Assessment of pesticide residue in tomatoes in the Fanteakwa Districts in the Eastern Region of Ghana

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The Fanteakwa district of the Eastern Region of Ghana is one of the major tomato producing areas and so is faced with the challenges of pesticide usage. The objective of this study was, therefore, to find out the various pesticides used by tomato farmers, determine pesticide residue levels in tomato fruits and assess the effect of storage method on pesticide residue in tomato fruits produced from the Fanteakwa district. The study was conducted in two parts; a field survey and laboratory work. The survey was conducted using structured and semi-structured questionnaires administered to 120 farmers, 10 agrochemical sellers, 10 buyers and 20 consumers in the Fanteakwa district. Data collected was analysed using Statistix (version 9) Statistical Package and descriptive statistical tools. The result showed male dominance (85%) in tomato production with majority of the farmers (64%) having basic education. The result from the survey showed that thirty-eight (38) different pesticides with different trade names were used by farmers, of which 71.1% were organophosphates and pyrethroids, while 28.9% were fungicides and these chemicals were used in various cocktail forms. Contrary to laboratory results none of the farmers indicated their use of organochlorines in their routine pest control. Pesticide usage by farmers seemed to be highly influenced by agrochemical sellers in the farming communities. Majority of the consumers interviewed indicated that they did not have any complications after consuming fresh tomato fruits while only a few of the consumers indicated that they had diarrhoea. The laboratory analysis, involved the use of the Quick Easy Cheap Effective Rugged and safe (QuEChERS) Mini-Multi residue method, confirmed the presence of twenty-three (23) different pesticide residues comprising of organochlorines and pyrethriods pesticide. Compounds namely Beta_HCH, Gamma_HCH, Heptachlor, Aldrin, Allethrin, Gamma-Chord, α-Endosulfan, β-Endosulfan, Endosulfan Sulphate, Dieldrin, Endrin, PP-DDT. PP-DDD, Bifenthrin, Fenpropathri, Methoxyclor, Lambda Cyhalothrin, Permethrin, Cyfluthrin, Cypermethrin Fenvalerate and Deltamethrin. Even though the survey results indicated that majority of the farmers did not allow for any pre-harvesting interval (safe harvest period), result from the laboratory analysis indicated that the mean concentrations of the 23 different pesticides residue found in the tomato samples were all below the MRL (WHO/FAO guidelines) of 0.05mg/kg and 0.02 mg/kg for those specific pesticides except for Delta-HCH which was found to be above the recommended maximum residue level of 0.05mg/kg for export for both fruits kept in ambient condition and in refrigerators. Significant differences (P < 0.00) were observed between tomato fruits kept under ambient conditions and those kept in the refrigerator for Delta-HCH (t=24.68, p=0.00), Lambda Cyhalothrin (t=27.58, p=0.00) and Permethrin (t=36.06, p=0.00. From the result of the study, storing tomato fruits for ten (10) days under ambient condition reduced pesticide reduced as compared to 10 days of refrigerated storage which could be due to photolytic decay.
A thesis Submitted to the School of Research and Graduate Studies, Kwame Nkrumah University of Science And Technology, Kumasi, in partial fulfilment of the requirement for the award of Masters of Science (Msc.) Postharvest Technology) Degree, June-2012