Risk assessors endeavor to define a risk that will be realized under actual or anticipated conditions by establishing the "average truth" from numerous probabilities. Assessing risk based on conclusions drawn from an infinite number of integrations cannot be expressed in terms of "safe" or "non-toxic." Such expressions imply that a chemical or an event (e.g., accident) is without risk or harm, which may be misleading. Instead a chemical or an event is ranked as minor, moderate, or high to reflect the degree of risk that it represents within a given set of parameters. Such is the role of the risk assessor to calculate the effects of variables while classifying the uncertainties and presenting risk managers with a list of choices.

Comprehending the number of variables and uncertainties associated with an event can be explored in the following example. If one were to assess the number...