For environmental health risks, researchers combine information about the toxicity of a a substance with the amount of exposure a population has to the substance to calculate what is likely to happen. This relationship, the dose-response relationship, between toxicity and exposure is key to risk assessment. Uncertainty arises, however, from the question of how much exposure is necessary to create a health risk. Substances like mercury and benzene are known to be toxic in small amounts, but there is less certainty about the threshold of exposure at which other substances are dangerous to human health. A risk assessment, therefore, is a statement of a range of probabilities of harm.
Risk management differs from risk assessment.
Risk management is the effort to reduce the level of risk, taking into consideration social, economic, and political factors, using information from assessments of risk that have been performed. Risk assessment is a tool that helps policy makers and risk managers make rational decisions about managing and protecting public health. Advancing Understanding of Knowledge's Role in Lay Risk Perception Written by a research scientist at the New Jersey Department of Environmental Protection and Energy, this article discusses the relationship between knowledge and risk. The Management of Risk and Uncertainty A Policy Analysis article by John Adams, this work addresses why the general population often assesses risk differently than experts do. Informing Decisions in a Democratic Society .