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Author: search.filters.author.ASRAT FEKADU DEMSIEHas files: Yes

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    ECOLOGICAL AND HUMAN HEALTH RISK ASSESSMENTS BASED ON HEAVY METAL AND PESTICIDE RESIDUES IN SOIL AND VEGETABLES AROUND LAKE ZIWAY, ETHIOPIA
    (Hawassa University, 2024-09) ASRAT FEKADU DEMSIE
    The excessive use of pesticides can lead to harmful residues accumulating in vegetables, posing risks to human health. Therefore, regular monitoring and assessment of these potential health hazards are crucial. This study utilized the QuEChERS extraction method to analyze 15 composite samples (vegetables and soil). It employed an inductively coupled plasma optical emission spectrometer (ICP-OES) to detect heavy metal contamination in 18 composite samples of vegetables and soil. The findings revealed that some pesticide residues exceeded safety limits in tomatoes and onions. In tomatoes, α-endosulfan (0.58 mg/kg), β-BHC (beta-benzene hexachloride) (0.04 mg/kg), heptachlor (0.02 mg/kg), and Malathion (0.03 mg/kg) surpassed safety limits. Similarly, the average concentrations of heptachlor epoxide (0.04 mg/kg) and propargite (0.11 mg/kg) exceeded safety limits for onions. The study also evaluated potential health risks for adults and children, identifying both carcinogenic and non-carcinogenic risks. Non-carcinogenic health risk estimates indicated that onion heptachlor epoxide posed a systemic health risk for adult and child consumers with THQ (Target hazard quetient) > 1. Carcinogenic health risks (CHRs) revealed that heptachlor epoxide was present in levels exceeding acceptable limits (10–4) for both adults and children, while the CHRs of tomatoes and onions surpassed acceptable limits only for children. Additionally, heavy metal contamination of vegetables presents a significant concern, especially in areas with prolonged irrigation. The excessive use of agrochemicals particularly impacts the central region of the Rift Valley in Ethiopia. In a study of a soil-vegetable system irrigated by Lake Ziway in Ethiopia, researchers analyzed the levels of nine heavy metals (As, Cd, Cr, Co, Cu, Hg, Ni, Pb, and Zn). The analysis revealed that the concentrations of lead (Pb), arsenic (As), mercury (Hg), and chromium (Cr) in all tomato and onion samples exceeded the thresholds set by the FAO/WHO. In addition, the average ix concentrations of Zn, Pb, Cd, and Hg in all soil samples under tomato and onion plants were found to be above the recommended levels. This poses significant health risks, including systemic and cancerous effects. Moreover, traditional farming methods in the region were found to pose a high ecological risk to non-target soil species due to the use of common pesticides. The study aimed to assess the ecological risks that pesticides could pose to soil biotas, such as earthworms, springtails, and nitrogen mineralization organisms. The evaluation was based on the use of toxicity exposure ratios (TERs) and risk quotient (RQ) methodologies to determine general and worst-case scenarios, respectively. Of the detected pesticides, α-BHC, heptachlor, fenthion, parathion, and propoxur were detected at a rate of 100%. The highest concentration of 119.9 μg/kg was found for p,p'-DDE. Fenthion and Chlorpyrifos methyl posed a chronic exposure risk to F. candida (TERmax=0.86) and N mineralization organisms (TERmax=1.2), respectively. Non-target soil species are at high ecological risk (RQs > 1) due to Alpha endosulfan, which contributes to more than 90% of the risk than the other pesticides. The ecological risk assessment (ERA) reported that the overall pesticide mixture in soil poses a high ecological risk ∑RQ=5.3 in both scenarios. Conventional farming practices in the study area put soil organisms at risk. Therefore, it is crucial to establish effective monitoring protocols and raise awareness among stakeholders to ensure the preservation of the environment and the population's well-being. Furthermore, replacing harmful pesticides with low-risk alternatives is recommended to mitigate these risks. Urgent policies for awareness and surveillance are necessary to protect public health within and beyond the research field.