Abstract
Evaluation of radiation exposure from diet is necessary under the assumption of a virtual accident as a part of emergency preparedness. Here, we developed a model with complete consideration of the regional food trade using deposition data simulated by a transport model, and estimated the dietary intake of radionuclides and the effectiveness of regulation (e.g., restrictions on the distribution of foods) after the Fukushima accident and in virtual accident scenarios. We also evaluated the dilution factors (i.e., ratios of contaminated foods to consumed foods) and cost-effectiveness of regulation as basic information for setting regulatory values. The doses estimated under actual emission conditions were generally consistent with those observed in food-duplicate and market-basket surveys within a factor of three. Regulation of restricted food distribution resulted in reductions in the doses of 54–65% in the nearest large city to the nuclear power plant. The dilution factors under actual emission conditions were 4.4% for radioiodine and 2.7% for radiocesium, which are ~20 times lower than those used in the Japanese provisional regulation values after the Fukushima accident. Strict regulation worsened the cost-effectiveness for both radionuclides. This study highlights the significance and utility of the developed model for a risk analysis of emergency preparedness and regulation.
Highlights
Internal exposure from diets is one of the pathways of radionuclides at nuclear power plant accidents [4,5]
The estimated doses generally agreed within a factor of three with those observed when these variations were taken into consideration
Since the observed data in food-duplicate or market-basket surveys were not available just after the accident, we compared the effective doses of radioiodine and radiocesium estimated in this study in the first year after the accident with those previously reported [6], which were estimated from the observed concentrations of food categories in each municipality and the regional trade of foods (Figure S4)
Summary
Internal exposure from diets is one of the pathways of radionuclides at nuclear power plant accidents [4,5]. The thyroid doses among evacuees after the 1986 Chernobyl accident (490 mGy in the first year) were mainly derived from diets and contributed to the increase in thyroid cancer occurrence in young children [4]. There were limited doses from both internal and external exposures in the 2011 Fukushima accident [5]. The internal exposure from diets was very minor (e.g., the first-year exposure in Fukushima City: 0.84 mSv of the thyroid equivalent dose) [6], Int. J. Res. Public Health 2018, 15, 1589; doi:10.3390/ijerph15081589 www.mdpi.com/journal/ijerph
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