Inventory of pesticides used in Rwanda and assessment of profenofos and cypermethrin residues in eggplants and cucumbers sold in Kigali markets

Abstract

In Rwanda, pesticides are generally applied for pest control practices in agricultural activities. However, higher levels of pesticide residues in food constitute a potential source of exposure to consumers. Therefore, there is a need for continuous monitoring of pesticide residue levels in both environment and crops in order to protect consumers against possible intoxication. In this study, the 104 agricultural pesticides were inventoried by illustrating trade names, active ingredients, formulations and WHO classes. Moreover, 50 household pesticides were listed by including their common names, active ingredients and use. Furthermore, Cypermethrin and Profenofos residues were assessed in eggplants and cucumbers sold in the markets found in Kigali City including Kimironko, Nyabugogo and Zinia markets. Pesticides residues were extracted using QuEChERS residues extraction method and were analyzed using gas chromatography coupled with mass spectrometer (GC-MS). Profenofos residues were detected in 23 samples out of 60 (38.33 %) while 24 samples out of 60 (40 %) indicated the presence of Cypermethrin residues. In eggplant, out of the 30 samples, 16 samples (53.33 %) were found to contain Profenofos residues while 13 samples (43.33 %) contained Cypermethrin residues. The maximum detected concentrations were 0.026 mg/kg and 0.033 mg/kg for Profenofos and Cypermethrin residues, respectively. In cucumber samples, out of the 30 samples, 11 samples (36.66 %) indicated Cypermethrin residues while 8 samples (26.66 %) were found containing Profenofos residues. The Profenofos and Cypermethrin residues were detected in cucumbers with maximum concentrations of 0.021 mg/kg and 0.039 mg/kg, respectively, in the analyzed samples. The results of calculated acute health risk (aHI) and chronic health risk (HQ) revealed that the human health risk for consumption of eggplants is negligible. The levels of contamination with Profenofos and Cypermethrin residues may be due to overuse of pesticides to control pests and/or to the lack of awareness about pesticide application doses and standard preharvest intervals (PHIs).