In toxicology, the<unk> ,<unk>  (abbreviation for<unk>  dose, 50%"), LC50<unk>  concentration, 50%) or LCt50 is a measure of the<unk>  dose of a toxin, radiation, or pathogen. The value of<unk>  for a substance is the dose required to kill half the members of a tested population after a specified test duration.<unk>  figures are frequently used as a general indicator of a substance's acute toxicity. A lower<unk>  is indicative of increased toxicity. The test was created by J.W. Trevan in 1927. The term semilethal dose is occasionally used in the same sense, in particular with translations of foreign language text, but can also refer to a sublethal dose.<unk>  is usually determined by tests on animals such as laboratory mice. In 2011, the U.S. Food and Drug Administration approved alternative methods to<unk>  for testing the cosmetic drug Botox without animal tests.
Median lethal dose
Incubation period
Fractional kill
Epidemic curve
Apparent infection rate
Case fatality rate
Risk of mortality
Minimal infective dose