RECOVERY FROM NUCLEAR DISASTER IN FUKUSHIMA: COLLABORATION MODEL.

Since 2011, Nagasaki University has been assisting the reconstruction efforts of Kawauchi Village in the Fukushima Prefecture, which was the first village to declare it safe for residents to return to their homes. In April 2013, Nagasaki University and the Kawauchi government office concluded an agreement concerning comprehensive cooperation toward reconstruction of the village. The present study evaluates the internal and external exposure doses of residents and conducted a risk communication based on each resident's radiation dose. Furthermore, researchers began a comprehensive support of Tomioka residents who have returned to their hometown in 2017. Based on the experiences in Kawauchi village, it is clear that the cooperation of residents, local authorities and specialists is essential for the recovery of areas affected by the nuclear disaster. Accumulated experiences and practices should be carefully evaluated and recorded to prepare for future unexpected nuclear disasters.

Radiocesium contamination and estimated internal exposure doses in edible wild plants in Kawauchi Village following the Fukushima nuclear disaster.

Kawauchi Village, in Fukushima Prefecture, is located within a 30-km radius of the nuclear disaster site of the Fukushima Daiichi Nuclear Power Plant (FDNPP). "Sansai" (edible wild plants) in this village have been evaluated by gamma spectrometry after the residents had returned to their homes, to determine the residents' risk of internal exposure to artificial radionuclides due to consumption of these plants. The concentrations of radiocesium (cesium-134 and cesium-137) were measured in all 364 samples collected in spring 2015. Overall, 34 (9.3%) samples exceeded the regulatory limit of 100 Bq/kg established by Japanese guidelines, 80 (22.0%) samples registered between 100 Bq/kg and 20 Bq/kg, and 250 (68.7%) registered below 20 Bq/kg (the detection limit). The internal effective doses from edible wild plants were sufficiently low (less than 1 mSv/y), at 3.5±1.2 µSv/y for males and 3.2±0.9 µSv/y for females (2.7±1.5 µSv/y for children and 3.7±0.7 µSv/y for adults in 2015). Thus, the potential internal exposure doses due to consumption of these edible wild plants were below the applicable radiological standard limits for foods. However, high radiocesium levels were confirmed in specific species, such as Eleutherococcus sciadophylloides ("Koshiabura") and Osmunda japonica (Asian royal fern, "Zenmai"). Consequently, a need still might exist for long-term follow-up such as environmental monitoring, physical and mental support to avoid unnecessary radiation exposure and to remove anxiety about adverse health effects due to radiation. The customs of residents, especially the "satoyama" (countryside) culture of ingesting "sansai," also require consideration in the further reconstruction of areas such as Kawauchi Village that were affected by the nuclear disaster.

Radiocesium concentrations in wild mushrooms after the accident at the Fukushima Daiichi Nuclear Power Station: Follow-up study in Kawauchi village.

Since the accident at the Chernobyl Nuclear Power Plant, it has become well known that radiocesium tends to concentrate in wild mushrooms. During the recovery process after the accident at the Fukushima Daiichi Nuclear Power Station (FDNPS), it is important to perform follow-up measurements of the activity concentrations of radiocesium in mushrooms. We evaluated the activity concentrations of the detected artificial radionuclides (radiocesium) in wild mushrooms collected from Kawauchi village, which is within 30 km of the FDNPS, in 2015, four years after the accident. We found that the radiocesium was determined in 147 of 159 mushroom samples (92.4%). Based on the average mushroom consumption of Japanese citizens (6.28 kg per year), we calculated committed effective doses ranging from <0.001 to 0.6 mSv. Although committed effective doses are relatively limited, even if residents have consumed mushrooms several times, continuous monitoring of the radiocesium in mushrooms in Fukushima is needed for sustained recovery from the nuclear disaster.

Determinants of intention to leave among non-medical employees after a nuclear disaster: a cross-sectional study.

OBJECTIVE: To conduct a survey among non-medical employees working at the time of the Fukushima Daiichi Nuclear Power Station accident, in order to determine the factors associated with their intentions to leave their jobs during the nuclear disaster. PARTICIPANTS: We asked 287 employees (166 men and 121 women) in the study. METHODS: We asked about their intentions to leave their jobs after the nuclear disaster. We also asked about relevant factors, including the participants' demographic factors, living situations and working environments. RESULTS: We found that in employees younger than 40 (OR=4.73, 95% CI 1.74 to 12.85, p=0.002), being married (OR=3.18, 95% CI 1.03 to 9.79, p=0.044), measurements of the ambient dose rates in their homes after the accident (OR=5.32, 95% CI 1.65 to 17.14, p=0.005), anxiety about their relationships with their colleagues after the accident (OR=3.91, 95% CI 1.51 to 10.16, p=0.005) and the influence of radiation on the workplace (OR=0.33, 95% CI 0.14 to 0.80, p=0.014) were independently associated with the non-medical employees' intentions to leave their jobs after the nuclear disaster. CONCLUSIONS: Our results suggest the need for continuous risk communication regarding such factors and the provision of information about the health effects of radiation exposure to non-medical employees after nuclear disasters.

Changes in radiological imaging frequencies in children before and after the accident at the Fukushima Daiichi Nuclear Power Plant in Fukushima Prefecture, Japan.

PURPOSE: The accident at the Fukushima Daiichi Nuclear Power Plant has raised concerns about radiation exposure, including medical radiation exposure such as X-ray and CT, in residents of Fukushima. MATERIALS AND METHODS: We compared the numbers and the ratio of outpatients less than 10 years old who underwent imaging examinations [e.g., CT, X-ray, MRI, ultrasonography (US), etc.] at Fukushima Medical University hospital in Fukushima, Japan before (April 1, 2008-March 31, 2011) and after (April 1, 2011-March 31, 2014) the accident. RESULTS: The number of outpatients less than 10 years old decreased after the accident. The number of outpatients less than 10 years old who underwent CT and X-ray examinations also significantly decreased after the accident (p < 0.001, p < 0.01, respectively). CONCLUSION: Our results suggest that the number of pediatric radiological examinations decreased after the accident in Fukushima. We should continue to communicate with patients and their families to ensure that they understand the risks and benefits of radiological imaging in order to overcome their concerns about the nuclear disaster.

Bipolarization of Risk Perception about the Health Effects of Radiation in Residents after the Accident at Fukushima Nuclear Power Plant.

The late health effects of low-dose rate radiation exposure are still a serious public concern in the Fukushima area even four years after the accident at Fukushima Daiichi Nuclear Power Plant (FNPP). To clarify the factors associated with residents' risk perception of radiation exposure and consequent health effects, we conducted a survey among residents of Kawauchi village in May and June 2014, which is located within 30 km of FNPP. 85 of 285 residents (29.8%) answered that acute radiation syndrome might develop in residents after the accident, 154 (54.0%) residents responded that they had anxieties about the health effects of radiation on children, and 140 (49.1%) residents indicated that they had anxieties about the health effects of radiation on offspring. Furthermore, 107 (37.5%) residents answered that they had concerns about health effects that would appear in the general population simply by living in an environment with a 0.23 µSv per hour ambient dose for one year, 149 (52.2%) residents reported that they were reluctant to eat locally produced foods, and 164 (57.5%) residents believed that adverse health effects would occur in the general population by eating 100 Bq per kg of mushrooms every day for one year. The present study shows that a marked bipolarization of the risk perception about the health effects of radiation among residents could have a major impact on social well-being after the accident at FNPP.

Measurement of individual doses of radiation by personal dosimeter is important for the return of residents from evacuation order areas after nuclear disaster.

To confirm the availability of individual dose evaluation for the return of residents after the accident at the Fukushima Dai-ichi Nuclear Power Plant (FNPP), we evaluated individual doses of radiation as measured by personal dosimeters in residents who temporarily stayed in Evacuation Order Areas in Kawauchi village, which is partially located within a 20 km radius of the FNPP. We also compared individual doses with the external radiation doses estimated from the ambient dose rates and with doses estimated from the concentrations of radionuclides in the soil around each individual's house. Individual doses were significantly correlated with the ambient doses in front of the entrances to the houses (r = 0.90, p<0.01), in the backyards (r = 0.41, p<0.01) and in the nearby fields (r = 0.80, p<0.01). The maximum cumulative ambient doses in the backyards and fields around the houses were 6.38 and 9.27 mSv/y, respectively. The maximum cumulative individual dose was 3.28 mSv/y, and the median and minimum doses were 1.35 and 0.71 mSv/y. The estimated external effective doses from concentrations of artificial radionuclides in soil samples ranged from 0.03 to 23.42 mSv/y. The individual doses were moderately correlated with external effective doses in the backyards (r = 0.38, p<0.01) and in the fields (r = 0.36, p<0.01); however, the individual doses were not significantly correlated with the external effective doses in front of the entrances (r = 0.01, p = 0.92). Our study confirmed that individual doses are low levels even in the evacuation order area in Kawauchi village, and external effective dose levels are certainly decreasing due to the decay of artificial radionuclides and the decontamination of contaminated soil. Long-term follow-up of individual doses as well as internal-exposure doses, environmental monitoring and reconstruction of infrastructure are needed so that residents may return to their hometowns after a nuclear disaster.

Factors associated with nurses' intention to leave their jobs after the Fukushima Daiichi Nuclear Power plant accident.

We conducted a survey among nurses who were working at the Fukushima Medical University Hospital at the time of the Fukushima Daiichi Nuclear Power Plant accident to clarify the factors associated with their intention to leave their jobs during the radiation emergency. We asked 345 nurses (17 men and 328 women) about their intention to leave their jobs after the accident. We also asked about relevant factors including the participants' demographic factors, living situation, working status, and knowledge of radiation health effects. We found that living with preschoolers (OR = 1.87, 95%CI: 1.02-3.44, p = 0.042), anxiety about life in Fukushima City after the accident (OR = 5.55, 95%CI: 1.18-26.13, p = 0.030), consideration of evacuation from Fukushima after the accident (OR = 2.42, 95%CI: 1.45-4.06, p = 0.001), consideration of the possible radiation health effects in children (OR = 1.90, 95%CI: 1.02-3.44, p = 0.042), and anxiety about relationships with colleagues in the hospital after the accident (OR = 3.23, p = 0.001) were independently associated with the nurses' intention to leave their jobs after the accident. On the other hand, the percentage of nurses with knowledge on radiation health effects was relatively low among those who had the intention to leave the job and among those who did not have the intention to leave the job after the accident, with no significant differences between the two groups. Our results suggest the need for an education program for nurses regarding radiation health effects.

Internal radiation exposure dose in Iwaki city, Fukushima prefecture after the accident at Fukushima Dai-ichi Nuclear Power Plant.

As a result of the accident at the Fukushima Daiichi Nuclear Power Plant (FNPP) on 11 March 2011, a huge amount of radionuclides, including radiocesium, was released and spread over a wide area of eastern Japan. Although three years have passed since the accident, residents around the FNPP are anxious about internal radiation exposure due to radiocesium. In this study, we screened internal radiation exposure doses in Iwaki city of Fukushima prefecture, using a whole-body counter. The first screening was conducted from October 2012 to February 2013, and the second screening was conducted from May to November 2013. Study participants were employees of ALPINE and their families who underwent examination. A total of 2,839 participants (1,366 men and 1,473 women, 1-86 years old) underwent the first screening, and 2,092 (1,022 men and 1,070 women, 1-86 years old) underwent the second screening. The results showed that 99% of subjects registered below 300 Bq per body in the first screening, and all subjects registered below 300 Bq per body in the second screening. The committed effective dose ranged from 0.01-0.06 mSv in the first screening and 0.01-0.02 mSv in the second screening. Long-term follow-up studies are needed to avoid unnecessary chronic internal exposure and to reduce anxiety among the residents by communicating radiation health risks.