A group of Brazilian scientists calculated the radiation dose in the jaw bone of a Hiroshima bombing victim using a technique called electron spin resonance spectroscopy. The technique yielded the exact amount of radiation that can be fatal to humans. ( Angela Kinoshita, Oswaldo Baffa, Sérgio Mascarenhas | PLOS ONE )
A method used by Brazilian scientists was able to calculate the exact amount of radiation that killed a victim during the Hiroshima bombing in 1945.
The scientists were under the supervision of Oswaldo Baffa, a professor at the University of São Paulo’s Ribeirão Presto School of Philosophy, Science & Letters.
Baffa explains that they used the technique called electron spin resonance spectroscopy to perform the dose calculation or what is scientifically known as retrospective dosimetry.
The method they used was not new in the field. However, Baffa said that there is renewed interest in the system due to risks of terrorist attacks in the present-day scenario.
In the United States, for example, a suspect located in New York can plant an ordinary bomb with a small amount of radioactive material in the explosive. Using the technique, authorities can identify who has been exposed to radioactive fallout and who needs an immediate medical attention.
The Brazilian scientists were headed by Angela Kinoshita, a professor at Universidade do Sagrado Coração in Bauru, São Paulo State. Their full study is published in the journal PLOS ONE.
Electron Spin Resonance Spectroscopy Technique
In their approach, Kinoshita and her team were able to measure a dose of approximately 9.46 grays of radiation.
“About half that dose, or 5 Gy, is fatal if the entire body is exposed to it,” explains Baffa.
As mentioned, performing retrospective dosimetry using electron spin resonance spectroscopy is not a brand new approach. In fact, the scientists have only built on a continuing research that started in the 1980’s by physicist Sergio Mascarenhas. At this time, the method was used to identify the age of ancient bones through calculating its contact with different environmental factors, including radiations.
The current analysis by Kinoshita and her team, however, became pioneering because it was conducted on human tissue from the jawbone of a victim during the Hiroshima bombing.
A similar analysis was conducted in the past using non-human tissues, such as the brick and roof tile fragments found at the bomb sites. There was also a study calculating the effect of the radiation through DNA analysis of Hiroshima bombing survivors. All yielded results close to or similar to the one achieved by the Brazilian scientists.
The Hiroshima bombing in 1945 was the first and the only use of nuclear weapons aimed at civilians. The unfortunate event, however, paved the way for the end of World War 2.
Two atomic bombs were dropped on Japan at this time, killing 80,000 people instantly. Combined with the number of people who died from radiation and other aftermaths, the event killed a total of 192,020 people.
The bomb was detonated over Hiroshima at more than 1,800 feet above the ground. It weighs 9,700 pounds and created a mushroom cloud of more than 60,000 feet over Nagasaki.