Kentucky Licensed Clinical Alcohol and Drug Counselors (LCADC) Practice Test

In toxicology, the amount of a substance that would cause death in a portion of exposed individuals is described as the lethal dose. When the reference specifies death in about half of the population, this is the lethal dose expressed as LD50. The phrase captures both the outcome (death) and the proportion affected (about 50%). The other terms describe different concepts: half-life is the time it takes for the substance to reduce by half in the body, additive effect refers to combined effects of substances adding up, and independent effect isn’t a standard term for this idea. So the correct term for a dose that would commonly kill 50% is the lethal dose (LD50).