© 2017 MRIC Global

Dr. Tsubokura's Radiation Lecture Vol.13

November 20, 2018

Author: Masaharu Tsubokura

Editors: Akihiko Ozaki M.D., Yuki Senoo

 

25. All drinking water is safeJune

 In the previous article, it was mentioned that the level of radiation contamination in food is not influenced by the “place of production” but the “types” of food.

 

How about water?

As with rice and vegetables, tap water is also classified as a “highly safe product.”

The reason for this is that cesium firmly binds with mud. Water pumped from rivers is first purified by a precipitation of the mud inside. After this process, the supernatant of the purified water is further sanitized before being used.

 

Because cesium binds to mud, hardly any radioactive substances are contained in tap water, which is supernatant.

 

On the other hand, soil contains radioactive substances.

The safety of water from wells is ensured as well because cesium binds with mud and cannot penetrate deep into the ground.

 

The examinations of continuous internal exposure have revealed that the level of internal exposure did not differ among the residents, regardless of the selection of drinking water, whether mineral water, tap water, or water from wells.

 

26. The safety level of well water is high enough

 In the previous episode, we introduced that in regard to contamination levels, tap water is “highly safe.”

 

How about water from wells?

Well, you might think that well water would be dangerous because this type of water is pumped from underground areas, where radioactive substances might have penetrated.

 

However, this is not true.

Radioactive substances firmly bind to mud in the superficial soil, and they cannot penetrate deep into the ground. Moreover, it was reported that radioactive substances did not penetrate into the ground in the case of the Chernobyl nuclear accident.

 

Indeed, the boring soil examination conducted more than 20 years after the accident confirmed that more than 90% of cesium remained within 10 cm from the top of the ground.

 

Muddy canal water may still contain radioactive substances. However, in clear water, such as well water, radioactive substances precipitate at the bottom, so it can be considered as safe enough for everyday use, even for drinking.
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The Japanese version of the manuscript was originally published in Fukushima Minyu, a local newspaper in Fukushima prefecture, Japan, on June 28th and July 5th 2015, and was reproduced for MRIC Global under the author's permission.

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