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Dr. Tsubokura's Radiation Lecture Vol.53

Author: Masaharu Tsubokura

Editors: Akihiko Ozaki M.D., Yuki Senoo

105. Investigations of radiation-related health effects have been conducted under various conditions.

Radiation’s impact on health is determined by the extent of the exposure dose, not by the number of past exposures. Numerous investigations have been conducted to determine what extent of radiation exposure is dangerous, including studies of (1) medical, (2) natural background, and (3) occupational radiation exposure.

Regarding occupational radiation exposures, researchers have reported on the health information of workers at nuclear facilities in several countries. As a result, a variety of research papers on occupational radiation are available, including a review of the data from 15 countries and an investigation of the number of cancer deaths among 200,000 nuclear-power workers (with an average radiation exposure of 12 millisieverts).

The results from studies such as these reveal that the relationship between the risk of cancer death and the level of occupational radiation exposure is almost identical to the relationship seen after the atomic bombings of Hiroshima and Nagasaki.

The results of tuberculosis studies had similar results, as explained in the previous article ( The relationship between the level of exposure and the risk of cancer under various circumstances have been continuously examined, and the results have suggested that there is a correspondence between these studies’ results; none significantly contradict each other.

In addition, a report from Japan suggests that lifestyle habits such as smoking and drinking have much mor

106. Radiation exposure in excess of 100 millisieverts increases the risk of cancer death.

The extent of the exposure dose determines the impact of radiation on health. Numerous investigations have been conducted to determine what extent of radiation exposure is dangerous .

According to the results from a variety of studies, it has been confirmed that after 100 millisieverts of radiation exposure, the more one receives radiation exposure, the more chances of dying due to cancer. Of course, this does not mean that a person will definitely have cancer after receiving radiation exposure in excess of this amount.

About 30% of people die from cancer. Furthermore, those who receive 100 millisieverts of radiation exposure have a 0.5% increased risk of cancer death; for exposure of 200 millisieverts, the risk increases by 1%, and for exposure of 400 millisieverts, it increases by 2%.

On the other hand, the health effects for radiation exposures of less than 100 millisieverts are not known. The research results on the risk of radiation-induced cancer in such cases are inconsistent. Additionally, there is no clear evidence that supports an increased cancer risk for radiation exposures below 100 millisieverts. Even if there is such an increase, lifestyle factors such as dietary, smoking, and drinking habits have a much more significant influence on health.


The Japanese version of the manuscript was originally published in Fukushima Minyu, a local newspaper in Fukushima prefecture, Japan, on January 15th and 22nd 2017 was reproduced for MRIC Global under the author's permission.

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