Assessment of heavy metal exposure and cancer risk in Addis Ababa: Trends, risk factors and demographic variations in urinary cadmium, lead and chromium levels

This study aims to assess the exposure levels of Pb, Cd, and Cr and evaluate trends in heavy metal exposure among the population of Addis Ababa. A cross-sectional study was conducted involving 417 participants randomly selected from the population. Spot urine and water samples, socio-demographic characteristics, and food consumption frequency were collected. Heavy metals were analyzed using microwave plasma-atomic emission spectroscopy. Metal exposure risk from drinking water was assessed. The median concentrations of urinary Pb, Cr, and Cd were 19.4865 µg/g creatinine, 55.65 µg/g creatinine, and below the detection limit (Bd), respectively. Female participants and individuals who consumed meat daily had the highest median concentration of Pb (p < 0.005). Those who drank two or more cups of water daily had lower Pb (P < 0.01). Females who consumed eggs daily and drank two or more cups of water had the highest concentration of Cd, ranking in the 75th percentile. The median Cr concentration was higher in underweight participants (BMI < 18.5 kg/m²) at 88.41 µg/g creatinine and in overweight participants (BMI ≥ 25 kg/m²) at 66.49 µg/g creatinine compared to normal-weight participants, who had a median concentration of 48.44 µg/g creatinine (P < 0.01). Three metals were detected in 14.4 % and two metals in 52.8 %, and their levels showed an increasing trend over 12 years. Health risk analysis revealed that the highest Cumulative Incremental Life Cancer Risk (CILCR) values were found in Kirkos (KR-10–1.9 ×10⁻³), Lideta (LI-10–2.33 ×10⁻³), and Nifas Silk (NS-11–2.46 ×10⁻³) districts, indicating a significant cancer risk associated with cumulative exposure.