FUKUSHIMA Lives on the Line

271chap.VConveying to PosterityFUKUSHIMA: Lives on the LineFigure 2. Radiation in Daily Life Measure (unit of measure: mSv [millisieverts])1000250106.92.410. dose limit for emergency workers (per year)High natural background radiation area (Guarapari, Brazil) (per year)Amount of background radiation(1–1.3 mSv/year)Amount of background radiation per person (world average per year)CT scan (once)Mass stomach X-ray (once)Air travel from Tokyo to New York (one way)Radiation dose limit for the general public (per year)(Excluding doctors)Upon consuming 1 kg of food or drink containing 300 Bq/kg of radioactive iodine-131 (provisional regulation value for drinking water, dairy products, etc.).Upon consuming 100 g of food or drink containing 500 Bq/kg radioactive cesium-137 (provisional regulation value for vegetables, grains, etc.).Source: Ministry of Education, Culture, Sports, Science and Technology “Radiation in Daily Life,” National Institute of Radiological Sciences homepage.of measurement is sieverts (Sv). The level of carcinogenic risk is determined by the magnitude of this value.(2)As the amount of external radiation greatly differed among individuals during the four month period following the earthquake, we use the basic survey of the prefectural people’s health survey. Once the questionnaire is submitted, the amount of radiation is analyzed and the individual is notified. (3)The amount of external radiation for an eight-month period or from five months to one year after the earthquake will be calculated on an individual basis. Using the readings from the film badges that were distributed to school children by the municipal governments, calculate the estimation by choosing a reading for a behavioral pattern that is similar to yours. The estimation values are available on the websites of each municipal government. (4)To calculate internal radiation, we refer to the results of a prior survey of evacuated residents. Most residents would receive less than 1 mSv over a 50-year period. To prevent underestimations, we calculate the value using the vastly front-loaded figure assuming that the maximum amount potentially received over a 50-year period has been received over the past year. We assume a maximum amount of as 1 mSv.(5)(External radiation [basic survey results for four months + results from the film badge for eight months] + internal radiation [maximum 1 mSv]) = amount of additional radiation received in the one-year period following the earthquake, over and above that received in previous years.2. Applying Risk MeasuresWe apply this value to the carcinogenic risk measure (Figure 1) and the radiation in daily life measure (Figure 2). It is possible to compare various risk measures of risks affecting the human body. Science has proven that the amount of radiation required to affect the human body (effect amount) is above 100 mSv. On the other hand, the values we often hear pertain to evacuations and food regulations and are “protective amounts” meant to guarantee safety. These protective amounts have been set as the values at which the human body is not affected. In the days following the earthquake, the distinction between the two amounts was not made clear, thus causing significant social disruption.