Japan: A surprising 45 per cent of people who survived being blasted with radiation from the atom bombs dropped on Japan at the end of the second World War are still alive, it was reported yesterday.
They are now the subject of the largest investigation carried out to date on the long-term effects of radiation exposure.
There are still many unanswered questions about the impact of the nuclear attacks on Hiroshima and Nagasaki 60 years ago, said New Scientist magazine.
A review published last spring by the Radiation Effects Research Foundation, based in Japan, concluded: "We still have no clear answers as to how the A-bomb radiation has caused biological effects in humans."
With 150 researchers in the two cities and funding from the US and Japanese governments, the research foundation has been closely following the health of survivors and their children since the 1950s.
The horrors of "atom bomb disease" were first described in the Lancet medical journal in 1946.
The first symptoms were anorexia, nausea and vomiting, followed by a failure of the bone marrow to make blood cells efficiently - then death.
Exposure to the radiation increased the long-term risk of cancer and, for solid tumours like those affecting the stomach, colon, lung and breast, the risk lasted a lifetime.
Studies have also shown that unborn children exposed to radiation in the womb grow up smaller and less intelligent than their peers. Many survivors however appear to have withstood the effects of radiation.
More than 150,000 people are thought to have died when the bombs - "Little Boy" and "Fat Man" - fell on the Japanese cities on August 6th, 1945.
Of the 280,000 or so survivors hit by radiation, though, 45 per cent are still alive today, New Scientist said.
Leukaemia is commonly thought to be one of the main legacies of the A-bomb, but new research suggests that only a small and vulnerable subset of the population may have been at real risk of developing leukaemia after the bombs.
Doubts have also been raised over claims that radiation exposure increased the risk of diseases other than cancer, such as chronic liver disease.
The idea that genetic abnormalities in people affected by radiation are passed on to offspring appears to be a myth, according to evidence collected so far.
Research on 22,000 children, half of whom had a parent within 2km of the A-bomb "ground zero", suggests they do not have unusually high rates of disease.
"Genetic studies have also failed to find evidence of inherited radiation-related mutations," New Scientist said.
However, the magazine pointed out that it was still too soon to assume the children were in the clear.
"Their average age is still just 48 - too young for most cancers to appear," it added. - (PA)