Groundwater contamination from urban dumping site leachate and human health risk assessment in Addis Ababa, Ethiopia
摘要
Uncontrolled municipal solid waste disposal remains a critical environmental challenge in rapidly urbanising cities, where open dumping sites pose significant threats to groundwater resources. Koshe Dumping Site operates without engineered liners or leachate collection systems, raising serious concerns regarding subsurface contamination and public health risks. This study aims to evaluate groundwater contamination associated with landfill leachate and the related human health risks. Dumping site leachate and groundwater samples were analysed physicochemical parameters and toxic metals using standard analytical procedures. The Canadian Council of Ministers of the Environment Water Quality Index (CCMEWQI) was used to assess groundwater suitability for drinking and the Leachate Pollution Index (LPI) to evaluate leachate contamination potential. Geographic Information System (GIS) was applied to delineate spatial contamination patterns, while a United States Environmental Protection Agency (USEPA) based human health risk assessment was used to estimate both non-carcinogenic and carcinogenic risks for adults and children. Groundwater CCME-WQI values ranged from 67.35 to 78.22 as ‘fair’ indicating marginal suitability and rendering it unsafe for direct consumption. LPI value was 20.01, indicating moderate pollution potential. Hazard Index values were below 1, indicating no immediate non-carcinogenic risk, carcinogenic risks exceeded acceptable limits, with total cancer risks of 4.21 × 10⁻4 for adults and 1.49 × 10⁻3 for children, driven mainly by Cr, Cd, As, and Pb. The findings highlight the importance of continued monitoring, improved waste management practices, and the use of appropriate water treatment methods prior to consumption to reduce potential risks.