Gintamo et al. 2022 — Physicochemical quality and health risk of borehole groundwater in Oromia, Ethiopia
A seasonal survey of 17 borehole drinking water sources in the Sebeta zone, Oromia (35 km southwest of Addis Ababa) measured physicochemical parameters and six heavy metals (Fe, Cu, Mn, Cr, Zn, Pb) across dry and wet seasons in 2020. Hazard index values for children exceeded 1 in the dry season (HI = 1.861), indicating a non-carcinogenic health risk from chronic groundwater consumption, while adult HI was lower (1.331 dry season, 0.075 wet season). Iron, potassium, and fluoride exceeded WHO and Ethiopian standards in both seasons, with iron elevated in 88.5% of dry-season samples. The study provides baseline contamination data for an area subject to rapid industrialization, agricultural runoff, and uncontrolled waste disposal.
Key numbers
- n=102 samples (17 boreholes × 2 seasons × 3 replicates); Sebeta zone, Oromia, Ethiopia, 2020
- Hazard Index children dry season: HI = 1.861; wet season HI = 0.105
- Hazard Index adults dry season: HI = 1.331; wet season: HI = 0.075
- Iron: elevated in 88.5% of dry-season samples, 23.5% of wet-season samples; exceeded WHO/Ethiopian standard
- Potassium: exceeded standard in 53% dry, 41% wet
- Fluoride: exceeded standard in 47.1% dry, 5% wet
- Phosphate: exceeded standard in 100% of samples in both seasons
- Lead (Pb): no significant seasonal variation reported; hazard quotient calculated with RfD 0.014 mg/kg/day
- Chromium: RfD 1.5 mg/kg/day applied; hazard quotient calculated for both seasons
- AAS used for Fe and Cu; rapid digital pack test (Kyoritsu) for NO3, NO2, Cr
Methods (brief)
17 borehole sources selected purposively based on population served and proximity to expanding industries. Triplicate samples per site per season; mean of triplicates used for analysis. AAS (acid digestion method) for Fe and Cu; colorimetric (UV-vis) for phosphate; rapid digital pack test (Kyoritsu Chemical-Check) for Cr, NO3, NO2; Argentometric for Cl. Health risk calculated as hazard quotient (daily intake / RfD) following USEPA guidelines. Statistical analysis: SPSS v20, Pearson correlation, paired-sample t-test (95% CI, df=16).
Implications
Certification: Provides baseline data on groundwater contamination in peri-urban Ethiopia; relevant for supply-chain water source assessment where groundwater feeds irrigation or processing. Courses: Useful case study for seasonal variation in drinking water contamination and how industrialization and agricultural expansion affect groundwater quality in Sub-Saharan Africa. App: Demonstrates that groundwater-sourced drinking water in industrializing African peri-urban zones can present non-carcinogenic risk to children at current background levels without point-source pollution.