Analysis of Pesticide Residues in Tomatoes and French Beans from Murang’a and Kiambu Counties, Kenya

Abstract

Poor Pesticide-handling practices during production of tomatoes and French beans pose adverse health and environmental effects. This study was conducted to determine the concentrations of pesticide residues in tomatoes and French beans grown and sold in Murang’a and Kiambu counties, Kenya. Samples were collected in farms and markets during the wet and dry seasons. Pesticide residues were extracted using the QuEChERS method and quantified using GC-MS/MS and LC-MS/MS. The recoveries of pesticides from spiked samples were within the acceptable range (70-120%) for quantitative pesticide residue methods. The concentration range of pesticides residues in tomatoes were: profenofos, <LOQ to 0.18 mg/Kg; omethoate, <LOQ to 0.03 mg/Kg; indoxacarb, <LOQ to 0.05 mg/Kg; chlorantraniliprole <LOQ to 0.11 mg/Kg; spirotetramat <LOQ to 0.01 mg/Kg; and metalaxyl < LOQ to 0.02 mg/Kg. The concentration range of pesticides residues in French beans were: imidacloprid <LOQ to 0.29 mg/Kg; chlorantraniliprole <LOQ to 0.37 mg/Kg; spirotetramat <LOQ to 0.01 mg/Kg; indoxacarb <LOQ to 0.05 mg/Kg; and metalaxyl <LOQ to 0.02 mg/Kg. The concentrations of pesticide residues in tomatoes and French beans were below the Maximum Residue Levels set by the Joint FAO/WHO Food Standards Programme and the European Union except for concentrations of omethoate in tomatoes, which were higher in 29% of analyzed samples. The presence of omethoate in tomatoes, whose use in vegetables is banned, suggests poor pesticide handling practices by some tomato farmers in the two counties.