News from Japan

Distribution of oceanic 137Cs from the Fukushima Dai-ichi Nuclear Power Plant simulated numerically by a regional ocean model

The aim of this review was to summarize the lessons learned from the experience in protecting the health of workers engaged in operations following the accident at the Fukushima Daiichi Nuclear Power Plant (NPP). We reviewed all types of scientific papers examining workers' health found in Medline and Web of Sciences as well as some official reports published by the Ministry of Health, Labour and Welfare of Japan and other governmental institutes. The papers and reports were classified into those investigating workers at the Fukushima Daiichi and Daini NPPs, workers engaged in decontamination operations in designated areas, and other workers. Regarding workers at the NPPs, many efforts were made to establish an emergency-care and occupational health system. Risk management efforts were undertaken for radiation exposure, heat stress, psychological stress, outbreak of infectious diseases, and fitness for work. Only a few reports dealt with decontamination workers and others; however, the health management of these workers was clearly weaker than that for workers at the NPPs. Many lessons can be learned from what occurred. That knowledge can be applied to ongoing decommissioning work and to future disasters. In addition, it is necessary to study the long-term health effects of radiation exposure and to accumulate data about the health of workers engaged in decontamination work and other areas.

Fuel debris in the Fukushima Daiichi nuclear power plant is thought to contain borides that are generated from B4C control material. In order to successfully devise methods to effectively remove the debris material, characterization of the properties of the fuel debris is essential. This paper presents some of the thermophysical and mechanical properties of two types of borides, FeB and CrB, and compares them with those of Fe2B and ZrB2. These are the representative borides that might have been generated in the Fukushima Daiichi (1F) nuclear power plant accident. We observed that the thermal conductivity values of both CrB and FeB are much lower than that of ZrB2, and are similar to that of Fe2B. Moreover, the Vickers hardness and fracture toughness of FeB and CrB are almost identical to each other, and similar to those of ZrB2 and Fe2B.

Following the Great East Japan Earthquake (GEJE) and the Fukushima Daiichi nuclear power plant accident in 2011, mandatory evacuation orders were issued to residents living near the nuclear power plant in Fukushima prefecture, including some patients receiving home oxygen therapy. Although the vulnerability of patients with home oxygen therapy (one of the population groups most vulnerable to disasters) has been noted, there is little information on the health effects of evacuation in the event of a radiation disaster. A 90-year-old man diagnosed with chronic obstructive pulmonary disease since the age of 70, and lived in a town located approximately 20 km south of the nuclear power plant, died 8 months after the disaster due to worsening health conditions. This case reveals the potential for both physical and psychological burdens experienced by vulnerable groups like patients undergoing home oxygen therapy during evacuations in times of disaster. Although it is only a case report and the information is limited, severe respiratory distress requiring home oxygen therapy may present a significant risk factor for disaster-related deaths, especially in cases where evacuations are prolonged, such as in nuclear disasters. Due to the challenge of obtaining prompt public support immediately after a disaster, home oxygen therapy patients may need to prioritize self-help and mutual assistance in their disaster preparedness efforts.

Influence of the Fukushima Daiichi Nuclear Power Plant Accident on the Use of Computed Tomography in Children with Mild Head Injuries: A Retrospective Cohort Study

A more complete record is emerging of radionuclide measurements in fish tissue, sediment, and seawater samples from near the Fukushima Daiichi Nuclear Power Plant (FDNPP) and across the Pacific Ocean. Our analysis of publicly available data indicates the dose rates to the most impacted fish species near the FDNPP (median 1.1 mGy d(-1), 2012-2014 data) have remained above benchmark levels for potential dose effects at least three years longer than was indicated by previous, data-limited evaluations. Dose rates from (134,137)Cs were highest in demersal species with sediment-associated food chains and feeding behaviors. In addition to (134,137)Cs, the radionuclide (90)Sr was estimated to contribute up to approximately one-half of the total 2013 dose rate to fish near the FDNPP. Mesopelagic fish 100-200 km east of the FDNPP, coastal fish in the Aleutian Islands (3300 km), and trans-Pacific migratory species all had increased dose rates as a consequence of the FDNPP accident, but their total dose rates remained dominated by background radionuclides. A hypothetical human consumer of 50 kg of fish, gathered 3 km from the FDNPP in 2013, would have received a total committed effective dose of approximately 0.95 mSv a(-1) from combined FDNPP and ambient radionuclides, of which 0.13 mSv a(-1) (14%) was solely from the FDNPP radionuclides and below the 1 mSv a(-1) benchmark for public exposure.

An example of environmental radiation status in and around Tokyo immediately after the TEPCO Fukushima Dai-ichi Nuclear Power Plant (NPP) disaster is introduced. The east part of the Metropolis of Tokyo and northwest of Chiba Prefecture are located about 200–250 km south from the NPP. The local governments in the area have officially surveyed the environmental radiation status after the disaster in response to numerous requests from their citizens. The radiation surveillance by local governments has been conducted and technically guided by the radiation protection specialists. The two main goals of the surveillance are (1) to measure the ambient radiation dose (microsieverts per hour) at all the schoolyards, public parks, and representative measuring points selected by the local government, and (2) to measure the specific radioactivity (becquerels per kilogram) of drinking water and local food items. In parallel with these movements, radiation experts in the University of Tokyo also organized a special correspondence team to survey the environmental radiation status immediately after the nuclear disaster. These activities and related data are introduced in this chapter.KeywordsAmbient radiation doseChibaSpecific radioactivityTokyo

For the investigation of the characteristics and behavior of fallout deposits of the accident at the Fukushima Daiichi Nuclear Power Plant (NPP) in March 2011, autoradiographic imaging was used to examine tree leaves, branches, and barks from locations at 10–60 km south of the Fukushima Daiichi NPP. The autoradiographs revealed particulate contamination in many old leaf samples; few contaminations were present in current-year leaves. Although no particulate contamination was observed on leaves that had grown after the accident, a relatively small amount of radiocesium had become incorporated in the upper leaves of the sampled branches.

On 11 March 2011, the Great East Japan Earthquake followed by a gigantic tsunami hit the Pacific coast of Northeast Japan (Tohoku) and damaged Tokyo Electric Power Company's Fukushima Daiichi Nuclear Power Plant, causing a radiation hazard in the entire Fukushima Prefecture. The radiation dose exposed either externally and internally in Fukushima residents have been evaluated to be low so far and it is hardly believed that they may have any direct radiation risk on physical condition. The purpose of this report is, therefore, to describe results of a mental health and lifestyle survey intended to facilitate adequate care for residents who are at a higher risk of developing mental health problems after the complicated accident. The target population of this survey is the residents of evacuation zones including Hirono Town, Naraha Town, Tomioka Town, Kawauchi Village, Okuma Town, Futaba Town, Namie Town, Katsurao Village, Minamisoma City, Tamura City, Yamakiya district of Kawamata Town, and Iitate Village. The targeted population was 210,189 in fiscal year 2011 (FY2011) and 211,615 in fiscal year 2012 (FY2012). Questionnaires have been mailed since January 2012, and subsequently, January 2013, 10 and 22 months after the disaster. Among of them, children 63.4%, adults 40.7% for FY2011, and children 41.0%, adults 29.7% for FY2012 responded to the questionnaires mailed. Sociodemographic data showed that many evacuee households were separated after the disaster and had to move several times. K6 was used in this survey to estimate general mental health. The proportion (14.6% in FY2011 and 11.9% inFY2012) of adults who scored above the K6 cut-off (≥13) for general mental health was higher than usual, indicating severe mental health problems among evacuees. The proportion (21.6% in FY2011 and 18.3% inFY2012) of adults who scored above the cut-off (≥44) of PTSD checklist (PCL), reflecting traumatic symptoms, was almost equal to that of the workers after the 9.11 World Trade Center attacks. These results also indicate the presence of severe traumatic problems among evacuees. The proportions of children (4-6 years old) and children of primary school age (6-12 years old) who scored above the cut-off (≥16) of Strengths and Difficulties Questionnaire (SDQ) reflecting the mental health status in children, 24.4% and 22.0% in the survey of FY2011, were double the usual state respectively, whereas 16.6% in children of 4-6 years old and 15.8% in children of 6-12 years old in FY2012 were 1.5 times. These findings also disclosed the presence of severe mental difficulties in children, with relative improvement year by year. As revealed by the present mental health survey, the earthquake and tsunami followed by the nuclear accident caused psychological distress among residents in Fukushima prefecture. Continuous survey and mental care programs are required.

Effect of evacuation on liver function after the Fukushima Daiichi Nuclear Power Plant accident: The Fukushima Health Management Survey

The Great East Japan Earthquake and Fukushima Daiichi nuclear disaster in 2011 forced the evacuation of a large number of residents and created changes in the lifestyle of the evacuees. These changes may have affected the evacuees' glucose metabolism, thereby leading to an increase in the incidence of diabetes. This study included Japanese men and women who were living near the Fukushima Daiichi Nuclear Power Plant in Fukushima prefecture before the disaster. Subjects subsequently underwent annual health checkups with a focus on metabolic syndromes, which were conducted under the Health Care Insurers. Using the Comprehensive Health Check survey, we analyzed changes in the glucose metabolism before and after the disaster. A total of 27,486 subjects underwent follow-up examinations after the disaster, with a mean follow-up period of 1.6 years. After the disaster, the prevalence of diabetes increased significantly, and we observed that the incidence of diabetes was significantly greater among evacuees than among nonevacuees. Furthermore, multivariate logistic regression analysis revealed that evacuation was significantly associated with the incidence of diabetes. In conclusion, this is the first study to demonstrate that evacuation is associated with the incidence of diabetes. This information may be used to guide follow-up recommendations for evacuees.

An investigation into the impact of information behaviour on information failure: The Fukushima Daiichi nuclear power disaster

Prolonged impact of the Fukushima Nuclear Power Plant Accident on health and society Naomi Ito, Research Assistant at the Fukushima Medical University, tells us how the 2011 Fukushima Daiichi Nuclear Power Plant Accident impacted and continues to impact local residents. The health effects on local residents following a nuclear power plant accident are diverse, not only because of radiation exposure but also because of changes in lifestyle and social environment. It has also been indicated that various environmental changes that could emerge during the restoration process may affect residents in various ways over a long time. On March 11, 2011, the Great East Japan Earthquake struck Japan with a magnitude of 9.0. Within an hour, a tsunami hit the shore. Three reactors at the Fukushima Daiichi Nuclear Power Plant (FDNPP, operated by Tokyo Electric Power Company) lost power. The reactors could not be cooled, and core meltdowns occurred, which resulted in an explosion due to hydrogen being generated at high temperatures. As a result, radioactive materials were released and scattered northwest from the power plant.

Re: Associations Between Childhood Thyroid Cancer and External Radiation Dose After the Fukushima Daiichi Nuclear Power Plant Accident.

BackgroundThe Great East Japan Earthquake triggered accidents at the Fukushima Daiichi Nuclear Power Plant, becoming the first complex disaster that included both a natural and a nuclear power disaster. This study examines how complex disasters affect patients with dementia.MethodsParticipants included the 331 people diagnosed with dementia out of the 2482 new patients (between January 2008 and December 2015) at a psychiatric hospital located in the indoor sheltering zones nearby mandatory evacuation zones. Medical records were retrospectively examined to identify the number of new patients with dementia, the severity, their chief complaints, and the behavioural and psychological symptoms of dementia (BPSD) types. BPSD were classified into the hyperactive BPSD group and the hypoactive BPSD group. The hyperactive BPSD group was further subdivided into the hyperactivity‐impulsivity‐irritability‐disinhibition‐aggression‐agitation group, which exhibited agitation, disinhibition, and irritability, and the psychosis group, which exhibited delusions and hallucinations. The hypoactive BPSD group included depression, inactivity, apathy, and anxiety. Results were divided into the period before the complex disaster (2008–2010) and after (2012–2015) and were compared. In addition, the post‐complex‐disaster period was subdivided into the early phase (2012–2013) and the late phase (2014–2015).ResultsThe proportion of new patients with dementia increased significantly after the disaster. Although there was no change in patients' age and the disease's severity, the proportion of patients whose chief complaint was BPSD increased significantly after the disaster. Furthermore, there was a significant increase in the hyperactivity‐impulsivity‐irritability‐disinhibition‐aggression‐agitation group in the early post‐complex‐disaster phase and a significant increase in the psychosis group in the late post‐complex‐disaster phase.ConclusionThis complex disaster caused increased consultations from patients with dementia and increased BPSD. Additionally, it increased participants' symptoms of agitation and irritability in the early post‐complex‐disaster phase and the proportion of hallucinations and delusions in the late post‐complex‐disaster phase.