An evaluation was conducted of the efficacy of the quantitative modification of the chromogenic Limulus amebocyte lysate test (LALT) for detecting endotoxin contamination in airborne dusts from spring wheat and oats. The evaluation included tests to determine the effects of different extraction solutions, extraction time, and repeated freezing and thawing cycles on the detectable endotoxin levels. Reconstituted commercial lipopolysaccharides from different bacteria were utilized. Extraction solutions included water and 1% aqueous solutions of Tween-20, Tween-80, Triton X-100, and Saponin, as well as 1% and 0.01% solutions of human, bovine, and chicken egg albumin. Tests to determine the endotoxin contamination of these extraction solutions indicated that all solutions, except for human and chicken egg albumins, were basically free of endotoxins. Tests to determine the effect of extraction solution on the detectable endotoxin levels in spring wheat and oat dusts indicated water to be the medium of choice. The effects of extraction time were analyzed using water as the extraction solvent. For both dusts, the peak extractable endotoxins were determined after extraction for 2 hours. The effects of repeated freezing and thawing of a water extract revealed day to day variations in detectable endotoxins from both dusts and demonstrated that endotoxin analysis of spring wheat and oat dusts could be performed on extracts that had been frozen. The authors conclude that the chromogenic modification of the LALT can be used effectively in the analysis of environmental dusts for endotoxin quantification.