Question

Which pesticide is most persistent in environment?

• A. Malathion
• B. Dieldrin
• C. Carbofuran
• D. Indoxacarb

Hint:

Organochlorines = Forever Chemicals (High Persistence).
Organophosphates/Carbamates = Temporary Chemicals (Low Persistence).
The "Dirty Dozen" list of POPs includes Dieldrin and DDT.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
Persistence refers to the length of time a chemical remains active and present in the environment before breaking down. The question asks to identify the most persistent pesticide from the list.
Detailed Explanation:

• Classification and Persistence:
Pesticides are grouped by their chemical families, which largely determines their environmental half-life.
Organochlorines (like DDT, Dieldrin, Aldrin) are the most persistent. They can remain in soil and water for years or even decades.
Organophosphates (Malathion) and Carbamates (Carbofuran) are relatively non-persistent and break down in days or weeks.

• Characteristics of Dieldrin:
Dieldrin is an organochlorine insecticide. It is highly resistant to chemical and biological degradation.
It is also "lipophilic" (fat-soluble), meaning it accumulates in the fatty tissues of animals (bioaccumulation) and moves up the food chain (biomagnification).
Due to its extreme persistence and toxicity, its use has been banned or severely restricted globally under the Stockholm Convention on Persistent Organic Pollutants (POPs).

• Analyzing Other Options:
Malathion: An organophosphate with very low persistence. It is often used for residential mosquito control because it degrades quickly.
Carbofuran: A carbamate insecticide/nematicide. While toxic, it degrades in the soil within a few weeks.
Indoxacarb: A modern oxadiazine insecticide designed to be environmentally friendly with low persistence.

• Environmental Impact:
Persistent pesticides like Dieldrin pose long-term risks to soil health, groundwater, and non-target wildlife (like birds of prey).

Step 3: Final Answer:
Dieldrin is the most persistent pesticide among the options provided.