Probabilistic health risk assessment of heavy metals in vegetables cultivated near tin mining sites in Jos Plateau State, Nigeria

Abstract

This study conducted a comprehensive probabilistic health risk assessment of heavy metals in vegetables cultivated near tin mining sites in Jos Plateau State, Nigeria. Samples of tomatoes, cabbage, and carrots were collected from the Kwata area and around the University of Jos and analyzed for arsenic (As), antimony (Sb), cadmium (Cd), lead (Pb), and tin (Sn). Results revealed elevated concentrations of all metals, with As and Sb frequently exceeding WHO permissible limits of 0.01 mg/kg and 0.02 mg/kg, respectively. Cabbage from University of Jos recorded the highest levels, with As (0.06 ± 0.010 mg/kg) and Pb (0.07 ± 0.013 mg/kg). Deterministic estimates of Estimated Daily Intake (EDI), Target Hazard Quotient (THQ), and Hazard Index (HI) showed significant non-carcinogenic risks, particularly among children, with THQ values for As ranging from 2.4 to 2.9 and HI peaking at 4.6 in cabbage. To enhance risk characterization, Monte Carlo Simulation (10,000 iterations) was applied to estimate Lifetime Carcinogenic Risk (LCR) under uncertainty. As emerged as the dominant contributor to cancer risk, accounting for approximately 96 % of the total burden. Children exhibited the highest Total LCR values, ranging from 1.2 × 10⁻³ to 1.5 × 10⁻³, more than tenfold above the USEPA’s acceptable threshold of 1.0 × 10⁻ 4 . These findings highlight a significant environmental health challenge linked to vegetable consumption in mining-impacted areas. Immediate public health interventions, environmental remediation, and sustained monitoring are urgently recommended to mitigate long-term exposure, especially in vulnerable populations.