WST-1 assay results for BTE cytotoxicity in A549 cells. Results indicate the absorbance level (an average of three separate samples on the same plate), which relates to the amount of live or viable cells for each treated sample. A higher absorbance level indicates more living or viable cells than a lower absorbance level. As a reference, media containing no live cells with WST-1 produced an absorbance level of 0.211 (data not shown). Values represent ± SD.