LD50/30 is defined as the radiation dose at which what percentage of individuals die within 30 days without medical treatment?

• A. 25%
• B. 50%
• C. 75%
• D. 10%

Answer: (B)

LD50/30 means the dose that will cause death in 50% of exposed individuals within 30 days if no medical treatment is given. The "50" represents half of the population, and the "30" is the observation window used to capture deaths from acute radiation effects such as bone marrow suppression. This metric provides a standard way to compare radiosensitivity and to plan emergency responses. In practice, the lethal dose for humans without treatment is around a few grays for whole-body exposure, so the key point is that half of those exposed would be expected to die within 30 days.