Dr. Tsubokura's Radiation Lecture Vol.21

Author: Masaharu Tsubokura

Editors: Akihiko Ozaki M.D., Yuki Senoo

41. Determination of radiation abundance using cesium

A main cause of internal exposure is the ingestion of contaminated food. To prevent an excessive level of internal exposure from food, the reference value of cesium has been established as 100 Becquerel/kg.

Although the reference value is only determined for cesium, it does not mean that we do not consider the influence of other radioactive substances, including strontium, the measurement of which is not simple.

Currently, cesium is considered a predominant part of the radioactive substances that can enter our bodies, and previous studies reported a rough ratio of the amount of each radioactive substance in the environment compared to that of cesium.

For example, the amount of strontium in the environment is approximately one-thousandth of that of cesium.The reference value of cesium in food is established to limit the total annual radiation exposure to below 1 millisieverts.

An influence of radioactive substances other than cesium has been estimated using the above mentioned ratio, and their effects are also considered in cesium’s reference value.

42. No influence of radiation exposure on the next generation

I am often asked about the health effects of radiation exposure on generations to come.

The atomic bomb was used in Hiroshima and Nagasaki in 1945 and caused severe external radiation exposure for residents. The investigations to examine the health effects of the exposure to the individuals born after these incidents have continued. These studies have confirmed that the incidence of cancer and other diseases has not increased among the affected residents.

Also, after the Chernobyl accident, when internal exposure was highest, the health effects of the radiation exposure have not been detected in the generations born after the accident. These are not animal experiments or examinations in vitro but actual data taken from humans.

Moreover, the level of external and internal radiation exposure among the local residents in Fukushima prefecture is significantly lower than in Hiroshima, Nagasaki, and Chernobyl.

The current situation in Fukushima is nowhere near the level where we should be concerned about the influence on subsequent generations. ---------------------------------------------------------------------------------------------------------------

The Japanese version of the manuscript was originally published in Fukushima Minyu, a local newspaper in Fukushima prefecture, Japan, on October 18th ,25th 2015, and was reproduced for MRIC Global under the author's permission.