Knowledge of genetic effects of radiation exposure in Fukushima after the nuclear accident in relation to health literacy
論文ID: 2023-15
詳細
論文ID: 2023-15
Purpose:Since the nuclear power plant accident in Fukushima, there has been anxiety about the effects of radiation exposure on future generations, specifically that the effects of radiation exposure may be inherited by descendants. We explored the relationship between health literacy and knowledge of the genetic effects of radiation exposure on this anxiety in both men and women.
Methods:In August 2016, a mail survey was conducted among 2,000 Fukushima residents aged 20-79 years. The objective variable was a true/false question, “No genetic effects have been observed among second- and third-generation atomic bomb survivors of Hiroshima and Nagasaki.” The explanatory variable was the Critical and Communicative Health Literacy (CCHL) scale score. We also asked about variables including attributes of age, sex, affiliation with an organization or group, and media used for information about radiation.
Results:There were 861 valid responses (43.4%). Logistic regression analysis revealed that both men and women with higher CCHL scores were more knowledgeable about genetic effects. Men who were older and women who used government publications were knowledgeable about genetic effects, but men who belonged to community groups and women in evacuation areas who used private national broadcast TV or word-of-mouth were not knowledgeable about genetic effects.
Conclusions:CCHL was significantly associated with knowledge about genetic effects of radiation exposure. For men and women in Fukushima, the results suggest that improvement in health literacy is necessary to select media that disseminate accurate information. For men, recommendations regarding suitable sources of information cannot be ascertained through this study, because the source of information for men was not significantly associated with KOGEORE by multivariate logistic regression analysis.
The Great East Japan Earthquake that occurred on March 11, 2011, led to an accident at the Tokyo Electric Power Company Fukushima Daiichi Nuclear Power Plant (NPP). After that, various accurate and inaccurate pieces of information in the media about the invisible threat of radiation spread, and some citizens of Fukushima were swayed by this1). According to the Fukushima Health Management Survey, the proportion of those who answered that radiation exposure after the nuclear accident was likely to have an impact on the health of future generations decreased significantly in FY2014 and has remained at 30% since then2). In addition, the UNSCEAR 2013 report (published on April 2, 2014) stated that exposure during pregnancy does not cause miscarriage, perinatal mortality, congenital effects, cognitive impairment, or genetic effects3). However, there were still fears and concerns about the effects of radiation exposure on future generations, which can have a negative psychological impact on the people of Fukushima.
According to the results of our previous study, in Hamadori and evacuation areas in Fukushima Prefecture, those who were aware that “the survey on the health effects of the second and third generations of atomic bomb survivors in Hiroshima and Nagasaki did not show any genetic effects” had significantly lower anxiety about the effects of the Fukushima NPP accident on future generations4). Therefore, further dissemination of this knowledge may reduce such anxiety about future generations .
Recently, the concept of health literacy has been attracting attention5). Health literacy is not just the knowledge and understanding of health and illness, but the ability to collect and utilize the necessary information5). As a measure of health literacy, the communicative and critical health literacy scale (CCHL) in Japanese was developed by Ishikawa et al.6)
It is presumed that during the nuclear accident, Fukushima residents needed to utilize their health literacy to collect and utilize appropriate information on radiation7). In Fukushima after the earthquake, Nakayama et al. reported that higher health literacy resulted in lower radiation health anxiety8). However, no studies have been conducted investigating a possible connection between Fukushima residents’ health literacy after the NPP accident and their Knowledge Of Genetic Effects Of Radiation Exposure (KOGEORE). Therefore, the purposes of the present study were to examine the relationship between health literacy and the KOGEORE of Fukushima residents after the nuclear accident, and to gather information about the dissemination of accurate information about the genetic effects of radiation exposure. The hypothesis was that Fukushima residents with high health literacy are more likely to seek out KOGEORE as essential information. As the objective variable was the presence or absence of knowledge, social factors and the means of obtaining information were considered to be relevant in addition to health literacy and factors other than health literacy were considered. This was also an exploratory study. In addition, previous studies have shown that there are gender differences regarding perceptions of the effects of low-dose radiation exposure and anxiety about radiation9-11). Therefore, in the present study, we also conducted a stratified analysis by gender.
This study was based on data from the Survey of Health and Information conducted on 2,000 Fukushima residents aged 20-79 years from August to October 2016. We divided Fukushima Prefecture into four areas, consisting of Aizu, Nakadori, Hamadori, and the evacuation area (the restricted, evacuation-prepared, and deliberate evacuation areas as determined on April 22, 2011), and selected 500 people from each area. The selection was based on a two-stage stratified random sampling. We received 916 responses from 1,985 survey subjects (excluding those that had been returned to sender). After excluding 55 respondents who did not include their age or sex, we analyzed data from a total of 861 respondents;a valid response proportion of 43.4% (36.7% for men 50.7% for women).
MethodsThe study methods were approved by the Fukushima Medical University Ethics Committee (Approval Number:2699). The questionnaire used in the present study, entitled Survey of Health and Information, was administered as an anonymous, self-reporting postal questionnaire. Returned questionnaires were considered the subjects’ informed consent to participate in the study.
The questionnaire included 35 questions and was reported Nakayama et al.8) In this survey, the item used to measure KOGEORE stated “Surveys on the health effects of the second and third generations of atomic bomb survivors in Hiroshima and Nagasaki have not found any genetic effects”;if the participant thought it was true they entered ○ in the answer column;if they thought it was incorrect, they entered ×;and if the they were unsure, they were to enter △8). The item was correct, so we considered a response of ○ to be the only correct answer. This was the study’s objective variable.
The explanatory variable was health literacy, using the communicative and critical health literacy scale (CCHL) in Japanese developed by Ishikawa et al.6) CCHL requires a total of five items, rated on a scale of 1 to 5 points per item6). In the present study, this was used in the analysis as a continuous quantity. The Cronbach’s alpha coefficient for the present study sample was 0.89. This was calculated as the total score for each item. Higher scores indicate higher health literacy.
The moderator variables were age and sex. For age, the respondents were divided into two groups:20-64 years (non-elderly), and ≥ 65 years (elderly). Currently, the World Health Organization (WHO) defines older people as those aged 65 years and older;therefore, this study followed the age criteria used to distinguish between non-elderly and elderly people in this study.12) For area, the participants were divided into two groups, those in the evacuation area and “other” (Aizu, Nakadori and Hamadori). We asked the participants about their current and pre-earthquake housing and divided them into two groups, homeowners and renters. We asked whether the participants had children at the time of the accident and divided them into those with and without children. We inquired about family structure and divided the participants into single-person households and others. Educational background was divided into two groups, people in university / graduate school level education or above, and other. We asked the participants about employment status and divided them into those who had a job (including temporary retirement) and those who did not. We inquired about the participants social capital and divided them into those who scored above average (“high”) and those who scored below average (“low”). The question on social capital consisted of four statements. 1. People living in the area help each other. 2. I can trust people living in the area. 3. People living in the area greet each other. 4. If problems occur in the area, people work together to try to resolve the problems. Subjects answered on a five-point scale from ‘1. not at all agree’ to ‘5. strongly agree’. These were rated in a total score.
We asked the participants how often they exercised and divided them into those who exercised more than once a week and those who exercised less than once a week. We inquired of the participants sleep quality and divided them into four categories:“satisfied”, “slightly dissatisfied”, “fairly dissatisfied”, and “very dissatisfied”. “Satisfied” was its own group, and the other categories were classified under “dissatisfied”. Health status was divided into five categories:“extremely good”, “very good”, “good”, “fair”, and “unhealthy”. Those who answered “extremely good”, “very good”, and “good” were classified as “healthy”, and those who answered “fair” and “unhealthy” were classified as “not healthy”. We asked about drinking habits and smoking habits and divided the participants into those who were current drinkers or smokers and others.
We asked the participants if they were affiliated with an organization or group and asked them to choose all of the six options that apply. The choices were:“Neighborhood associations/resident associations”; “Regional groups such as youth groups, women’s associations, elderly associations, PTAs (Parent-Teacher Associations), or child associations (training groups)”;“NPOs (Nonprofit organizations), volunteer/citizen activity organizations, or co-operative associations”;“Vocational organizations, such as business associations, peer associations, industry groups, labor unions, etc.”;“Other groups”;and “No participation”. We inquired the health examinations, seminars, and briefings that they received after the Great East Japan Earthquake, with multiple answers. The choices were: “Regular health checks at municipality/workplace”; “Other kinds of health checkup”;“Individual dosimeter measurement of external radiation”;“WBC internal radiation measurement”;“Fukushima Health Management Survey”;“Thyroid Examination field information session”;“Lectures on radiation and the thyroid gland”;and “Other lectures or information sessions”. We inquired if the impact caused by the rumors of the NPP accident affected their lives. We also asked if there was posttraumatic growth (PTG) obtained from the experience of the Great East Japan Earthquake. The following questions were asked regarding the presence or absence of PTG:“It goes without saying that the Great East Japan Earthquake was a hugely negative experience;however, did you gain anything from it?” (Options 1:“No”, 2:“Yes”). Next, if they answered “Yes” to the above question, they were asked to freely describe the PTG content13).
The survey participants were asked to select the main sources of information they trust, and were allowed to select 3 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; citizen groups;and “none of the above”. The participants were asked to indicate media used for information about radiation by selecting 3 main items from the following 13 options: local newspapers;national newspapers; NHK; 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”.
However, the answers to the questions regarding knowledge of radiation other than genetic effects (properties of radiation, probability of death from cancer, DNA repair, and food reference values) were not included in the analysis, as we considered them to also be the result of CCHL.
Analysis PlanExcluding those who did not answer the question related to KOGEORE, 378 men and 466 women, a total of 844 people, were included in the analysis. First, for each item, the distribution of men and women was compared by univariate analysis.
Next, in order to compare men and women, it was considered necessary to perform multivariate analyses using the same model. To determine the explanatory variables, univariate analyses were first conducted between KOGEORE and all variables. These variables were also considered to be potentially relevant to knowledge acquisition, particularly media use, which was considered to be strongly related. Next, multiple logistic regression analyses were conducted for each sex in the same models, using as explanatory variables those items that were significant for at least one sex in the univariate analysis.
The hypothesis was that Fukushima residents with high health literacy are more likely to seek out KOGEORE as essential information. As the objective variable is the presence or absence of knowledge, social factors and the means of obtaining information are considered to be relevant in addition to health literacy. Therefore, multiple logistic regression analyses that included these variables as explanatory variables were used to examine the relevant factors. P < 0.05 was considered statistically significant.
The mean age (years ± SD) of all participants was 56.4 ± 14.8 years. Table 1 shows the characteristics of the participants by sex. The proportion of the correct answer to the question related to KOGEORE was significantly higher in the men at 37.3%, compared to 28.8% in the women. Regarding CCHL, there was no significant difference, with 15.4 ± 4.0 points for men and 15.7 ± 4.1 points for women.
Tables 2 and 3 show the results of the univariate analysis by sex. For men, the mean CCHL score was 16.1 ± 4.1 points in the correct-answer group and 15.0 ± 4.0 points in the incorrect-answer group. CCHL was significantly higher in the correct-answer group. The proportion of elderly people was significantly higher in the correct-answer group. The proportion of those who have PTG was significantly higher in the correct-answer group. The proportion of participants who joined the regional groups was significantly higher in the incorrect-answer group. In the women, the mean CCHL score was 16.5 ± 3.7 points in the correct-answer group and 15.4 ± 4.2 points in the incorrect-answer group. CCHL was significantly higher in the correct-answer group. The proportions of those who were considered healthy and used local government publications were significantly higher in the correct-answer group. The proportion of those who have PTG was significantly higher in the correct-answer group. The proportions of those who were in the evacuation area, used private national broadcast television, and used word-of-mouth communication was higher in the incorrect-answer group.
Table 4 shows the results of multiple logistic regression analysis by sex, with KOGEORE as the objective variable and items that were significant in at least either men or women in the univariate analysis as the explanatory variables. In the men , high CCHL and being elderly were significantly associated with accurate KOGEORE (OR = 1.08 and 1.75, respectively). In addition, membership in regional groups was significantly associated with the lack of accurate KOGEORE (OR = 0.48). In the women, high CCHL and use of local government publications were significantly associated with accurate KOGEORE (OR = 1.07 and 2.02, respectively). In addition, in the women, being in the evacuation area, use of private national broadcast television, and use of word-of-mouth communication were significantly associated with inaccurate KOGEORE (OR = 0.37, 0.54, and 0.41, respectively).
Table 5 shows the results of the univariate analysis between the male members of the regional groups who incorrectly answered the question regarding genetic effects of radiation. This population was significantly younger, and a significantly higher proportion had children.
Basic information on respondents
Results of univariate analysis for all items with KOGEORE (men)
Results of univariate analysis for all items with KOGEORE (women)
Multivariate logistic regression analysis with the knowledge of the genetic effect as the response variable
Characteristics of male members of regional groups
The proportion of respondents who answered the question regarding KOGEORE correctly was significantly higher in the men. A previous study reported that men had a higher proportion of radiation-related knowledge about the Fukushima NPP accident than women,8-10) which is partially consistent with the results of the present study. For both men and women, high CCHL was significantly associated with accurate KOGEORE (OR = 1.08 and 1.07, respectively). If a person has high CCHL, they can select the essential information from various pieces of information, understand it, and utilize it5). Therefore, we considered that raising health literacy would help disseminate accurate information regarding KOGEORE.
In the present study, for men, being elderly was significantly associated with accurate KOGEORE. The proportion of those with accurate KOGEORE was 45.6% for elderly men, 32.6% for non-elderly men, 25.6% for elderly women, and 30.7% for non-elderly women. The reason why the proportion of correct answers was highest among the elderly men may be related to the respondents’ views of marriage.
In the Basic Survey on Birth Trends (National Survey on Marriage and Childbirth), conducted in men and women by the National Institute of Social Security and Population Problems every five years, questions are asked about thoughts on marriage and children. Regarding single men aged between 18 and 34 years, in response to the statement, “you should have a child after you get married,” 53.0% answered “totally agree” in the 10th survey (1992)14); however, that proportion gradually decreased to 23.1% the 15th survey (2015)15). Regarding single women of the same age group, in response to the same statement, 49.2% answered “totally agree” in the 10th survey,14) and that proportion also gradually decreased to 17.2% in the 15th survey15). This particular question was newly added in the 10th survey;therefore, no data on this topic had been collected previously. However, because the number of participants who answered “totally agree” decreased as the number of surveys increased, it is speculated that the proportion of older men before 1992 who would have answered “totally agree” would have been even higher. In addition, men were more likely to answer “totally agree” to the statement in every survey. From this, as stated in the study by Akai16), it can be considered that in Japan, older men are more likely than women to believe that the purpose of marriage is to have children. It can be thought that, for this reason, the older men who took this survey were highly concerned about the effects of radiation on future generations, and they had obtained accurate KOGEORE. Of course, there are limitations to this assumption, as views on marriage can change over time and there are no data available before 1992.
Table 5 shows that the average age of the group who joined regional groups and answered incorrectly was significantly younger than that of the group who did not answer incorrectly, and the proportion of those who chose the item “had children” was significantly higher. As mentioned earlier, younger men were less likely to have accurate KOGEORE than older men in the present study. In addition, in this survey, the items for the regional groups were “regional groups such as youth groups, women’s associations, elderly associations, PTAs (Parent-Teacher Associations), and child associations (training groups)”8);therefore, we believe that the male members of the regional groups who answered the question related to KOGEORE incorrectly were mainly members of youth groups, PTAs and child associations, and not elderly associations. It is probable that many men who joined the regional groups originally felt anxious about genetic effects on their children. Alternatively, incorrect knowledge may spread within a community group. In both cases, the lack of KOGEORE may have had an impact; however, this could not be confirmed in the present study.
Women in the evacuation area were exposed to various sources of information, both accurate and inaccurate, and were forced to evacuate as a result of government evacuation orders and the fear of invisible radiation. Therefore, it was possible that they thought the radiation exposure dose was so high that they had to evacuate. As a result, their risk perception of radiation can increase17), it is possible that they answered incorrectly, thinking that the sentence about atomic bomb survivors was inaccurate information.
Nakayama et al. reported that those who trust local governments as a source of information about radiation had significantly lower radiation-induced health anxiety.8) They state that, as an administrative organization involved directly in residents’ daily lives, local governments are responsible for implementing radiation countermeasures on-site, and each local government releases the results of air and food radiation testing on their home pages8). From these findings, it is considered that use of local government publications as a source of information by women was significantly associated with accurate KOGEORE.
Use of private national broadcast television was associated with higher anxiety about the impact of radiation on future generations in a previous study4), which is partially consistent with the results of the present study. In addition, according to a former producer of private local broadcast television, private national broadcast company showed sensational content regarding radiation in Fukushima in their TV program, while private local television in Fukushima did not18). Therefore, it is possible that those who used private national broadcast television could not obtain accurate KOGEORE by watching programs with misleading content about radiation.
Word-of-mouth communication can be accurate or inaccurate. However, harmful rumors are much more likely to be spread via word-of-mouth than other forms of communication19,20). This is likely the reason that the use of word-of-mouth communication was significantly associated with inaccurate KOGEORE. Men and women use word-of-mouth communication in almost equal proportions. However, the proportion of those who are incorrect is higher for women, suggesting that word-of-mouth use is significantly associated with inaccurate KOGEORE for women only.
First, since this study was cross-sectional, cause and effect cannot be determined. In addition, the subjects of the survey were relatively old. Furthermore, in this study, the presence or absence of PTG was measured using one item, and a free description was requested. This study aimed to broadly identify and examine the feelings and PTG of victims of the Great East Japan Earthquake, a large-scale and unprecedented disaster. Adding “It goes without saying that the Great East Japan Earthquake was a hugely negative experience,” to the question may have resulted in more positive statements13). However, to our knowledge, after more than 10 years following the Great East Japan Earthquake, the present study is the first to report on the relationship between health literacy and knowledge of the genetic effects of radiation exposure.
Implications for further studyGiven the relationship between health literacy and the KOGEORE found in the present study , a selective approach to groups which had factors associated with inaccurate KOGEORE is recommended as a future measure. First, we can promote the dissemination of information related to KOGEORE itself. Specifically, in the most recent Fukushima Health Management survey, the proportion of those who were anxious about the health impact on the future generation was 30%2), so reducing this percentage is very important4). For men, this information should be disseminated with an emphasis on non-elderly people. It is also important to focus on dissemination among women. Furthermore, the emphasis will be on women in evacuation areas, since that group was strongly associated with lower KOGEORE. It is also considered useful to enhance CCHL for both men and women7). In addition, this result suggests the need for media literacy education to enable the selection of accurate information regarding radiation and nuclear accidents, which requires advanced knowledge. Therefore, for women in Fukushima, we believe that it would be useful to improve media literacy so that correct information can be understood, and to promote the use of local government publications. However, for men, suitable sources of information cannot be ascertained through this study, because the source of information for men was not significantly associated with KOGEORE by multivariate logistic regression analysis (Table 4).
