Fundamentals Of Industrial Hygiene (IH) Practice Test

LC50 refers to the lethal concentration for what percentage of the population?

50 percent 25 percent 75 percent 100 percent

Correct Answer:

50 percent

Explanation:

LC50 means the concentration of a substance in air (for inhalation) that would cause death in about half of exposed organisms within a defined time. It comes from dose–response data and serves as a way to compare acute hazards and estimate risk under those conditions. Because it’s a statistical estimate, it can vary with species, exposure duration, and other factors, so the LC50 is not a universal threshold for every individual. The key idea is that it represents fifty percent of the population, i.e., half, not a quarter, three quarters, or all of them.

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