Which of the following statement about DDT is false -
DDT is a synthetic contact poison. It acts on the nervous system of insects. It does not cause immediate death, take several hours to kill. The residual action of DDT may last for 18 months depending on the treated surface. Has no repellent action. As residual spray, the dose is 100 -200 mg per sq.ft area. Park's Textbook of Preventive and Social Medicine, 25th Edition, Pg 833
It is contact poison
Residual effect lasts for 18 months
immediately kills the prey
Permethrin has synergistic action
Environment and health