What does LD50 stand for?

• A. Median Lethal Dose
• B. Low Dose
• C. Lethal Dose 50%
• D. Lethal Concentration 50%

Answer: (A)

LD50 is a toxicity metric that identifies the dose expected to kill 50% of a defined population under a set observation period. The standard expansion is “Lethal Dose 50%,” meaning the amount of substance that causes death in half of the test subjects, typically expressed as mg of substance per kg of body weight. The lower the LD50, the more toxic the substance. This differs from “Lethal Concentration 50%,” which would refer to a concentration in the environment rather than dose per body weight. While the idea can be described as the median lethal effect, the accepted phrasing for this measure is Lethal Dose 50%.