Figure 1.

The three categories of biomarkers: biomarkers of exposure, biomarkers of effect, and biomarkers of susceptibility. The markers fall along the spectrum from exposure (e.g., prenatal exposure to alcohol) to disease (e.g., fetal alcohol syndrome). Biomarkers of exposure are designed to detect exposure rather than the effect of exposure. Conversely, biomarkers of effect are designed to detect the effect of exposure or the development of disease. Biomarkers of susceptibility can mark increased vulnerability at any of the steps between exposure and clinical disease.