DDT (dichloro-diphenyl-trichloroethane) is a pesticide
widely used for protection of crops as well as for prevention of diseases like malaria.
Though DDT has been found to be very effective and economical for the basic function of
destroying pests, it also has many harmful side
effects.
Harmful effects of DDT are directly linked to the
fact that DDT decays very slowly. Thus the DDT that is sprayed gets collected on land
and in water. This DDT then gets absorbed by the plants that grow in such environment.
Similarly, cells of animals living in water polluted by DDT also absorb it. The DDT then
gets transferred to other animals that eat animals and plants containing DDT. In this
way, because of the very slow decay rate of DDT, the chain of transfer of DDT from one
organism to others continues.
In this way birds, fishes,
and even humans develop high levels of DDT, with negative effect on their health. Among
other effects, accumulation of DDT in fishes and birds causes sharp drop in their
reproductive rate and population. Because of such harmful effects, use of DDT has been
banned in many countries.
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