Public Perceptions of the Iodine Tablets Distribution Around French Nuclear Power Plants

Transcription

1 Public Perceptions of the Iodine Tablets Distribution Around French Nuclear Power Plants S.Charron, D. Morin and J. Brenot Institute for Protection and Nuclear Safety (IPSN) BP 6, Fontenay-aux-Roses, France 1. INTRODUCTION In April 1996 the French Ministry of Health decided to distribute stable iodine tablets to the population living in the vicinity of all nuclear power plants (NPP) in France. In case of a severe nuclear accident, the intake of stable iodine would prevent irradiation of the thyroid by the radioactive iodine released by the plant. This preventive distribution began in late 1996 around four pilot sites (Chooz, Fessenheim, Golfech, and Saint Alban) and was extended to all French sites in During this period, IPSN conducted two large opinion surveys which contained questions about countermeasures and, more specifically, about the distribution of stable iodine tablets. The goal was to know whether the general public was aware of this decision and to obtain feedback about its reactions. This paper presents a detailed analysis of the two sets of responses made by the public, at the beginning and at the end of the information campaign that accompanied this distribution. Responses are compared, their consistency evaluated, and the relation between distance to the nearest nuclear site and public responses analysed. 2. CONTEXT OF THE STUDY 2.1 Countermeasures for a nuclear accident In case of a severe NPP accident, countermeasures should be initiated in the short term by authorities to reduce the consequences to the neighbouring population of the radioactivity released into the atmosphere. Protective measures envisaged in the early phase of the accident are evacuation, sheltering and administration of stable iodine. Evacuation is fully effective only when completed before the accidental release. Sheltering reduces doses due to external irradiation and inhalation doses during a period of time depending on the ventilation of the dwellings. The intake of stable iodine prevents thyroid irradiation by the radioactive iodine releases. Stable iodine is most beneficial when the tablets are taken just before or shortly after exposure to radioiodine and its effectiveness decreases with time. In 1996, the French Ministry of Health decided to distribute iodine tablets to the population living in the immediate vicinity of all the nuclear power plants in France. As far as NPP are concerned, this preventive distribution addressed people living at a distance of 10 km or less from a plant. For distances farther than 10 km, it was decided to store iodine tablets in various places (pharmacies, town halls, etc.) where people could take them. 2.2 The public opinion surveys IPSN conducted two large public surveys, one in 1996 and an other in 1997, which contained questions about countermeasures recommended in case of nuclear accidents and, more specifically, about the distribution of stable iodine tablets (1, 2). The interviews for the 1996 survey (Poll Survey) were carried out by the BVA Institute. They were conducted in face-to-face and concerned 1009 persons who constituted a representative sample of the French population aged 18 years and older. The sample was stratified (housing type x region) and respected national quotas (sex, age of the person interviewed, and occupational status of the head of household). In 1997 the survey (Panel Survey) was performed by the GALAXY Institute. This survey was conducted -1

2 in a population issued from a panel of individuals ( households) representative of the French population, in terms of region, housing type, age and occupational status of the head of household, and number of persons in the household. The protocol called for self-administered mail questionnaires to the entire panel. Completed questionnaires were received from 8423 households, corresponding to a response rate of 64.79%. 2.3 Issues / Hypothesis The aim of the two surveys was to ascertain whether the general public was aware of the Ministry of Health decision to distribute stable iodine tablets on a preventive basis and to obtain some feedback on public reactions. As an information campaign accompanied this pre-distribution around the nuclear sites, the moment was to study the possible differences in perceptions and attitudes of the interviewees according to their distance to the French NPP. Consequently, we wanted to see if the answers to three questions about the decision to distribute stable iodine differed according to the respondent's distance to the nearest nuclear plant, that is, to test for a distance effect. More precisely, in view of the information campaigns around the sites, we supposed that the closer respondents lived to a nuclear site (<=10 km), the more they knew and the more positive were their attitudes towards the distribution. 3. METHODS 3.1 Questions related to the distribution of stable iodine In the June 1996 BVA Poll Survey, the following three questions concerned the preventive distribution of stable iodine: The Ministry of Health has recently announced that iodine tablets will be distributed to persons living near nuclear power plants. Are you aware of this decision? Do you think it is a wise decision? Would you like to have stable iodine tablets at your home? In the vember 1997 GALAXY Panel Survey, these three questions were appeared again, together with an additional question: "Do you know where to procure these tablets?". 3.2 Characteristics of the respondents For comparison, the same demographic variables were used to set the quotas in both studies: region, housing type, and occupational status of the head of household. The other variables considered in the BVA survey were age, sex, and occupation of the person interviewed, and in the GALAXY survey, age and occupational status of the woman of the house. Answers to the question "Do you have children younger than 18 years?" (GALAXY, vember 1997) were compared with those to "Do you have children younger than 15 years?" (BVA, June1996). To see if the perceptions of an individual varied according to the location of the town in which he lived, his distance to the nearest NPP was calculated using the geographic coordinates for the town and the 26 nuclear energy production sites in France. 3.3 Statistical Analysis Data treatment and analysis were performed using S.A.S and EXCEL softwares (3, 4). Basic descriptive statistics allowed comparison of response frequencies. Cross-tabulations and Chi-2 test helped to determine when individual characteristics influenced the responses. To examine the possible association between individual responses and the distance to the nearest nuclear power plant, first the distance to the site was categorized, [0-5 km], [5-10 km], [10-20 km], [more than 20 km] and second cross-tabulations and the Chi-2 test were performed. Because the categories for the distance variable are ordered, the Armitage trend test was used too. A logit linear model was also experienced to explain responses as a function of the distance. -2

3 4. COMPARISON OF RESPONSES FROM 1996 TO Results Tables 1 and 2 report the results for the questions proposed in both surveys. Table 1. BVA Poll Survey (1 009 individuals interviewed, June 1996). " The Ministry of Health has recently announced that iodine tablets will be distributed to persons living near nuclear power plants." WORDING NUMBER % QUESTION 1: Are you aware of this decision? QUESTION 2: Do you think it is a wise decision? QUESTION 3: Would you like to have stable iodine tablets at your home? Table 2. GALAXY Panel Survey ( individuals responded to the questionnaire, vember 1997). "The Ministry of Health announced in April 1996 that iodine tablets would be distributed to persons living near nuclear power plants." WORDING NUMBERS % QUESTION 1: Are you aware of this decision? QUESTION 2: Do you think it is a wise decision? QUESTION 3: Would you like to have stable iodine tablets at your home?

4 4.2 Comments Respondents were more aware of the decision in 1997 than in A review of the circumstances may explain this finding. The 1996 Survey was carried out in June. Given that the Secretary of Health made the announcement in April, the decision must certainly have been either too recent or not sufficiently publicized. The GALAXY Survey took place in vember The preventive distribution of stable iodine tablets to those persons living near nuclear facilities had begun in June Consequently, the public information campaigns accompanying the distribution had been going on for 5 months. netheless, although the majority was aware of this decision, they did not know the consequences or the arrangements very well. That is, 64.9% of the interviewees responded negatively to the question "Do you know where to procure these tablets (of stable iodine)?" (in 1997). In addition, public opinion about the pre-distribution decision also improved from one year to the next: in 1996, 63.1% of those interviewed thought that it was a wise decision, and in 1997, 68.7%. netheless, we note that in 1997, despite the people's confidence in this decision, the respondents were very undecided about having stable iodine tablets in their home; only 31.1% wanted it. 5. RELATIONS BETWEEN RESPONSES AND PERSONAL CHARACTERISTICS 5.1 Synthesis of results Table 3. Cross-Tabulations of the BVA Poll Survey (1009 individuals interviewed, June 1996). Aware Wise decision Want iodine Region *** *** *** Age ** *** *** Sex * Occupational status of the person interviewed * * Occupational status of the head of household * * Educational Level * Nuclear Plants Dangerous Protection from plants needed *** *** Truth told about nuclear dangers Live near nuclear plant *** * Children younger than 15 years * *** Political position *** * Political party ** * Income *** *** ** Religion *** * Housing type *** *** * Chi-2 Test Significant at 5%, ** at 1% and *** at 1 0 / 00. Table 4. Cross-Tabulations of the GALAXY Panel Survey (8258 individuals responding, vember 1997). Aware Wise decision Want iodine Can procure iodine Housing type * *** *** Region *** * *** *** Occupational status of the head of household *** ** ** *** Occupational status of the woman of the house *** * *** Age head of household *** *** *** *** Age woman of the house *** *** *** *** Number in the household *** *** *** *** Children younger than 18 years *** ** *** *** * Chi-2 Test Significant at 5%, ** at 1% and *** at 1 0 /

5 5.2 Comments Generally and in decreasing order of significance, the respondents aged from 35 to 49 years, those residing in the Paris metropolitan area, those with low income, housewives, retired persons, and those living in small towns were aware of the decision to distribute stable iodine preventively and reacted favorably to it. People in the 35 to 49 year age group were more concerned by the risks of nuclear plants than the other age groups did. This group also had the most young children. We can suppose that this interest is due to fear that their loved ones, and especially their children, might be placed in danger. In the BVA Poll Survey the results suggest this explanation: the majority of the people who were aware of the decision and supported it had children. This was not, however, the case in the GALAXY Panel Survey: the majority of those aware of the decision did not have children. 5.3 Is there a distance effect? "The Ministry of Health has recently announced that iodine tablets will be distributed to persons living near nuclear power plants..." Are you aware of this decision? % of YES <= 10 km 10 à 20 km > 20 km Distance to the nearest nuclear facility GALAXY 97 BVA 96 In the 1996 BVA Poll Survey, responses to the question did not really change according to the distance to the nearest nuclear facility. This is confirmed by the Chi-2 test which was not significant (probability of exceedance: 0.28). The small differences observed can be due to sampling fluctuations. netheless, we do note a slight difference between those living at a distance of 20 km or less and those living more than 20 km away from a nuclear plant. In the 1997 GALAXY Panel Survey, the difference in the responses as a function of distance is clearly visible on the graph and confirmed by the Chi-2 (difference significant at 1 0 / 00 ). The farther the respondents lived from a nuclear site, the less likely they were to be aware of the decision to distribute stable iodine tablets. This is due, as we said above, to the fact that in 1997 the preventive distribution had already begun, but also to the fact that the distance less than 10 km corresponds to the perimeter of the PPI 1 (Plan Particulier d'intervention, Special Intervention Plan) and that the populations within this perimeter are those concerned by the individual pre-distribution. Those residing at 10 to 20 km from a nuclear site were notified that tablets of stable iodine are available to them in specific places. They are thus aware of the distribution of stable iodine because the authorities have informed them of the procedures to follow in case of a nuclear accident. On the other hands, those living at more than 20 km away from a nuclear plant have not been contacted concerning this distribution, as their responses make that clear. 1 PPI : Plan Particulier d Intervention, special intervention plan, to be launched by the Prefect, in case of an accident that might have consequences outside the plant. -5

6 "The Ministry of Health has recently announced that iodine tablets will be distributed to persons living near nuclear power plants..." % of YES 75 Do you think this is a wise decision? GALAXY 97 BVA <= 10 km 10 à 20 km > 20 km Distance to the nearest nuclear site In 1996, the persons living farthest (> 20 km) had a slightly more favorable reaction to this decision, while the opposite was true in netheless the difference in the answers according to the distance to the nearest nuclear site is not significant (probability of exceedance 0.98 for the 1996 BVA Poll Survey and 0.35 for the 1997 GALAXY Panel Survey). This indicates that the distance to the nearest nuclear site does not affect the answers to this question. The differences observed are due to sampling fluctuations. "The Ministry of Health has recently announced that iodine tablets will be distributed to persons living near nuclear power plants..." % of YES Would you like to have stable iodine tablets at your home? <= 10 km 10 à 20 km > 20 km Distance to the nearest nuclear site GALAXY 97 BVA 96 The difference in the responses according to distance to the nearest nuclear site is very clear. In 1996, slightly less than 60% of the individuals who lived at less than 5 kilometers from a nuclear plant wanted to have stable iodine tablets at home, while only 40% of those living more than 20 kilometers so wished. The significance of these differences is verified by the Chi-2 test, which was significant at 3% in 1996 and at 3 0 / 00 in Accordingly, we can say that the distance to the nearest site influences the willingness to have stable iodine tablets on hand. This result is highly reasonable, because the people living within the perimeters of the PPI are most likely to benefit from taking stable iodine in case of a nuclear accident. Table 5. Summary of the three Analyses of the Distance Effect. BVA Poll Survey Chi-2 test Trend test Logit Linear Model Aware independent independent independent Wise decision independent independent independent Want iodine dependent dependent dependent GALAXY Panel Survey Chi-2 test Trend test Logit Linear Model Aware dependent dependent dependent Wise decision independent independent dependent Want iodine dependent dependent dependent Overall, the three analyses led to the same conclusion, except for the question " Do you think it is a wise decision? " in the GALAXY Panel Survey, where the distance effect is arguable. -6

7 6. CONCLUSION We have shown that the distance to the nearest nuclear site has an effect on the response to some questions about the preventive distribution of stable iodine and also about its use in the case of a nuclear accident. Living near a nuclear plant influenced the willingness to have stable iodine among the people interviewed and also their knowledge and awareness of the decision of pre-distribution. The distance between the residence and the nearest nuclear site did not, however, affect their opinion of the decision; throughout France, the sample considered that the preventive distribution of stable iodine tablets to those living near a nuclear site was a wise decision. We have also seen that although a majority was aware of the decision, most people did not know the consequences and the arrangements very well. These findings are confirmed by the results of the most recent poll, in October 1999, for the IPSN Barometer (5), which shows that 51% of the population knew about the decision (compared with 42% in 1996), but only 21% of the respondents knew where to procure iodine tablets. We can conclude that during the information campaigns that accompanied the pre-distribution, the authorities successfully informed the people concerned about the decision, its reasons, and its consequences, but they did not seek to understand why some people were not especially interested in the risks of nuclear plants. These individuals probably refuse to believe that a nuclear accident could occur. The findings from our study (2) should be compared with those from a sociological study commissioned by IPSN about the iodine distribution. G. Decrop (6) carried out this study based on the distribution feedback from the four pilot sites (Chooz, Fessenheim, Golfech and Saint-Alban) and found that the distribution would be more effective only if a process of information and debate takes place before the distribution. This process, in turn, can be implemented and developed only if the information/debate extends beyond the strict limits of stable iodine distribution to deal with a more global management of the crisis. Information must deal with the diverse issues involved in such a crisis and not only with its technical and medical aspects. To that extent, information policy can contribute to making the social representation and perception of nuclear accidents evolve from catastrophic to manageable and may then reinforce nuclear risk culture and social trust in the risk domain. From an operational point of view, these results will be useful to the public authorities (national and local) who will have to begin a new distribution of iodine tablets to the populations concerned this year (2000). To facilitate an active coping of the public, revisions are currently taking place in the countermeasures management and more generally in the management of a nuclear accident, with a clear impact on national strategies (for instance new guidelines design ). REFERENCES 1. S. Bonnefous, J. Brenot and V. Richard, Perception des risques et de la sécurité : résultats du sondage de juin te SEGR/LSEES 96/63, juin D. Morin and S. Charron, Distribution d iode stable autour des sites nucléaires : attitudes du public dans les enquêtes BVA 1996 et GALAXY tes Technique SEGR/99 n 42, Juin SAS language : Reference, Version 6, First Edition, SAS Institute Inc., Cary, NC, USA, SAS/STAT User s guide, Version 6, Fourth Edition, Volume 2, SAS Institute Inc., Cary, NC, USA, S. Charron, H. Mansoux and J. Brenot, Perception des risques et de la sécurité : résultats du sondage d octobre te SEGR 99/116, novembre G. Decrop and P. Blancher, Protection civile sur ordonnance : la distribution préventive d iode stable dans les sites pilotes de Chooz, Fessenheim, Golfech et Saint-Alban. Rapport commandité par l IPSN, Référence A700370, novembre