Radiation-driven migration: the case of Minamisoma City, Fukushima, Japan, after the Fukushima nuclear accident

Health Information Seeking on the Internet Among Patients With and Without Cancer in a Region Affected by the 2011 Fukushima Triple Disaster: Cross-Sectional Study

BACKGROUND

Health information seeking via the internet among patients with cancer in disaster-affected areas is underresearched.

OBJECTIVE

This study aims not only to assess the extent and means of web-based health information seeking among patients with cancer living in the disaster-affected area of the 2011 Fukushima triple disaster but also to compare these patterns with those without cancer, identifying distinct and shared factors influencing their web-based health information behaviors.

METHODS

We surveyed 404 patients (263 with and 141 without cancer) from the surgery department outpatient office at Minamisoma Municipal General Hospital, from October 2016 to January 2017. The survey included self-administered questions on internet and digital device use. Descriptive analyses were performed to examine the use patterns of digital devices and the internet and their impact on health information seeking across different age groups of patients with and without cancer. Multivariable logistic regression was used to examine factors associated with web-based health information seeking, stratifying by cancer diagnosis.

RESULTS

The proportion of participants who sought health information on the internet was comparable between patients with cancer and patients without cancer (19% vs 17.4%; P=.71). Digital device use varied significantly with age, with peak smartphone use occurring among the youngest cohorts for both groups. Multivariable logistic regression revealed that patients with cancer using smartphones or tablets daily were significantly more likely to gather web-based health information (odds ratio [OR] for smartphones 3.73, 95% CI 1.58-8.80; OR for tablets 5.08, 95% CI 1.27-20.35). Trust in institutional websites also significantly influenced web-based health information gathering among patients with cancer (OR 2.87, 95% CI 1.13-7.25). Conversely, among patients without cancer, unemployment was associated with a lower likelihood of seeking web-based health information (OR 0.26, 95% CI 0.08-0.85), whereas trust in both institutional and personal websites significantly increased this likelihood (OR for institutional websites 6.76, 95% CI 2.19-20.88; OR for personal websites 6.97, 95% CI 1.49-32.58).

CONCLUSIONS

This study reveals that a small proportion of both patients with cancer and patients without cancer engage in health information seeking via the internet, influenced by age, digital device use, and trust in institutional websites. Given the growing prevalence of digital literacy, strategies to enhance accessible and reliable web-based health information should be developed, particularly for patients with cancer in postdisaster settings. Future efforts should focus on tailored health communication strategies that address the unique needs of these populations.

Emerging paradigms into bioremediation approaches for nuclear contaminant removal: From challenge to solution

The release of radionuclides, including Cesium-137 (137Cs), Strontium-90 (90Sr), Uranium-238 (238U), Plutonium-239 (239Pu), Iodine-131 (131I), etc., from nuclear contamination presents profound threats to both the environment and human health. Traditional remediation methods, reliant on physical and chemical interventions, often prove economically burdensome and logistically unfeasible for large-scale restoration efforts. In response to these challenges, bioremediation has emerged as a remarkably efficient, environmentally sustainable, and cost-effective solution. This innovative approach harnesses the power of microorganisms, plants, and biological agents to transmute radioactive materials into less hazardous forms. For instance, consider the remarkable capability demonstrated by Fontinalis antipyretica, a water moss, which can accumulate uranium at levels as high as 4979 mg/kg, significantly exceeding concentrations found in the surrounding water. This review takes an extensive dive into the world of bioremediation for nuclear contaminant removal, exploring sources of radionuclides, the ingenious resistance mechanisms employed by plants against these harmful elements, and the fascinating dynamics of biological adsorption efficiency. It also addresses limitations and challenges, emphasizing the need for further research and implementation to expedite restoration and mitigate nuclear pollution's adverse effects.

Citizens’ Communication Needs and Attitudes to Risk in a Nuclear Accident Scenario: A Mixed Methods Study

The potential devastation that a nuclear accident can cause to public health and the surrounding environment demands robust emergency preparedness. This includes gaining a greater knowledge of citizens’ needs in situations involving radiation risk. The present study examines citizens’ attitudes to a remediation scenario and their information and communication needs, using focus group data (n = 39) and survey data (n = 2291) from Sweden. The focus groups uniquely showed that adults of all ages express health concerns regarding young children, and many also do so regarding domestic animals. Said protective sentiments stem from a worry that even low-dose radiation is a transboundary, lingering health risk. It leads to doubts about living in a decontaminated area, and high demands on fast, continuous communication that in key phases of decontamination affords dialogue. Additionally, the survey results show that less favorable attitudes to the remediation scenario—worry over risk, doubt about decontamination effectiveness, and preferences to move away from a remediation area—are associated with the need for in-person meetings and dialogue. Risk managers should thus prepare for the need for both in-person meetings and frequent information provision tasks, but also that in-person, citizen meetings are likely to feature an over-representation of critical voices, forming very challenging communication tasks.

Returning Home after Decontamination? Applying the Protective Action Decision Model to a Nuclear Accident Scenario

Studies of the aftermath of nuclear power plant accidents show that affected citizens assess higher risks and adopt more risk-avoidant behaviors than authorities expect. This results in differences between the planned recovery and actual outcomes. Based on this knowledge, this study examined the factors that affect citizens’ preference to continue living in a decontaminated area. Testing the key aspects of the protective action decision model (PADM), this study analyzed Swedish survey data (N = 2291) regarding such an accident scenario. Several aspects of the PADM, from the layperson’s view of threats and protective actions, to stakeholders and situational factors, were strongly supported. The most influential variables affecting settlement choices are perceptions of radiation risk, perceptions of decontamination effectiveness, government information, living with certain restrictions, and attachment to an area because of one’s work. A novel contribution of this study is that it ranked the significance of such effects on behavioral intentions in an emergency scenario. Regarding the policy recommendations, this study concluded that a recovery program must facilitate most aspects of people’s lives and provide trustworthy information on decontamination efficiency. As some people will avoid potential health risks and leave a decontaminated area, planning to implement one solution for everyone would likely not be optimal.

Overall health information exposure, its barriers and impacts on attitude toward healthcare among cancer patients. The long-term aftermath of the 2011 triple disaster in Fukushima, Japan: A single institution cross-sectional study

Disasters can hinder access to health information among cancer patients. However, little is known regarding overall health information exposure (HIE), its barriers and its impacts on attitudes toward healthcare among cancer patients in the long-term aftermath of disasters. The aims of this study were threefold: assess the extent of HIE; identify associations between family composition and a non-engagement with HIE; and examine the effects of HIE on attitudes toward healthcare among local cancer patients-5 years after the 2011 triple disaster (earthquake, tsunami, and nuclear disaster) in Fukushima, Japan. We conducted self-administered surveys with all cancer and non-cancer surgery department outpatients at Minamisoma Municipal General Hospital (MMGH), Minamisoma City, from October 2016 to January 2017. In total, 404 patients (263 cancer patients and 141 non-cancer patients) voluntarily participated in the study. The results revealed that a regular level of HIE occurred among 90.5% of the cancer patients. In cancer patients, family composition was not significantly associated with HIE, and HIE was not associated with attitude toward healthcare. In conclusion, most cancer patients visiting the MMGH surgical department were regularly engaged in HIE.

Return migration after the Fukushima Daiichi nuclear disaster: the impact of institutional and individual factors

This paper explores two groups of factors, individual and institutional, that have influenced return migration since the Fukushima Daiichi nuclear accident in Japan on 11 March 2011. Based on an analysis of statistical data on evacuees, a questionnaire completed by 289 people who migrated, and 19 semi-structured interviews with disaster-affected people, the research found (apropos of institutional factors) that while the lifting of the government's evacuation order has had no immediate effect on return decisions, the termination of monetary compensation and housing subsidies has had a significant bearing on them. As for individual factors, a strong sense of attachment to home and the possession of property, job obligations, and having family members in the home location are key determinants of return decisions. Moreover, the paper suggests that there could be differing opinions among Japanese government officials and evacuees regarding radiation exposure risk and the degree to which infrastructure and social services have been rehabilitated.

Gender and life-stage dependent reactions to the risk of radioactive contamination: A survey experiment in Sweden

This article proposes and examines gender and life-stage factors as determinants of public worry and risk avoidance in a nuclear fallout scenario. Drawing on a survey (N 2,291) conducted in Sweden, the article demonstrates statistically significant results that women as well as parents with children at home are more likely to express high levels of worry for radiation exposure and have a preference to move away from a fallout area despite assurance of successful remediation. Moreover, a negative relationship is shown between age and both worry for radiation exposure and preference to move. These novel results from Northern Europe thus support a life-stage framing of public risk attitudes. As radiation physicists develop new methods showing that women and children are at higher risk of cancer than other groups at the same radiation exposure, we may actually see the precaution among women and parents as a regulating mechanism for the higher objective risk they face. The results are moreover in agreement with studies of public risk reactions in Japan, creating a strong knowledge base that human-induced radiation pollution is largely an intolerable risk to the public. Considering the public opinion, managing an intolerable risk through risk mitigation by remediation alone is likely insufficient in many cases. A viable strategy would offer a range of social support options that enable individual decision-making and the protection of risk groups.

Determinants and supporting factors for rebuilding nursing workforce in a post-disaster setting

BACKGROUND

The workforce shortage is one of the major issues associated with the recovery of Minamisoma City in Fukushima Prefecture, after the Great East Japan Earthquake and the subsequent accidents at the Fukushima Daiichi Nuclear Power Plants in March 2011. While the radiation risks are often discussed as a major factor of evacuation, little is known about the actual reasons why the residents chose to evacuate, and what enables them to return. This study aims to find the essential factors for rebuilding the workforce in a post-disaster setting by analysing the residents' decisions about evacuation and the return to Minamisoma. In particular, we focus on the experiences of nurses as an example of healthcare workers, who play an important role in the disaster recovery.

METHODS

The data were obtained through qualitative interviews in a semi-structured form with 25 nurses from four hospitals in Minamisoma City. The interview questions focused on the reasons of their decisions on evacuation and return. The data were analysed by a thematic approach to investigate the major factors which led them to evacuate and enabled them to return afterwards, as well as the support they needed to resettle.

RESULTS

Nearly two-thirds of the interviewees chose to evacuate from Minamisoma with their family. Family conditions seem to be the predominant factor that influenced their decisions. In particular, having small children was a strong cause for evacuation. After a certain period of time, the nurses that evacuated were then faced with another decision about returning to the area; once again, having children, as well as other life factors, such as livelihoods, job opportunities and emotional attachment to the work, influenced this decision. On the other hand, radiation risk was a minor factor. Therefore, we analyse that improved support considering their life situations would contribute to the better retention of the nurses.

CONCLUSIONS

We suggest measures such as parenting supports, ensuring job opportunities after return, and psychological support in the workplace as possible solutions for higher job retention.

Breast Cancer Provider Interval Length in Fukushima, Japan, After the 2011 Triple Disaster: A Long-Term Retrospective Study

BACKGROUND

Minimizing the interval from symptom onset to treatment commencement is essential for a favorable outcome among breast cancer (BC) patients. This study examined whether provider interval (time elapsed from first consultation to treatment initiation) lengthened among BC patients after Japan's 2011 earthquake, tsunami, and nuclear disaster in Fukushima. Factors associated with the length of postdisaster interval and whether the interval was associated with BC stage were also investigated.

PATIENTS AND METHODS

So-so District (study site) was an area damaged by the 2011 disasters. Data of all BC patients who made their first medical consultation and received initial treatment at the core medical institutions in the area 5 years before or after the disaster were extracted from patient medical records. We used several regression approaches to fulfill our study objectives.

RESULTS

We included 263 (140 predisaster and 123 postdisaster) patients. After adjustment for covariates, the interval did not significantly change after the disaster compared to before the disaster. Those with 4 or 5 cohabiting family members experienced a shorter interval after the disaster than those with 0 or 1 cohabiting family members (relative length, 0.47; 95% confidence interval, 0.28-0.78). Those with an interval of > 60 days had lower odds of stage III or IV cancer after the disaster than those with an interval of < 30 days (odds ratio, 0.09; 95% confidence interval, 0.01-0.84).

CONCLUSION

Overall, provider interval did not lengthen after the disaster. However, those with fewer cohabiting family members might have experienced a longer total interval. Cancer stage may not necessarily reflect the influence of interval on patient outcome.

Efficacy of group intervention involving physical activity on subjective well-being of elderly returnees after evacuation following the Great East Japan Earthquake

AIM

In general, physically activity contributes to better subjective well-being (SWB) in the elderly. However, the physical activity level of older people who experienced relocation after the Great East Japan Earthquake has been reported to be low, possibly leading to low SWB. This study aimed to examine the efficacy of group intervention involving physical activity on SWB among older returnees after the Great East Japan Earthquake.

METHODS

The participants were randomly allocated to an intervention group (4 men, 10 women) or a control group (7 women). Participants in the intervention group attended a series of weekly classes over eight weeks to encourage daily physical activity, whereas participants in the control group received no intervention. SWB, the primary outcome, was assessed by the World Health Organization Five Well-Being Index.

RESULTS

Median variation in the World Health Organization Five Well-Being Index scores at 3 months from the baseline in the intervention and control groups was -1.0 and -2.0 points, respectively; the difference was borderline significant (P = 0.06). There was no significant difference between the groups in the median of variation in muscle strength (P = 0.79) or mobility (P = 0.77) at 3 months.

CONCLUSION

The intervention might prevent deterioration in participants' SWB. Further studies involving older returnees with poor physical activity and/or sedentary lifestyle may be beneficial for health promotion in the area.

Predicting the Public Health Consequences of a Nuclear Terrorism Attack: Drawing on The Experiences of Hiroshima and Fukushima

The increasing threat of nuclear terrorism warrants consideration of the health consequences of a terrorist incident should preventive measures fail. Although there has not yet been a nuclear terrorist attack of any kind, experiences with the aftermath of the bombing of Hiroshima and the core meltdowns at Fukushima can provide useful insight and allow some inferences to be made regarding the types of casualties that might be sustained and the rescue efforts that might be required. There are many parallels between the events at Hiroshima and what might be expected from an improvised nuclear device, and there are parallels between the radioactivity released to the environment at Fukushima and the aftermath of a radiological dispersal device attack. Nevertheless, there are some unique aspects to a ground-detonated improvised nuclear device that pose health threats beyond those seen at Hiroshima (i.e., fallout). And psychological health may be impacted more than physical health in the case of a radiological dispersal device. Preparedness requires consideration of all of these various health hazards in order to determine how best to mitigate the consequences of a nuclear terrorism attack.

Disappearing everyday materials: The displacement of medical resources following disaster in Fukushima, Japan

This study draws upon interviews of medical staff working in the city of Minamisoma, Japan, following the 2011 Triple Disaster. It investigates staff responses to the disruption of material resources as a consequence of the disaster and its management. The disruption of spaces, and the loss of oxygen supplies, food, and medications impacted upon staff experience and the ability of institutions to care for patients. This resulted in a restructuring of spaces and materials as workers made efforts to reconfigure and reestablish healthcare functions. This is one of the few qualitative studies which draws upon the experience and perspectives of health workers in understanding material disruption following disaster. This is particularly important since this case did not involve the breakdown of lifeline infrastructure, but rather, brought to attention the way everyday material objects shape social experience. In highlighting these effects, the paper makes the case for the social scientific investigation of the impact of disasters on healthcare, shedding light on an area of research currently dominated by disaster medicine.

American Thyroid Association Scientific Statement on the Use of Potassium Iodide Ingestion in a Nuclear Emergency

This document serves to summarize the issues and the American Thyroid Association (ATA) position regarding the use of potassium iodide as a thyroid blocking agent in the event of a nuclear accident. The purpose is to provide a review and updated position statement regarding the advanced distribution, stockpiling, and availability of potassium iodide in the event of nuclear radiation emergencies in the United States.

Breast cancer patient delay in Fukushima, Japan following the 2011 triple disaster: a long-term retrospective study

Background

Little information is available concerning how patient delay may be affected by mass disasters. The main objectives of the present study are to identify whether there was a post-disaster increase in the risk of experiencing patient delay among breast cancer patients in an area affected by the 2011 triple disaster in Fukushima, Japan, and to elucidate factors associated with post-disaster patient delay. Sociodemographic factors (age, employment status, cohabitant status and evacuation status), health characteristics, and health access- and disaster-related factors were specifically considered.

Methods

Records of symptomatic breast cancer patients diagnosed from 2005 to 2016 were retrospectively reviewed to calculate risk ratios (RRs) for patient delay in every year post-disaster compared with the pre-disaster baseline. Total and excessive patient delays were respectively defined as three months or more and twelve months or more from symptom recognition to first medical consultation. Logistic regression analysis was conducted for pre- and post-disaster patient delay in order to reveal any factors potentially associated with patient delay, and changes after the disaster.

Results

Two hundred nineteen breast cancer patients (122 pre-disaster and 97 post-disaster) were included. After adjustments for age, significant post-disaster increases in RRs of experiencing both total (RR: 1.66, 95% Confidence Interval (CI): 1.02–2.70, p < 0.05) and excessive patient delay (RR: 4.49, 95% CI: 1.73–11.65, p < 0.01) were observed. The RRs for total patient delay peaked in the fourth year post-disaster, and significant increases in the risk of excessive patient delay were observed in the second, fourth, and fifth years post-disaster, with more than five times the risk observed pre-disaster. A family history of any cancer was the only factor significantly associated with total patient delay post-disaster (odds ratio: 0.38, 95% CI: 0.15–0.95, p < 0.05), while there were no variables associated with delay pre-disaster.

Conclusions

The triple disaster in Fukushima appears to have led to an increased risk of patient delay among breast cancer patients, and this trend has continued for five years following the disaster.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-017-3412-4) contains supplementary material, which is available to authorized users.

Effect of Residence in Temporary Housing After the Great East Japan Earthquake on the Physical Activity and Quality of Life of Older Survivors

OBJECTIVE

This study aimed to compare the physical activity level and health-related quality of life (HRQOL) between older survivors residing in temporary housing after the Great East Japan Earthquake (GEJE; temporary housing group) and older individuals residing in their own homes (control group) and to clarify whether mobility function and muscle strength were correlated with physical activity among older temporary housing residents.

METHODS

Subjects were recruited to the temporary housing group (n=64, 19 men and 45 women) or control group (n=64, 33 men and 31 women) according to their residence. Physical activity was assessed by the number of walking steps determined by using a triaxial accelerometer, mobility function by the Timed Up and Go test, muscle strength by the grasping power test, and HRQOL by the Medical Outcome Study 36-Item Short Form Survey v2.

RESULTS

In the temporary housing group, reduced physical activity and correlation between physical activity and mobility function in men, and muscle strength in both men and women, were observed. There was no significant difference in HRQOL between groups except for bodily pain in women.

CONCLUSION

Support for older evacuees should focus on maintaining their physical activity level as well as on HRQOL to avoid deterioration of health in these survivors. (Disaster Med Public Health Preparedness. 2017;11:701-710).

Birth Outcomes after the Fukushima Daiichi Nuclear Power Plant Disaster: A Long-Term Retrospective Study

Changes in population birth outcomes, including increases in low birthweight or preterm births, have been documented after natural and manmade disasters. However, information is limited following the 2011 Fukushima Daiichi Nuclear Power Plant Disaster. In this study, we assessed whether there were long-term changes in birth outcomes post-disaster, compared to pre-disaster data, and whether residential area and food purchasing patterns, as proxy measurements of evacuation and radiation-related anxiety, were associated with post-disaster birth outcomes. Maternal and perinatal data were retrospectively collected for all live singleton births at a public hospital, located 23 km from the power plant, from 2008 to 2015. Proportions of low birthweight (<2500 g at birth) and preterm births (<37 weeks gestation at birth) were compared pre- and post-disaster, and regression models were conducted to assess for associations between these outcomes and evacuation and food avoidance. A total of 1101 live singleton births were included. There were no increased proportions of low birthweight or preterm births in any year after the disaster (merged post-disaster risk ratio of low birthweight birth: 0.98, 95% confidence interval (CI): 0.64–1.51; and preterm birth: 0.68, 95% CI: 0.38–1.21). No significant associations between birth outcomes and residential area or food purchasing patterns were identified, after adjustment for covariates. In conclusion, no changes in birth outcomes were found in this institution-based investigation after the Fukushima disaster. Further research is needed on the pathways that may exacerbate or reduce disaster effects on maternal and perinatal health.

Social isolation and cancer management - advanced rectal cancer with patient delay following the 2011 triple disaster in Fukushima, Japan: a case report

Background

Little is known about the effects of social isolation in the elderly on their process of gaining health information and seeking health care.

Case presentation

In March 2011, Fukushima, Japan experienced an earthquake, tsunami, and nuclear disaster, also known as Japan’s triple disaster. In June 2016, an 80-year-old Japanese man, who lived alone after divorce at the age of 42, presented to our hospital with bloody stools and dizziness. Although his bloody stools initially occurred in May 2015, a year earlier, he did not pursue the possibility of malignancy. He was diagnosed as having stage IIIA rectal cancer. Detailed history taking revealed that he experienced social isolation after the disaster, due to the evacuation of his friends, losing his regular opportunities for socialization. He additionally reported that the current diagnosis of rectal cancer made him feel he had lost his health in addition to his social relationships. Although radical surgery was attempted, it failed to resect the lesion completely, and thereafter his disease gradually progressed. As support from family or friends was not available, he was not able to receive palliative radiation therapy or home-based care in his end-of-life period. He died at a long-term care facility in February 2017.

Conclusions

This case suggests that intense social isolation after the Fukushima disaster was a likely contributor to the patient delay, poor treatment course, and poor outcome of an elderly patient with rectal cancer. Direct communication with family and friends may play an indispensable role in increasing health awareness and promoting health-seeking behaviors, and in the midst of social isolation, elderly patients with cancer may lose these opportunities and experience increased risk of patient delay. Although health care providers may be able to alleviate isolation-induced delay by promoting cancer knowledge and awareness widely among local residents, policy-led interventions at the community level may be essential to reducing social isolation and its health consequences.

Decontamination Work and the Long-term Increase in Hospital Visits for Hymenoptera Stings Following the Fukushima Nuclear Disaster

Objective

Animals, including arthropods, are one health threat that can be affected by disasters. This institution-based study aimed to assess trends in Hymenoptera stings following the 2011 Fukushima nuclear disaster.

Methods

We reviewed the medical records of patients with hymenopteran stings who visited Minamisoma Municipal General Hospital, located 23 km from Fukushima Daiichi Nuclear Power Plant, from March 2005 to March 2016. Patient and sting characteristics of post-disaster patients were examined, and the annual incidence of hospital visits for hymenopteran stings was compared with the pre-disaster baseline, calculating an incidence rate ratio (IRR) for each year.

Results

We identified 152 pre-disaster patients (2005-2011) and 222 post-disaster patients (2011-2016). In the post-disaster period, 160 males (72.1%) were identified, with a median age of 59 years (range: 2-89 years). A total of 45 patients (20.3%) were decontamination workers. Post-disaster increases were found in the IRR for hymenopteran stings, peaking first in 2011 (IRR: 2.8; 95% confidence interval [CI]: 1.9-4.2) and later in 2014 (IRR: 3.2; 95% CI: 2.4-4.3) and 2015 (IRR 3.3; 95% CI: 2.5-4.4).

Conclusions

Long-term increases were found in the IRR of hospital visits for hymenopteran stings in an institution affected by the Fukushima nuclear disaster. Decontamination workers appear to have been particularly affected by this phenomenon. Better disaster field worker monitoring and education about potential environmental health hazards may help to identify and prevent worker exposure to insect stings and other vectors in these settings. (Disaster Med Public Health Preparedness. 2017;11:545–551)

Agricultural land management options after the Chernobyl and Fukushima accidents: The articulation of science, technology, and society

The options adopted for recovery of agricultural land after the Chernobyl and Fukushima accidents are compared by examining their technical and socio-economic aspects. The analysis highlights commonalities such as the implementation of tillage and other types of countermeasures and differences in approach, such as preferences for topsoil removal in Fukushima and the application of K fertilizers in Chernobyl. This analysis shows that the recovery approach needs to be context-specific to best suit the physical, social, and political environment. The complex nature of the decision problem calls for a formal process for engaging stakeholders and the development of adequate decision support tools. Integr Environ Assess Manag 2016;12:662-666. © 2016 SETAC.

Estimated association between dwelling soil contamination and internal radiation contamination levels after the 2011 Fukushima Daiichi nuclear accident in Japan

OBJECTIVES

Measurement of soil contamination levels has been considered a feasible method for dose estimation of internal radiation exposure following the Chernobyl disaster by means of aggregate transfer factors; however, it is still unclear whether the estimation of internal contamination based on soil contamination levels is universally valid or incident specific.

METHODS

To address this issue, we evaluated relationships between in vivo and soil cesium-137 (Cs-137) contamination using data on internal contamination levels among Minamisoma (10-40 km north from the Fukushima Daiichi nuclear power plant), Fukushima residents 2-3 years following the disaster, and constructed three models for statistical analysis based on continuous and categorical (equal intervals and quantiles) soil contamination levels.

RESULTS

A total of 7987 people with a mean age of 55.4 years underwent screening of in vivo Cs-137 whole-body counting. A statistically significant association was noted between internal and continuous Cs-137 soil contamination levels (model 1, p value <0.001), although the association was slight (relative risk (RR): 1.03 per 10 kBq/m(2) increase in soil contamination). Analysis of categorical soil contamination levels showed statistical (but not clinical) significance only in relatively higher soil contamination levels (model 2: Cs-137 levels above 100 kBq/m(2) compared to those <25 kBq/m(2), RR=1.75, p value <0.01; model 3: levels above 63 kBq/m(2) compared to those <11 kBq/m(2), RR=1.45, p value <0.05).

CONCLUSIONS

Low levels of internal and soil contamination were not associated, and only loose/small associations were observed in areas with slightly higher levels of soil contamination in Fukushima, representing a clear difference from the strong associations found in post-disaster Chernobyl. These results indicate that soil contamination levels generally do not contribute to the internal contamination of residents in Fukushima; thus, individual measurements are essential for the precise evaluation of chronic internal radiation contamination.

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 1^st April 2012 to 31^st 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.