Assessing insecticide residues in stored maize in Southern and Central Benin

Abstract

In Benin, protection of maize against storage insect pests remains a major challenge and motivates maize growers to rely on synthetic chemicals. The overuse/misuse of such compounds can lead to high residue levels and potential health risks. This current study was designed to assess insecticide residues in stored maize in Southern and Central Benin. Thirty-five (35) samples of shelled, husked and dehusked maize were collected in both areas especially in seven major maize production municipalities namely Adjohoun, Aplahoue Djidja Kétou, Lokossa, Ouesse and Toffo. Samples were taken from different types of storage structures in five villages (one sample per village) in each municipality. Both villages and growers were selected randomly. Chemical residues were extracted using the QuEChERS method with 4 replicates while analysis was performed using High Performance Liquid Chromatography (HPLC) coupled with an Ultra-Violet spectrophotometer technique for the four commonly applied chemicals on stored maize in the study area. Residues of Pirimiphos-methyl, Aluminium phosphide and Permethrin were found in 80–100, 40–100, and 0–100% of the samples collected, respectively, but none contained Lambda-Cyhalothrin. In total, 97% of the samples contained at least one of the pesticides tested, and 94% contained at least one of the pesticides tested at a concentration above the European Union international standard (Maximum residual limits) (MRL). Of these, 77%, 91% and 14% of the samples contained residues above the MRL for aluminum phosphide, pirimiphos-methyl and permethrin, respectively. Data were discussed with regard to potential human health concerns.