Glossary

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LD50 value

Measurement of the toxicity of a substance or radiation.

The LD50 value is the amount of a substance or radiation which causes the death of 50 percent of a population of test animals (LD = lethal dose).

A specific quantity of a substance is administered to the animals in one dose. The LD50 is usually expressed as the amount of substance administered (e.g. in grams or milligrams) per kilogram of body weight. When expressing the value for radiation, the time taken to die is also included. The test animal and method of administration (oral, subcutaneous or intravenous) are also stated, since these two parameters are essential for estimating the toxicity for and transferability to humans.

The lethal concentration (LC50) refers to the quantity of a substance in an organism’s environment that causes the death of half the organisms within a specific time.