Why is it so difficult to clearly and simply explain radiation risk?


I wonder, if there is no recommendation on how much radiation is safe, does this mean data is missing? What data is needed to explain radiation risk?  (Female, 20s, Tochigi)


When you hear “This is not immediately harmful to human health”, you might feel frustrated. But the health effects of radiation are not that simple.

At first, there are two major types of health effects from exposure radiation. Plus, we also need to know the different signs the human body show if exposed to radiation. One is the decrease of white blood cells, or cataracts in the eyes caused by cell death. Cells that keep the body alive will die when radiation hits the body. These signs are almost always seen in the early phase, and yet there are individual differences, a relationship between health effects and radiation dose has been understood to a great.extent.

The other concern is the long-term effect of cancer or genetic change from radiation. When radiation hits a cell, DNA is damaged. So, damaged DNA are thought to contribute to the development of cancer and leukemia. The point is a “boundary” of the limits occurring health hazards. Acute effects of cell death is clear with major radiation exposure, while the long-term impact such as cancer is still difficult to determine. In theory, it is still unclear be said that as to the impact on health from low radiation doses. Research is ongoing.

The data from Hiroshima and Nagasaki survivors showed an increased risk of cancer if exposed to more than 100 mSv of radiation dose. But lower doses than that were not observed, and no clear relationship between low doses and cancer were discovered. Also, it should be considered that our bodies have a DNA damage-repairing mechanism.

As a result, difficulties of determining a causal relationship between long-term effects of radiation and health, and of calculating our defense mechanisms or biological effects of a low dose, all with individual differences invite a vague expression “radiation damage”. Please check various updated data, so you can make a better decision.

Science Communicator: Yoko Takeshita