Prevalence of Organophosphate Pesticide Residues and the Associated Risks of Dietary Exposure through Selected Vegetables from Ilala District, Dar es Salaam, Tanzania

Abstract

The increasing reliance on pesticide use in agricultural practices, particularly in developing regions such as Tanzania, poses significant risks to food safety and public health. This study investigated the prevalence and concentration of organophosphate-based pesticide residues in commonly consumed vegetables, specifically Amaranth (Amaranthus), Chinese cabbage (Brassica rapa Pekinensis) and Sweet potato leaves (Ipomoea Batatas) cultivated in Ilala district of Dar Es Salaam City. Data on vegetable consumption were collected from 138 vegetable farmers using the 24-hour dietary recall method. The analytical methodology employed gas chromatography coupled with mass spectrometry (GC-MS). Vegetable samples were prepared through a series of extraction and purification steps. The results revealed significant variation (P < 0.05) in organophosphate residue concentrations across the different vegetable types and sampling sites. The potential health risks associated with dietary exposure to these pesticide residues were evaluated by employing deterministic approaches. The average residual concentration of profenofos in chinese cabbage was found to be 0.044 ± 0.014mg/kg, while in amaranth exhibited a higher concentration of 0.182 ± 0.056mg/kg. Notably, the concentration of diazinon in amaranth reached 0.272 ± 0.156mg/kg, indicating a significant presence of this pesticide. From this study, chlorpyrifos and marathion emerged as the predominant pesticides, significantly surpassing Maximum Residue Limits (MRLs) established by international food safety standards. The Estimated dietary intake (EDI) for chlorpyrifos was determined to be 0.004mg/kg body weight per day, with an acceptable daily intake (ADI) of 0.01mg/kg body weight per day, the resulting hazard index (HI) values for chlorpyrifos in both chinese cabbage and amaranth was >1, indicating a significant risk of adverse health effects from chronic exposure. The findings underscore a critical public health concern as consumption of these vegetables may expose consumers to harmful pesticide levels, particularly vulnerable populations such as children and agricultural workers.