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Environmental gamma-ray
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Akio Iwata* and Nobuhiko Takagi**
(*Office of JPE Human and Geoscience, **Nissaku co.,Ltd.)
Abstract : We found the age distribution of
childhood leukemia is the probability distribution that followed the two hit
mutation theory (Knudson, 1971). The group of childhood leukemia under five
years old in Japan is caused by simple two hit mutation theory. Based on the fact of
the leukemia to be shown frequently to A-bomb victims, we considered that the
factor which brings about the two hit was gamma-ray. Generally it thinks that the injury of the human body by
radiation (ionizing radiation) is originated by
artificial radiation (strictly controlled radiation) contamination. Such an idea is
based on the way of thinking as follows the natural radiation has existed
anywhere on the earth on the almost same level since human-beings birth. However the dose
of environmental gamma-ray is increasing in the urbanized area by reason of the significant
level gamma-ray to be emitted from the concrete
structure.The penetration force of gamma-ray is strong and its energy is large.
Because of it, the gamma-ray raids deeply in a human body, and gives damage. According to
probability theory, the risk from gamma-ray should not be determined by the limit of
dose equivalent. Risk is proportional to the number of gamma-ray.
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