been involved in ongoing studies. University of Pittsburgh professor Bernard L. Cohen has testified before Congress that "there is unanimous agreement in the scientific community that the cancer risk from radon far exceeds that from all of the other widely publicized radiation threats in our society combined."

He said he continued to believe that, but noted that the evidence is indirect so far. He is now measuring radon levels and comparing them to lung cancer rates in the Pennsylvania counties with the highest radon emissions. He estimated that it would be two years before any conclusions could be drawn, and he conceded that if the estimates were indeed too high, "she Yalow may be correct."

Yalow, who will speak to the American College of Pathologists here later this month, plans to urge them to conduct autopsies looking particularly for the appearance of precancerous lung lesions in radon-exposed people to "examine the distribution of cell types" to see if such exposure contributed to their death, she said.

She noted that 25 years ago, long before it was clear that smoking was linked to lung cancer, such precancerous lesions were found in the lungs of smokers. Moreover, she noted, lung cancers caused naturally, as opposed to those induced by "environmental insult," are structurally different, made up of different types of cells.

Some of the controversy among scientists over the level of risk in background radiation is rooted in the statistical method used to extrapolate from the experience of the 80,000 survivors of the Hiroshima and Nagasaki bombings.

One system holds that if, for example, a large amount of radiation exposure is known to cause a certain number of excess cancers, then an exposure of 1 percent of that large dose could be expected to cause 1 percent of the excess cancers.

Some scientists say this method gives results that are too high. The National Academy of Sciences, for example, uses a modifed version of this system. In the third of its ongoing series of reports on radiation risks, the Academy's committee on the Biological Effects of Ionizing Radiation, the so-called BEIR committee, said that "the cancer of any given person cannot be attributed with certainty to radiation, as opposed to some other cause. In general, the smaller the dose of radiation, the smaller the likelihood that radiation was the cause."

The report was criticized by scientists who believed its estimates of low-level hazards were too low and by other scientists who believed they were too high.

Yalow believes that most of the most highly publicized studies in recent years that tend to link low-level radiation to increased risks of cancer are flawed. She says it is her obligation as a Nobel laureate to "go out and talk to public groups in areas where I have expertise."

(She also likes to point out that she has worked with radiation for years with no ill effects to her or her children or grandchildren.)

Risks, she notes, are relative. "If you were a newsstand worker in Grand Central Station," she said, "you'd get 120 millirems of radioactivity per working year from those magnificent granite columns spewing out their radon. I can tell you, since Grand Central is the home from 6 a.m. one morning to 1 a.m. the next of the homeless in New York City, the most dangerous thing in Grand Central Station is not the background radiation.

"When you talk about risks, you have to remember that one of the greatest risks of all is staying in bed -- you get osteoporosis, insulin insensitivity, let alone bedsores . . ."

Dr. Jacob I. Fabrikant, now chairman of the BEIR committee that is currently wrestling with the radon problem, among others, agrees with Yalow that there does seem to be "a certain apprehension and anxiety, an emotional overtone, that is unwarranted" on nuclear issues.

"You get controversy," he says, "when you get people who are interpreting sparse data as though it was highly reliable and drawing conclusions from their own interpretations and coming up with the information that risks might be double or triple what the other scientists are saying.

"Yalow has said that even if they were, the risk is so low that doubling or tripling it is relatively unimportant."

"It is clear," says Fabrikant, a professor and research scientist at the Donner Laboratory of the University of California at Berkeley, "that we have distorted the perspective on the issue of radiation." On radon, for example, he said, "we've been examining it for a number of years. It is a tedious, time-consuming study.

"We were born in a radioactive environment, developed in it, breathing it, and we've figured out a way to live with radon or we wouldn't be the way we are."