Risk Analysis

THE SOCIETY for Risk Analysis defines risk analysis as “risk assessment, risk characterization, risk communication, risk management, and policy relating to risk.” The risks being assessed and considered are, in this context, risks to human health from activities and agents as diverse as bioterrorism, neglecting to use sunscreen, working at a location where soil is contaminated, eating improperly stored food, and driving while intoxicated.

Risk is a measure of the probability of harm from a given activity or agent, often calculated as[Page 691] the likelihood of one additional death per one million people. It is important to note that nothing is completely free of risk. The role of risk analysis is to measure and manage acceptable risks, not to eliminate harms completely.

Risk assessment is a statistical modeling technique that uses known exposures and harms to predict unknown exposures and harms. The Food Safety Risk Analysis Clearinghouse defines a fourstep process of hazard identification, hazard characterization, exposure assessment, and risk characterization that is typical of risk assessment in general. At each stage, it is possible for false assumptions or misunderstood analysis to result in an incorrect assessment of risks.

Hazard identification involves discovering what potential causes of harm could be present in the substance or situation being assessed. Accurate hazard identification depends both on knowing what substances cause what harms and on knowing which of those substances is likely to be present. In West Chicago, Illinois, for example, homeowners used radioactive thorium tailings from an old American Potash plant as garden fill because they did not know that a hazardous substance was present. Many companies who are now responsible for contaminated site clean-ups aver that, although they knew they were dumping chemicals into the local groundwater, they did not know that the chemicals were harmful. Because hazard identification has become refined over the past 50 years, it is now a standard part of major property transactions to have include a document search, survey of aerial photos, and walk of the grounds, looking for signs of potential contamination. Similarly, the Environmental Protection Agency (EPA) is requiring chemical manufacturers to document the qualities of substances that have been manufactured and used for years but about which little is known.