150 The World Health Report 2002 IDENTIFYING PRIORITY RISK FACTORS FOR PREVENTION The scientific basis for the burden attributable to the main risk factors addressed in this report is reasonably well understood; for these risks, remaining data gaps should not diminish the importance of adopting control policies today if disease burden is to be lowered in the near future. Much of the scientific and economic information necessary for making health policy decisions is already available. Many of these are also well known, common, substantial and widespread. They are also more likely to have cost-effective risk reduction strategies. Lack of uncertainty and availability of cost-effective interventions for large risks leads to agreement in society about the need for action. Examples would be increasing tobacco consumption, particularly in Asia and astern Europe, and the role of unsafe sex in the HIVIAIDS epidemic, particularly in Africa Many of these risks are common to populations in both industrialized and developing countries, though the degree of exposure may vary. Risk factors with smaller disease burdens should also not be neglected; although smaller than other factors, they still contribute to the total burden of disease in various regions Large industrial activity involving coal, ambient air pollution and lead exposure, for exam- ple, has health effects comparable to other major risk factors. Some risks, such as occupa tional ones, are concentrated among certain sectors of society. This implies not only that these sectors are disproportionately affected, but also that the concentration makes target ing risk easier, as successful occupational safety interventions and policies in many region lave shown For other risk factors such as childhood sexual abuse, ethical considerations may outweigh direct contributions to disease burden. Even though the burden of disease attributable to a risk factor may be limited, highly effective or cost-effective interventions may be known. Reducing the number of unnecessary medical injections coupled with the use of sterile syringes are effective methods for controlling transmission of communicable diseases. Similarly, reductions in exposure to lead or ambient air pollution in industrialized countries in the second half of the 20th century were achieved by effective use of technology which often also led to energy saving and other benefits. In the case of these risk factors, therefore, the benefits to population health stemming from risk assessment, together with other considerations, provide the best possible policy guides for specific actions. The management of risk factors or hazards that have uncertain or highly uncertain risk probabilities or adverse consequences, such as exposure to climate change or genetically modified foods, is considered in the next section, in the context of cautionary approache and the use of the precautionary principle The national context is very important for assessing the options for risk prevention. For instance, in many middle and low income countries a lack of scientific expertise and equipment may mean that appropriate data for making local risk assessments are not available. In addition, many risks may also have low priority for any political action. In these situations, public awareness of risk factors may need to be enhanced and knowledge about the most dangerous risk factors brought openly to public attention, while interest groups and the mass media may need to be encouraged to debate publicly local risks to health ny leadership for political action will have to come from the ministries of health. Collective actions at regional and international levels are also called for, as many risk factors and risks to health are not limited by national borders. This is where the World Health Organization can play an effective advisory and coordinating role150 The World Health Report 2002 IDENTIFYING PRIORITY RISK FACTORS FOR PREVENTION The scientific basis for the burden attributable to the main risk factors addressed in this report is reasonably well understood; for these risks, remaining data gaps should not diminish the importance of adopting control policies today if disease burden is to be lowered in the near future. Much of the scientific and economic information necessary for making health policy decisions is already available. Many of these are also well known, common, substantial and widespread. They are also more likely to have cost-effective risk reduction strategies. Lack of uncertainty and availability of cost-effective interventions for large risks leads to agreement in society about the need for action. Examples would be increasing tobacco consumption, particularly in Asia and Eastern Europe, and the role of unsafe sex in the HIV/AIDS epidemic, particularly in Africa. Many of these risks are common to populations in both industrialized and developing countries, though the degree of exposure may vary. Risk factors with smaller disease burdens should also not be neglected; although smaller than other factors, they still contribute to the total burden of disease in various regions. Large industrial activity involving coal, ambient air pollution and lead exposure, for exam￾ple, has health effects comparable to other major risk factors. Some risks, such as occupa￾tional ones, are concentrated among certain sectors of society. This implies not only that these sectors are disproportionately affected, but also that the concentration makes target￾ing risk easier, as successful occupational safety interventions and policies in many regions have shown. For other risk factors, such as childhood sexual abuse, ethical considerations may outweigh direct contributions to disease burden. Even though the burden of disease attributable to a risk factor may be limited, highly effective or cost-effective interventions may be known. Reducing the number of unnecessary medical injections coupled with the use of sterile syringes are effective methods for controlling transmission of communicable diseases. Similarly, reductions in exposure to lead or ambient air pollution in industrialized countries in the second half of the 20th century were achieved by effective use of technology which often also led to energy saving and other benefits. In the case of these risk factors, therefore, the benefits to population health stemming from risk assessment, together with other considerations, provide the best possible policy guides for specific actions. The management of risk factors or hazards that have uncertain or highly uncertain risk probabilities or adverse consequences, such as exposure to climate change or genetically modified foods, is considered in the next section, in the context of cautionary approaches and the use of the precautionary principle. The national context is very important for assessing the options for risk prevention. For instance, in many middle and low income countries a lack of scientific expertise and equipment may mean that appropriate data for making local risk assessments are not available. In addition, many risks may also have low priority for any political action. In these situations, public awareness of risk factors may need to be enhanced and knowledge about the most dangerous risk factors brought openly to public attention, while interest groups and the mass media may need to be encouraged to debate publicly local risks to health. Any leadership for political action will have to come from the ministries of health. Collective actions at regional and international levels are also called for, as many risk factors and risks to health are not limited by national borders. This is where the World Health Organization can play an effective advisory and coordinating role