Soil - Plant Transfer, Bio-accumulation and Health Risks of Potentially Toxic Elements in Vegetables from Wudil, Northern Nigeria

This study assessed potentially toxic elements (PTEs) in peri-urban agricultural soils and vegetables from Wudil, Kano State, Nigeria, using Microwave Plasma–Atomic Emission Spectroscopy (MP-AES, Agilent 4210). A total of n = 42 soil and vegetable samples were collected during the dry season of 2025, and analysed on a dry-weight basis. Soil concentrations of Cd, Ni, Pb, Mn and Cr ranged from 0.25–1.16 mg/kg, while vegetable concentrations spanned 0.08–11.03 mg/kg, reflecting clear metal- and crop-specific uptake patterns. Lettuce showed the highest Mn accumulation (7.58–11.03 mg/kg), whereas spinach exhibited elevated Cr levels (0.24–0.85 mg/kg). Cd and Pb concentrations in vegetables were low but toxicologically relevant due to their low safe-exposure thresholds. Estimated Daily Intake (EDI) values for most metals remained below international tolerable limits; however, cumulative non-carcinogenic risk exceeded the safety threshold for several vegetables (Hazard Index, HI = 1.01–1.80). Carcinogenic risk (CR), driven primarily by Cd and Cr(VI), fell within the 10⁻⁴–10⁻³ range for pepper and spinach, indicating a moderate but non-negligible lifetime cancer risk. Although soil contamination was moderate (PLI = 0.44), plant uptake substantially amplified potential dietary exposure. Overall, the findings indicate low immediate but meaningful long-term health risks, particularly for Mn- and Cr-accumulating leafy vegetables. Continuous monitoring, improved wastewater-irrigation management and targeted food-safety interventions are needed to reduce chronic exposure in peri-urban farming systems.