Biological effect of radiations

Japanese: 放射線生物効果 - ほうしゃせんせいぶつこうか（英語表記）biological effect of radiations

The biological effects of radiation begin with the moment that radiation passes through the body of an organism, losing its energy; from the organism's perspective, it begins with the absorption of energy. As a result of energy absorption, various molecules in the cells that make up the body (especially the cell nuclei) lose electrons that are involved in covalent bonds between atoms, or gain electrons that are lost, turning them into positive and negative ions, which undergo a secondary change into free radicals. This is called the direct action of radiation. The radicals produced from the water molecules in the cells as a result of the direct action further react with nearby molecules, causing changes to them.

Source: Heibonsha World Encyclopedia, 2nd Edition Information

Japanese:

放射線の生物効果は，放射線が生物の体を通り抜ける瞬間にそのエネルギーを失う，生物側からいえばエネルギーを吸収することから出発する。エネルギー吸収の結果，体を構成する細胞(とくに細胞核)のいろいろの分子が，原子間の共有結合にあずかる電子がはじき飛ばされるか，飛ばされた電子が付加されるため，正負のイオンとなり二次的に変化して遊離基(ラジカル)となる。これが放射線の直接作用と呼ばれる。直接作用の結果，細胞の水分子から生じたラジカルはさらに近傍の分子と反応し，それを変化させる。

出典　株式会社平凡社世界大百科事典第２版について　情報

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