LD50 is defined as the dose that causes death in what percentage of a test population?

LD50 is defined as the dose that causes death in what percentage of a test population?

• A. 50%
• B. 25%
• C. 75%
• D. 100%

Answer: (A)

LD50 is the median lethal dose—the amount of a substance that will kill half of a defined test population under the study’s specific conditions. In toxicology, you create a dose–response curve and locate the dose where mortality reaches 50%; that dose is the LD50. This standard lets you compare how toxic different substances are: a lower LD50 means a substance is more acutely toxic because a smaller amount is enough to reach half the fatalities. Keep in mind that LD50 isn’t a universal human value. It depends on the species tested, the exposure route (ingestion, inhalation, skin contact), the health and age of subjects, and the exact experimental setup. The other percentages (like 25% or 75%) refer to different points on the curve but aren't the LD50.

LD50 is the median lethal dose—the amount of a substance that will kill half of a defined test population under the study’s specific conditions. In toxicology, you create a dose–response curve and locate the dose where mortality reaches 50%; that dose is the LD50. This standard lets you compare how toxic different substances are: a lower LD50 means a substance is more acutely toxic because a smaller amount is enough to reach half the fatalities.

Keep in mind that LD50 isn’t a universal human value. It depends on the species tested, the exposure route (ingestion, inhalation, skin contact), the health and age of subjects, and the exact experimental setup. The other percentages (like 25% or 75%) refer to different points on the curve but aren't the LD50.