The statistics seem clear and compelling, and completely at odds with common sense: In Japan, site of the world's only nuclear attacks, radiation victims are outliving their peers.

It's one of the stranger twists in 50 years of scientific monitoring of atom bomb survivors. As expected, the people closest to ground zero have died in high numbers of cancers that began in a white-hot flash of nuclear radiation. But as one moves farther from the blast site, the death rate plunges until it actually dips below the baseline.

The question, which has divided scientists and academicians for years, has flared again because of a number of provocative new studies that seem to refute prevailing views about low-level radiation -- the relatively low-grade sort found in some kinds of medical waste or in the natural radon gas found in many homes.