Overview
The authors measured 19 elements by ICP-MS, and mercury by direct mercury analyzer, in Brassica pekinensis leaves from 19 sampling points at two intensive urban gardening sites in Kinshasa in August 2025. Cecomaf leaves carried much more lead, cadmium and copper than Lutendele leaves. Lead and cadmium exceeded the cited FAO/WHO limits at nearly every point.
Key numbers
- Cecomaf lead 2.39 to 30.94 mg/kg dry weight (CS3P 30.94, CS4P 24.69); Lutendele lead 1.22 to 3.91 mg/kg (Table 1).
- Cecomaf cadmium 0.11 to 2.95 mg/kg (CS2P 2.95); Lutendele 0.08 to 0.57 mg/kg (Table 1).
- Arsenic 0.04 to 0.39 mg/kg; mercury 0.005 to 0.058 mg/kg (Table 1).
Methods (brief)
Leaves were washed, lyophilized, ground under liquid nitrogen and digested in nitric acid and hydrogen peroxide for ICP-MS; mercury was measured by thermal decomposition and gold amalgamation (AMA-254). Each sampling point was analyzed in triplicate. BCR-482 lichen reference material recovered above 93%. Per-point values are printed in Table 1.
Evidence Fitness
Per-sample values with a certified reference material and stated detection limits, on a dry-weight basis. The samples come from two urban gardens with known soil and irrigation water contamination, so they describe contaminated garden produce rather than retail supply. Some text statements conflict with Table 1 (for example the site comparison for manganese and the Lutendele exceedance factors). Chinese cabbage is a Brassica leaf proxy for collard-greens; collards were not measured.