Browsing by Author "Lugwisha, Esther H.J."

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    Assessment of Pesticide Residues in Tomatoes and Watermelons (Fruits) from Markets in Dar es Salaam, Tanzania
    (University of Port Harcourt, 2017) Mahugija, John A.M.; Khamis, Farhat A.; Lugwisha, Esther H.J.
    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 cleaned-up 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.
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    Determination of Levels of Organochlorine, Organophosphorus, and Pyrethroid Pesticide Residues in Vegetables from Markets in Dar es Salaam by GC-MS
    (Hindawi, 2017) Mahugija, John A.M.; Khamis, Farhat A.; Lugwisha, Esther H.J.
    This study investigated the levels of pesticides and metabolites in vegetables from major markets in Dar es Salaam city, Tanzania. Samples of fresh cabbage, spinach, and onions from the markets were analysed for pesticide residues. Extraction was performed using acetone followed by dichloromethane : cyclohexane mixture and the extracts were cleaned up using Florisil. The compounds were determined by gas chromatography-mass spectrometry (GC-MS). Pesticides and metabolites were detected in 72.2% of the samples. The detected pesticide residues and their highest mean concentrations were p,p′-DDT 4.00 × 10−3 mg/kg, p,p′-DDD 6.40 × 10−1 mg/kg, o,p′-DDD 1.00 × 10−2 mg/kg, α-endosulfan 6.00 × 10−1 mg/kg, β-endosulfan 2.10 × 10−1 mg/kg, chlorpyrifos 3.00 mg/kg, and cypermethrin 4.00 × 10−2 mg/kg. The most frequently detected compounds were p,p′-DDD and chlorpyrifos. The order of contamination was spinach > cabbage > onions. Generally, there were no significant variations in concentrations of pesticide residues among samples and sampling sites, which indicated similarities in contamination patterns. The concentrations of contaminants were above the maximum residue limits (MRLs) in 33.3–50% of the samples. The findings indicated risks and concerns for public health.
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    Levels of formaldehyde and acetaldehyde in selected bottled drinking water sold in urban areas in Tanzania
    (College of Natural and Applied Sciences, University of Dar es Salaam, 2016) Lugwisha, Esther H.J.; Mahugija, John A.M.; Mwankuna, Christopher
    The levels of formaldehyde and acetaldehyde in bottled drinking water and the effect of storage time and storage conditions on their levels were determined. A total of 144 samples of six brands of bottled drinking water were purchased from Dar es Salaam, Iringa, Mwanza and Arusha regions in Tanzania. Analysis was performed using HPLC on the 1st day and after 14 and 42 days of storage in a refrigerator, at room temperature and exposure to sunlight. The levels of formaldehyde and acetaldehyde in the refrigerated samples ranged from 2.46 to 19.25 μg/L and from not detected (ND) to 58.70 μg/L, respectively. In samples stored at room temperature, the levels of formaldehyde and acetaldehyde were up to 23.26 μg/L and 36.10 μg/L, respectively. The highest levels of formaldehyde and acetaldehyde in samples exposed to sunlight were 46.0 μg/L and 187.0 μg/L, respectively. The lowest levels of the aldehydes were found in refrigerated samples and the highest levels were in samples exposed to sunlight. The levels of these aldehydes increased with increased storage time. The levels were below the WHO acceptable limits; however, the findings indicate that the levels could be elevated with increased storage time and exposure to sunlight.
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    Occurrence of organochlorine and organophosphorus pesticide residues in poultry feeds, raw and cooked eggs from selected farms in Ilala and Kibaha Districts, Tanzania
    (University of Port Harcourt, 2018) Mahugija, John A.M.; Chibura, Patrick E.; Lugwisha, Esther H.J.
    This study assessed the levels of seventeen pesticides and metabolites residues in chicken feeds and raw eggs as well as the effects of processing methods on the levels in eggs in samples obtained from six poultry farms in Ilala and Kibaha districts, Tanzania. Extraction was performed by solid dispersion method and the extracts were cleaned-up by adsorption column chromatography. The analytes were determined by Gas Chromatography–Mass Spectrometry (GC–MS). The highest mean concentrations of the contaminants in feeds and eggs were as follows, respectively: aldrin 0.62 and 2 mg/kg, dieldrin 0.71 and 1.3 mg/kg, total DDT 6.68 and 8.14 mg/kg, total endosulfan 3.53 and 3.74 mg/kg, total HCHs 0.91 and 1.21 mg/kg, chlorpyrifos 12.2 and 0.59 mg/kg, fenitrothion 4.9 and 0.64 mg/kg and pirimiphos methyl 22.11 and 1.6 mg/kg. Chicken feeds were found to be the most contaminated followed by raw eggs and finally cooked eggs. Most of the concentrations were above the maximum residue limits (MRLs) indicating risks and concerns. Proper selection and preparation of poultry feeds could reduce the levels in the feeds and eggs.
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    Residues of pesticides and metabolites in chicken kidney, liver and muscle samples from poultry farms in Dar es Salaam and Pwani, Tanzania
    (Elsevier Ltd., 2018) Mahugija, John A.M.; Chibura, Patrick E.; Lugwisha, Esther H.J.
    The concentrations of organochlorine and organophosphorus pesticides and metabolites were investigated in chicken kidney, liver and muscle samples obtained from chickens collected from four poultry farms in Dar es Salaam and Pwani regions in Tanzania. The samples were extracted by solid dispersion using cyclohexane:ethyl acetate. The extracts were cleaned by adsorption column chromatography. The analytes were determined using gas chromatography-mass spectrometry (GC-MS). The concentrations of total DDT, total endosulfan and total HCHs in the samples ranged from 0.71 to 26, 0.3 to 7.9 and 0.02-10.4 mg/kg lipid weight (lw), respectively. The highest concentrations of aldrin, dieldrin, chlorpyrifos, fenitrothion and pirimiphos methyl were 5.5, 4.8, 9.7, 5.6 and 7.8 mg/kg lw, respectively. The highest concentrations of the contaminants were found in the kidney and liver samples. The sites in Dar es Salaam showed the highest concentrations of the compounds. Most of the concentrations were above the maximum residue limits (MRLs) indicating risks and concerns for livestock and public health.