Evaluation of the impacts of trace metals on market gardening consumers: The case of Kimwenza-Gare

Introduction The reliance of agriculture on mineral fertilizers and pesticides has raised concern for decades. In Kinshasa, market gardening contributes substantially to feeding the local population. Purpose This study assesses the impacts of trace metals accumulated in leafy vegetables cultivated in Kimwenza-Gare (Mont-Ngafula Commune), with a particular focus on potential risks to consumer health. Methods A survey of market gardeners was conducted to identify the most frequently sold vegetables throughout the year and to document the agricultural inputs used for soil fertilization and pest control. Six vegetable samples and three soil samples were analyzed for ionic composition using an energy-dispersive X-ray fluorescence spectrometer (ED-XRF). Statistical analyses included Student’s t-test, as well as Spearman and Pearson correlation coefficients, performed using RStudio (version 4.3). Results were compared with World Health Organization (WHO) standards. Results Trace elements were detected in all vegetable samples at a 95% confidence interval. Chromium (Cr) concentrations exceeded the WHO guideline value (2.3 mg/kg dry weight) in all Amaranthus viridis samples from the Lukaya sector, reaching a maximum concentration of 9.46 ± 1.26 mg/kg. Lead (Pb) concentrations also exceeded the guideline value (0.30 mg/kg) in this vegetable, with the highest level recorded in the same sector (0.67 ± 0.01 mg/kg). Cadmium (Cd) was detected but remained below the detection limit. Overall, vegetables accumulated heavy metals present in the soil, particularly Amaranthus viridis in the Lukaya sector (ρ = 1). Conclusion Although the overall concentrations of trace metals were relatively low, consumers remain exposed to potential risks of chronic poisoning. Preventive measures, including awareness campaigns targeting market gardeners, should be implemented.