Biomarkers: Coming of age for environmental health and risk assessment

Biological markers, or biomarkers, reflect molecular and cellular alterations that occur along the temporal and mechanistic pathways connecting exposure to toxic chemicals or physical agents and the presence or risk of clinical disease. Biomarkers include a vast array of measurements that reflect exposure, effect, and/or susceptibility. The development and validation of potential biomarkers is a long-term endeavor that proceeds from basic research to pilot human studies to full-scale epidemiological investigations. The past decade has seen extensive research investigation of biomarkers and the beginnings of their practical application for risk assessment and environmental health management. These potential applications include improved exposure characterization and dose-response assessment, measurement of interindividual variability, and evaluation of causation in toxic tort and environmental litigation. This paper reviews the biomarker paradigm as applied to xenobiotic exposure in humans, discusses progress toward applying biomarker technology in environmental epidemiology, and summarizes recent biomarker data for three important environmental and occupational agents, benzo[a]pyrene, 1,3-butadiene, and acrylamide.