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Hiroshima victims' bones reveal how much radiation they experienced after bomb blast

Publicado em 30 abril 2018

Hiroshima and Nagasaki stand as a testament to what would happen if a nuclear bomb was ever detonated over a populated area and why it should never be used again in war. A new research has now found out how much radiation victims of the "cruel bomb" experienced.

This study is based on research that started in the 1970s, notes a report by ScienceAlert. Sergio Mascarenhas from the University of Sao Paulo found that X-ray and gamma irradiation led human bones to become "weakly magnetic", this phenomenon was then named paramagnetism.

A jaw bone from a Hiroshima victim was obtained and studied by Mascarenhas in the 1970s to find out how much radiation the bones had absorbed. The recent study also took samples from the same jaw, but used modern methods including electronic spin resonance (ESR) spectroscopy, notes the report. To get a more accurate measure of the radiation levels the unidentified victim of the bombing experienced, the samples were irradiated back to their original level of radiation that the bone was put through.

"We then constructed a curve and extrapolated from that the initial dose, when the signal was presumably zero. This calibration method enabled us to measure different samples, as each bone and each part of the same bone has a different sensitivity to radiation, depending on its composition," said the study's co-author Oswaldo Baffa, from the University of Sao Paulo.

After scientists completed their analysis, they found that the victim's jaw bone had taken 9.46 grays (Gy) worth of radiation. It only takes 5 Gy to kill a human, noted Baffa. This figure also matches up with the radiation levels recorded in the brick and roof tiles in Hiroshima and Nagasaki after the bombings.

"We used a technique known as electron spin resonance spectroscopy to perform retrospective dosimetry. Currently, there's renewed interest in this kind of methodology due to the risk of terrorist attacks in countries like the United States," Baffa said.

"Imagine someone in New York planting an ordinary bomb with a small amount of radioactive material stuck to the explosive. Techniques like this can help identify who has been exposed to radioactive fallout and needs treatment."

The study titled 'Electron spin resonance (ESR) dose measurement