ATS is comprised of the organic contaminants remaining on surgical instruments after clinical use, including protein (2200 μg/ml), hemoglobin (670 μg/ml) and carbohydrates (560 μg/ml). These quantities are reflective of the “worse case” levels found to remain on instruments after patient use, but before reprocessing. The FDA and other international regulatory agencies specify that simulated-use testing should approximate as closely as possible the actual soiling the instrument is exposed to during clinical use. ATS meets this requirement with extensive research (available upon request) to support it.