LD50 testing is typically conducted on which subjects?

• A. Laboratory animals
• B. Humans
• C. Plants
• D. Microorganisms

Answer: (A)

LD50 testing measures the dose that causes death in 50% of a test population, so it relies on observing outcomes in living organisms. To obtain a meaningfully comparable measure of acute toxicity for risk assessment, researchers historically use laboratory animals such as mice or rats. Humans aren’t used in this type of testing for ethical and safety reasons, and plants or microorganisms don’t provide results that translate reliably to human toxicity because their biology and responses differ from mammalian systems. So the typical subjects are laboratory animals.