Biomarkers of Exposure, Effect, and Susceptibility

Epidemiological research fundamentally involves the identification of relationships between previous exposures to putative causative agents and subsequent adverse biological effects in study populations. Molecular epidemiology encompasses the use of biomarkers in epidemiological research through the incorporation of molecular, cellular, organ system, and other biochemical and physiological measurements into studies of association, etiology, prevention, and control of health risks encountered by human populations. Application of validated biomarkers to traditional epidemiological studies helps to delineate the continuum of events between an exposure and resulting disease, to identify smaller exposures to specific xenobiotics, to indicate earlier events in the natural history of diseases and reduce misclassification of dependent and independent variables, to enhance individual and group risk monitoring and assessments, and to reveal toxicological mechanisms by which an exposure and a disease are related. This field of research has been most extensively explored in cancer, but in recent years, the use of molecular biomarkers reflecting the progression pathways in cardiovascular disease and neurological disorders has been rapidly increasing. Thus, methods to more accurately and sensitively characterize exposure, effects, and susceptibility are needed in research involving environmental agents. Collectively, these data also help to inform the risk assessment process, where regulations can be tested against biological measurements of exposure to determine the efficacy of the regulations, and most recently, these tools have been applied to the problems of assessing cumulative risk.