Diseases & National Health Programme
The following statement about DDT is fasle
|A||Pyrethrum has synergistic action|
|B||It is a contact poison|
|C||Immediately kills the prey|
|D||Residual effect lasts for 18 months|
a. DDT is primarily a contact poison, acting on the nervous system of insects. It does not cause immediate death but takes several hours to kill.
b. The residual action may last as long as 18 months depending upon the treated surface. It has no repellant action.
c. Most space sprays contain pyrethrum & DDT or other synthetic insecticides which are added for synergistic action.
d. Some imp facts about DDT: the technical DDT contains 70-80% of para-para isomer which is the most active fraction of DDT. As a residual spray, DDT is applied in the dosage of 100-200 mg per square foot area. As a dust, it is used in 5-10% strength for the control of lice, fleas, ticks & bugs. In the recent years DDT has been incriminated as an environmental pollutant because of its persistence in the living organisms & plants & hence many countries have banned its use.
e. But the benefits of its application in health programs far outweighs its hazards & hence WHO does not prohibits its use.