The Effects of Lead Species and Growth Time on Accumulation of Lead in Chinese Cabbage

A major pathway for heavy metal exposure in contaminated areas is via consumption of locally produced food. This study investigated the accumulation of lead in Chinese cabbage grown in contaminated soils and estimated the weekly dietary intake. Experiments were conducted to determine the effects of different growth times, concentrations, and lead species (carbonate, nitrate, and sulfide) on the uptake of lead in shoots. Results show that Chinese cabbage accumulated up to 38 mg kg−1 in the shoots. There was a significant difference in lead uptake by plants grown in soils with 400 mg kg−1 (Upper Critical Limit: UCL) and those grown in 600 mg kg−1 (Above Critical Limit: ACL) lead concentrations. However, there was no significant difference in the ACL shoots despite the different growth period. The cabbages grown for eight weeks (at UCL) had four times more lead than those grown for four weeks. The elemental form also affected lead uptake with the lead sulfide (mineral form) having the least uptake and lead carbonate (solution) having the highest. Calculated weekly dietary intake levels of lead were higher (above 0.28 mg kg−1 per human body weight) than the recommended levels for human consumption (0.025 mg kg−1 per human body weight). Heavy metal contamination of food is a global concern. Due to the local reliance on food produced in contaminated areas, it is imperative to know the contamination levels and quantities that can be consumed before these foods become detrimental to human health. This study focuses on accumulation of lead in Chinese cabbage and calculates the weekly dietary intake limits of consumption.