Food safety regulations: what we learned from the Fukushima nuclear accident

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• 作者：Nobuyuki Hamada ; ^{hamada-n@criepi.denken.or.jp} ; Haruyuki Ogino
• 关键词：Emergency exposure situation ; Existing exposure situation ; Food safety regulation ; Fukushima nuclear accident ; Graded triphasic reference level ; Internal radiation exposure
• 刊名：Journal of Environmental Radioactivity
• 出版年：2012
• 期刊代码：45_0265931x
• 类别：env
• 出版时间：September, 2012
• 卷：111
• 期：Complete
• 页码：83-99
• 文件大小：544 K

摘要

On 11 March 2011, the magnitude-9.0 earthquake and a substantial tsunami struck off the northeast coast of Japan. The Fukushima nuclear power plants were inundated and stricken, followed by radionuclide releases outside the crippled reactors. Provisional regulation values for radioactivity in food and drink were set on 17 March and were adopted from the preset index values, except that for radioiodines in water and milk ingested by infants. For radiocesiums, uranium, plutonium and transuranic 伪 emitters, index values were defined in all food and drink not to exceed a committed effective dose of 5 mSv/year. Index values for radioiodines were defined not to exceed a committed equivalent dose to the thyroid of 50 mSv/year, and set in water, milk and some vegetables, but not in other foodstuffs. Index values were calculated as radioactive concentrations of indicator radionuclides (¹³¹I for radioiodines, ¹³⁴Cs and ¹³⁷Cs for radiocesiums) by postulating the relative radioactive concentration of coexisting radionuclides (e.g., ¹³²I, ¹³³I, ¹³⁴I, ¹³⁵I and ¹³²Te for ¹³¹I). Surveys were thence conducted to monitor levels of ¹³¹I, ¹³⁴Cs and ¹³⁷Cs. Provisional regulation values were exceeded in tap water, raw milk and some vegetables, and restrictions on distribution and consumption began on 21 March. Fish contaminated with radioiodines at levels of concern were then detected, so that the provisional regulation value for radioiodines in seafood adopted from that in vegetables were additionally set on 5 April. Overall, restrictions started within 25 days after the first excess in each food or drink item, and maximum levels were detected in leafy vegetables (54,100 Bq/kg for ¹³¹I, and a total of 82,000 Bq/kg for ¹³⁴Cs and ¹³⁷Cs). This paper focuses on the logic behind such food safety regulations, and discusses its underlying issues. The outlines of the food monitoring results for 24,685 samples and the enforced restrictions will also be described.