the dose of a toxicant killing 50% of a large group of individuals of one species. See dose.

Statistically derived dose of a pesticide expected to kill 50% of test organisms in a given population under a defined set of conditions. Normally expressed as mg of test material per kg of body weight of the organism. (Duffus, 1993)

The dose that is just lethal to 50% of the specimen. This terminology is used in biological experiments. It is the same as the LD50 or the median.

Statistically derived dose of a chemical or physical agent (radiation) expected to kill 50% of organisms in a given population under a defined set of conditions.

n: Amount of a toxic material per unit body weight of test animals that kills half the test population in a certain time.