p,p’-Dichlorodiphenyltrichloroethane(DDT)

DDT was the first modern pesticide, was first synthesized in 1873 by Othmar Ziedler .

Insecticidal properties of DDT were discovered in 1939, by the Swiss scientist Paul Hermann Müller. Paul Muller was awarded the Nobel Prize

in Medicine and Physiology in 1948 for this discovery.

Preparation of DDT

DDT is prepared by the reaction of chloral with chlorobenzene in the presence of sulphuric acid.

Properties of DDT

DDT is a white, crystalline powder with a weak odour.

It shows low solubility in water and high solubility in organic solvents, fat and oils.

Effect of DDT on Environment

DDT was used extensively during World war II by Allied troops and certain civilian populations to control insect

typhus and malaria vectors (as a result nearly eliminating typhus).

DDT was also extensively used as an agricultural insecticide after 1945.

By the 1950s, in some uses, doses of DDT and other insecticides had to be doubled or tripled as resistant

insect strains developed.

Effect of DDT on Environment

Many species of insects developed resistance to DDT, and it was also discovered to have a high toxicity towards

fish.

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.

The use of DDT was banned in the United States in 1973, although it is still in use in some other parts of the world.