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RERF epidemiological study finds no difference in mortality risk between children of A-bomb survivors and others

by Kyosuke Mizukawa, Staff Writer

An epidemiological study conducted by the Radiation Effects Research Foundation has found “no significant difference” in mortality risk between the children of atomic bomb survivors and others of the same generation. The results of the study were announced at an October 5 press conference at the facility in Hiroshima’s Minami Ward. The research, which examined the relationship between A-bomb survivors’ radiation exposure and the mortality risk of their children, relied on data on deaths from cancer or other illnesses through the end of 2009. Because the children of A-bomb survivors are still relatively young, the foundation plans to continue the research.

RERF has conducted follow-up studies on a total of 75,327 children of A-bomb survivors and others born in Hiroshima and Nagasaki between 1946 and 1984. The latest study analyzed the deaths of 5,183 people, classifying them into two groups, one for those who died of cancer and one for those who died of other illnesses. The mortality risk for those who were not children of A-bomb survivors was set at 1.0. This figure was then compared against the data for the children of survivors.

The risk of death from cancer for those with a parent who was an A-bomb survivor was found to be between 0.5 and 1.36. Because the mean of these values is close to 1.0, the researchers determined that there was “no significant difference” between the children of A-bomb survivors and others. Analysis of the data on those who had died from illnesses other than cancer led to a similar result. No value that would indicate an increased mortality risk was found in comparisons of the two groups on the basis of amount of radiation exposure or whether death occurred before or after the age of 20.

Data compiled in late 1999 produced similar results. At the press conference, Eric Grant, assistant chief of RERF’s Department of Epidemiology, said that because the children of survivors are still relatively young it cannot yet be stated with assurance that they will suffer no effects from their parents’ radiation exposure. He added that a molecular biological study was also needed to determine whether there were effects that were not apparent through epidemiology.

(Originally published on October 6, 2015)

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