Definitions for "LETHAL CONCENTRATION 50"
The concentration of a material in air which, on the basis of laboratory tests, is expected to kill 50 percent of a group of test animals when administered as a single exposure (usually one to four hours).
The concentration of an air contaminant that will kill 50% of the test animals in a group within the first 30 days following exposure.
The concentration of a chemical in the diet or in the water that kills 50 percent of a group of test animals over a specified length of exposure.