Contamination of Japanese foodstuffs of terrestrial originafter the Fukushima nuclear accident and related dose assessment

Abstract

This article proposes an assessment of the ingestion doses potentially received by peopleliving in the Japanese areas most severely affected by the radioactive deposits due to theFukushima nuclear accident. The assessment distinguishes two consecutive periods: thefirst 2 months (March 15th to May 15th 2011) and the rest of the year 2011, according tothe two main foodstuff contamination periods identified (Renaud et al.,2013). On the basis of the worst-case hypothesis that can reasonably be made, theestimated doses are much lower than they might have been in other circumstances, onaccount of generally moderate levels of contamination for most foods, early evacuation ofthe most severely affected areas and the consumption bans ordered by the Japaneseauthorities. Thus, a single ingestion of 100 g of leafy vegetables in the early days by aone-year-old child living in non-evacuated localities near Iitate and Kawamata could haveled to an equivalent dose to the thyroid of about 25 mSv; and to a thyroid dose of about140 mSv for the rather unrealistic scenario of a daily consumption. Because of the rapiddecrease in the contamination of vegetables and a much weaker contamination of othercrops, and thanks to measures taken by the authorities (prohibition of consumption, use ofcertain fodder, etc.), the ingestion doses potentially received during the remainder ofthe year 2011 are estimated to be below 1 mSv. In the event that sales limits would havebeen ignored, only repeated consumption of mushrooms would have led to doses above thatlevel. Even with the worst-case hypotheses, the doses potentially caused by ingestion aremuch lower than those resulting from outdoor exposure to radioactive deposits:approximately several millisieverts in a year for the population living in thenon-evacuated localities near Iitate and Kawamata.