Malathion is used once every -
Malathion has the least toxicity of all organophosphorus compounds. Water disperaible powders are available. Malathion is used in doses of 100-200 mg/sq.ft. every 3 months. (Lindane, malathion OMS-33 duration of effectiveness is 3 months) while DDT has effectiveness for 6 to 12 months. Due to low toxicity malathion is recommended as an alternative to DDT. Park's Textbook of Preventive and Social Medicine, 25th Edition, Pg 833
3 months
6 months
9 months
12 months
Environment and health