Biomarkers are used in many aspects of health surveillance to identify disease pr- ence, track disease progression, monitor drug delivery or metabolism, or monitor chemical exposure. There is a recognized need to expand and improve biomarker identi?cation and quanti?cation. Exposures to the xenobiotic organophosphates (OPs) range from low-level, chronic exposure during pesticide application (e. g., on farms, in residences, or in the workplace) to high-dose, acute exposures incl- ing release of nerve agents or toxic industrial OPs. OPs can have both rapid and chronic toxicity, due to their...