Contamination level and dietary risk assessment of trace elements in Brassica pekinensis Lour. from gardening areas under tropical conditions

This study examined the levels of trace elements in <i>Brassica pekinensis Lour</i>. collected from urban gardening sites (Cecomaf and Lutendele) in Kinshasa (Democratic Republic of the Congo) and associated potential human health risks for the consumer. The toxic metal concentrations in leaf samples were analysed using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and Atomic Absorption Spectrophotometer (AAS). Results showed that Cr, Cu, Cd, Pb, and Hg concentrations in samples from both sites exceeded the FAO/WHO maximum permissible limits, with Cecomaf displaying notably high levels of Cu (115.39 mg·kg⁻¹), Cd (2.95 mg·kg⁻¹), Pb (30.94 mg·kg⁻¹), and Hg (0.058 mg·kg⁻¹). Health risk assessments associated with the consumption of <i>Brassica pekinensis</i> L, based on Estimated Daily Intake (EDI), Target Hazard Quotient (THQ), and Hazard Index (HI), indices indicated that EDI values for Cd and Pb exceeded recommended limits in several samples, while THQ values exceeded 1 for most metals except As, suggesting potential non-carcinogenic risks. HI values ranged from 2.98 to 16.11 at Cecomaf and 4.85-12.15 at Lutendele, highlighting a high cumulative risk from individual and multi-metal exposure to consumers. Monte Carlo simulation further confirmed these findings by showing that a significant proportion of the exposed population exceeded the WHO safety thresholds for Cd, Pb, and Cu, thereby reinforcing the robustness of the deterministic risk estimates and illustrating the uncertainty associated with age, sex, and local consumption variability. Spearman correlation analysis revealed strong positive associations between Cr-As, Cr-Pb, and Cd-Hg, suggesting common anthropogenic sources or shared environmental pathways. Results of this study highlight the importance of continuous monitoring of trace elements in leafy vegetables for food safety evaluation, adopting stricter agricultural practices in policy making and management, and public health measures to mitigate long-term exposure risks to urban and peri-urban areas populations.