Ecological and Human Health Risks from Potentially Toxic Elements in Environmental Matrices of Kiteezi Landfill, Uganda

By the time of this study, Kiteezi landfill was Uganda's largest waste disposal site and received substantial volumes of municipal solid waste. In the present study, water (<i>n</i> = 36), leachates (<i>n</i> = 36), superficial sediments (<i>n</i> = 30), and <i>Colocasia esculenta</i> corms (<i>n</i> = 6) were sampled from Kiteezi landfill in the dry and wet seasons of 2022 before its tragic collapse in 2024. The physicochemical parameters (pH, electrical conductivity, temperature, and oxidation-reduction potential) and concentration of potentially toxic elements (As, Cu, Cr, Pb, and Zn) were analyzed using standard methods and inductively coupled plasma-optical emission spectrometry, respectively. Significant seasonal variations (<i>p</i> < 0.05) were observed for all the physicochemical parameters of water and leachates except temperature. Further, significantly higher concentrations (<i>p</i> < 0.05) of potentially toxic elements (PTXEs) were quantified in environmental matrices sampled during the dry season than the wet season. Arsenic and Pb concentrations in water surpassed their WHO permissible limit of 0.01 mg/L. The concentrations of PTXEs were higher in downstream samples (<i>p</i> < 0.05), indicating that landfill activities led to their enrichment in matrices near the facility. Ecological and pollution risk indices indicated that there is severe enrichment of Cu and Zn in the sediments, with dry season downstream samples having contamination factors and geoaccumulation indices of 539.3 and 74.7 and 8.5 and 5.6, respectively. Although ingestion of water may not cause probable health risks, consumption of <i>Colocasia esculenta</i> corms could lead to non-carcinogenic and cancer health risks in both children and adults (hazard indices = 0.085-189.0 and total cancer risk values of 7.33 × 10^-6-4.87 × 10^-3). These results emphasize the need that any new replacement for Kiteezi landfill should be properly planned and managed to mitigate potential environmental pollution with xenobiotics.