Historically, environmental regulatory programs designed to protect public health have monitored pollutants only in geophysical carrier media (for example, outdoor air, streams, soil). Field studies have identified a gap between the levels observed in geophysical carrier media and concentrations with which people actually come into contact: their daily exposures. A new approach--Total Human Exposure (THE) has evolved to fill the gap and provide the critical data needed fpr accurately assessing public health risk. The THE approach considers a three-dimensional 'bubble' around each person and measures the concentrations of all pollutants contacting that bubble, either through the air, food, water, or skin. Two basic THE approaches have emerged: (1) the direct approach using probability samples of populations and measuring pollutant concentrations in the food eaten, air breathed, water drunk, and skin contacted; and (2) the indirect approach using human activity pattern-exposure models to predict population exposure distributions.