Which term refers to the dose that results in death?

• A. Threshold dose
• B. Effective dose
• C. Maximum effect
• D. Lethal dose

Answer: (D)

In toxicology, the dose that can cause death is called the lethal dose. A common way to express this is LD50—the amount of substance required to kill 50% of a defined group under specific conditions. This concept helps compare how dangerous different substances are, since a lower LD50 means higher toxicity. Other terms describe different outcomes: the threshold dose is the smallest amount that begins to produce any effect, the effective dose is the amount needed to achieve a desired therapeutic effect, and the maximum effect refers to the greatest response a substance can produce. The lethal dose is specifically about death, and its exact value can vary widely depending on species, age, health, and how the substance is taken.