Perceiving Risks Risks that are both highly uncertain and highly dreaded are also clearly the most diffi- cult to predict and control. Two very important factors for dread were found to be global catastrophe and risks that involve members of future generations. The advent of glol terrorism and the development of genetically modified foods are two recent examples.Less dreaded risks tend to be those that are individual, controllable and easily reduced. The more acceptable risks are those that are known, observable and have immediate effects. In addition, the more equitable the risks, the more likely they are to be generally accepted. useful to consider perceptions of dread and unknown risk in relation to public health interventions for reducing risks. If risk factors are to be controlled, the interventions should be perceived to have low dread and a low risk of adverse events. Higher risks from such interventions will normally only be accepted by individuals in the higher risk groups However, population-wide interventions to reduce risk typically have to cover all people, even those at low risk. Thus interventions used in public health programmes need to have low dread and known low and acceptable levels of risk, combined with high safety levels. Typically, vaccination and screening programmes fall into this category, particularly as they are usually targeted at whole populations and involve many healthy people who are at low risk of getting ill and dying. The favourable perception of the public to prescribed medicines, for example, has been attributed to the direct benefits of such medicines and to the trust people place in their safety, achieved through research and testing carried out by medical and pharmaceutical professionals Figure 3. 1 Hazards for dread and riska not observable unknown to those exposed effect delayed risks unknown to science Food irradiation◆ Oral contraceptives Low dread risk Vaccinations. High dread risk controllable uncontrollable Pregnancy, childbirth. Surgery Alcoholic beverages◆ own risk risks known to science from interrelationships of 18 risk characteristics. Fador 3 (not shown)reflects the number of people exposed to the hazard and the degree of their personal exposure.Perceiving Risks 33 Risks that are both highly uncertain and highly dreaded are also clearly the most diffi￾cult to predict and control. Two very important factors for dread were found to be global catastrophe and risks that involve members of future generations. The advent of global terrorism and the development of genetically modified foods are two recent examples. Less dreaded risks tend to be those that are individual, controllable and easily reduced. The more acceptable risks are those that are known, observable and have immediate effects. In addition, the more equitable the risks, the more likely they are to be generally accepted. It is useful to consider perceptions of dread and unknown risk in relation to public health interventions for reducing risks. If risk factors are to be controlled, the interventions should be perceived to have low dread and a low risk of adverse events. Higher risks from such interventions will normally only be accepted by individuals in the higher risk groups. However, population-wide interventions to reduce risk typically have to cover all people, even those at low risk. Thus interventions used in public health programmes need to have low dread and known low and acceptable levels of risk, combined with high safety levels. Typically, vaccination and screening programmes fall into this category, particularly as they are usually targeted at whole populations and involve many healthy people who are at low risk of getting ill and dying. The favourable perception of the public to prescribed medicines, for example, has been attributed to the direct benefits of such medicines and to the trust people place in their safety, achieved through research and testing carried out by medical and pharmaceutical professionals. Food irradiation Lasers Nuclear power Water fluoridation Oral contraceptives Asbestos Radiation therapy Pesticides Diagnostic X-rays Vaccinations Antibiotics Anaesthetics Smoking Pregnancy, childbirth Surgery Alcoholic beverages Open-heart surgery Morphine Nerve gas Terrorism Low dread risk - controllable - not dreaded - not global catastrophic - consequences not fatal - equitable - individual - low risk to future generations - easily reduced - risk decreasing - voluntary - doesn't affect me Known risk - observable - known to those exposed - effect immediate - old risk - risks known to science Unknown risk - not observable - unknown to those exposed - effect delayed - new risk - risks unknown to science High dread risk - uncontrollable - dreaded - global catastrophic - consequences not fatal - not equitable - catastrophic - high risk to future generations - not easily reduced - risk increasing - involuntary - affects me Figure 3.1 Hazards for dread and riska a Adapted from: Slovic P, Fischhoff B, Lichtenstein S. Facts and fears: understanding perceived risk. In: Schwing RC, Albers WA Jr, editors. Societal risk assessment: how safe is safe enough? New York: Plenum; 1980. Locations of 20 hazards – instead of 90 in the original – on factor 1 (dread) and factor 2 (unknown risk) of the three-dimensional figure derived from interrelationships of 18 risk characteristics. Factor 3 (not shown) reflects the number of people exposed to the hazard and the degree of their personal exposure