|T| Divide line [6] by 64,S5O andmultiplyby1OO Ssw =

FIG. 11.7.1 Surface water route worksheet.

FIG. 11.7.1 Surface water route worksheet.

The term "risk" refers to the probability that an event will have an adverse effect, indirectly or directly, on human health or welfare. Risk is expressed in time or unit activity, e.g., cancer cases per pack of cigarettes smoked. Risk assessment takes into account the cumulative effects of all exposure. For example, in assessing the risk that a person will suffer from air pollution, both indoor and outdoor pollution must be taken into account.

The function of an effective hazardous materials management program is to identify and reduce major risks. This involves both risk assessment and risk management. The flowchart in Figure 11.8.1 shows the factors affecting the hazardous waste risk assessment procedure. This procedure begins with identification of the waste and the laws and regulations pertaining to that waste. When the waste is identified, its toxicity and persistence must be determined to evaluate the risk of human and the environmental exposure. The risk management process involves selecting a course of action based on the risk assessment.

One way to highlight differences between risk assessment and risk management is to look at differences in the information content of the two processes. Data on tech-

FIG. 11.8.1 Factors affecting the risk assessment of hazardous waste.

nological feasibility, on costs, and on the economic and social consequences of possible regulatory decisions are of critical importance to risk management but not to risk assessment. As statutes require, risk managers consider this information with risk assessment outcomes to evaluate risk management options and make environmental decisions (Figure 11.8.2).

Environmental risk assessment is a multi-disciplinary process. The risk assessment procedure is an iterative loop that the assessor may travel several times. It draws on data, information, and principles from many scientific disciplines, including biology, chemistry, physics, medicine, geology, epidemiology, and statistics. After evaluating individual studies for conformity with standard practices within each discipline, the most relevant information from each is combined and examined to determine the risk. Although studies from single disciplines are used to develop risk assessment, such studies alone are not regarded as risk assessment or used to generate risk assessments.

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