Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).

Assertion (A): DDT bioaccumulates in tissues of many species including humans.

Reason (R): DDT is relatively insoluble in water but readily soluble in fats and oils. In the light of the above statements,

choose the most appropriate answer from the options given below:

The correct option is: Both (A) and (R) are correct and (R) is the correct explanation of (A).

Let's analyze the given statements step-by-step to understand why this option is correct:

1. Understanding Assertion (A):
Assertion (A) states that DDT bioaccumulates in the tissues of many species, including humans.
DDT (dichlorodiphenyltrichloroethane) is a synthetic organochlorine pesticide. Bioaccumulation refers to the process where a chemical substance builds up in the body of an organism over time because the rate of intake is faster than the rate at which the organism can eliminate or metabolize the substance. Since DDT is highly resistant to environmental degradation and metabolic breakdown within living organisms, it remains in the body for long periods, leading to bioaccumulation across various species (including humans). Therefore, Assertion (A) is correct.

2. Understanding Reason (R):
Reason (R) states that DDT is relatively insoluble in water but readily soluble in fats and oils.
DDT is a lipophilic (fat-soluble) and hydrophobic (water-insoluble) compound. Its chemical structure makes it highly insoluble in polar solvents like water, but highly soluble in non-polar solvents such as organic lipids, fats, and oils. Therefore, Reason (R) is correct.

3. Evaluating the Link between (A) and (R):
Why does DDT bioaccumulate in animal and human tissues?
Because DDT is virtually insoluble in water, it cannot be easily dissolved and excreted through water-based biological fluids (like urine). Instead, due to its high solubility in lipids, it is readily absorbed and stored in the adipose (fatty) tissues of organisms. Over time, as organisms ingest food containing trace amounts of DDT, the chemical continuously accumulates in their fat stores rather than being flushed out of the body. This fat-solubility is the direct biological mechanism behind its bioaccumulation. Therefore, Reason (R) is the correct explanation of Assertion (A).