Which statement best describes how LD50 relates to toxicity?

Which statement best describes how LD50 relates to toxicity?

• A. Lower LD50 indicates lower toxicity
• B. LD50 is used to describe chronic toxicity
• C. Lower LD50 indicates higher toxicity
• D. LD50 measures the rate of absorption

Answer: (C)

LD50 measures the dose of a substance that will kill 50% of a test population. The smaller that dose, the more toxic the chemical is because only a tiny amount is needed to reach the lethal threshold for half the individuals. This is a way to compare acute toxicity between substances. It doesn’t describe chronic effects, nor does it tell you anything about how fast the substance is absorbed into the body—that would be a different measurement. So saying that a lower LD50 indicates higher toxicity correctly captures how LD50 relates to how dangerous a substance is in acute exposure.

LD50 measures the dose of a substance that will kill 50% of a test population. The smaller that dose, the more toxic the chemical is because only a tiny amount is needed to reach the lethal threshold for half the individuals. This is a way to compare acute toxicity between substances. It doesn’t describe chronic effects, nor does it tell you anything about how fast the substance is absorbed into the body—that would be a different measurement. So saying that a lower LD50 indicates higher toxicity correctly captures how LD50 relates to how dangerous a substance is in acute exposure.