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Concept: Government of Japan


This paper focuses on an overview of radioactive cesium 137 (quasi-Cs137 included Cs134) contamination of freshwater fish in Fukushima and eastern Japan based on the data published by the Fisheries Agency of the Japanese Government in 2011. In the area north and west of the Fukushima Nuclear plant, freshwater fish have been highly contaminated. For example, the mean of active cesium (quasi-Cs137) contamination of Ayu (Plecoglossus altivelis) is 2,657 Bq/kg at Mano River, 20-40 km north-west from the plant. Bioaccumulation is observed in the Agano river basin in Aizu sub-region, 70-150 km west from the plant. The active cesium (quasi-Cs137) contamination of carnivorous Salmondae is around 2 times higher than herbivorous Ayu. The extent of active cesium (quasi-Cs137) contamination of Ayu is observed in the entire eastern Japan. The some level of the contamination is recognized even in Shizuoka prefecture, 400 km south-west from the plant.

Concepts: Chernobyl disaster, Japan, Freshwater fish, Prefectures of Japan, Government of Japan, Honshū, Shizuoka Prefecture, Ayu


The Fukushima nuclear accident released radioactive materials into the environment over the entire Northern Hemisphere in March 2011, and the Japanese government is spending large amounts of money to clean up the contaminated residential areas and agricultural fields. However, we still do not know the exact physical and chemical properties of the radioactive materials. This study directly observed spherical Cs-bearing particles emitted during a relatively early stage (March 14-15) of the accident. In contrast to the Cs-bearing radioactive materials that are currently assumed, these particles are larger, contain Fe, Zn, and Cs, and are water insoluble. Our simulation indicates that the spherical Cs-bearing particles mainly fell onto the ground by dry deposition. The finding of the spherical Cs particles will be a key to understand the processes of the accident and to accurately evaluate the health impacts and the residence time in the environment.

Concepts: Solubility, Chemical substance, Chemical element, Uranium, Radioactive contamination, Lists of nuclear disasters and radioactive incidents, Government of Japan, Cabinet of Japan


Annually in Japanese waters, small cetaceans are killed in “drive hunts” with quotas set by the government of Japan. The Taiji Fishing Cooperative in Japan has published the details of a new killing method that involves cutting (transecting) the spinal cord and purports to reduce time to death. The method involves the repeated insertion of a metal rod followed by the plugging of the wound to prevent blood loss into the water. To date, a paucity of data exists regarding these methods utilized in the drive hunts. Our veterinary and behavioral analysis of video documentation of this method indicates that it does not immediately lead to death and that the time to death data provided in the description of the method, based on termination of breathing and movement, is not supported by the available video data. The method employed causes damage to the vertebral blood vessels and the vascular rete from insertion of the rod that will lead to significant hemorrhage, but this alone would not produce a rapid death in a large mammal of this type. The method induces paraplegia (paralysis of the body) and death through trauma and gradual blood loss. This killing method does not conform to the recognized requirement for “immediate insensibility” and would not be tolerated or permitted in any regulated slaughterhouse process in the developed world.

Concepts: Spinal cord, Blood, Blood vessel, Developed country, Bleeding, Japan, Dolphin, Government of Japan


In an unprecedented food monitoring campaign for radionuclides, the Japanese government took action to secure food safety after the Fukushima nuclear accident (11 March 2011). In this paper we analyze a part of the immense data set, in particular radiocesium contaminations in food from the first year after the accident. Activity concentrations in vegetables peaked immediately after the campaign had commenced, but they decreased quickly, so that by early summer 2011 only few samples exceeded the regulatory limits. Later, accumulating mushrooms and dried produce led to several exceedances of the limits again. Monitoring of meat started with significant delay, especially outside Fukushima prefecture. After a buildup period, contamination levels of meat peaked by July 2011 (beef). Levels then decreased quickly, but peaked again in September 2011, which was primarily due to boar meat (a known accumulator of radiocesium). Pre-Fukushima 137Cs and 90Sr levels (resulting from atmospheric nuclear explosions) in food were typically lower than 0.5 Bq/kg, whereby meat was typically higher in 137Cs, and vegetarian produce was usually higher in 90Sr. The correlation of background radiostrontium and radiocesium indicated that the regulatory assumption after the Fukushima accident of a maximum activity of 90Sr being 10% of the respective 137Cs concentrations may soon be at risk, as the 90Sr/137Cs ratio increases with time. This should be taken into account for the current Japanese food policy as the current regulation will soon underestimate the 90Sr content of Japanese foods.

Concepts: Nuclear medicine, Food, Japan, Radioactive contamination, Prefectures of Japan, Government of Japan, Honshū, Cabinet of Japan


Since the nuclear power plant accident in Fukushima in March 2011, the Japanese government has conducted screening and removal of contaminated foods from the market that exceed provisional regulation limits for radionuclides. This study aimed to provide an urgent estimate of the dietary exposure of adult residents recruited from three areas in Japan to cesium 134 (134Cs), cesium 137 (137Cs), and, for comparison, natural potassium 40 (40K) on December 4, 2011. Fifty-three sets of 24-hr food-duplicate samples were collected in Fukushima Prefecture and neighboring regions. The 134Cs, 137Cs, and 40K levels in the samples were measured using a germanium detector. Items in the food-duplicate samples were recorded and analyzed for radiocesium intake. Radiocesium was detected in 25 of 26 samples from Fukushima. The median dietary intake of radiocesium was 4.0 Bq/day (range <0.26-17 Bq/day). The estimated annual dose from radiocesium was calculated assuming that the daily intake of radiocesium was constant throughout the year. The median estimated dose level was 23 μSv/year (range <2.6-99 μSv/year). The estimated dose level of radiocesium was significantly higher in Fukushima than in the Kanto region and western Japan. Stepwise multiple linear regression analyses demonstrated that the intake of fruits and mushrooms produced in Fukushima were significant factors for the dietary intake of 137Cs in the 26 participants from Fukushima. The average radioactivity (±SD) of locally produced persimmons and apples (n=16) were 23±28 and 30±35 Bq/kg for 134Cs and 137Cs, respectively. The preliminary estimated dietary dose levels among Fukushima residents were much lower than the maximum permissible dose 1 mSv/year, based on new Japanese standard limits for radiocesium in foods (100 Bq/kg for general foods). In future studies, the exposure estimates should be refined by probability sampling to eliminate biases.

Concepts: Regression analysis, Linear regression, Chernobyl disaster, Japan, Prefectures of Japan, Government of Japan, Fukushima Prefecture, Honshū


The Japanese government ordered the analysis of thousands of foods after the Fukushima nuclear accident to ascertain compliance with regulatory limits for anthropogenic radionuclides in food. Four hundred and fourty five samples from 11 prefectures exceeded the regulatory limits that were in force until 31 March 2011. The possibility of these 445 samples representing localized areas of high radiocesium concentration was investigated. The objective of this study was to determine the radiocesium activity ratio (134Cs/137Cs) in foods from each geographic area to possibly identify the radioactive signature of the four different reactors (i.e. four independent sources) in the distinct regions. The average 134Cs/137Cs activity ratio was 0.98+/-0.01 for all samples. However, no clear deviations from this value could be confirmed in the various regions. Since there was no statistically significant deviation in the radiocesium activity ratio, the releases from reactor No. 4 (carrying a significantly smaller activity ratio) are assumed to be small when compared with the other three reactor release. The individual radioisotopic signatures of reactors No. 1, 2, and 3 could not be identified in various Japanese regions using the food samples, indicating integral radiocesium contamination from these sources. Subsequent releases of fission products from the reactors (e.g. after possible criticalities reported in October 2011) proved to have no impact on the radiocesium activity ratio. A discussion of the development of the regulatory limits in Japan and Europe with regard to the current limits and radiological food safety are also included.

Concepts: Food, Radioactive decay, Japan, Standard deviation, Radioactive contamination, Prefectures of Japan, Government of Japan, Cabinet of Japan


Palmatier and Rovner (2014) discussed the possible interplay of two major methods of polygraph examination, the Comparison Question Test (CQT) and the Concealed Information Test (CIT). In this comment, we argue that such an attempt overlooks fundamental differences between the two methods. Specifically, both methods differ in their criterion variables; detecting deception versus detecting memory traces. This difference can lead to a different evaluation concerning their outcomes within a forensic context. However, Palmatier and Rovner’s (2014) attempt may blur the distinction between the two methods. Furthermore, at least for the present, it is difficult to give a unified explanation of physiological responses in the CQT and CIT based on the preliminary process theory of the orienting response. In sum, Palmatier and Rovner’s (2014) paper may add further confusion to the research and practice of polygraph testing. Additionally, their paper has no relevance to the current practice of Japanese polygraph examination, because Japanese law enforcement uses only the CIT for memory detection in real-life criminal investigations.

Concepts: Present, Physiology, Difference, Differences, Japan, Police, Government of Japan, Polygraph


Japan is rapidly becoming a full-fledged aged society, and physician shortage is a significant concern. The Japanese government has increased the number of medical school enrollments since 2008, but some researchers warn that this increase could lead to physician surplus in the future. It is unknown how many physicians will be required to accommodate future healthcare needs.

Concepts: Medicine, Future, Physician, Anatomy, Pediatrics, Medical school, Government of Japan


Five years have passed since the Great East Japan Earthquake and the subsequent Fukushima Daiichi Nuclear Power Plant accident on 11 March 2011. Countermeasures aimed at human protection during the emergency period, including evacuation, sheltering and control of the food chain were implemented in a timely manner by the Japanese Government. However, there is an apparent need for improvement, especially in the areas of nuclear safety and protection, and also in the management of radiation health risk during and even after the accident. Continuous monitoring and characterisation of the levels of radioactivity in the environment and foods in Fukushima are now essential for obtaining informed consent to the decisions on living in the radio-contaminated areas and also on returning back to the evacuated areas once re-entry is allowed; it is also important to carry out a realistic assessment of the radiation doses on the basis of measurements. Until now, various types of radiation health risk management projects and research have been implemented in Fukushima, among which the Fukushima Health Management Survey is the largest health monitoring project. It includes the Basic Survey for the estimation of external radiation doses received during the first 4 months after the accident and four detailed surveys: thyroid ultrasound examination, comprehensive health check-up, mental health and lifestyle survey, and survey on pregnant women and nursing mothers, with the aim to prospectively take care of the health of all the residents of Fukushima Prefecture for a long time. In particular, among evacuees of the Fukushima Nuclear Power Plant accident, concern about radiation risk is associated with psychological stresses. Here, ongoing health risk management will be reviewed, focusing on the difficult challenge of post-disaster recovery and resilience in Fukushima.

Concepts: Chernobyl disaster, Management, Coal, Nuclear power, Nuclear safety, Prefectures of Japan, Government of Japan, Three Mile Island accident


After a major radioactive incident, accurate dose reconstruction is important for evaluating health risks and appropriate radiation protection policies. After the 2011 Japan Fukushima nuclear incident, we assessed the level of agreement between the modeled and directly measured dose and estimated the uncertainties. The study population comprised 520 school children from Minamisoma city, located 20 km north of the nuclear plant. The annual dose 18 to 30 months after the incident was assessed using two approaches: estimation using the model proposed by the Japanese government and direct measurement by radiation dosemeters. The ratio of the average of modeled and measured doses was 3.0 (standard deviation (SD): 2.0). The reduction coefficient, an index for radiation attenuation properties, was 0.3 (SD: 0.1) on average, while the value used in the government model was 0.6. After adjusting for covariates, the coefficient had a significant negative correlation with the air dose rate in the dwelling location (p<0.001), indicating that stronger building shielding effects are valuable in areas with higher air contamination levels. The present study demonstrated that some overestimation may have been related to uncertainties in radiation reduction effects, and that the air contamination level might provide a more important indicator of these effects.

Concepts: Chernobyl disaster, Measurement, Radiobiology, Radioactive contamination, Lists of nuclear disasters and radioactive incidents, Nuclear safety, Government of Japan, Three Mile Island accident