Death within how many days is expected for LD50 Oral and LC50 Inhalation endpoints?

• A. 14 days
• B. 7 days
• C. 24 hours
• D. 30 days

Answer: (A)

In acute toxicity testing, LD50 and LC50 describe the dose or concentration that causes death in 50% of the test animals, and the timing of observing deaths is standardized. For both oral (LD50) and inhalation (LC50) endpoints, the standard observation period after exposure is 14 days. This window is long enough to capture deaths that occur a bit later, while still reflecting an acute effect rather than long-term or chronic toxicity. Shorter periods like 24 hours or 7 days can miss late fatalities, and a much longer period (such as 30 days) shifts the focus away from acute toxicity toward subacute or chronic effects. Therefore, death within 14 days is the expected timeframe for these endpoints.