Question

Susceptibility (LD 50/30) of different species for ionizing radiations, in decreasing order is:
(A). Rat
(B). Guinea pig
(C). Rabbit
(D). Hamster
Choose the correct answer from the options given below:

• A. (A), (B), (D), (C)
• B. (C), (B), (D), (A)
• C. (C), (D), (A), (B)
• D. (C), (A), (D), (B)

Hint:

Guinea pigs are highly sensitive to radiation!
They have the lowest \(\text{LD}_{50}\) value among common laboratory rodents, meaning they will always be at the end of a decreasing list of \(\text{LD}_{50}\) values.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
The radiosensitivity of different animal species varies significantly.
Radiosensitivity is often quantified using the \(\text{LD}_{50/30}\) value, which represents the radiation dose required to kill \(50%\) of a population within 30 days.
A lower \(\text{LD}_{50/30}\) value indicates higher susceptibility (greater sensitivity) to radiation, while a higher value indicates lower susceptibility (greater resistance).

Step 2: Detailed Explanation:
Let us analyze the approximate \(\text{LD}_{50/30}\) values (measured in Gray, Gy) for the listed laboratory rodent species:
- Rabbit (C): Has an \(\text{LD}_{50/30}\) of approximately \(8.0 \text{ to } 8.4 \text{ Gy}\). This is a relatively high value among these species, indicating low susceptibility.
- Rat (A): Has an \(\text{LD}_{50/30}\) of approximately \(6.0 \text{ to } 7.5 \text{ Gy}\).
- Hamster (D): Has an \(\text{LD}_{50/30}\) of approximately \(8.5 \text{ to } 10.0 \text{ Gy}\).
- Guinea Pig (B): Is well-known as one of the most radiosensitive laboratory mammals, with an \(\text{LD}_{50/30}\) of only \(2.5 \text{ to } 4.0 \text{ Gy}\), indicating high susceptibility.
When arranging these species in decreasing order of their \(\text{LD}_{50/30}\) values (from highest dose/least susceptible to lowest dose/most susceptible):
\[ \text{Rabbit (C)} > \text{Rat (A)} > \text{Hamster (D)} > \text{Guinea Pig (B)} \]
This sequence matches Option (D).

Step 3: Final Answer:
The correct decreasing sequence of \(\text{LD}_{50/30}\) values is (C), (A), (D), (B). This corresponds to option (D).