The world health report

Chapter 1

Reducing the risks

People everywhere are exposed all their lives to an almost limitless array of risks to their health, whether in the shape of communicable or noncommunicable disease, injury, consumer products, violence or natural catastrophe. Sometimes whole populations are in danger, at other times only an individual is involved. Most risks cluster themselves around the poor.

No risk occurs in isolation: many have their roots in complex chains of events spanning long periods of time. Each has its cause, and some have many causes.

In this report, risk is defined as "a probability of an adverse outcome, or a factor that raises this probability".

Human perceptions of and reactions to risk are shaped by past experience and by information and values received from sources such as family, society and government. It is a learning process that begins in childhood -- when children learn not to play with fire -- and is constantly updated in adulthood. Some risks, such as disease outbreaks, are beyond our individual control; others, such as smoking or other unhealthy consumptions, are within our power to either heighten or diminish.

The challenge and responsibility of reducing risks as much as possible, in order to achieve a long and healthy life, is shared by individuals, whole populations and their governments. For example, putting on a car seat belt is an individual action to reduce risk of injury; introducing a law to make wearing seat belts compulsory is a government action on behalf of the population.

Many people believe it is their government's duty to do all it reasonably can to reduce risks on their behalf, such as making sure that foods and medicines are safe. This is particularly important where individuals have little control over their exposure to risks. Such actions are commonly referred to as "interventions". In this report, an intervention means "any health action -- any promotive, preventive, curative or rehabilitative activity where the primary intent is to improve health".

Although governments rarely can hope to reduce risks to zero, they can aim to lower them to a more acceptable level, and explain, through open communication with the public, why and how they are doing so. Governments must also develop high levels of public trust, because the public is quick to judge how well risks are being managed on its behalf. This applies whether the risk relates to a rapidly moving new epidemic or to a long-term exposure.

In order to protect the people -- and help them protect themselves -- governments need to be able to assess accurately how great the risks are. Until now, that has been a seriously neglected task. Without some quantitative approach to gauging the importance of specific risks, in terms of the likely size of their impact on populations, government policies might be driven exclusively by factors such as pressure groups or the emotive weight of individual cases.

A key purpose of this report is to provide governments with a strategy for that assessment as an avenue towards developing the best policies and an array of intervention options for risk reduction. It also offers a comprehensive approach to the definition and study of risks.

In this report, risk assessment is defined as "a systematic approach to estimating the burden of disease and injury due to different risks". It involves the identification, quantification and characterization of threats to human health. Risk assessment can provide an invaluable, overall picture of the relative roles of different risks to human health; it can illuminate the potential for health benefits by focusing on those risks, and it can help set agendas for research and policy action. The broader activity of risk analysis is a political activity as well as a scientific one and embraces public perception of risk, bringing in issues of values, process, power and trust.