Cotton dust from the Memphis area was treated with 1) ethanol and sodium hydroxide, 2) ethanol and hydrochloric acid, 3) dimethyl sulfoxide, or 4) pyrogenfree water with a wetting agent. A second set of samples was prepared by treating the dust with 1) 95% ethanol and sodium hydroxide five times, 2) 80% ethanol and sodium hydroxide, or 3) pyrogen-free water and sodium hydroxide. Endotoxin levels in the treated dusts were determined by the Limulus amebocyte lysate (LAL) assay. Samples of the dusts were distributed to scientists in cotton dust research for chemical, biological, microbiological and animal model assays.