Will There Ever Be a Role for Risk Assessments?

Click to increase image sizeClick to decrease image size

Notes

Definitions for risk and uncertainty vary and their operational meaning in chemical risk assessment diverges from classical definitions (Knight 1933). A decision-maker typically confronts a number of alternatives and must choose one of them. Each alternative could give rise to more than one possible identifiable outcome, each with a different ascertainable probability. All future outcomes are therefore uncertain, and remain so until realized. The probabilities assigned to these outcomes are a measure of their uncertainty, which emerges from, among other factors, changing combinations of stochastic variation in parameter values, missing or inconclusive scientific data, errors in applying statistical procedures, various knowledge deficits with regards the system in question, or poorly informed model assumptions. Risk describes the specific case where one or more (but not necessarily all) of these uncertain outcomes involves a loss (i.e., a negative consequence). The measure of uncertainty refers only to an outcome's probability, while the measure of risk requires both an outcome's probability and quantification of the associated loss. Thus one may have uncertainty without risk but not risk without uncertainty (Hubbard 2007, p. 46).