When DDT is taken in by an animal at a steady rate, it builds up within the animal over time. Which two properties of DDT are responsible for this?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Chemical stability and fat solubility
DDT is the first chlorinated organic insecticide. Because it is chemically stable, animals do not break it down quickly; because it is fat soluble, it is not washed out but is deposited and stored in the fatty tissues. With steady intake, the stored amount keeps rising.
Option (2) Rapid metabolism and water solubility — Incorrect. Both properties would help the body get rid of the compound. DDT is not metabolised rapidly, and it dissolves in fat.
Option (3) Rapid metabolism and fat solubility — Incorrect. Fat solubility is right, but a compound that is metabolised rapidly would not build up; DDT is metabolised only slowly.
Option (4) Chemical stability and water solubility — Incorrect. Stability is right, but DDT is fat soluble, which is why it collects in fatty tissue.
NCERT (2026-27 edition):
6.8.6 p,p’-Dichlorodiphenyltrichloroethane (DDT) – “…The chemical stability of DDT and its fat solubility compounded the problem. DDT is not metabolised very rapidly by animals; instead, it is deposited and stored in the fatty tissues. If ingestion continues at a steady rate, DDT builds up within the animal over time.”