Microplastics and trace metals across the drinking water supply system of Addis Ababa, Ethiopia: A case study for low and middle-income countries

Despite growing global concern about the potential public health impacts of microplastics and trace metals in drinking water, data from low and middle-income countries remain limited, particularly for microplastics, due to outdated and inconsistent sampling and analysis methods. Therefore, we examined microplastics and trace metals in tap water in Addis Ababa, Ethiopia, using advanced spectroscopic techniques as a case study for lower and middle-income countries. Samples were collected from randomly selected standard and slum areas of Addis Ababa during the dry and wet seasons, which included 71 samples analysed for microplastics with μFTIR spectroscopy and 48 samples analysed for dissolved trace metals with ICP-OES. Microplastics were detected in all tap water samples, with concentrations ranging from 0.004 to 1.33 MP L −1 (average = 0.31 ± 0.31 MP L −1 ), comparable to values in high-income countries. Statistically higher concentrations were measured in slum areas (0.41 ± 0.33 MPs/L) and during the wet season (0.36 ± 0.34 MPs/L). Polypropylene and polyethylene were the most common polymers, and particles sized 25–125 μm were predominant. Dissolved Ba, Zn, V, Cu, and Fe, with mean concentrations of 28.3 ± 6.5, 16.2 ± 19.7, 7.5 ± 0.5, 7.0 ± 2.6, and 5.1 ± 3.7 µg/L, respectively, were the only trace metals detected, showing no significant variation across locations or seasons and remaining below WHO and national drinking water guidelines. Estimated daily intake (EDI) and hazard index (HI) values of trace metals indicated minimal non-carcinogenic risk. No significant correlation was found between microplastic and trace metal concentrations. Overall, drinking water contamination levels were comparable to those reported in high-income countries. • Microplastics were detected in all samples, comparable to high-income countries. • Only dissolved Ba, Zn, Fe, V and Cu were detected, all below WHO and national limits. • Unlike trace metals, microplastics showed significant spatial and temporal variation. • Trace metals pose minimal health risk, based on hazard index and target hazard quotient values. • Despite low estimated daily intake values for microplastics, caution is still warranted.