Pesticides are considered a necessary evil today. The use of pesticides has progressively increased over the last few decades. Prior to World War II, a few inorganic pesticides were used on a negligible scale. The use of synthetic chemicals as pesticides started with the invention of DDT (dichloro diphenyl trichloroethane). Since then, the use of pesticides has grown enormously both in terms of the number of pesticides and the volume of the use of pesticides. The use of synthetic pesticides supports a large number of industries and involves business worth billions of dollars.

Pesticides can be primarily classified into three groups, based on which sector uses them:

Agricultural: to kill insects, to control diseases and pests, to destroy other soil-borne animals and to check the proliferation of weeds.

Public health: to check the spread of many human diseases caused by bacteria/virus which live on insects such as mosquitoes.

Domestic: to control household insects and pests.

The major consumption of pesticides is in the agricultural sector, while it is negligible in the domestic sector. Pesticides have proved to be indispensable, especially in controlling the spread of many contagious diseases like malaria and dengue. They have also helped reduce foodgrain losses during storage or at the time of production.

Types of Pesticides

The classification of pesticides based on the sector where they are used (agriculture, public health and domestic) or based on the organisms they kill (insecticides, bactericides, fungicides) is inadequate to study the impact of pesticides on the ecosystem, hydrosphere, biosphere and human health.