Dr. Tsubokura's Radiation Lecture Vol.54

Author: Masaharu Tsubokura

Editors: Akihiko Ozaki M.D., Yuki Senoo

107. The reasons for 1 millisievert as the annual dose limit for the general public

The extent of the exposure dose determines the impact of radiation on health. It has been shown that a high level of radiation exposure (exceeding 100 millisieverts) increases the risk of death from cancer. On the other hand, it remains unknown whether radiation exposure below 100 millisieverts contributes to death from cancer. Even if it does, lifestyle factors (including obesity, smoking, and drinking) are considered to have a more significant impact on our health than radiation exposure below 100 millisieverts.

However, this does not mean we should stop protecting ourselves from radiation exposure, even below 100 millisieverts. To avoid unnecessary radiation exposure and to maintain a reasonable and realizable range, a variety of reference levels for radiation dose limits have been established.

The reference level for exposure through air and food contamination is based on the annual dose limit of 1 millisievert per year. This standard was established to ensure public safety; the reference levels, such as 0.23 microsieverts per hour or 100 becquerels, are not necessarily the border between “safe” and “dangerous” radiation levels.

108. An unbalanced lifestyle can lead to cancer

The extent of the exposure dose determines the impact of radiation on health; a small amount of radiation exposure does not lead to cancer.

Evidence from many studies suggests that radiation exposure exceeding 100 millisieverts increases the risk of developing cancer or dying from cancer, and the risk increases as the exposure dose increases.

Similarly, eating habits and lifestyle factors, including tobacco and alcohol use, can negatively affect your health and lead to cancer. The impact of lifestyle on cancer development is enormous, and smoking or drinking more than three units a day has the same health effects as radiation exposure of 1000 millisieverts.

Additionally, being underweight, obese, or sedentary has more negative health effects than exposure to 100 millisieverts of radiation. Even in the case of passive smoking, in which family members smoke around you and cause you to involuntarily inhale smoke, has only slightly less impact than being exposed to 100 millisieverts of radiation.

The reference level for air and food contamination is set to 1 millisievert per year, 1/ 100th of 100 millisieverts. You can see the importance of managing your current lifestyle to protect your health.


The Japanese version of the manuscript was originally published in Fukushima Minyu, a local newspaper in Fukushima prefecture, Japan, on January 29th and February 5th 2017 was reproduced for MRIC Global under the author's permission.

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