CentralNotice From Wikipedia, the free encyclopedia (Redirected from LD50 ) Jump to: navigation , search "LD50" redirects here. For other uses, see LD50 (disambiguation) . In toxicology , the median lethal dose , LD 50 (abbreviation for " lethal dose , 50%"), LC 50 (lethal concentration, 50%) or LCt 50 is a measure of the lethal dose of a toxin , radiation , or pathogen . The value of LD 50 for a substance is the dose required to kill half the members of a tested population after a specified test duration. LD 50 figures are frequently used as a general indicator of a substance's acute toxicity . A lower LD 50 is indicative of increased toxicity. The test was created by J.W. Trevan in 1927. [ 1 ] The term semilethal dose is occasionally used with the same meaning, in particular in translations from non-English-language texts, but can also refer to a sub lethal dose; bec...