nonspecific "lux" bioreporters are typically used for the detection of chemical toxins. they are usually designed to continuously bioluminesce. upon exposure to a chemical toxin, either the cell dies or its metabolic activity is retarded, leading to a decrease in bioluminescent light levels. their most familiar application is in the microtox assay where, following a short exposure to several concentrations of the sample, the decreased bioluminescence can be correlated to relative levels of toxicity.