The genetic damage done by both sudden, high-dose nuclear radiation and chronic, low-level radiation has been massively overestimated, and the amount of radiation necessary to cause genetic harm has been greatly underestimated, according to two of the nation's most prominent geneticists.

One result, said Dr. James V. Neel of the University of Michigan, apparently has been an unwarranted fear of the possible effects of low-level radiation on offspring of nuclear workers or the children of residents of the West who have been exposed to A-bomb test fallout.

This comes on the heels of a dispute over whether the amount of radiation needed to cause cancer has been underestimated or overestimated.

Neel, in an editorial in today's issue of Science magazine, weekly organ of the American Association for the Advancement of Science, urges the president or Congress to name "a blue-ribbon committee of wide representation" and strong credibility to consider studying exposed American populations to make sure the new view is right.

The view--that estimates of genetic effects in man based on research in mice are too great and the dose actually needed to harm genes is four times greater than believed--is summed up in an eight-page article in today's Science.

It is based not on animal experiments but on observation of Japanese children whose parents were heavily irradiated at Hiroshima and Nagasaki.

The report's authors are Dr. William Schull, Masanori Otake and Neel.

Schull, head of the Center for Demographic and Population Genetics at the University of Texas Health Science Center in Houston, is former epidemiology chairman at the Radiation Effects Research Foundation in Hiroshima, the successor to the post-World War II Atomic Bomb Casualty Commission in studying the Hiroshima and Nagasaki populations.

Neel, professor of human genetics at Michigan, has been a consultant to the same groups and a member of many of the organizations that have set American and world guidelines for radiation exposure. Otake is a statistician with the radiation effects foundation.

Their discussion is based mainly on the "doubling dose" or amount of radiation that will cause 100 percent more mutations in parents' sex cells and, therefore, possible defects in their offspring, than occur spontaneously.

Based on study of mice, the International Commission on Radiological Protection most recently set the doubling dose for human exposure at 100 rems of low-dose radiation (in this case technically called low-LET or linear energy transfer at a low dose and low dose-rate exposure). The rem is a standard measure of radiation.

Based on study of Japanese children, and particularly effects on babies born between 1948 and 1953, the human doubling dose needs to be 468 rems to cause mutations through genetic defects, Schull, Otake and Neel estimate.

The Japanese were exposed to acute, high-dose radiation. But in mice the genetic effects of chronic radiation are only one-third the effects of acute radiation. And Schull, Otake and Neel use this fact, one they feel is safe to use, in calculating possible human effects.

"In short," Neel said in an interview yesterday, "we've assumed for lack of other data that man would be like the mouse. Now we say man is less sensitive than the mouse.

"Given these new data, it is extremely unlikely the children of occupationally exposed workers or the children in the West have been at increased risk."

Still, he said, there is so much emotion "and fear approaching hysteria" among nuclear workers and other possibly exposed populations that "we believe an intensive effort" should be made to observe these populations "in the same way we have observed the Japanese."

He said there should be parallel study of chemical industry workers and their offspring "since there is a lot of thinking today about exposure to possible mutagens there."

Genetic damage is not the only harm radiation can cause. There is also cancer. And one recent reappraisal of Japanese data by Lawrence Livermore and Oak Ridge National Laboratory physicists concluded that the dose required to cause cancers was lower than previously calculated.

There is disagreement here, too. In July, 1980, the majority of the members of a National Academy of Sciences study group said the risk of cancer too was less than thought.