Background

A body of literature indicates that media plays an important role not only in providing information but also in shaping perceptions. Content as well as volume of coverage are important considerations. For example, Kasperson et al. (1988) [16] developed a theoretical framework to demonstrate that information about contemporary disasters obtained from the media has a major effect on risk perception, i.e., a human being’s subjective estimation of risk. Furthermore, research has indicated that anxiety can actually be reduced by an intervening perception that the risk is dangerous but manageable [17]. Renn et al. (1992) demonstrated that an expanded volume of media reporting tends to heighten risk perception [18]. Vestermann et al. (1999) showed that massive press coverage following a major catastrophe increases anxiety among individuals [19].

Several studies have examined the correlation between risk perception, anxiety, information, and the mass media following the Fukushima nuclear accident. However, none of these studies has focused specifically on the residents of Fukushima Prefecture including evacuation zone. This study is the first to focus on Fukushima Prefecture residents to determine how anxiety about radiation has been associated with information source and the media.

Sugimoto et al. (2013) surveyed 1560 residents of Soma City in July 2011 and found that radiation/health fears were high among those who used word-of-mouth, or rumors, as a means to obtain information. In addition, survey findings indicated that fear for the future was low among users of national newspapers and high among users of local newspapers. Furthermore, this research effort found that fear about social disruption was high among radio listeners [20]. In a survey of the headlines of national newspapers published between the date of the earthquake (March 11, 2011) and January 2012, Kanda et al. (2014) identified many reports about “danger and risk” in March 2011. Kanda and colleagues noted that although the circumstances of radiation exposure remained unclear; these reports were important for disseminating information necessary for risk avoidance. This study also suggests the possibility that these reports may have had a subsequent impact on increasing risk perception among the general population [21].

The Fukushima nuclear accident was the first nuclear disaster in the world to occur since the widespread proliferation of the internet. Needless to say, the internet became an important source of information for residents of Fukushima [22, 23]. A December 2015 online survey of 9249 residents of Tokyo, Osaka, and Fukushima, Murakami et al. (2016) found that those who trusted the government had a low “dread” risk perception according to Slovic’s classification, while those who trusted TV and radio, direct information from friends, and online information from researchers and others had a high “dread” risk perception [24]. In contrast, Rubin et al. (2012) examined 284 citizens of the UK who were in Japan at the time of the nuclear accident and found that anxiety levels were high among people who obtained information from Japanese government websites and blogs [25]. Another study conducted in Belgium, only marginally related, found that risk perception about the Fukushima accident was higher among television viewers and consumers of word of mouth, but lower among those who were satisfied with media coverage of Fukushima and who had been exposed to the issue for an extended period of time [26].

Against this backdrop, the present study aimed to examine a possible link between health-related anxiety and residents’ trusted sources of information. Considered in this study were additional factors such as demographics, knowledge, and health literacy skills.

Participants

This survey targeted 2000 residents of Fukushima Prefecture aged 20 to 79. We divided Fukushima Prefecture into four areas based on the general regional classification of Aizu, Nakadōri, Hamadōri, and the evacuation area (the restricted area, evacuation prepared area, and deliberate evacuation area as determined on April 22, 2011), and selected 500 people from each area. The selection was based on a two-stage stratified random sampling (stage one survey of region, stage two of individuals selected randomly from the Basic Resident Registration). Nakadōri and Hamadōri included local municipalities that were partially in the evacuation area; these were included in the evacuation area. The instrument used in the present study, entitled “Survey of Health and Information,” was administered as an anonymous, self-reporting postal questionnaire. We considered a returned questionnaire as participant consent to the objective of the study and their voluntary participation in it. We received 916 responses from 1985 survey subjects (excluding those returned to sender because no one was residing at the address). After excluding 55 respondents who left age or sex blank, we analyzed data from 861 respondents, for a valid response rate of 43.4%.

Survey instrument

For demographic information, respondents were asked to report their age, sex, area of residence, as well as current residence status. Options included: own home, public housing, government subsidized housing, rental home or apartment, temporary housing, home of friend/relative or other. Respondents were asked to specify whether they had children aged 18 or younger, 19 or above, were pregnant, had a pregnant family member, or had “none” (no children) at the time of the earthquake. Survey participants were also asked about their educational background, employment status, family structure, housing prior to the earthquake, whether or not they had relocated to avoid radiation.

Questions also included indications of social capital and social participation as well as health related behaviors such as exercise, sleep satisfaction, alcohol consumption, and smoking. Respondents were asked to rate their health status on a five-point scale (“extremely good,” “very good, “good,” “fair,” and “not healthy”). Participants completed the health literacy scale developed by Ishikawa et al. for use with the general public [28]. The Cronbach’s alpha coefficient of the scale has been reported as 0.86, and in the present study sample it was 0.89. Knowledge about radiation was assessed according to a respondent’s knowledge of the following five areas: properties of radiation, probability of death from cancer, genetic impact, DNA repair, and food reference values. Participants were asked to rate short sentences which were well known and often misunderstood as true or false, and correct answers scored one point each for a total of five questions. The Cronbach’s alpha for knowledge about radiation was 0.52.

A specific group of health related questions focused on anxiety. Participants were asked to rate their level of health anxiety immediately after the nuclear accident and current level about the effects of radiation on their health due to the nuclear accident on a five-point scale ranging from “None” to “Extreme”. Questions asked about receiving health examinations or attending lectures (8 items). Participants were asked to rate their radiation anxiety (the 7-item Radiation Anxiety Scale developed by Fukasawa et al. [29]). The Cronbach’s alpha coefficient of the scale has been reported as 0.81, and in the present study sample it was 0.84. Participants were asked about actions to protect against radiation (4 items). They were asked to comment on the impact of harmful rumor and indicate something gained through the earthquake experience such as posttraumatic growth which can be seen as positive psychological change experienced as a result of the struggle with a major life crisis or a traumatic event.

Several questions focused on sources of information to trust. Survey participants were asked to select up to three main items from the following 11 options: International organizations (UN, WHO, etc.), experts from universities and other academic institutions, government ministries, local newspapers, national newspapers, NHK (public broadcasting), private local broadcast television, private national broadcast television, local government, volunteer organization such as citizen groups, and “none of the above.” Participants were asked to indicate media used for information about radiation by selecting up to three main items from the following 13 options: Local newspapers, national newspapers, NHK television (public broadcasting), private local broadcast television, private national broadcast television, radio, internet news, internet sites/blogs, SNS (Facebook, Twitter, etc.), magazines/books, local government publications, word of mouth, and “none of the above.”

Analysis plan

Many of the survey answers were collapsed in two or three categories for analysis. For example, for age, respondents were divided into three groups comprising those aged 20 to 44 years (prime adults), 45–64 years (middle aged), and 65 years and older (elderly). For area, two groups were created, and comprised those in the evacuation area or ‘other’ (Aizu, Nakadōri and Hamadōri). Respondents specified whether they had children and, for analysis, they were divided into those with and without children.

Respondents were asked to rate their health status on a five-point scale (“extremely good,” “very good, “good,” “fair,” and “not healthy”) and were then divided into the two groups of ‘healthy’ (those who responded “extremely good,” “very good, and “good,”) and ‘not so healthy’ (those who responded “fair” or “not healthy”). For health literacy, scores are determined as the sum of the values of the five items, with those above the second tertile placed in the “high” group and those in the second tertile or below placed in the “low” group. Scores of knowledge about radiation were determined as the sum of the values of the five items. Those above the second tertile placed in the “high” group and those in the second tertile or below placed in the “low” group

Participants were asked to rate “Your current level of anxiety about the effects of radiation on your health due to the nuclear accident” on a five-point scale ranging from “None” to “Extreme,” with responses treated as a continuous variable ranging from 1 to 5. The objective variable was “Your current level of anxiety about the effects of radiation on your health due to the nuclear accident”. The explanatory variables were“Trusted sources of information about radiation,” and “Media used for information about radiation”. Respondents were asked to select the three main sources/media,

In order to consider the correlation between “current anxiety” and all other items, we first performed univariate analysis (Student’s t-test, and variance analysis when there were multiple categories for explanatory variables), with “current anxiety” as the objective variable and all other responses as explanatory variables. P<0.05 was considered statistically significant. Next, multiple regression analysis was performed using explanatory variables found to be significant in the univariate analysis, with “current anxiety” as the objective variable. Of the explanatory variables found to be significant, we excluded responses of “none of the above” for trusted information source. Ultimately, health status, health literacy score, residing at one’s own home, having no children, and working were used as moderator variables. Finally, age, sex, area, and knowledge score on radiation were forcefully input as basic moderator variables.

Questions about the trusted source of information and media used for information about radiation elicited multiple answers from participants (who were instructed to choose three main items). Due to the restriction that "Please select up to 3 main items", these explanation variables are not independent of each other completely. Therefore, we created six multiple regression models that included explanatory variables one by one. However, we did not see the confounding of "trusted information sources" and "media to use" to avoid complexity. Thus, variables found to be significant through univariate analysis, i.e., “trust in government ministries,” “trust in local government,” “trust in citizen groups,” “use of private local broadcast television,” “use of internet sites/blogs,” and “use of word of mouth,” were applied in different six models to examine their associations with current anxiety levels.

Limitations

This study has some limitations. First, because of its cross-sectional design, causation could not be established. For example, it is possible that, rather than anxiety being low because participants trusted government ministries as a source of information, there were people who trusted the government as a source of information because their anxiety levels were low. Second, the respondents may have included a disproportionate number of those inclined to be relatively more cooperative with a Fukushima Medical University survey. Thus, there may have been fewer responses from people who do not trust authorities. Third, because respondents tended to be relatively older, our study population included fewer users of the internet, especially SNS, which represented a limitation to understanding the actual conditions in this area. Finally, those with poor physical or mental health are generally less likely to respond to a survey, which may have influenced the overall results.

There is a possibility that the difference in interpretation and data used will vary depending on the intended audience. Local mass media responds to the local residents’ demand and national mass media responds to the people in many parts of the country. In addition, there are many citizen groups that respond to the demand of those who are not satisfied with the information coming from sources of authority, including commonly available mass media. Furthermore, information might be shaped for commercial purposes such as highlighting sensationalism for popular sales. Headlines around the globe indicate that there are many sources of information on the internet that promulgate misinformation, fake news, and harmful rumors[35, 36] along with trusted experts' scientific information [37, 38].

Implications for further study

In this study, it was found that the significant relationship to anxiety varies depending on the sources of trust and media used. In a nuclear disaster, the raw data is difficult for lay people to interpret. People often rely, instead, on the interpretation of others. However, the interpretations of government, local government, mass media, citizen groups and others may differ from one another. Nuclear issues are not just a matter of science, but are sometimes shaped by political factors which influence interpretation. In addition, even the choice of data and information might be different.

People may well need help and guidance identifying reliable sources of information. Media literacy education, popular in the U.S. [39, 40] may be useful in schools and help prepare the next generation to identify legitimate sources of information. Choosing reliable information from mass media and the internet is critically important for people facing nuclear disaster.

Health literacy is also very important. In this study, those in the upper group of health literacy scores tended to be less anxious. Health literacy is determined by interactions–such as those between scientists and the lay public, between health professionals and patients. Professionals can improve the health literacy of the public by ‘translating’ health information into everyday language and avoiding jargon and complex mathematical terms.

When nuclear accidents requiring high-level expertise occurred, scientific knowledge and medical knowledge of media managers, reporters and program makers inside the mass media institutions proved to be insufficient [41, 42]. At the same time, the scientists and scholars did not focus on providing information suitable to the public. During and after the Fukushima nuclear power plant accident, confusion occurred among those reporting through the mass media and contradictory information was also disseminated [43]. Therefore, the improvement of health literacy of the mass media and the news organizations is indispensable and could prove to be effective for dealing with the preparation for and aftermath of disasters. Clear communication supports informed policy makers, journalists, and communities.