Dr. Tsubokura's Radiation Lecture Vol.147

Author: Masaharu Tsubokura M.D., PhD.

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

293. There are no cases of detectable adverse birth outcomes associated with radiation exposure in Fukushima

　　　　The investigation of atomic bomb survivors in Hiroshima and Nagasaki demonstrated no detectable genetic effects, including an increase in cancer risk and other diseases among the offspring (the second generation exposed to radiation) of the survivors. Although several animal studies confirmed the increased incidence of genetic disorders related to high-dose radiation exposure during pregnancy, the genetic effects of radiation exposure are currently not confirmed among humans. Therefore, there is no need to worry about the genetic effects of the radiation caused by the 2011 Fukushima Daiichi Nuclear power plant accident.

　The above presented genetic effects of radiation exposure were found in couples who received a high-dose of radiation before conception. The birth outcome is different in the case of experiencing radiation exposure during pregnancy (after conception).

　　　　According to the report on the survivors of the atomic bombings of Hiroshima and Nagasaki, exposure of a fetus to high-dose radiation, prenatal radiation exposure, can lead to altered organ and mental development. Furthermore, it is also known that there is a “threshold level” (the level that must be reached for an effect to be produced) of radiation to cause such genetic effects. Radiation exposure during pregnancy above the threshold level of 100 millisieverts causes genetic effects, whereas exposure below this threshold level does not.

　Therefore, the magnitude of radiation contamination caused by the 2011 Fukushima Daiichi Nuclear power plant accident was not at a level to cause concern about genetic effects on a fetus at the time of the accident.

294. The fetal formation, no effect seen

　　　　The investigation of atomic bomb survivors in Hiroshima and Nagasaki demonstrated no detectable genetic effects, including an increase in cancer risk and other diseases among the offspring (the second generation exposed to radiation) of the survivors. Therefore, there is no need to worry about the genetic effects of the radiation caused by the 2011 Fukushima Daiichi Nuclear power plant accident.

　　　　On the other hand, it is known that prenatal radiation exposure (exposure of a fetus in the mother’s belly to high-dose radiation) can cause altered organ and mental development.

　　　　In addition, previous studies have revealed that the susceptibility of the fetus to radiation differs depending on the gestational stage (a measure of the progression of pregnancy). The gestational stage where the fetus is most sensitive to radiation is when its vital organs are forming. Generally, pregnant women are instructed to avoid taking unnecessary medications during this stage. From the early stage of pregnancy to the golden period, around the second trimester, is when the fetus is susceptible to radiation and medication.

　　　　However, the genetic effects of radiation on the fetus do not occur below a certain level of radiation. The magnitude of radiation contamination caused by the 2011 Fukushima Daiichi Nuclear power plant accident was not at a level to cause concern about genetic effects on a fetus at the time of the accident.

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The Japanese version of the manuscript was originally published in Fukushima Minyu, a local newspaper in Fukushima prefecture, Japan, 30th August and 6th September 2020 was reproduced for MRIC Global under the author's permission.