Masaharu Tsubokura

Internal radiocesium contamination of adults and children in Fukushima 7 to 20 months after the Fukushima NPP accident as measured by extensive whole-body-counter surveys

The Fukushima Dai-ichi NPP accident contaminated the soil of densely-populated regions in Fukushima Prefecture with radioactive cesium, which poses significant risks of internal and external exposure to the residents. If we apply the knowledge of post-Chernobyl accident studies, internal exposures in excess of a few mSv/y would be expected to be frequent in Fukushima. Extensive whole-body-counter surveys (n = 32,811) carried out at the Hirata Central Hospital between October, 2011 and November, 2012, however show that the internal exposure levels of residents are much lower than estimated. In particular, the first sampling-bias-free assessment of the internal exposure of children in the town of Miharu, Fukushima, shows that the 137Cs body burdens of all children (n = 1,383, ages 6–15, covering 95% of children enrolled in town-operated schools) were below the detection limit of 300 Bq/body in the fall of 2012. These results are not conclusive for the prefecture as a whole, but are consistent with results obtained from other municipalities in the prefecture, and with prefectural data.

Internal Radiation Exposure After the Fukushima Nuclear Power Plant Disaster

Author Affiliations: Department of Psychiatry, National Defense Medical College, Saitama, Japan (Drs Shigemura and Nomura); and Department of Public Health, Ehime University Graduate School of Medicine, Ehime, Japan (Drs Tanigawa [tt9178tt9178@gmail.com] and Saito). Author Contributions: Drs Shigemura and Tanigawa had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: Shigemura, Tanigawa, Nomura. Acquisition of data: Shigemura, Tanigawa. Analysis and interpretation of data: Shigemura, Tanigawa, Saito. Drafting of the manuscript: Shigemura, Tanigawa, Saito. Critical revision of the manuscript for important intellectual content: Shigemura, Tanigawa, Nomura. Statistical analysis: Shigemura, Tanigawa, Saito. Obtained funding: Shigemura, Tanigawa, Nomura. Administrative, technical, or material support: Tanigawa. Study supervision: Tanigawa, Nomura. Conflict of Interest Disclosures: All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Drs Shigemura and Nomura provided voluntary mental health assistance to Tokyo Electric Company Fukushima Daiichi and Daini nuclear power plant employees according to official requests from Daini and a Japanese government cabinet order to the Ministry of Defense. Dr Tanigawa is a Daini part-time occupational physician. Dr Saito reported no conflict of interest disclosures. Funding/Support: This work was supported by Health and Labour Sciences Research Grants (Research on Occupational Safety and Health H24-001) from the Ministry of Health Labour and Welfare of Japan. Role of the Sponsor: The funding organization had no role in the design and conduct of the study; in the collection, management, analysis, and interpretation of the data; or in the preparation, review, or approval of the manuscript. Disclaimer: The views expressed in this article are those of the authors and do not reflect the position or policy of Tokyo Electric Company, Ehime University, National Defense Medical College, the Ministry of Defense, or the Japanese government. Additional Contributions: We thank Tomoko Yamamoto, RN (Tokyo Electric Company [TEPCO] Fukushima Daini nuclear power plant), the medical team employees of Daiichi and Daini plants, and Yoshiko Kage (TEPCO R&D Center) for their invaluable cooperation. We also thank the plant workers for their study participation and dedicated recovery efforts. No compensation was received for their services.

Mortality Risk amongst Nursing Home Residents Evacuated after the Fukushima Nuclear Accident: A Retrospective Cohort Study

Background Safety of evacuation is of paramount importance in disaster planning for elderly people; however, little effort has been made to investigate evacuation-related mortality risks. After the Fukushima Daiichi Nuclear Plant accident we conducted a retrospective cohort survival survey of elderly evacuees. Methods A total of 715 residents admitted to five nursing homes in Minamisoma city, Fukushima Prefecture in the five years before 11th March 2011 joined this retrospective cohort study. Demographic and clinical characteristics were drawn from facility medical records. Evacuation histories were tracked until the end of 2011. The evacuations impact on mortality was assessed using mortality incidence density and hazard ratios in Cox proportional hazards regression. Results Overall relative mortality risk before and after the earthquake was 2.68 (95% CI: 2.04–3.49). There was a substantial variation in mortality risks across the facilities ranging from 0.77 (95% CI: 0.34–1.76) to 2.88 (95% CI: 1.74–4.76). No meaningful influence of evacuation distance on mortality was observed although the first evacuation from the original facility caused significantly higher mortality than subsequent evacuations, with a hazard ratio of 1.94 (95% CI: 1.07–3.49). Conclusion High mortality, due to initial evacuation, suggests that evacuation of the elderly was not the best life-saving strategy for the Fukushima nuclear disaster. Careful consideration of the relative risks of radiation exposure and the risks and benefits of evacuation is essential. Facility-specific disaster response strategies, including in-site relief and care, may have a strong influence on survival. Where evacuation is necessary, careful planning and coordination with other nursing homes, evacuation sites and government disaster agencies is essential to reduce the risk of mortality.

Limited Internal Radiation Exposure Associated with Resettlements to a Radiation-Contaminated Homeland after the Fukushima Daiichi Nuclear Disaster

Resettlement to their radiation-contaminated hometown could be an option for people displaced at the time of a nuclear disaster; however, little information is available on the safety implications of these resettlement programs. Kawauchi village, located 12–30 km southwest of the Fukushima Daiichi nuclear power plant, was one of the 11 municipalities where mandatory evacuation was ordered by the central government. This village was also the first municipality to organize the return of the villagers. To assess the validity of the Kawauchi villagers’ resettlement program, the levels of internal Cesium (Cs) exposures were comparatively measured in returnees, commuters, and non-returnees among the Kawauchi villagers using a whole body counter. Of 149 individuals, 5 villagers had traceable levels of Cs exposure; the median detected level was 333 Bq/body (range, 309–1050 Bq/kg), and 5.3 Bq/kg (range, 5.1–18.2 Bq/kg). Median annual effective doses of villagers with traceable Cs were 1.1 x 10-2 mSv/y (range, 1.0 x 10-2-4.1 x 10-2 mSv/y). Although returnees had higher chances of consuming locally produced vegetables, Cochran-Mantel-Haenszel test showed that their level of internal radiation exposure was not significantly higher than that in the other 2 groups (p=0.643). The present findings in Kawauchi village imply that it is possible to maintain internal radiation exposure at very low levels even in a highly radiation-contaminated region at the time of a nuclear disaster. Moreover, the risks for internal radiation exposure could be limited with a strict food control intervention after resettlement to the radiation-contaminated village. It is crucial to establish an adequate number of radio-contaminated testing sites within the village, to provide immediate test result feedback to the villagers, and to provide education regarding the importance of re-testing in reducing the risk of high internal radiation exposure.

Changes in metabolic profiles after the Great East Japan Earthquake: a retrospective observational study

BackgroundA magnitude 9.0 earthquake struck off eastern Japan in March 2011. Many survivors have been living in temporary houses provided by the local government since they lost their houses as a result of the great tsunami (tsunami group) or the expected high-dose radiation resulting from the nuclear accident at the Fukushima Daiichi Nuclear Power Plant (radiation group). The tsunami was more than 9u2009m high in Soma, Fukushima, which is located 30u2009km north of the Fukushima Daiichi Nuclear Power Plant and adjacent to the mandatory evacuation area. A health screening program was held for the evacuees in Soma in September 2011. The aim of this study was to compare the metabolic profiles of the evacuees before and after the disaster. We hypothesized that the evacuees would experience deteriorated metabolic status based on previous reports of natural disasters.MethodsData on 200 subjects who attended a health screening program in September or October of 2010 (pre-quake) and 2011 (post-quake) were retrospectively reviewed and included in this study. Pre-quake and post-quake results of physical examinations and laboratory tests were compared in the tsunami and radiation groups. A multivariate regression model was used to determine pre-quake predictive factors for elevation of hemoglobin A1c (HbA1c) in the tsunami group.ResultsSignificantly higher values of body weight, body mass index, waist circumference, and HbA1c and lower high-density lipoprotein cholesterol levels were found at the post-quake screening when compared with the pre-quake levels (p = 0.004, p = 0.03, p = 0.008, p < 0.001, and p = 0.03, respectively). A significantly higher proportion of subjects in the tsunami group with high HbA1c, defined as ≥5.7%, was observed after the quake (34.3%) than before the quake (14.8%) (p < 0.001). Regional factors, periodic clinic visits, and waist circumference before the quake were identified as predictive factors on multivariate analysis for the deterioration of HbA1c.ConclusionsPost-quake metabolic variables were impaired compared with pre-quake baseline levels in survivors who were living in temporary houses. A natural disaster could affect metabolic profiles, and careful follow-up for survivors should be planned.

Reduction of High Levels of Internal Radio-Contamination by Dietary Intervention in Residents of Areas Affected by the Fukushima Daiichi Nuclear Plant Disaster: A Case Series

Maintaining low levels of chronic internal contamination among residents in radiation-contaminated areas after a nuclear disaster is a great public health concern. However, the efficacy of reduction measures for individual internal contamination remains unknown. To reduce high levels of internal radiation exposure in a group of individuals exposed through environmental sources, we performed careful dietary intervention with identification of suspected contaminated foods, as part of mass voluntary radiation contamination screenings and counseling program in Minamisoma Municipal General Hospital and Hirata Central Hospital. From a total of 30,622 study participants, only 9 residents displayed internal cesium-137 (Cs-137) levels of more than 50 Bq/kg. The median level of internal Cs-137 contamination in these residents at the initial screening was 4,830 Bq/body (range: 2,130–15,918 Bq/body) and 69.6 Bq/kg (range: 50.7–216.3 Bq/kg). All these residents with high levels of internal contamination consumed homegrown produce without radiation inspection, and often collected mushrooms in the wild or cultivated them on bed-logs in their homes. They were advised to consume distributed food mainly and to refrain from consuming potentially contaminated foods without radiation inspection and local produces under shipment restrictions such as mushrooms, mountain vegetables, and meat of wild life. A few months after the intervention, re-examination of Cs levels revealed remarkable reduction of internal contamination in all residents. Although the levels of internal radiation exposure appear to be minimal amongst most residents in Fukushima, a subset of the population, who unknowingly consumed highly contaminated foodstuffs, experienced high levels of internal contamination. There seem to be similarities in dietary preferences amongst residents with high internal contamination levels, and intervention based on pre- and post-test counseling and dietary advice from medical care providers about risky food intake appears to be a feasible option for changing residents dietary practices, subsequently resulting in a reduction in Cs internal contamination levels.

Absence of Internal Radiation Contamination by Radioactive Cesium among Children Affected by the Fukushima Daiichi Nuclear Power Plant Disaster.

AbstractChronic internal radiation contamination accounts for a substantial fraction of long-term cumulative radiation exposure among residents in radiation-contaminated areas. However, little information is available on ongoing chronic internal radiation contamination among residents near the crippled Fukushima Daiichi nuclear power plant. Using a whole body counter, internal radiation contamination levels among elementary and middle school students who commute to 22 schools located within Minamisoma city were assessed between May and July 2013 (26 to 28 mo after the disaster). Of 3,299 elementary and middle school students in the city, 3,255 individuals (98%) were screened through school health check-ups. Not a single student was detected with internal radiation contamination due to radioactive cesium. The study found no risk of chronic internal radiation exposure among residents near the crippled nuclear power plant. Current food inspection by local governments, volunteers, and farmers has been functioning well within Fukushima prefecture. However, food management by screening suspected contamination along with whole body counter screening are key public health interventions and should be continued to avoid further internal radiation exposure in radiation-contaminated areas.

Assessment of the Annual Additional Effective Doses amongst Minamisoma Children during the Second Year after the Fukushima Daiichi Nuclear Power Plant Disaster.

An assessment of the external and internal radiation exposure levels, which includes calculation of effective doses from chronic radiation exposure and assessment of long-term radiation-related health risks, has become mandatory for residents living near the nuclear power plant in Fukushima, Japan. Data for all primary and secondary children in Minamisoma who participated in both external and internal screening programs were employed to assess the annual additional effective dose acquired due to the Fukushima Daiichi nuclear power plant disaster. In total, 881 children took part in both internal and external radiation exposure screening programs between 1st April 2012 to 31st March 2013. The level of additional effective doses ranged from 0.025 to 3.49 mSv/year with the median of 0.70 mSv/year. While 99.7% of the children (n = 878) were not detected with internal contamination, 90.3% of the additional effective doses was the result of external radiation exposure. This finding is relatively consistent with the doses estimated by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). The present study showed that the level of annual additional effective doses among children in Minamisoma has been low, even after the inter-individual differences were taken into account. The dose from internal radiation exposure was negligible presumably due to the success of contaminated food control.

Acute intake of radionuclides immediately after the incident as the main contributor of the internal radiation exposure after Fukushima Daiichi nuclear disaster.

Acute Intake of Radionuclides Immediately After the Incident as the Main Contributor of the Internal Radiation Exposure After Fukushima Daiichi Nuclear Disaster The Fukushima Daiichi nuclear disaster is a series of equipment failures, nuclear meltdowns, and release of radioactive materials, raising serious health concerns in nearby residents. We recently reported that levels of internal radiation exposure (IRE) by radioactive cesium in Minamisoma, Fukushima were low1; however, it is not as certain whether the detected levels of exposure were due to low ongoing exposure or decay from high-exposure values. To address this issue, transition of IRE among Minamisoma residents was monitored for children younger than 16 years, with biological half-lives of cesium in children up to age 15 years described as less than 93 days.2

The voice of the most vulnerable: lessons from the nuclear crisis in Fukushima, Japan

On 11 March 2011, the great earthquake in eastern Japan and its accompanying tsunami caused a meltdown at the Daiichi nuclear power plant in Fukushima. Large amounts of airborne radioactive materials were released into the atmosphere, causing widespread environmental contamination throughout eastern Japan with potentially damaging long-term health consequences.1 The International Atomic Energy Association classified the nuclear disaster as a “levelxa07” eventxa0– the most dangerous possible in the era of modern atomic energy.2 Confronted with this scenario, the Japanese government acted immediately to evacuate the population in designated evacuation zones within Fukushima prefecture. Initially a concentric circle was drawn around the power plant and a 20-km area was declared a “no-entry zone”.3 On 22 April, however, in the face of continued release and atypical expansion of radioactive material, this protective cordon was redrawn to include villages in a 20–30xa0km zone, now designated as an “evacuation zone in case of emergency”, as well as several villages within a 30–50xa0km zone north of the plant, which was declared a “planned evacuation zone”.3 n nAlthough this multi-faceted disaster is not the only large-scale calamity to strike Japan in recent years, it differs from previous events in several important respects. First, the situation at Fukushima, with its potential for future catastrophe, is a continuing one. Second, the effects of prolonged exposure to low-level radiation on human health have not yet been determined.4 Finally, the convergence of three separate disastersxa0– earthquake, tsunami and nuclear crisisxa0– is not only unique in terms of its scale and complexity, but also as regards the complicated interaction of health problems to which it may have given rise. The great Hanshin-Awaji (Kobe) earthquake that killed over 6000 people in 19955 showed that in Japan disasters can affect different population groups with differing severity and that the elderly are especially vulnerable.5 But when it comes to dealing with the health challenges resulting from the Fukushima disaster, with its unprecedented scale and complex characteristics, past experience may not be the best guide. In this article we highlight the importance of taking the social and cultural context into account during emergency planning and response. To support our views we present the results of a health check we conducted in one of the villages most affected by the nuclear disaster. Although the social context in which the Fukushima disaster occurred is quite specific to Japan, the implications for disaster planning apply to a wide range of settings, especially those with populations like Japan’s that are ageing rapidly. n nAnnual health checks are an important part of Japan’s system of universal health coverage and play a role in both health monitoring and intervention planning. Accordingly, in May 2011 volunteers from the University of Tokyo, in collaboration with local governments in Fukushima prefecture, conducted a free health check among villagers in the “planned evacuation zone”. This was an essential measure, since widespread confusion and logistical difficulties had made it impossible to monitor the health of the local population after the disaster. For many villages, such as Iitate, it was the last opportunity to obtain information on the health of the population before the enactment of a compulsory group evacuation order on 25xa0May. Before 11xa0March, this particular village had a population of 6152, but within a few months this figure had dropped dramatically. With the elderly comprising 28.1% of its population, the village provides a good example of the ageing of Japanese society. The majority of its dwellers work in the primary industry sector. Of an expected 300 residents, which were the only ones that the local government could locate because of confusion after the evacuation order, 257 attended the health check. The majority of them were older than 60xa0years. The purpose of the health check was primarily to provide relief to those who had been affected physically and psychologically by the crisis, as well as to better understand the existing health situation and the feelings and opinions of residents of the area. Information about the health check was disseminated to all villagers in advance. Each person’s health check lasted about one hour and was divided into two sections: (i)xa0a health interview that included questions on pre-existing conditions, family history, self-reported symptoms, mental health and time spent outdoors since the disaster; (ii)xa0a health examination that included urinalysis, blood tests, blood pressure measurement and a physical examination by a physician. n nAlthough many people had co-morbid chronic conditions, no direct radiation damage was detected in blood tests. Greater morbidity is naturally expected in an older population, but recent events in Fukushima could have led to an exacerbation of underlying chronic conditions. The life of villagers working in agriculture changed dramatically after the nuclear disaster. Whereas before they had spent most of their time outdoors, after the disaster they became more sedentary and avoided going outside the house. It soon became apparent from the health interviews that ambiguous official information disseminated through the media after the nuclear crisis had confused the inhabitants and resulted in self-imposed “grounding” and lack of physical activity. In its efforts to minimize the long-term risk of cancer, the government issued an evacuation order while advising residents to stay indoors. This indirectly encouraged the population to adopt a sedentary lifestyle that may have exacerbated existing chronic conditions in the elderly. n nPsychological health is inseparable from physical health.6 During the interviews, a woman in her late 80s made a lasting impression. Smiling at all times, she expressed no worry with respect to the radiation and had only one concern: “For generations, my family has lived in a close relationship with this land. I will feel accursed for losing the lands that my ancestors passed down to me.” A man in his late 60s gave us similar food for thought, as he said with a laugh,“I do not know much about radiation, although I have heard it’s dangerous. For the sake of my cattle, I have worked outside every day since the disaster. To me, watching my cattle die is like witnessing the killing of my own children”. In two days’ time he was confronted with the reality of having to abandon his cattle and move away from the land where he was born and raised and spent his entire life. Feelings such as these were expressed by many members of this population on the verge of displacement to an unfamiliar area. For elderly Japanese people reared in country villages, being torn from the land of their ancestors and moved to an unfamiliar environment can cause more stress and harm than direct exposure to radiation. Whereas their physical health is not likely to be affected in the short term by the radiation or the measures taken to protect them from it, evacuation from the land of central importance to the stability of their community and sense of belonging can greatly undermine their health. n nThe World Health Organization includes “a state of social well-being” in its definition of health. In Fukushima’s post-disaster setting, attention to this dimension of health may be just as important as concerns about the immediate physical effects of radiation, especially among an active elderly population that judges its self-worth in terms of its ability to safeguard and convey basic social and cultural values and to contribute to society through farming or the custodianship of land long after retirement. What the elderly want is not necessarily a cancer-free life in 20xa0years’ time, but rather, the ability to continue living their normal lives. n nWhen an emergency occurs, governments have no choice but to prioritize people’s health by taking some form of action. Beyond health considerations, under such circumstances evacuation becomes ethically mandatory. However, the current nuclear crisis in Japan is likely to be long-lasting, given the destruction of homes and businesses in the area by the tsunami. A year after the disaster, Fukushima is still suffering. Mitigating the effects of the disaster will require government leadership, accountability and transparency on multiple levels. Our interactions with the villagers suggest the need to not only monitor their health status and that of their communities, but also to establish a system for listening to their voices, particularly during the reconstruction phase, as a way to gain an understanding of sociocultural issues and how they affect people’s physical and mental health. Health is a multi-faceted concept whose definition varies at different stages of the life cycle. If health interventions fail to take into account or to alleviate the fears and concerns of the people they target, they may ultimately prove more harmful than beneficial for some segments of the population, such as the elderly, in both the short and long term.