Impacts of environmental decontamination on the rebuilding of returnees’ lives after the Fukushima accident

Environmental decontamination after a nuclear disaster not only contributes to reducing the public’s exposure to radiation, it also introduces waste disposal issues arising from the decontamination process. In addition to that issue, the optimisation of decontamination efforts necessitates the consideration of various environmental, economic, and societal factors. Stakeholders’ perspectives are important for identifying the multifaceted aspects to be considered. We conducted a semi-structured interview survey in 2019 with ten residents in a rural community in Fukushima, Japan, which experienced a six-year-long evacuation due to the 2011 Fukushima Daiichi Nuclear Power Plant accident. The main survey questions addressed returnees’ perceptions of the decontamination of farmlands and forests. The ‘Steps for Coding and Theorization’ procedure was used for qualitative analysis. The analysis illuminated the positive and negative impacts of the decontamination process on the rebuilding of the returnees’ rural lives from various perspectives and identified elements to be considered for the optimisation of future remediation efforts. The removal of radioactive materials had a positive psychological impact on the returnees, fostering a sense of security that their crops were safe and instilling confidence that the high-quality environment of the region had been restored. These aspects were not included among the initial governmental objectives for decontamination, which were aimed solely at reducing radiation exposure. By contrast, the removal of fertile topsoil from farmland had a negative impact on the residents, making them hesitant to resume farming. Our findings suggest that emphasising procedural fairness in decision-making of decontamination options such as reflection of stakeholders’ opinions led to residents perceiving their post-decontamination situation more positively. Our results provide valuable insights for optimising remediation strategies for the recovery process following a significant nuclear accident.


Introduction
The objectives for people's radiological protection following a large nuclear accident are not only to mitigate radiation-induced health effects, but also to contribute to rebuilding the lives of the affected people in the long term, including ensuring sustainable living conditions [1]. Protective measures following a large-scale nuclear accident ensure that the intended benefits outweigh the negative effects, and the protective measures should be optimised, taking into account societal, environmental, and economic factors [1,2]. Environmental decontamination is an effective measure to reduce exposure among remediation efforts. It was conducted after the Chernobyl Nuclear Power Plant accident, in 1986, and the Fukushima Daiichi Nuclear Power Plant accident, in 2011. The massive environmental decontamination that characterised the Fukushima accident subsequently resulted in the generation of a large amount of removed soil and waste, and has brought a new social challenge issue of the final disposal of them. Therefore, the relationship between exposure reduction and waste generation is one of the issues that should be considered carefully when optimising environmental decontamination after a large-scale nuclear accident [1][2][3]. In addition, stakeholder involvement in decision-making on decontamination is an important aspect to consider [4]. There are undoubtedly many other items to consider from a variety of viewpoints, including environmental, economic, and societal aspects, but they have not been generalised, in part due to the lack of actual cases. Stakeholders' perspectives are useful for identifying the multidimensional elements to be considered. According to Wieder et al, the stakeholders' perspectives include information such as risk perception, community values, and the historical context of the place, all of which influence decisions on protective measures and are important factors, in addition to the rationale and resources needed, to derive reasonableness [5]. With the above in mind, for the application of an optimised remediation to ensure preparedness during a nuclear disaster and future nuclear disaster situations, a multidimensional assessment of the impacts of environmental decontamination activities would be informative for rebuilding affected people's lives.
Following the Fukushima accident, environmental decontamination was conducted to reduce the impact on human health and the surrounding environment. These efforts were targeted to include residences, roads, public facilities, farmlands, and forests near residential areas. There were several choices for farmland decontamination, including the removal of 5 cm of topsoil, disposing of it as waste, and replacing contaminated topsoil with clean deeper soil through methods such as reverse cultivation and deep plowing. The decontamination method used was selected according to the situation in each region. In forests, the organic layer of the forest floor was removed only in those areas within 20 m of the forest edge, with the aim of reducing the air dose rate in those residential areas [6]. As a result, reductions in air dose rates were observed at an average of 60% in residential areas and farmlands, and by 27% in the forests of the evacuation order areas within the 11 municipalities closest to the power plant [7,8]. The environmental decontamination efforts also contributed to the lifting of the evacuation order. However, in 2016, Fukushima Prefecture authorities submitted to the government an opinion requesting further measures for forest areas [9,10], indicating that the government's protective actions in forests were insufficient for people in the affected areas. From an economic perspective, about 13 million m 3 of contaminated soil and other waste were generated in the Fukushima Prefecture due to the decontamination [11], and about 3 trillion yen was invested by 2016, including storage of the waste in an interim storage facility [8]. Although it was decided that the contaminated soil and waste held in the interim storage facility would finally be disposed of outside the Fukushima Prefecture by 2045, a detailed plan has not yet been decided, and it is expected to become a nationally controversial topic.
The Japanese government reported the efficacy and impacts of the decontamination efforts on environmental and economic aspects as described above, and from an academic perspective, Evrard et al was extensively summarised, focusing on the details and effectiveness of the decontamination efforts [12]. However, only a few studies have been conducted on the direct or indirect societal impacts of environmental decontamination programs on residents' lives. Murakami et al showed in a quantitative study of residents in a region without an evacuation order that decontamination reduces residents' anxiety and contributes to an improvement in their subjective well-being [13]. Murakami et al suggests that environmental decontamination tends to have a mentally positive effect, in addition to reducing residents' exposure to radiation. Yamaguchi and Sakata focused on procedural justice in environmental decontamination and conducted a quantitative survey of residents in decontamination areas. They showed that the perceived necessity of decontamination affects perceived procedural justice [14]. As situations associated with the process of rebuilding are unique and complex for each person, there are a variety of influences that cannot be captured by quantitative research alone. Accordingly, the multidimensional impacts of environmental decontamination on the rebuilding of residents' lives in affected areas needs to be supplemented by a qualitative approach.
In the present study, we clarified the multidimensional impacts of environmental decontamination efforts on rebuilding residents' lives using a qualitative approach interviewing residents who had returned after evacuating from a rural area of the Fukushima Prefecture. We focused on the decontamination of farmlands, where large amounts of waste were generated, and in forests, where some argue that the measures were inadequate. A qualitative analysis of the interviews revealed both positive and negative aspects of environmental decontamination in rebuilding lives from multiple perspectives and identified issues to be considered for the optimisation of future efforts. Our study provides valuable information regarding the optimisation of remediation efforts for rebuilding following a large-scale nuclear accident.  [15]. The main industry in the district is agriculture. The evacuation period was for approximately six years, from 2011 to 2017. The population of the district was about 1300 before the accident, and about 350 people had returned as of 1 July 2020 [16], most of whom were elderly. Additional site information can be found in Takada et al study [17]. Decontamination of the district was carried out by the Ministry of the Environment during the residents' evacuation. In addition to decontaminating residential areas and roads, approximately 5 cm of topsoil was removed in a farmland decontamination effort. In forest areas, the organic layer on the forest floor was removed in areas within approximately 20 m of the forest edge near residential areas.

Interviews
Semi-structured interviews were conducted with ten returnees to the district between May and June 2019, and transcript data were used for the analysis. The data were also used by Takada et al [17], but the objectives of the two studies and the applied methods were completely different. The present study focused on the impact of the decontamination of farmland and forests on rebuilding returnees' lives, using a qualitative approach, while Takada et al [17] focused on the factors affecting the resumption of forest use after the accident, applying a quantitative approach based on a text mining analysis.
Interviewees from the district were selected according to age and gender, and interviews were conducted by two interviewers for 30 min to one hour per person. Table 1 shows information about the interviewees regarding their farmland and forest use. To clarify their perceptions of the district's environmental remediation efforts, the interviews consisted of questions about (1) the current situation in the district, (2) their perceptions regarding radiation in the forests and forest use, (3) their perceptions regarding the decontamination of farmland, and (4) changes in their own quality of life [17].

Analysis
The transcriptions of interviews were analysed using Steps Coding and Theorization (SCAT) [18]. Otani, from Nagoya University, developed SCAT as an accessible qualitative data analysis method. It has mainly been used by researchers in the fields of medical education and palliative care [19]. Our analysis consisted of two steps: decontextualisation, in which themes were generated from the text, and theorisation, in which the collected information was summarised to construct theories. In the first decontextualisation, keywords to focus on were extracted from the original texts, and themes were created through a process of rephrasing them. In the next recontextualisation process, a story was developed from the themes that emerged and were theorised. All offered theories derived from the analysis are included in the supplemental information (table S1).

Ethical considerations
All participants voluntarily participated in the survey and agreed that the data could be used for research purposes and published in research papers. Prior to the start of all interviews, the interviewer provided an overview of the survey and detailed information about participation, including the handling of personal information and the possibility of withdrawing from the survey at any time. Then, they obtained the participant's signed consent form. Data collection was submitted to the Committee for Ergonomic Experiments at the National Institute of Advanced Industrial Science and Technology, and reviews were waived.

Returnees' concerns after the completion of decontamination efforts
While residential areas, farmlands, and forests near residential areas have been decontaminated, parts of forests more than 20 m from the forest edge have not been, which led to perceptions among the returnees that there was a mosaic of safe and unsafe areas in the district. One returnee was aware that, even though decontamination had been carried out, the air dose levels had not returned to pre-accident levels. For most returnees, the district is basically safe now, but concerns remain about the effects of radiation in the future.

Significance of decontamination for returnees
For the returnees, the significance of the environmental decontamination efforts created a circumstance in which the contaminants no longer exist in the district, rather than reducing exposure to radiation. Some returnees expressed disgust with radioactive materials from the accident and believed they should be removed from their surroundings. This opinion was noted by several returnees and was unrelated to their degrees of perceived radiation risk. Several also pointed out that 'decontamination' means that the polluter returns the contaminated area to its original environment.

Leaving contaminants is not acceptable; it's like having a dirty toilet but not cleaning it…So, decontamination is a necessity…Moreover, an activity of our community was not the cause of the contamination. (c)
Other returnees expressed that the decontamination work, as an act of cleaning up the community, positively affected their feelings (table 2). Some said that the decontamination efforts would have motivated them to resume their lives after returning their community.
When we decided on a decontamination method in the district, I said to my colleagues, "Let's throw away the dirt. We have to start fresh in our lives." (f) Another participant said that decontamination gave the returnees confidence that a high-quality environment had been restored to their community, as before the accident.

Significance of farmland decontamination methods
The returnees suggested that farmlands should be decontaminated with crop safety as the top priority. They believed that the removal of topsoil containing radioactive materials would assure greater safety, compared with alternatives, such as deep plowing (table 2). 'Safety,' here, means not only that the presence of radioactive materials in crops is below the standard value, but also refers to the level at which consumers consider the crop to be safe. Another reason for the returnees' thorough pursuit of safety was the pressure to avoid suspensions after resuming farming. If radiocesium is detected in the crops above the standard level, all shipments of that crop would be stopped for the entire district. The situation would obstruct everyone's farming efforts and lead to delays in the revitalisation of the entire district.
If radiocesium is detected [above the standard value] from crops, .. the whole community will lose all sales. Everything would be over. (j) One negative impact of farmland decontamination that the returnees mentioned was that the fertile topsoil was removed, resulting in a serious decline in soil fertility (table 2). The removed topsoil was extremely valuable to farmers, and the damage caused to agriculture by the removal was significant.
It takes decades to produce fertile soil one centimeter thick. Therefore, it takes courage for a farmer to strip off the topsoil. The topsoil itself is an inheritance. (b) As described above, the decontamination of farmlands by topsoil removal led to both positive and negative results. However, as the negative impact is a tradeoff for safety, the topsoil removal was basically accepted by the entire community. Several returnees had already overcome the declining quality of their soil's fertility.

Giving up on forest decontamination
The returnees still had complicated feelings about the forests, which had been decontaminated in only the 20 m nearest residential areas. They reported that, before the accident, they used more than the areas 20 m from the forest edge to collect wild foods and for other purposes. Therefore, they felt it was unreasonable for the decontamination targets not to include the full area used before the accident. At the same time, the returnees noted that forest decontamination was not cost-effective, compared to efforts in farmlands, and that excessive decontamination increases risks, such as landslides. Accordingly, the returnees did not make strong demands for further measures in the forests. There was also the perception that attachment to the forest and demands for additional measures have decreased over time.

Decontamination of the entire forest is no longer important. I have come to feel that I don't need to go into the forest anymore. (d)
Some returnees have a special attachment to forest use and still feel strongly about the need to decontaminate the entire forest area.
The returnees viewed wild foods in the district as basically contaminated; however, the older returnees, in particular, have tended to continue collecting wild foods as they did before the accident, indicating a difficulty in changing habits. In some of these cases, family members disposed of the wild foods collected by other members of the household. Traditional forest uses, apart from foraging, such as the agricultural use of compost made from fallen leaves, were also interrupted throughout the district. While some returnees were adapting to a new lifestyle without forest use, others were searching for alternative methods or were unwilling to accept a change in lifestyle. In addition, there were several unresolved issues related to the forests. One returnee accepted the situation, in terms of his own safety, but could not accept the loss of the forests' economic value. Recently, cases of the re-contamination of farmlands adjacent to forests, due to the inclusion of fallen leaves, have been observed, and some returnees were concerned about its impact on their farming.

Decision-making concerning the method and scope of decontamination
Some returnees who have been district leaders were involved in decision-making regarding farmland decontamination. They believed that the level of stakeholder involvement was appropriate. Other returnees thought that the opinions of returnees had not been adequately reflected. Some pointed out that, as opinions differ even among returnees, stakeholders' involvement via representative participation has a limit, in terms of reflecting diverse opinions. While some returnees were dissatisfied with the results of the farmland decontamination efforts, those who were satisfied felt that their opinions were reflected in the decontamination policy.

We rejected reverse cultivation or the use of zeolite [as proposed by the Ministry of the Environment]. Our request was only for removal…Decontamination was done properly, and our farmland was relatively well decontaminated. (f)
In contrast to the farmland efforts, there was nothing but dissatisfaction with the forest decontamination. Returnees perceived that the forest decontamination policy was unilaterally imposed by the government and did not reflect their opinions. Of course, there were also some returnees who did not emphasise procedural values on the decision-making process and accepted the situation.

Impacts of environmental decontamination on rebuilding returnees' lives
The positive impacts of environmental decontamination in the rural areas of Fukushima encouraged returnees to resume their lives in the community and to regain confidence that a high-quality environment had been restored to the district. The most positive impact of the farmland decontamination was the returnees' perception that their crops were safe. Conversely, the removal of fertile topsoil created a new problem for the residents: farming could not resume without restoring the soil's quality. The problem appears to have been caused by a strong desire to avoid the business suspensions that would follow if acceptable radiation levels were exceeded, which led to demands for removal of topsoil, which is highly effective but also very damaging to soil's quality. If the decontamination projects had been more flexible, such as by considering a more optimised method for each step of the process, efforts to restore the soil's fertility may have been unnecessary as a result of choosing other, less damaging (and less waste-creating) decontamination methods, such as reverse cultivation or deep plowing. In addition, decontamination was a passive, rather than active, project for most residents, which may have made them more cautious and led them to demand excessive decontamination.
Positive topics regarding the forests' decontamination were not identified in the present set of interviews. The limited decontamination area prevented some returnees from resuming the traditional rural lifestyle that they had hoped for. Despite the situation, few requests for further measures in the contaminated forests were observed. Yasutaka and Naito [21] estimated that the decontamination of Fukushima's entire forested area would cost more than 16 trillion yen and have limited effectiveness in reducing the public's radiation exposure; the returnees seem to intuitively, if not specifically, understand this fact. At the same time, a questionnaire survey of local municipalities in 2019 indicated that further forest decontamination was one of the remaining issues for the municipalities [22]. The opinions from the municipalities were inconsistent with returnees' perceptions indicated in the present study. There is a possibility that less-positive feelings among the public toward the forests, as observed in the present study, were mistakenly interpreted by the municipalities as a need for further decontamination. Given the fact that radiocesium in a forest ecosystem is currently distributed in the system and circulates [23], there is no guarantee that additional decontamination efforts would enable returnees to resume following a traditional lifestyle. Environmental remediation techniques encouraging resumption of the traditional lifestyles is required in the future.
The right-hand column of table 2 shows the objectives of the decontamination projects set by the Japanese government. The basic goal was to lower additional doses from external exposure and, accordingly, to lower the air dose rates in residential areas, where people spend most of their time [8]. With regard to farmlands, the objective was to provide safe crops, in addition to the above [20]. Notably, the significance of decontamination for the returnees did not coincide with the government's objectives, except for crop safety. Although the government's goal of decontamination, by reducing radiation exposure, was not included in the returnees' perceptions as a positive impact, the positive effects on the returnees' mental states were observed, even though these were not included in the government's objectives. There was no indication that the large amount of waste generated or cost issues, which were pointed out internationally by the ICRP and others, affected the rebuilding of returnees' lives. This may be because the area was not the home of interim storage facilities or final disposal sites, and because there have been no cost burdens imposed on the returnees.
Murakami et al showed that decontamination efforts were associated with a reduction in residents' anxieties in one area without an evacuation order [13], but none of the returnees in the present study emphasised that the decontamination efforts had reduced their anxiety about radiation. Differences in the residents' circumstances may have led to the differences between the results noted by Murakami et al [13] and ours. In Murakami et al [13] study, decontamination was carried out while residents continued living in the area, and the decontamination lowered ambient radiation levels. In this study, however, residents returned from evacuation sites, where the radiation impact was small, to areas that had been decontaminated but were still heavily affected by the accident. Thus, the returnees would have had little opportunity to understand first-hand that the radiation levels around them had been greatly reduced by the decontamination program. In the radiation protection system, dose reduction by decontamination corresponds to the concept of averted doses [1]; this may be a concept that is difficult to grasp for people who have experienced various radiological situations due to evacuation.
The returnees understood that decontamination efforts aimed to restore the contaminated environment, and this helped them to regain confidence in the local natural environment. This may also have restored their positive affective connection to their home district. In recent years, many studies have examined the impact of disasters on place attachment and shown that major environmental changes due to natural disasters and climate change negatively affect residents' affective connection to places and reduce their willingness to return, while coping with the situation, including the implementation of remediation efforts, positively affects residents' place attachment [24][25][26][27][28][29]. The above studies mainly focused on natural disasters, but similar results could have occurred following a nuclear disaster situation. As understanding place attachment is important for policy makers to enhance recovery in disaster-affected areas [28], additional studies on the relationship between decontamination and residents' attachment to their places are needed.
One of the essential procedural values of any radiological protection system is stakeholder involvement, which leads to respect for the affected people and the restoration of dignity [4]. The present study also suggests that stakeholder involvement may have a positive impact on rebuilding lives. Among the returnees who participated in the decision-making process on the decontamination method for the farmlands, we recorded statements that were relatively positive about the situation after the decontamination. By contrast, the methods for forest decontamination were an imposed decision for most returnees, and none expressed positive views of the current situation. Some even felt that the lack of traditional forest use had resulted in a loss of freedom in their lifestyle. Various case studies have shown that decision-making efforts that lack procedural fairness prevent public acceptance [30][31][32]. For instance, in the construction of a hazardous waste facility in Canada in the 1980s and 1990s, top-down decisions felt like imposed decisions to stakeholders [33] and the project failed [31]. The feelings about decision-making regarding environmental decontamination we found were also consistent with these previous cases. Strategies for the unsolved issues related to forests in Fukushima must not be imposed on the region by the government, but proactive involvement of local residents is required.

Implication for optimised environmental remediation
Our study clarified residents' risk perception and the community values associated with environmental decontamination after the Fukushima accident through interviews with returnees, who are important stakeholders. As the public perspective influences decisions on protective measures in the event of an accident, our results provide useful information in the framework of reasonableness related to radiological protection, as proposed by Wieder et al [5]. In particular, the suggestion that decontamination had a mentally positive impact on the returnees is a new and noteworthy finding. However, the fact that decontamination efforts led to a problem disposing of the large amount of contaminated waste, and that it cost more than 3 trillion yen, cannot be ignored. We cannot conclude that the decontamination performed in Fukushima was the universally optimal remediation strategy. To optimise remediation and rebuild the lives of people affected by a large-scale nuclear accident, the positive impacts observed in the Fukushima case need to be recalled, and other impacts not considered by the affected people, such as contaminated waste and cost issues, should also be taken into account. The implications from the study are as follows: • When residents value safety and security and demand excessive decontamination efforts in the view of radiological protection experts, complying with their demands may not be the best approach for the remediation of their area/situation. Authorities need to base all projects on good communication with residents, to better understand their concerns and values, and to practice flexible planning. Sometimes, a case-by-case approach, such as the co-expertise process [1,34,35], may be more effective. • The perception that contaminated land has been remediated has a mentally positive impact on residents.
Remediation restores the positive affective connection to the place or maintains it at the pre-accident level, encouraging them to rebuild their lives in the affected area. • The consideration of the ethical aspects (such as procedural values noted by the ICRP) of remediation strategy decisions will lead to residents' more positive perceptions of the circumstances. Procedural fairness must be pursued to ensure that remediation is satisfactory to residents while balancing safety with cost and waste concerns.

Limitations of the study
In the present study, the qualitative approach of using interviews clarified the multidimensional impacts of environmental decontamination on rebuilding the lives of returning residents and provided valuable suggestions for the optimisation of future remediation strategies. However, our study has several limitations.
The study was conducted in only one rural district in the former evacuation zone, so the generalisability of the results needs to be verified. In particular, as noted in the difference between the present study and Murakami et al's [13] work, divergent opinions might be gathered from residents of non-evacuated areas. Furthermore, since our interviewees were exclusively among returning residents, the perceptions of those who did not return and who opted to relocate would likely be quite different. Therefore, it is not possible to deduce from this study the impact of decontamination on the rate of return. It should also be noted that perceptions of the impact of environmental decontamination on rebuilding lives are likely to evolve over time, and the results we present only reflect the state eight years after the accident and two years after the residents' return. Future research should include studies in several areas with different situations, similar studies in the same area on people who moved permanently serving as a control group, and long-term follow-up studies.
The study also has limitations regarding the optimisation of remediation efforts. We identified various impacts of decontamination, but these are qualitative but not quantitative information. For assessing optimisation, an assessment for larger populations is required about quantitative or semi-quantitative importance of these aspects, including aspects outside the scope of this study, such as exposure reduction, waste issues, and economic impacts. Furthermore, while our study assessed the efficacy of the decontamination efforts as a radiological protection measure, other crucial aspects, such as the sustainability of the project, were not the main focus of our work. The concept of sustainable remediation [36], developed in the field of soil and groundwater contamination for managing contaminated land, may also be relevant.

Conclusion
In 2019, we interviewed returnees in a rural area of the Fukushima Prefecture to explore the multidimensional impacts of environmental decontamination on rebuilding their lives following the nuclear accident and to identify key considerations for optimising remediation strategies. Our study identified returnees' perceptions of risk and the community values that influence protective measure decisions. We observed a negative impact from the removal of fertile topsoil from farmlands, which made the returnees hesitant to resume farming. However, there were also positive psychological effects, including a sense of security regarding the safety of their commercial crops and confidence that the high-quality environment of the area had been restored. It is noteworthy that the environmental decontamination efforts exhibited certain positive impacts that deviated from the government's primary objective of reducing additional radiation exposure. The emphasis on procedural values also implies that returnees are more likely to perceive the post-decontamination state of the area positively. In terms of optimising remediation strategies during the recovery from a significant nuclear accident, such positive impacts should be retained and enhanced while considering other challenges, such as waste-generation and costs that might be difficult for affected residents to consider.

Data availability statement
The data cannot be made publicly available upon publication because they contain sensitive personal information. The data that support the findings of this study are available upon reasonable request from the authors.