median lethal dose(redirected from LD 50)
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median lethal doseor
mean lethal dose
1. (Medicine) the amount of a drug or other substance that, when administered to a group of experimental animals, will kill 50 per cent of the group in a specified time
2. (Medicine) the amount of ionizing radiation that will kill 50 per cent of a population in a specified time
me′dian le′thal dose′
the quantity of a lethal substance, as a poison or pathogen, or of ionizing radiation that will kill 50 percent of the organisms subjected to it in a specified time period. Symbol: LD50