Question

Given below are two statements:
Statement (I): LD 50 is the dose or amount of pesticide which would kill 50% of the test animals if ingested or absorbed through skin.
Statement (II): LT 50 is the concentration of a single pesticide which is lethal to 50% of the test animals if ingested or absorbed through skin.
In light of the above statements, choose the most appropriate answer from the options given below.

• A. Both Statement (I) and Statement (II) are correct.
• B. Both Statement (I) and Statement (II) are incorrect.
• C. Statement (I) is correct but Statement (II) is incorrect.
• D. Statement (I) is incorrect but Statement (II) is correct.

Hint:

Distinguish the toxicological terms:
$\text{LD}_{50}$ $\rightarrow$ Lethal Dose (expressed in $\text{mg/kg}$).
$\text{LC}_{50}$ $\rightarrow$ Lethal Concentration (expressed in $\text{ppm}$ or $\text{mg/L}$).
$\text{LT}_{50}$ $\rightarrow$ Lethal Time (expressed in hours or days).

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Toxicological parameters measure the relative toxicity of chemical pesticides using standardized benchmarks like median lethal dose, concentration, or time.

Step 2: Detailed Explanation:
Let us analyze each statement individually:
Statement (I) defines $\text{LD}_{50}$ (Lethal Dose 50).
$\text{LD}_{50}$ is the statistically derived single dose of a substance that can be expected to cause death in 50% of a treated population of test animals (usually rats or mice) when administered by oral or dermal routes.
It is expressed as milligrams of toxicant per kilogram of body weight ($\text{mg/kg}$).
Therefore, Statement (I) is correct.
Statement (II) defines $\text{LT}_{50}$ as a concentration.
This is incorrect. $\text{LT}_{50}$ stands for Lethal Time 50.
It refers to the time period required to cause death in 50% of the test animals exposed to a constant concentration of a toxicant.
The term for the concentration of a single pesticide that is lethal to 50% of the test animals (usually via inhalation or water exposure) is $\text{LC}_{50}$ (Lethal Concentration 50).
Thus, the definition given in Statement (II) is incorrect.
Therefore, Statement (I) is correct but Statement (II) is incorrect.

Step 3: Final Answer:
Statement (I) is correct but Statement (II) is incorrect.