What is DDT? Why is it banned for use in many developed nations?

Explanation

### Step-by-Step Solution:

1. **Definition of DDT**:
- DDT stands for Dichloro-Diphenyl-Trichloroethane. It is a synthetic chemical compound that was widely used as an insecticide.

2. **Usage of DDT**:
- DDT was primarily used to control insect populations, particularly in agriculture and for public health purposes, such as controlling malaria-carrying mosquitoes.

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