Risk Acceptability

History of Risk Acceptability

During the 1970’s public risk acceptability was usually based on mortality statistics and risk de minimis or the idea that some risks could be considered to be so negligible and small that they were not of societal concern.  The principle of de minimis risk stated that if a risk was effectively lowered to less than one additional fatality per million individuals, the risk was effectively zero and could be considered “virtually safe.”

Throughout the 1980’s, models were refined to incorporate social values into risk theory that showed the acceptance of risk was tightly linked to the perception of hazards.  Familiar social relationships influenced the acceptability of risk and showed that the analysis of risk could not be based on statistics or mortality numbers alone (Slovic, 1987; Vlek and Stallen, 1981).

The most widely adopted model, the psychometric paradigm, described risk as a psychological construct, drawing on various characteristics important in influencing risk acceptability and perception (Slovic, 1987). Another popular model that developed during the same time was the cultural theory of risk in which individuals could be assigned to different cultural groups based on shared values and similar belief systems (Douglas and Wildavsky, 1982).

The psychometric paradigm proposed that the risk itself generated individually held perceptions that would lead to either acceptance or rejection while the cultural theory held that the characteristics of the perceiver, in addition to the risk itself, were responsible for determining levels of acceptability.  Kasperson et al. (1988) added to these previous models by developing the social amplification of risk theory that suggested some perceived risks are disproportionately amplified over others due to associated social, cultural and individual characteristics ultimately altering their level of acceptability. 

More current models of risk acceptability suggest that risk involves the probability of an adverse event and its associated perceived severity (Torrance et al., 1996).  Individuals perceive linkages between events and give relative meaning to them incorporating the aspects of the previous three models  (Zwick and Renn, 2002; Rohrmann and Renn, 2000; Derby and Keeney, 1990). 

Risk Acceptability

In order to be accepted by individuals and society risks must be measured in some way and, as a result, risk as a concept embodies other dimensions. The probability of a hazardous event may differ between two individuals; the risk may not increase proportionately with exposure; the outcome from a hazardous event may be delayed in time; and there may be a multiplicity of possible outcomes.  The expected outcome from a particular hazard in a given time interval is determined by both risk and exposure. For some hazards, the number of deaths may increase exponentially with exposure, or there may be a safe limit below which the death rates are unaffected by exposure.  To evaluate the degree of impact of a hazard both risk and exposure levels must be taken into account.
In contrast to the early statistical assessment of risk, the intrinsic psychosocial nature of risk acceptability was initially studied through psychophysics and psychometrics of risk perception (Slovic et al., 1990; Tversky and Kahneman, 1974).  There were two main ideas that emerged at about the same time, first risk was recognized as a social construct and secondly that implicit theories of risk perception have developed among laypeople that describe how risks are evaluated, accepted and how personal decisions concerning different risks occur. (Heimer, 1988; Lupton, 1999ab).  Thus, risk acceptability was determined to be a measure of an individual’s tolerance for risk derived from a social construct influenced by a number of acquired factors.

References

Derby, S.L. and Keeney, R.L. (1990). Risk Analysis: Understanding "How Safe is Safe Enough". In T .S. Glickman and M. Gough (Eds.). Readings in Risk. (pp. 43-59). Washington, D.C.: Resources for the Future.

Douglas, M. and Wildavsky, A. (1982). Risk and Culture: An Essay on the Selection of Technical and Environmental Dangers. University of California Press (Berkeley). 221.

Heimer, C.A. (1988). Social Structure, Psychology and the Estimation of Risk. Annual Review of Sociology, 14: 491-519.

Kasperson, R., Renn, O., Slovic, P., Brown, H., Emel, J., Gobie, J., Kasperson, J. and Ratick, S. (1988). The social amplification of risk: A conceptual framework. Risk Analysis, 8(2): 177-187.

Lupton, D. (1999a). Introduction: risk and sociocultural theory. In D. Lupton (Ed.). Risk and sociocultural theory: new directions and Perspective. (pp. 1-11). Cambridge, UK: Cambridge University Press.

Lupton, D. (1999b). Risk and the ontology of pregnant embodiment. In D. Lupton (Ed.). Risk and sociocultural theory: new directions and Perspective. (pp. 59-85). Cambridge, UK: Cambridge University Press.

Rohrmann, B. and Renn, O., (2000). Risk Perception Research: An Introduction. In O. Renn and B. Rohrmann (Eds.). Cross-Cultural Risk Perception: A Survev of Empirical Studies. (pp. 11-43). Boston: Kluwer Academic Press.

Slovic, P. (1987). Perception of risk. Science, 236: 280-285.

Slovic, P., Fischhoff, B., and Lichtenstein, S. (1990). Rating the Risks. In T .S. Glickman and M. Gough (Eds.). Readings in Risk. (pp. 61-74). Washington, D.C.: Resources for the Future.

Torrance G.W., Feeny D.H., Furlong W.J., Barr R.D., Zhang Y. and Wang Q. (1996). Multiattribute utility function for a comprehensive health status classification system; Health Utility Index Mark 2. Medical Care, 34(7): 702-722.

Tversky, A. and Kahneman, D. (1974). Judgment under uncertainty: Heuristics and biases. Science, 185: 1124-1131.

Vlek, C. and Stallen, P. (1981). Rational and personal aspects of risk. ACTA psychologique, 45: 275-300.

Zwick, M.M. and Renn, O. (2002). Perception and Evaluation of Risks: Findings of the Baden- Wurttemberg Risk Survey 2001. Stuttgart: Center of Technology Assessment.