Pesticide Residues on Tomatoes Grown and Consumed in Mwea Irrigation Scheme, Kirinyaga County, Kenya

Abstract

The effects of pesticides on human health are of great concern worldwide despite their usefulness in agriculture. The aim of the study was to evaluate pesticide residues on tomatoes grown and consumed in Kirinyaga County in order to determine whether the levels fall within recommended MRLs. Reported increased use of unspecified pesticides and undocumented residue levels in tomatoes produced in the country justified the need to evaluate pesticide residues in tomatoes grown in the area and consumed locally. The study, which was conducted in Mwea Irrigation Scheme, Kirinyaga County, Kenya between July 2017 and July 2018 used analytical study design. Tomato samples of Rambo variety mainly grown in open fields and greenhouses in the Irrigation Scheme were purposively sampled from thirty-five sampling sites in open fields, greenhouses, markets and consumers. The samples were taken to Kenya Plant Health Inspectorate Services (KEPHIS) laboratory in Nairobi for analysis. Analysis was done using Quick Easy Cheap Effective Rugged and Safe (QuEChERS) multi-residue analytical method for Low-Fat products. Four pesticide residues detected on tomatoes above the recommended EU and Cordex MRLs were: malathion (0.0315±0.0032 mg/kg) in open fields, carbendazim (1.2341±0.1667 mg/kg) and thiamethoxam (0.3736±0.0358 mg/kg) from greenhouses and acephate (0.0321±0.0032 mg/kg) from the market. Pesticide residue levels of tomatoes from consumers were all significantly (p<0.001, p<0.01) below the EU and Cordex permitted MRLs. Occurrence of pesticide residues on tomatoes from production to consumption levels is of great concern to consumers because of the perceived long term negative health effects. Implementation, strengthening and enforcement of the food policy in the country will enhance frequent monitoring of pesticide residue levels in fresh produce consumed locally in Kenya.