Radiation Safety Research Center, Nuclear Technology Research Laboratory, Central Research Institute of Electric Power Industry, 2-11-1 Iwado-kita, Komae, Tokyo 201-8511, Japan.
J Environ Radioact. 2012 Sep;111:83-99. doi: 10.1016/j.jenvrad.2011.08.008. Epub 2011 Oct 11.
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 α 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 ((131)I for radioiodines, (134)Cs and (137)Cs for radiocesiums) by postulating the relative radioactive concentration of coexisting radionuclides (e.g., (132)I, (133)I, (134)I, (135)I and (132)Te for (131)I). Surveys were thence conducted to monitor levels of (131)I, (134)Cs and (137)Cs. 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 (131)I, and a total of 82,000 Bq/kg for (134)Cs and (137)Cs). 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.
2011 年 3 月 11 日，日本东北海岸发生了 9.0 级地震和大规模海啸。福岛核电站被淹没，随后反应堆发生故障，放射性核素泄漏。3 月 17 日，设定了食品和饮料中放射性物质的暂定管制值，并采用了预设指标值，婴儿摄入的水和牛奶中的放射性碘除外。对于放射性铯、铀、钚和超铀 α 发射体，所有食品和饮料中的指标值都被定义为不超过 5mSv/年的承诺有效剂量。放射性碘的指标值被定义为不超过甲状腺的 50mSv/年承诺当量剂量，并设定在水、牛奶和一些蔬菜中，但不在其他食品中。指标值是通过假设共存放射性核素的相对放射性浓度（例如，放射性碘中的 (131)I、放射性铯中的 (134)Cs 和 (137)Cs）来计算的（132）I、（133）I、（134）I、（135）I 和（132）Te）。此后进行了调查以监测 (131)I、(134)Cs 和 (137)Cs 的水平。自来水中、生牛奶中和一些蔬菜中的暂定管制值超标，3 月 21 日开始限制分发和消费。随后检测到放射性碘污染水平令人关注的鱼类，因此，4 月 5 日在蔬菜中采用的海鲜放射性碘暂定管制值也被额外设定。总的来说，在每种食品或饮料项目首次超标后 25 天内开始限制，在叶类蔬菜中检测到最高水平（(131)I 为 54100Bq/kg，(134)Cs 和 (137)Cs 总量为 82000Bq/kg）。本文重点讨论食品安全法规背后的逻辑，并讨论其潜在问题。还将描述 24685 个样本的食品监测结果和实施的限制的概况。
