A-BOMB FALLOUT

By Dick Thompson/Washington

One of the grim lessons of Hiroshima and Nagasaki was a medical one: radiation kills on a sliding scale. High doses kill quickly and horribly, burning off skin and destroying intestines and other internal organs. Low doses kill more slowly, triggering leukemia and other cancers. From this knowledge, scientists deduced the rough formula that underlies virtually all nuclear safeguards written since 1945: even the smallest exposure to nuclear radiation is harmful, and as the exposure increases, so do cancers and deaths.

But is that right? As scientists gathered in Washington last week to honor 50 years of research on the medical effects of fallout, one of the most surprising findings to emerge was that the 120,000 people who survived Hiroshima and Nagasaki are not being cut down in large numbers by cancer and other radiation diseases. In fact, by some measures, they seem to be outliving contemporaries who were not exposed.

Could fallout be good for you? Most scientists won't go that far. One possible explanation for the unexpected longevity of some atom-blast victims is that whatever enabled them to survive the blast in the first place--a natural resistance to disease, perhaps--continues to protect them. It is more likely, says the National Academy of Sciences' Evan Douple, a leading expert in the field, that radiation is not quite as harmful as was supposed. "Radiation in general is a very ineffective carcinogen," he says. Below certain very low levels, it may cause no harm at all.

The U.S. government is following these findings closely. It is in the process of setting the rules by which nuclear waste is stored, nuclear power plants are dismantled and nuclear weapons mothballed. Where the line gets drawn between safe and unsafe radiation exposure could cost, or save, tens of billions of dollars.

--By Dick Thompson/Washington