What is LC50 Inhalation?

• A. The median lethal concentration of a substance in air that, when inhaled, is lethal to half of test subjects within 14 days
• B. The median lethal dose administered orally
• C. The dose that kills all subjects
• D. The concentration time to 50% lethality in 24 hours

Answer: (A)

LC50 Inhalation means the concentration of a substance in air that, when inhaled, is lethal to 50% of the exposed subjects over a defined observation period, typically about 14 days. This focuses on how much of the substance people or animals breathe, not on the dose taken by mouth, and not on a time-to-death measure. The correct statement matches this idea: a median lethal concentration in air that kills half the test subjects within 14 days. The other options mix up routes (oral instead of inhalation), describe a dose that would kill all subjects, or refer to a time-to-lethality rather than a concentration causing 50% mortality.