An earthquake and tsunami of historic proportions caused massive damage across the northeastern coast of Japan on the afternoon of 11 March 2011, and the release of radionuclides from the stricken reactors of the Fukushima nuclear power plant 1 was detected early on the next morning. High levels of radioiodines and radiocesiums were detected in the topsoil and plants on 15 March 2011, so sampling of food and water for monitoring surveys began on 16 March 2011. On 17 March 2011, provisional regulation values for radioiodine, radiocesiums, uranium, plutonium and other transuranic α emitters were set to regulate the safety of radioactively contaminated food and water. On 21 March 2011, the first restrictions on distribution and consumption of contaminated items were ordered. So far, tap water, raw milk, vegetables, mushrooms, fruit, nut, seaweeds, marine invertebrates, coastal fish, freshwater fish, beef, wild animal meat, brown rice, wheat, tea leaves and other foodstuffs had been contaminated above the provisional regulation values. The provisional regulation values for radioiodine were exceeded in samples taken from 16 March 2011 to 21 May 2011, and those for radiocesiums from 18 March 2011 to date. All restrictions were imposed within 318 days after the provisional regulation values were first exceeded for each item. This paper summarizes the policy for the execution of monitoring surveys and restrictions, and the outlines of the monitoring results of 220 411 samples and the enforced restrictions predicated on the information available as of 31 March 2012.
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