Integrated Assessment of Potentially Toxic Elements and Microbial Contamination in Soil and Groundwater Around a Municipal Solid Waste Dumpsite in Zomba, Malawi

The present study assessed potentially toxic elements (PTEs) and microbial contamination in soil and groundwater around a municipal solid waste dumpsite in Zomba, Malawi. The potential ecological and health risks to communities were also examined. The results revealed that wet season groundwater had elevated total coliforms (20,900 CFU/100 mL), Escherichia coli (3300 CFU/100 mL), Staphylococcus aureus (2500 CFU/100 mL), and Vibrio cholerae (5900 CFU/100 mL), which were significantly higher than the permissible limits of the Malawi Standards. In water samples, PTEs, particularly cadmium (Cd; 0.011–0.08 mg/L) and chromium (Cr; 0.02–0.41 mg/L), were detected at concentrations of concern. In the soil samples, lead (Pb) concentrations ranged from 0.16 to 224.05 mg/kg, copper (Cu) concentrations ranged from 3.03 to 94.86 mg/kg, Cd concentrations varied between the BDL and 0.89 mg/kg, arsenic (As) ranged from BDL to 1.88 mg/kg, and the Cr varied between 0.07 and 0.91 mg/kg. Furthermore, the cancer risk (CR) assessment indicated that all sampling points had CR levels greater than 1 × 10−3 for adults, with 40% of the sampling points showing elevated CR levels for infants and children, highlighting the cancer risk from Cd exposure, especially among vulnerable populations.