• Kyodo


A study by Hiroshima University researchers has shown that men who entered the city just after the 1945 atomic bombing face a greater chance of dying from cancer than those who came three days later.

The findings suggest that human health may be impaired by residual radiation from the materials generated by a nuclear detonation, and challenge the view espoused by a state-funded institute that maintains such radiation caused no major difference in cancer risk in people who entered the city right after the bombing.

The team at the university’s Research Institute for Radiation Biology and Medicine will present the results of its statistical analysis Sunday at a meeting of the Japan Radiation Research Society to be held in the city of Aomori.

Keiko Otani, an assistant professor involved in the study, which focused on men between 30 and 49, said those in that age bracket were likely to have been asked to look for family members or carry their bodies near ground zero.

“We can assume they may have been most affected by residual radiation by inhaling dust containing radioactive materials,” she said.

The study tracked 28,638 men who were registered in a database between 1970 and 2011. They were among those who ventured within 2 km of the hypocenter in the two weeks after the bombing.

The team analyzed data on 4,610 men who died from solid cancerous tumors by age and by the date they entered the area. Leukemia deaths were excluded.

The team compared those who entered the area on the day of the bombing on Aug. 6 with those who did so on Aug. 9, when the effects of residual radiation were thought to have almost faded.

The survival rate for men between 30 and 49 who entered the area on Aug. 6 was lower than those who entered three days later, the study found.

More specifically, the risk of dying from cancer at age 75 was 18 percent higher among those who were 30 at the time and 40 percent higher among those who were 40, it said.

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