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Assessment of Pesticide Residues in Tomatoes and Watermelons (Fruits) from Markets in Dar es Salaam, Tanzania
MAHUGIJA, JOHN A.M.; KHAMIS, FARHAT A. & LUGWISHA, ESTHER H.J.
Abstract
This study investigated the levels of pesticide residues in selected fruits from major
markets in Dar es Salaam city. Samples of tomatoes and watermelons were analysed for eighteen
organochlorine, organophosphorus and pyrethroid pesticide residues. Extraction was performed
using acetone followed by dichloromethane: cyclohexane mixture and the extracts were cleanedup
using florisil. The compounds were determined by gas chromatography–mass spectrometry
(GC–MS). Pesticides and metabolites were detected in 95.8% of the samples. The compounds
detected included chlorpyrifos, α-endosulfan, β-endosulfan and cypermethrin and their highest
concentrations were 3810 ± 50, 370 ± 20, 120 ± 6 and 50 ± 4 ng/g, respectively. Others were p,p'-
DDD, o,p'-DDD, p,p'-DDE and α-HCH with highest concentrations varying from 1 ± 0.5 to 20 ±
1.2 ng/g. There were no significant variations in concentrations of the pesticide residues between
the fruits and among the sampling sites, indicating similarities in contamination patterns. The
concentrations of the contaminants were above the maximum residue limits (MRLs) in 41.7% to
50% of the tomatoes and watermelons indicating risks and concerns for public health. The
Tanzanian agrochemicals and food regulatory agencies (e.g. TPRI, TFDA and TBS) and the
government in general should ensure strict applications of laws that regulate pesticides in the
country and develop effective educational programmes for farmers to apply good agricultural
practices such as reducing the use of pesticides, applying appropriate pesticides and doses, and
restrict the spray before harvesting. The consumers should thoroughly wash or process the fruits to
reduce the levels.
Keywords
Pesticides; Fruits; Food; Contamination; Tanzania
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