Radiation dose rates now and in the future for residents neighboring restricted areas of the Fukushima Daiichi Nuclear Power Plant

Abstract

Radiation dose rates were evaluated in three areas neighboring a restricted area within a 20-to 50-km radius of the Fukushima Daiichi Nuclear Power Plant in August-September 2012 and projected to 2022 and 2062. Study participants wore personal dosimeters measuring external dose equivalents, almost entirely from deposited radionuclides (groundshine). External dose rate equivalents owing to the accident averaged 1.03, 2.75, and 1.66 mSv/y in the village of Kawauchi, the Tamano area of Soma, and the Haramachi area of Minamisoma, respectively. Internal dose rates estimated from dietary intake of radiocesium averaged 0.0058, 0.019, and 0.0088 mSv/y in Kawauchi, Tamano, and Haramachi, respectively. Dose rates from inhalation of resuspended radiocesium were lower than 0.001 mSv/y. In 2012, the average annual doses from radiocesium were close to the average background radiation exposure (2 mSv/y) in Japan. Accounting only for the physical decay of radiocesium, mean annual dose rates in 2022 were estimated as 0.31, 0.87, and 0.53 mSv/y in Kawauchi, Tamano, and Haramachi, respectively. The simple and conservative estimates are comparable with variations in the background dose, and unlikely to exceed the ordinary permissible dose rate (1 mSv/y) for the majority of the Fukushima population. Health risk assessment indicates that post-2012 doses will increase lifetime solid cancer, leukemia, and breast cancer incidences by 1.06%, 0.03% and 0.28% respectively, in Tamano. This assessment was derived from short-term observation with uncertainties and did not evaluate the firstyear dose and radioiodine exposure. Nevertheless, this estimate provides perspective on the long-term radiation exposure levels in the three regions.Fukushima nuclear disaster | exposure assessment | Strontium-90 | forest contamination | food duplicate

Understanding the Health Impacts and Risks of Exposure to Radiation

“…This is comparable to the global natural background average of ~2.4 mSv (range of 1-13 mSv depending on geographical location and radon exposure) [34,35]. Table 13.3 summarizes the annual doses received by the Japanese population as a function of source, in comparison with average doses estimated worldwide.…”

“…The mean dose rate attributed to the accident in 2022 is projected to be 0.31-0.87 mSv. In addition, annual internal exposure to fallout is estimated to be 0.0025 mSv [35]. An acute radiation dose of 100 mSv has been linked to an increase in the chance of developing cancer by a factor of 1.05, which is unlikely to be epidemiologically detectable [32,35,37].…”

“…In addition, annual internal exposure to fallout is estimated to be 0.0025 mSv [35]. An acute radiation dose of 100 mSv has been linked to an increase in the chance of developing cancer by a factor of 1.05, which is unlikely to be epidemiologically detectable [32,35,37]. The annual limit on the occupational effective dose for Japanese workers is 20 mSv/year and 100 mSv over 5 years [14,38].…”

Radiobiological Implications of Fukushima Nuclear Accident for Personalized Medical Approach

“…Several studies have indicated that the radiation exposure levels of Fukushima residents are much lower than predicted (Hayano et al 2013;Kamiya et al 2016). Furthermore, Harada et al (2014) showed that the mean annual radiation dose rate in 2012 associated with the accident was 0.89-2.51 mSv/y and the mean dose rate estimates for 2022 are comparable with the variations of the average 2 mSv/y background radiation due to exposure to natural radionuclides in Japan. These findings suggest that the extra lifetime integrated dose after 2012 will increase the estimated lifetime risk of cancer incidence by a factor of 1.03 to 1.05 at most, which is unlikely to be epidemiologically detectable (Harada et al 2014).…”

Internal Dose from Food and Drink Ingestion in the Early Phase after the Accident

“…Harada et al estimated internal doses for residents in three areas: village of Kawauchi, Tamano area of Soma and Haramachi area of Minamisoma, during August-September 2012 by food-duplicate survey [4]. The internal dose estimated from dietary intake of radioactive cesium averaged 0.0058, 0.019 and 0.0088 mSv/y.…”