Risk Assessment, Risk Management

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During the last two decades of the twentieth century, risk science evolved into an important academic and applied discipline. The U.S. National Research Council issued a pioneering report in 1983, titled Risk Assessment in the Federal Government: Managing the Process. This report represented the first formalized effort to describe the health-risk assessment and management process in a structured way. It consolidated earlier efforts at developing a comprehensive framework, and it has been widely endorsed throughout the world.

The framework consists of three components: research, risk assessment, and risk management. Research refers to the collection, analysis, and interpretation of biological, chemical, and physical data from laboratory and other scientific studies, including studies on human populations, where possible. Risk assessment is defined as the characterization of the potential adverse health effects of human exposures to environmental hazards. Risk assessment consists of four steps: hazard identification (the process of determining whether exposure to an agent can lead to adverse health outcomes), dose-response assessment (characterizing the relation between the dose of an agent administered or received and the occurrence of adverse health effects in exposed populations), exposure assessment (measuring or estimating the intensity, frequency, and duration of human exposures to an agent currently present in the environment), and risk characterization (estimating the risk of adverse health effects under specific conditions of human exposure).

At the risk-management stage, alternative regulatory options are developed and evaluated. Selection of a particular regulatory option involves consideration of the public health, economic, social, and political consequences of implementation. Other factors of significance include the technical feasibility of the proposed solution, the desired level of control, the ability to enforce regulations, uncertainty in scientific data and the corresponding inferential bridges used to fill gaps in knowledge, and the public perception and level of information. The implementation of a specific course of action should be accompanied by the communication of information concerning the basis of the decision to affected parties.

Catalyzed in part by the guidance provided by the U.S. National Research Council, risk science evolved rapidly. In Canada, Health Canada developed a comprehensive framework for the assessment and management of population health risks, which served to identify the critical steps involved in health-risk assessment and management in further detail. The Canadian Standards Association also issued a national standard for risk assessment. An important feature of this standard was its broad applicability, providing general risk-assessment guidelines for health, environmental, and engineering applications. This was followed by a similar standard focusing on principles for risk-management decision making. The Canadian Public Health Association used the Health Canada risk-determination framework to establish a benefit/risk/cost determination framework to describe and evaluate risk/benefit methodology as it is applicable to the field of prescription drug use, including the use of quality adjusted life years (QUALYs) to measure risks and benefits.

The most recent contribution to the field of health-risk assessment is the 1997 report of the U.S. Presidential/Congressional Commission on Risk Assessment and Risk Management, based on a dynamic process involving the ongoing engagement of stakeholders. The Commission's Framework for Environmental Health Risk Management is designed to help all types of risk managersincluding government officials, private-sector businesses, and individual members of the public make good risk-management decisions when dealing with any type of environmental health risk. The framework is general enough to work in a wide variety of situations, with the level and effort invested being scaled to the importance of the problem, the potential severity and economic impact of the risk, the level of controversy surrounding the risk, and resource constraints. The framework is intended primarily for risk decisions related to setting standards, controlling pollution, protecting health, and cleaning up the environment. The framework consists of six steps: (1) define the problem and put it into context, (2) analyze the risks associated with the problem in context, (3) examine options for addressing the risks, (4) make decisions about which options to implement, (5) take actions to implement the decisions, and (6) conduct an evaluation of the results of the action. All stages of the process are implemented with the involvement of interested and affected parties.

The three key principles underpinning this framework include adopting a broad context for risk assessment (instead of evaluating single risks associated with single agents in single environmental mediums, the framework puts health and environmental problems in their larger real-world contexts); involvement of stakeholders at all phases of the process; and adopting an iterative approach, so that any new information or perspectives that may emerge may be taken into account by revisiting early stages of the process.

In addition to the overall frameworks for risk assessment and risk management described here, progress has also been made in many areas, including the use of scientific data to characterize health risks; the principles underlying risk-management decision making; understanding public perception of risk (and differences between public and expert opinion); and the communication of information on risk, and its potential influence on perceived risk.

The development of these frameworks and associated principles and guidelines have brought an element of clarity to the field of risk assessment and risk management. Principles such as fairness, equity, utility, honesty, and autonomy encourage consistency, transparency, and completeness in decision making. Risk-management principles can be of value in assigning priorities to important risk issues competing for attention and resources, in reaching decisions in the face of scientific uncertainty about the level of risk associated with health hazards, in balancing benefits and risks, and in acknowledging social and cultural considerations in risk management. Without such guidance, risk-management decision making can be highly complex, raising difficult questions to which there are often no easy answers.

Daniel Krewski

(see also: Benefits, Ethics, and Risks; Environmental Determinants of Health; Exposure Assessment; Risk Communication; Toxicology )


Benett, P., and Calman, C., eds. (1999). Risk Communication and Public Health. Oxford, UK: Oxford Medical Publications.

Canadian Standards Association (1997). Risk Management: Guideline for Decision-Makers. Toronto: Author.

Hattis, D. (1996). "Drawing the Line: Quantitative Criteria for Risk Management." Environment 38:1115, 3539.

Health Canada (1990, revised 1993). Health Risk Determination: The Challenge of Health Protection. Ottawa: Author.

Krewski, D.; Slovic, P.; Bartlett, S.; Flynn, J.; and Mertz, C. K. (1995). "Health Risk Perception in Canada II: Worldviews, Attitudes, and Opinions." Human and Ecological Risk Assessment 1:5370.

Presidential/Congressional Commission on Risk Assessment and Risk Management (1997). Framework for Environmental Health Risk Management. Final Report, Vol. 1. Washington, DC: U.S. Government Printing Office.

U.S. National Research Council (1983). Risk Assessment in the Federal Government: Managing the Process. Washington, DC: National Academy Press.

(1994). Science and Judgement in Risk Assessment. Washington, DC: National Academy Press.

(2000). Scientific Issues in Developmental Toxicity Risk Assessment. Washington, DC: National Academy Press.