Pesticide Application, Their Residue Levels in the Environment, Kales and Tomatoes in Ewaso Narok Wetland, Laikipia County, Kenya
Otieno, Ngolo Peter B.M.
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Pesticide use in agriculture is beneficial in controlling losses from pest and diseases. However, unsafe pesticide use can harm environment and human health. The aim of this study was to assess pesticide use among Ewaso Narok wetland farmers and to determine their residue levels in environment, kales and tomatoes. A total of 86 farmers purposively selected participated in this study. A pre-tested structured questionnaire was administered on the farmers with the help of trained enumerators in which data on pesticide use was collected. For laboratory analysis, a total of 276 samples of soil, water, tomatoes and kales were collected and analyzed during wet/ rainy and dry/ sunny seasons. Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) protocol was followed for sample preparation. Extracts were analyzed using LC/MS/MS and data analyzed using SPSS version 22. The study revealed that farmers use pesticides in violation of safe recommendation; 99% of farmers used unsafe storage facilities, 60.5% did not use appropriate personal protective equipment (PPE), 38.4% mixed pesticides during application and 100% use unsafe disposal methods for the empty pesticide containers. Majority (97%) of the farmers had no training on pesticide use. On laboratory analysis, the results revealed the presence of residual organophosphorus, carbamates, pyrethroids, triazoles, morpholine, phenylamine, carbazate, anilinopyrimidine and beta-methoxyacylate in soil, water, kales and tomatoes. Residues namely aldicarb, triadimefon, azoxystrobin, chlorpyrifos, buprofezin, cyproconazole I and II, fenpropathrin, paclobutrazole, pyrimethanil, metalaxyl, diazinon, bifenazate, azinphos methyl and spiroxamine were detected and quantified. The levels of triadimefon (132-150)μg/L, cyproconazole I(59-66.50)μg/L and II(71-81)μg/L, fenpropathrin (27-30)μg/L, bifenazate (16-18)μg/L, pyrimethanil (62-89)μg/L, and spiroxamine (55-150)μg/L in kales and cyproconazole I (54-82) μg/L and II (80-92) μg/L, fenpropathrin (16-19) μg/L and spiroxamine (51-105) μg/L in tomatoes were above the European Food Safety authority Limits (EFSA-MRLs) which ranged between 10-100μg/L. All residue levels in tomatoes and kales were within the Maximum Residue Limits as set by the World Health Organization and Agricultural Food Organization. Pesticide residues levels in soil ranged between 2.17-1000.21μg/L which was significantly higher than the levels in kales and tomatoes. In water, six pesticide residues were detected and quantified in the range of 0.09-5.85μg/L which were above the European Union-Maximum Contamination Limits (EU-MCL) for the drinking water of 0.10 μg/L for individual residues and 0.50 μg/L for the sum concentrations of all the residues in water. Farmers need training to comply with the safety requirements which include but not limited to the use of appropriate and complete PPEs, reading of pesticide labels before use, adhere to safety intervals (re-entry and pre-harvest intervals), safe storage and disposal of empty pesticide containers. Farmers need to embrace Good Agricultural Practice and Integrated Pests Management to reduce overreliance on synthetic pesticide use. Further study on pesticides residues levels in cabbages, french beans, chilies and potatoes should be done. The findings of this study can be used by policy makers (Government, Non-Governmental Organizations), researchers/ scholars and farmers in making informed decisions on safe pesticide use that ensures safety of environment and human health.