Which statement best describes what LD50 measures?

Which statement best describes what LD50 measures?

• A. The amount to kill 100% of the test population
• B. The lethal dose to kill 50% of the test population, usually expressed as mg/kg
• C. The amount to kill 10% of the test population
• D. The amount to kill none of the test population

Answer: (B)

LD50 is the amount of a substance that would kill half of a test population under defined conditions. It’s the median lethal dose and is usually expressed as milligrams of substance per kilogram of body weight. This measure lets scientists compare how acutely toxic different substances are, because a smaller LD50 means a higher toxicity. Keep in mind it’s tied to a specific route of exposure and species, and it reflects mortality after a defined exposure, not sublethal effects. It does not imply everyone will die at that dose, nor is it about killing a fixed smaller percentage like 10% or none.

LD50 is the amount of a substance that would kill half of a test population under defined conditions. It’s the median lethal dose and is usually expressed as milligrams of substance per kilogram of body weight. This measure lets scientists compare how acutely toxic different substances are, because a smaller LD50 means a higher toxicity. Keep in mind it’s tied to a specific route of exposure and species, and it reflects mortality after a defined exposure, not sublethal effects. It does not imply everyone will die at that dose, nor is it about killing a fixed smaller percentage like 10% or none.