LD50 stands for "Lethal Dose 50". It is a standardized measure for expressing and comparing the toxicity of chemicals/22%3A_Poisons/22.04%3A_The_Lethal_Dose). The LD50 value is the amount of a substance that is needed to kill half of a test population of animals. The value of LD50 for a substance is the dose required to kill half the members of a tested population after a specified test duration. LD50 figures are frequently used as a general indicator of a substances acute toxicity. The LD50 is usually expressed as the mass of substance administered per unit mass of test subject, typically as milligrams of substance per kilogram of body mass. LD50 is usually determined by tests on animals such as laboratory mice. The LD50 test was created by J. W. Trevan in 1927. The LD50 gives a measure of the immediate or acute toxicity of a chemical in the strain, sex, and age group of a particular animal species being tested. However, it does not measure corrosiveness, caustic burning, irritability, cancer-causing properties, or other injurious reactions. The LD50 test was neither designed nor intended to give information on long-term exposure effects of a chemical.