The does or amount of an active ingredient which, when taken orally or absorbed through the skin, kills half of the test animals; an expression of a compound's toxicity.

lethal dose at which 50% of experimental population dies

The dose of a pesticide active ingredient taken by mouth or absorbed by the skin which is expected to cause death in 50 percent of the test animals; the lethal dose is measured in milligrams per kilogram of body weight. Lethal dose 50. The single dose of a substance that causes death of 50% of an animal population from exposure to the substance by any route other than inhalation.