ABSTRACT
WHAT IS A BIOMARKER? Biomarkers are defined by the National Academy of Sciences as xenobiotically induced alterations in cellular or biochemical components or processes, structures, or functions that are measurable in a biological system or sample. Kendall et al. (1) suggested adding to this list xenobiotically induced alterations in behavior. Therefore, biomarkers can be broadly categorized as markers of exposure, effects, or susceptibility (1).
