Pyrethroid insecticides are massively used in sub-Saharan Africa countries to control malaria. These chemicals are highly toxic for mosquitoes and other insects. For human and wildlife, such organic pollutants toxicity rate is a function of their environment bioaccumulation capacities. In this work we studied cyfluthrin chemical and photochemical degradation in local natural waters. Cyfluthrin is rapidly hydrolyzed in distilled water than in river and pond waters. Indeed, in little acidic aqueous media, its hydrolysis half-life time is 27, 205 and 3099 days respectively. Under UV-visible irradiation, the insecticide photolysis rate which is very important in distilled water decreased in natural waters. Under less intense neon lamps (18W), it is photolytically more stable in river water than in pond water. With intense simulated solar irradiations (200W), the insecticide is more stable in Niger River water (t1/2 = 693h) than in pond water (t1/2 = 495h). Here, the photolysis reactions induced by interfering reactive radicals in pond water are more important than the screen role played by the medium dissolved organic matter.
R. Adamou, A. Abdoulaye, M. Soumaila, I. Moussa, A. Coly, A. Tine, K. Ikhiri
pyrethroid insecticides, cyfluthrin, hydrolysis, photolysis, natural waters