Atsushi Kumagai

Nuclear disasters and health: lessons learned, challenges, and proposals

Past nuclear disasters, such as the atomic bombings in 1945 and major accidents at nuclear power plants, have highlighted similarities in potential public health effects of radiation in both circumstances, including health issues unrelated to radiation exposure. Although the rarity of nuclear disasters limits opportunities to undertake rigorous research of evidence-based interventions and strategies, identification of lessons learned and development of an effective plan to protect the public, minimise negative effects, and protect emergency workers from exposure to high-dose radiation is important. Additionally, research is needed to help decision makers to avoid premature deaths among patients already in hospitals and other vulnerable groups during evacuation. Since nuclear disasters can affect hundreds of thousands of people, a substantial number of people are at risk of physical and mental harm in each disaster. During the recovery period after a nuclear disaster, physicians might need to screen for psychological burdens and provide general physical and mental health care for many affected residents who might experience long-term displacement. Reliable communication of personalised risks has emerged as a challenge for health-care professionals beyond the need to explain radiation protection. To overcome difficulties of risk communication and provide decision aids to protect workers, vulnerable people, and residents after a nuclear disaster, physicians should receive training in nuclear disaster response. This training should include evidence-based interventions, support decisions to balance potential harms and benefits, and take account of scientific uncertainty in provision of community health care. An open and joint learning process is essential to prepare for, and minimise the effects of, future nuclear disasters.

Assessment of Internal Exposure Doses in Fukushima by a Whole Body Counter Within One Month after the Nuclear Power Plant Accident

Information on early internal radiation doses in Fukushima after the nuclear power plant accident on March 11, 2011, is quite limited due to initial organizational difficulties, high background radiation and contamination of radiation measuring devices. In Nagasaki, approximately 1,200 km away from Fukushima, the internal radioactivity in evacuees and short-term visitors to Fukushima has been measured by a whole body counter (WBC) since March 15, 2011. A horizontal bed-type scanning WBC equipped with two NaI(Tl) scintillation detectors was used for 173 people who stayed in the Fukushima prefecture between March 11 and April 10, 2011. The average length of stay was 4.8 days. The internal radioactivity was converted to an estimated amount of intake according to the scenario of acute inhalation, and then the committed effective dose and the thyroid dose were evaluated. 131I, 134Cs and 137Cs were detected in more than 30% of examined individuals. In subjects who stayed in Fukushima from March 12 to March 18, the detection rate was approximately 50% higher for each radionuclide and 44% higher for all three nuclides. The maximum committed effective dose and thyroid equivalent dose were 1 mSv and 20 mSv, respectively. Although the number of subjects and settlements in the study are limited, the results suggest that the internal radiation exposure in Fukushima due to the intake of radioactive materials shortly after the accident will probably not result in any deterministic or stochastic health effects.

Spatiotemporal Characteristics of Internal Radiation Exposure In Evacuees and First Responders after the Radiological Accident in Fukushima

After the Tokyo Electric Power Company Fukushima Daiichi nuclear power plant accident on March 11, 2011, the reconstruction of early internal radiation doses in residents of Fukushima plays a major role in evaluating their future heath risk, including thyroid cancer by internal radioiodine. Internal radioactivity was measured using a whole body counter (WBC) at the Nagasaki University Medical School to evaluate the health risks of residents and short term visitors in Fukushima. Measurable 131I, 134Cs and 137Cs were detected altogether in 49 out of 196 people who were in Fukushima prefecture at any time during March 11 and April 20, 2011. In 49 people, the 90 percentile of the thyroid equivalent dose by 131I and the committed effective dose (total effective dose over a lifetime) by the sum of 134Cs and 137Cs was 3 mSv and 0.06 mSv, respectively. The radionuclide intakes in early evacuees who left Fukushima before March 16 were more than five times as high as in the responders who moved to Fukushima later. The intake ratio of 131I/137Cs of the earlier evacuees was approximately three. The spatial analysis of 16 evacuees to the south indicated a reduction of internal radioactivity depending on the distance from the nuclear power plant. Among them, high internal 131I radioactivity in 6 people in a particular evacuation route could be explained by the arrival of a radioactive cloud with a high airborne 131I/137Cs ratio to the environment, as predicted by atmospheric dispersion simulations. Overall, the actual internal radioactivity assessed by a WBC examination comparatively agreed with the predicted airborne radioactivity. These results suggest that the accurate estimation of internal doses in the first week after the radiological accident is critical for the dose reconstruction. The evaluation of internal doses of residents based on their evacuation routes and the advanced estimation of airborne radioactivity from the atmospheric dispersion model should continue to be assessed.

Dedifferentiation of human primary thyrocytes into multilineage progenitor cells without gene introduction.

While identification and isolation of adult stem cells have potentially important implications, recent reports regarding dedifferentiation/reprogramming from differentiated cells have provided another clue to gain insight into source of tissue stem/progenitor cells. In this study, we developed a novel culture system to obtain dedifferentiated progenitor cells from normal human thyroid tissues. After enzymatic digestion, primary thyrocytes, expressing thyroglobulin, vimentin and cytokeratin-18, were cultured in a serum-free medium called SAGM. Although the vast majority of cells died, a small proportion (∼0.5%) survived and proliferated. During initial cell expansion, thyroglobulin/cytokeratin-18 expression was gradually declined in the proliferating cells. Moreover, sorted cells expressing thyroid peroxidase gave rise to proliferating clones in SAGM. These data suggest that those cells are derived from thyroid follicular cells or at least thyroid-committed cells. The SAGM-grown cells did not express any thyroid-specific genes. However, after four-week incubation with FBS and TSH, cytokeratin-18, thyroglobulin, TSH receptor, PAX8 and TTF1 expressions re-emerged. Moreover, surprisingly, the cells were capable of differentiating into neuronal or adipogenic lineage depending on differentiating conditions. In summary, we have developed a novel system to generate multilineage progenitor cells from normal human thyroid tissues. This seems to be achieved by dedifferentiation of thyroid follicular cells. The presently described culture system may be useful for regenerative medicine, but the primary importance will be as a tool to elucidate the mechanisms of thyroid diseases.

Communicating With Residents About Risks Following the Fukushima Nuclear Accident

The Fukushima nuclear accident in March 2011 posed major threats to public health. In response, medical professionals have tried to communicate the risks to residents. To investigate forms of risk communication and to share lessons learned, we reviewed medical professionals’ activities in Fukushima Prefecture from the prefectural level to the individual level: public communication through Fukushima Health Management Surveys, a Yorozu (“general”) health consultation project, communications of radiological conditions and health promotion in Iitate and Kawauchi villages, dialogues based on whole-body counter, and science communications through online media. The activities generally started with radiation risks, mainly through group-based discussions, but gradually shifted to face-to-face communications to address comprehensive health risks to individuals and well-being. The activities were intended to support residents’ decisions and to promote public health in a participatory manner. This article highlights the need for a systematic evaluation of ongoing risk communication practices, and a wider application of successful approaches for Fukushima recovery and for better preparedness for future disasters.

Radiation-related anxiety among public health nurses in the Fukushima Prefecture after the accident at the Fukushima Daiichi Nuclear Power Station: a cross-sectional study

Objective In Japan, public health nurses (PHNs) play important roles in managing the health of local residents, especially after a disaster. In this study, we assessed radiation anxiety and the stress processing capacity of PHNs in the Fukushima Prefecture in Japan, after the accident at the Fukushima Daiichi Nuclear Power Station (FDNPS). Methods We conducted a questionnaire survey among the PHNs (n=430) in July of 2015 via postal mail. The questions included demographic factors (sex, age and employment position), knowledge about radiation, degree of anxiety about radiation at the time of the FDNPS accident (and at present), by asking them to answer questions about radiation and the Sense of Coherence-13 (SOC-13). We classified the low and high levels of anxiety by asking them to answer questions about radiation, and compared the anxiety-negative (−) group with the anxiety-positive (+) group. Results Of the PHNs, 269 (62.6%) were classified in the anxiety (−) group and 161 (37.4%) were in the anxiety (+) group. When the multivariate logistic regression analysis was conducted, the PHNs at the time of the accident (OR: 2.37, p=0.007), current general anxieties about radiation (OR: 3.56, p<0.001), current possession of materials to obtain knowledge about radiation (OR: 2.11, p=0.006) and knowledge of the childhood thyroid cancer increase after the Chernobyl accident (OR: 1.69, p=0.035) were significantly associated with anxiety after the FDNPS accident. The mean SOC-13 was 43.0±7.7, with no significant difference between the anxiety (−) group and anxiety (+) group (p=0.47). Conclusions Our study suggested that anxiety about radiation was associated with materials and knowledge about radiation in the PHNs in the Fukushima Prefecture 4 years after the FDNPS accident. It is important for PHNs to obtain knowledge and teaching materials about radiation, and radiation education programmes for PHNs must be established in areas that have nuclear facilities.

Collaborative Processes of Developing A Health Literacy Toolkit: A Case from Fukushima after the Nuclear Accident

Abstract Following the Fukushima nuclear accident in 2011, the central government provided health and radiation-related information that was incomplete, difficult to understand and contradictory, leading to widespread distrust in the community. Thus, from 2013 to 2014, we developed and implemented a series of health literacy training workshops for local public health nurses, often the first health care professionals with whom members of the community interact. The results from our program evaluation revealed that the task of paraphrasing professional terms and skills related to relaying numeric information to the community were difficult for the nurses to acquire. In 2016, to further support the communication efforts of public health nurses, we developed a pocket-size “health literacy toolkit” that contained a glossary explaining radiation-related terms in plain language and an index to measure the accessibility of both text and numerical information, so that nurses could calibrate and appreciate the literacy demand of information. This case study documents an interprofessional collaborative effort for the development of the toolkit, and highlights the iterative process of building health literacy skills in health care professionals.

Pediatric computed tomography practice in Japanese university hospitals from 2008-2010: did it differ from German practice?

Computed tomography (CT) is an essential tool in modern medicine and is frequently used to diagnose a wide range of conditions, particularly in industrial countries, such as Japan and Germany. However, markedly higher doses of ionizing radiation are delivered during CT imaging than during conventional X-ray examinations. To assess pediatric CT practice patterns, data from three university hospital databases (two in Japan and one in Germany) were analyzed. Anonymized data for patients aged 0 to 14 years who had undergone CT examinations between 2008 and 2010 were extracted. To assess CT practice, an interdisciplinary classification scheme for CT indications, which incorporated the most common examination types and radiosensitive tissues, was developed. The frequency of CT examinations was determined according to sex, age at examination, and indications. A total of 5182 CT examinations were performed in 2955 children. Overall, the frequency of CT examinations at the Japanese university hospitals did not differ significantly from that at the German hospital. However, differences were detected in the age distribution of the patients who underwent CT examinations (the proportion of patients <5 years of age was significantly higher in Japan than in Germany) and in the indications for CT. Substantial practice differences regarding the use of CT in pediatric health care were detected between the three hospitals. The results of this study point towards a need for approaches such as clinical guidelines to reduce unwarranted medical radiation exposures, particularly abdominal and head CT, in the Japanese health system.

CURRENT STATUS OF THE FUKUSHIMA HEALTH MANAGEMENT SURVEY

Abstract The Fukushima Health Management Survey (FHMS) was implemented in the wake of the 2011 Fukushima Daiichi Nuclear Power Plant accident. The primary purpose of this survey was to monitor the long-term health of residents, promote their future well-being and confirm whether long-term low-dose radiation exposure affects health. The FHMS results indicated very low-radiation exposure doses among residents and that no discernible increased incidence of radiation-related health effects could be expected. However, psychological distress was found to be far greater among people in Fukushima than those in other areas affected by the accident’s preceding Great East Japan Earthquake and the resultant tsunami. Additionally, prevalence of lifestyle-related health problems such as being overweight, hypertension, diabetes mellitus, dyslipidaemia and liver dysfunction increased among evacuees. Thyroid examinations of asymptomatic individuals, using ultrasound techniques, also contributed to public concern and fear about the health effects of radiation. The FHMS ultimately revealed that ethical considerations are important in the design and implementation of health surveillance and epidemiological studies.