Which description is accurate for LD50?

Which description is accurate for LD50?

• A. The dose at which 50% of test subjects die from a single exposure.
• B. The concentration at which 50% of tested adults show irritation.
• C. The dose that causes death in 5% of test subjects.
• D. The total dose required to cause any effect in all subjects.

Answer: (A)

LD50 is the dose of a substance that, given in a single exposure, is expected to kill 50% of the test population. It’s a standard measure of acute toxicity and is derived from dose–response data, usually reported in mg of substance per kg of body weight. The description that matches is the dose that causes death in 50% of test subjects from one exposure. It’s not about irritation (that would be a different metric), not a dose that only kills 5% (that would be LD5), and not the total dose needed to cause any effect in all subjects (that relates to a different endpoint like NOAEL/LOAEL or a non-lethal threshold). Also, remember LD50 can vary by species and exposure route.

LD50 is the dose of a substance that, given in a single exposure, is expected to kill 50% of the test population. It’s a standard measure of acute toxicity and is derived from dose–response data, usually reported in mg of substance per kg of body weight. The description that matches is the dose that causes death in 50% of test subjects from one exposure. It’s not about irritation (that would be a different metric), not a dose that only kills 5% (that would be LD5), and not the total dose needed to cause any effect in all subjects (that relates to a different endpoint like NOAEL/LOAEL or a non-lethal threshold). Also, remember LD50 can vary by species and exposure route.