Assessment of pesticide residues in harvested tomato fruits at Makambako town council in Njombe Region, Tanzania.

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Date

2021

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Publisher

Sokoine University of Agriculture

Abstract

In modern agriculture, pest infestation has posed a great challenge to farmers. The use of pesticide has eventually become an important tool to ensure quality and quantity of crop yields. However, such chemicals might have residual impacts to consumers. This study was conducted to assess the extent of pesticide residues in harvested tomato fruits at Makambako Town Council in Njombe region, Tanzania. Specifically the study aimed at: (i) investigating adherence to recommended manufacturer’s instructions on pesticide application among tomato farmers (ii) determining level and frequency of occurrence of selected pesticide residues in tomato fruits and (iii) characterizing dietary risks associated with consumption of fresh tomato fruits containing pesticide residues. Forty seven (47) farmers were interviewed on pesticide types and their application using structured questionnaire. Forty two (42) fresh tomato fruits for laboratory analysis were sampled from interviewed farmers who were at harvesting season. QuEChERS (CEN) Method 15662.5 was employed for pesticide extraction and analyzed by Gas Chromatography Mass Spectrometer. It was found that all respondents mixed more than one pesticide in a single spray tank without adhering to recommended mixing procedures. The average withholding period was 5 days, below the recommended 7 days for mixture of mancozeb and metalaxyl which were commonly used fungicides at the study area. Eighty three percent of the respondents exceeded the mixing concentration of pesticide above the recommended mixing ratios. Residues of chlorpyrifos, profenofos, gamma cyhalothrin and cypermethrin were alternatingly detected in 78.51 % of analyzed samples. The average concentrations of residues were 0.014, 0.056, 0.003 and 0.2 mg/kg for chlorpyrifos, profenofos, gamma cyhalothrin and cypermethrin, and were all below Codex MRLs of 1, 10, 0.3 and 0.2 mg/kg respectively, as per FAO/WHO guidelines. The maximum residue concentration was 0.718 mg/kg for cypermethrin, which was above the Codex MRL of 0.2 mg/kg. Profenofos was the most frequently detected pesticide, occurring in 60 % of samples. The hazard indices for the selected pesticide indicate no potential health hazards to general population due to lifetime consumption of fresh tomato fruits from the study area. The study recommend regular training to farmers on good agricultural practices through extension officers and pesticide regulatory authority. Further research on pesticide residues and dietary risk assessment is recommended for other pesticide commonly used at the study area.

Description

Masters Dissertation

Keywords

Modern agriculture, Pest infestation, Pesticide residues, Harvested tomato fruits, Makambako Town Council, Njombe Region, Tanzania

Citation