ABSTRACT
Descriptions in prior chapters make it abundantly clear that chemicals differ greatly in the nature and potency of their toxicity. Because human exposure to chemicals is not always avoidable (it may even be desirable in certain cases), toxico logical evaluation of many chemicals must be carried out to determine the level of exposure (or intake in the case of food and water) under which no risk is likely to occur. A comprehensive review by Paustenbach (2000) covers risk assessment. Because of the gaps in our knowledge, it is prudent to be conservative in assessing the safety and risk. But when undue caution is incorporated into the process, the public may be denied chemicals of great value and society may be burdened with unnecessary economic costs, such as pollution prevention measures and environmental cleanup. Therefore, the most important function of toxicology is to establish the scientifi c basis for regulating the use (and disposal) of chemicals without undue human health hazards or undue cost.
