Introduction

“Risk group” refers to the actual or hypothetical exposed group for whom the risk assessment is being conducted. This group is composed of members of the general population and/or workers. The need to quantify the health risks associated with exposure to environmental and occupational toxicants has generated a new interdisciplinary methodology referred to as risk assessment. Risk assessment and risk management are an integral part of the contemporary regulatory activities of federal and state agencies and the industries with which these agencies interact. The major impetus for conducting risk assessments comes from federal legislation. Since 1972, federal health and safety statutes have adopted a general safety standard of “unreasonable risk”. When a risk group is exposed to a dose that is within the experimental dose range, the estimate of risk can be calculated from the same equation used to fit the experimental dose-response data.