[en] The report includes 10 papers prepared by the Swedish Risk Academy for the IAEA Conference on Radiation and Society: Comprehending Radiation Risk, held in Paris between 24-28 October 1994. A separate abstract was prepared for each paper. Refs, figs and tabs

[en] This paper introduces the problem area covered by nine papers submitted through Riskkollegiet (a Swedish academy on risk) to the IAEA at their request. It introduces the basic concepts of radioactivity, radioactive substances, ionizing radiation and radiation dose, as well as the general concept of risk. The concept ''risk'' has no universally accepted definition and the word ''risk'' is used with several different meanings. The authors discuss attributes usually employed in quantitative presentations of risk: probability of harmful events, and the consequences, should such events occur, but also non-quantitative aspects involved in risk perception, risk comparisons and risk communication. (author)

[en] Probability is one of the two major attributes of risk. It appears to be a basic and clear intuitive notion related to chance, but is not easy to formalize or explain. Going from intuition to a formalism useful for practical applications always requires great care and caution. By the ''probability'' of a given outcome, the author means our estimation - based on our experience and knowledge of the situation - of the relative frequency of the outcome in a representative experiment of chance, after a very long series of trials. If the probability of an event is very low, the assessment cannot be based on previous observations of the event, but must be based on studies of the process involved and by mathematical calculations from components of the event. (author)

[en] Risk comparisons are usually made for some specific purpose (to help communicating the message that a situation is either acceptable or not acceptable). However, the communication should be fair and, as the author of the next Chapter says: relevant, adequate, understandable and credible. Since ''risk'' has many attributes, the characterization of risks to be compared must involve appropriately compared attributes. The author of this Chapter begins by discussing the difficult task of risk characterization before he deals with the problems involved in risk comparison. He finally refers to the principle of ceteris paribus, which means that, in risk comparisons, all factors, circumstances and assumptions which are not explicitly presented in the risk characterization and quantification must be mutually equivalent. (author). 14 refs, 1 tab

[en] In this paper, the advantages and methods of epidemiology are first described briefly in general terms. Some of the problems encountered in applying epidemiological methods to the study of the effects of ionizing radiations are then examined in detail. The three main types of study are discussed, namely ecological studies, case-control studies and cohort studies. The author also deals with special problems such as clusters of cases of a rare disease and the ''healthy worker effect''. (author). 26 refs

[en] Radiation exposures of the world population have been assessed by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) for both natural and man-made sources. The largest component of exposure arises from the natural radiation background. Man-made sources involving releases of radionuclides to the environment include single events, such as atmospheric nuclear testing and the Chernobyl accident, and continuing practices, such as nuclear power production. Other exposures are received by patients from medical radiation procedures and by workers in some occupations. Comparisons of the various exposures give indications of the relative risks. (author). 4 refs, 4 tabs

[en] The present paper outlines perceptions of radiation risks within a general framework of risk perception research. The authors comment on the importance and the implications related to the choice of terminology, including the multiple definitions of ''risk'', for risk perception and risk communication. They describe the main factors influencing subjective risk assessments found in the literature, and illustrate how these factors guide the different reactions to indoor radon and radioactive fall-out due to nuclear accidents. They also exemplify the differences between risk assessments by experts and the public, present some successful models of perceived risk and risk acceptance, and draw some general conclusions from the research field. (author). 96 refs, 4 figs, 1 tab

[en] Studies of irradiated human populations are available from which estimates of the probability of cancer induction can be derived. However, in most of these studies, a large proportion of the population is still alive so the final number of cancer fatalities has yet to be determined. The exposures in these studies were usually at intermediate and high doses and dose rates. Additional information then needed to predict cancer probabilities associated with low dose rate exposures. Also the most important source of data is that on the Japanese atomic bomb survivors, and there is a problem in transferring the probabilities of cancer to populations with other baseline cancer rates. This paper summarizes the conclusions on the lifetime probability of fatal radiation-induced cancer and explores the uncertainties and the means of reducing them. (author). 31 refs, 2 figs, 2 tabs

[en] This paper deals with risk communication, understood as the exchange of knowledge and opinions between various actors involved in risk management. Because of new risks created by man's scientific and technological ingenuity, risk communication attains ever wider social functions, involving an increasing number of people. The tasks for risk communication often reflect conflicting perspectives and interests of the communicating parties. The author stresses the importance of communication quality, i.e. its adequacy, understandability and credibility. Risk communication has to cope with problems such as the discrepancy between the perspectives of laymen and experts, uncertainties in risk assessment and the lack of scientific literacy among the public. One of the major conditions for successful risk communication is trust in the communicators, balanced with some skepticism and critical mind. The author finally suggests that, instead of promoting ''understanding of technology'', risk communication should foster and understanding of the necessary compatibility of technology, societal and environmental issues. (author)

[en] It is of interest to compare risks to health and wellbeing with other risks in life. However, as evident from other chapters in this report, any risk comparisons should be made with great caution, and the acceptability of various risky situations and causes of risk is not merely determined by the magnitude of the risk. With this recognized, the general health situation and life expectancy in developed and developing countries still contributes to the understanding of the significance of changes in our baseline risk. The author presents new data from the World Health Organization and other sources on the global health situation. Unfortunately, good data describing health are not available. It is therefore necessary to limit the presentation to mortality rates and causes of mortality. (author). 19 refs, 2 figs, 9 tabs