Metals in leafy vegetables grown in Addis Ababa and toxicological implications

Abstract

Abstract

Background: Vegetables grown at environmentally contaminated sites in Addis Ababa could take up and accumulate metals at concentrations that are toxic to human health.

Objective: To analyze the metal/metalloid contents of some leafy vegetables in Addis Ababa with emphasis on their toxicological implications.

Method: Recently matured leaf samples of cabbage, Swiss chard, and lettuce at early maturity, from Peacock Park and Kera vegetable farms underwent pressurized digestion with HNO3/H2O2 to determine heavy metals.

Results: Cabbage was in general the least accumulator of metals/metalloids. Lettuce and Swiss chard grown at Kera had higher concentrations of metals/metalloids compared to those grown at the Peacock Park. In a few cases, As, Cr, Fe and Pb in these vegetables have surpassed maximum permitted concentrations, while Cu deficiency was observed in cabbage.

Conclusions: Metal uptake differences by the leafy vegetables is attributed to plant differences in tolerance to heavy metals. Vegetables from Kera consisted of higher metal/metalloids than from Peacock Farm because Kera River is more contaminated than Bulbula River. The intake of most of the metals constitutes less than 10% of the TMDI (theoretical maximum daily intake) at present, and hence health risk is minimal. But with increase in vegetable consumption by the community the situation could worsen in the future. Treatment of industrial effluents and phyto-extraction of excess metals from polluted environments could reduce health risk. [Ethiop.J.Health Dev. 2002;16(3):295-302]