Risk of leukemia more than 50 years after A-bombing

Follow-up study by RERF covers 1950-2001

by Rie Nii, Staff Writer

On July 4 the Radiation Effects Research Foundation (RERF) in Hiroshima announced the results of a study showing that an elevated risk of developing leukemia from the effects of radiation remains more than 50 years after the atomic bombing. The findings were based on a follow-up study of atomic bomb survivors conducted from 1950 through 2001.

The results indicated that, even 55 years later, survivors who were 10 years old at the time of the bombing and who were exposed to 1 sievert of radiation had twice the risk of developing leukemia as those who had not experienced the A-bombing. According to Harry Cullings, chief of RERF’s Department of Statistics, survivors’ risk of developing leukemia was 50 times normal five years after the bombing. Compared to this, the risk 50 years later is low. “But it is not zero,” he said. He added that the risk of developing acute myeloid leukemia was particularly high.

It was also found that the relative risk of developing leukemia based on the amount of radiation exposure was even higher than that shown by a previous survey, which was conducted from 1950 to 1987. In that study, a 70-year-old survivor who was exposed to 1 sievert of radiation at the age of 30 was found to be 2.74 times more likely to develop leukemia than someone with no exposure. For someone exposed to 2 sieverts of radiation the risk was found to be 6.37 times greater. But because the most recent study was conducted in a different manner, specific figures cannot be compared directly, Mr. Cullings said. One reason is that more data has been compiled.

The study looked at data on 113,000 survivors for whom a survey on life expectancy is being conducted.

(Originally published on July 5, 2013)