Drugs & Human Behavior 1 Practice Test

LD50 is the dose that would be lethal to 50% of the tested population. On a dose–response curve, this is the point where mortality reaches 50%, marking the median lethal dose. This measure helps compare how toxic a substance is: a lower LD50 means a more potent toxin because a smaller amount causes half the subjects to die. The idea of a dose that yields 50% death describes the same threshold, but the standard label used on the curve is the median lethal dose. A dose lethal to all subjects would be the LD100, and a dose that produces no effect is below the lethal threshold.