Pest control is one of the major problem in agriculture. Pesticides are widely used chemicals in the world for more than half a century to control the pests or insects that prevent the crops and on the other hand destroy, repel or mitigate any pests. Insects not only kill the crops but also sometimes humans by acting as a disease carrying agent. However, during the past decade, the use of chemicals increased steadily in the developing countries to enhance food production and to control vector-borne diseases. Although the use of most of the pesticides such as technical DDT and HCH were banned worldwide, illicit use of these chemicals still exist among few farmers and also regionally. In addition, the accumulation of these chemicals in the earth remain for a long-term, polluting the top soil. DDT is a well known, persistent and highly lipid soluble organochlorine pesticide. It was widely used to fight insect-borne diseases like malaria until legislative restrictions were imposed following the manifestation of ecological impairment. The low chemical and biological degradation, lipophilic nature and hydrophobicity have led DDT to accumulate into the biological tissues. In 1996, the World Health Organisation (WHO) assessed the acceptable daily intake for DDT from number of countries and found India as a largest consumers of DDT in terms of daily intake. In India, DDT has been used to control malaria since 1946. Due to awareness towards environment, measures were taken to control the use of this pesticide. The DDT applied for agriculture, not only accumulates into the sediment, but also contaminates water resources and through bio-chain it gets more concentrated (bio-magnification) and finally reaches humans. Especially, the coastal marine environment receives considerable input of DDT from various anthropogenic sources such as direct discharges or indirectly from river flows, runoff, as well as from long-distance transport through the atmosphere. The pesticides that reaches ponds, rivers, coastal oceans due to rain and runoffs affects the egg and sperm development, accumulates, initiates mutations in animals living in the aquatic environment. The concentration of DDT has significantly reduced after the ban on use of it in the year 1970, although it still remains as various of the environment such as air, sediments, fish and mammals and becomes a threat to human health. In humans, it is stored in the body fat and is excreted in the milk and reaches the infants from the time of birth. As, DDT persists for a long time in the community, the fear on adverse effects in future generations, metabolism and growth also exists. In India, we expect the day of real ban on the use of such chemicals like DDT. The use of such chemicals not only diminish the quality of the product but also the health of ours and future generations.

Contributed by: Dr. Arockiya Vasanthi, Scientist, NIOT.