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Dr. Tsubokura's Radiation Lecture Vol.118

Author: Masaharu Tsubokura M.D., PhD.

Editors: Akihiko Ozaki M.D., PhD., Yuki Senoo

235. The reference value range should be used as just a guide

   A blood test at medical check-ups and the hospital indicates the reference values for each test component. The blood test’s results present the reference values in a range "from XX to XX" for each test component, such as anemia, liver, or kidney panels. People often worry when their results are not within these reference values.


   However, none of us is identical to each other; hence, each person will have different blood test results. For example, although most people's height and weight are close to the average, some people have excessively or slightly high or low height and weight.

   For this reason, a reference range is the set of values within which the majority of the healthy population falls (95/100 people—that is, a 95% prediction interval).


   Therefore, even for those who are healthy, 5 out of 100 will have a high or low medical test result outside the reference values.


   Importantly, these values are not used to distinguish between normal and abnormal or to diagnose a particular disease. The reference values are not a strict boundary that determines whether a person has a health issue or not. Even when your medical test result is slightly out of the range, it does not mean you are unhealthy, and it does not mean you are healthy when your result is within the range.


   This is the same for the reference value for radiation exposure. It is not okay to be exposed to radiation exceeding the reference level. However, the reference value is not a threshold that determines whether people will develop a disease.

236. Reference values are developed considering the lifestyles of local people

   The blood test that you get during a medical check-up and at the hospital indicates the reference values for each test component. People often worry when their blood test results are not within the reference range. However, the reference values do not determine whether one has health issues or not.


   A variety of reference values exist to measure radiation exposure and its effect on human body too. Similar to a blood test, these values do not determine whether a person will develop particular diseases and are not a boundary between safe and harmful radiation exposure.


   The standard food-safety limit for radioactive contamination in Japan is set at 100 becquerels per kilogram. As you know, today, radioactive contamination exceeding this limit is rarely detected in food, and radiation contamination is only found in certain types of food.


   On the other hand, after the Chernobyl disaster in 1986, high radiation exposure among people living in a region of Northern Europe was caused by eating contaminated reindeer meat, which was a part of an important ritual for them. Back then, the standard limit for radioactive contamination in food of 6,000 becquerels per kilogram—60 times higher than that in Japan—was publicly accepted.


   In determining reference values of any kind, consumers’ health safety is the best priority. Still, they should take residents’ lifestyles, local cultural backgrounds, and mindsets into account as well.


The Japanese version of the manuscript was originally published in Fukushima Minyu, a local newspaper in Fukushima prefecture, Japan, 14th and 21st of July 2019 was reproduced for MRIC Global under the author's permission.


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