Dr. Tsubokura's Radiation Lecture Vol.12

Author: Masaharu Tsubokura

Editors: Akihiko Ozaki M.D., Yuki Senoo

23. What Is The Risk of Uninspected Ingredients?

The primary cause of internal exposure is the consumption of radiation-contaminated food. Food from the market is exceptionally safe.

On the other hand, internal exposure increases in the case of eating food with shipping restrictions on a daily basis without making those food inspected at all. The results of the previous examinations show that the risk of having the high level of internal contamination is extremely low.

Causal behaviors are limited accordingly: growing mushrooms with highly contaminated logs; hunting wild boars and mountain birds in evacuation zones, and fishing every day in contaminated ponds.Moreover, if those causal behaviors are not carried out on a daily basis, his/her internal exposure would not elevate so much.

Although I have used the word "much," the influence of exposure should be explained not by its presence, but by its "quantity." Even those who consumed contaminated food "on a daily basis" as described above, the level of annual additional radiation dose was 1 millisievert at most. This level is less than half of the natural radiation we receive annually.

24. What Is a Standard Value of Acceptable Radiation Dose in Food?

The leading cause of internal exposure is the consumption of radiation-contaminated food. The inspections are conducted on food at the market to avoid contamination. The "reference value" is set to regulate the shipment and avoid food with more than 100 Becquerel/kg of cesium.

Well, if you were to eat food with "reference value" of contamination, how much do you need to consume them to reach 1 millisievert of exposure annually?A mouth full? 100 grams? More than 1 kilogram?

The answer is, you need to consume 1 kilogram of food with 100 Becquerel/kg of radiation dose on a daily basis to reach the additional dose of 1millisievert annually.

This does not indicate that you can eat contaminated food as much as you like, but it assures that the existence of radioactive substances does not determine the health effect of radiation. However, the effect of radiation towards our body is determined by the extent of exposure dose. It would help if you take these reference value into account as one measure of judgment.

By the way, we are exposed to about 0.3 millisieverts of radiation annually by ingesting radioactive potassium contained in food. ---------------------------------------------------------------------------------------------------------------------------------------

The Japanese version of the manuscript was originally published in Fukushima Minyu, a local newspaper in Fukushima prefecture, Japan, on June 14th and 21st 2015, and was reproduced for MRIC Global under the author's permission.