What does LD50 represent?

What does LD50 represent?

• A. The dose that causes death in 50% of the test subjects.
• B. The dose that causes no effects.
• C. The dose that cures disease.
• D. The dose that causes death in 100%.

Answer: (A)

LD50 is the median lethal dose—the amount of a substance that, under defined test conditions, would kill half of the exposed population. It’s a statistical measure of acute toxicity, usually expressed as mg of substance per kg of body weight, used to compare how toxic different chemicals are. A lower LD50 means a chemical is more acutely toxic because a smaller dose causes death in 50% of subjects. Remember that LD50 depends on many factors—species, strain, age, sex, health, route of exposure, and study conditions—so it doesn’t reflect safe doses for humans or account for chronic or sublethal effects. It’s not the dose that causes no effects (that would be NOAEL) and not the dose that cures disease, nor is it the LD100, which would kill all subjects.

LD50 is the median lethal dose—the amount of a substance that, under defined test conditions, would kill half of the exposed population. It’s a statistical measure of acute toxicity, usually expressed as mg of substance per kg of body weight, used to compare how toxic different chemicals are. A lower LD50 means a chemical is more acutely toxic because a smaller dose causes death in 50% of subjects. Remember that LD50 depends on many factors—species, strain, age, sex, health, route of exposure, and study conditions—so it doesn’t reflect safe doses for humans or account for chronic or sublethal effects. It’s not the dose that causes no effects (that would be NOAEL) and not the dose that cures disease, nor is it the LD100, which would kill all subjects.