Heavy metals effects on plant growth and dietary intake of trace metals in vegetables cultivated in contaminated soil

Abstract

Arsenic, cadmium and lead are persistent environmental pollutants that severely affect the bioavailability of essential and other nonessential elements. The present study was conducted to evaluate the potential effects of these three notorious environmental pollutants on uptake and bioaccumulation of chromium, copper, nickel and zinc by lettuce, potato and tomato. Soil was contaminated with arsenic, cadmium and lead using three different levels of concentration for each metal. The concentrations of selected metals were determined using atomic absorption spectrophotometer. Substantial changes in growth parameters and trace element concentrations were observed in plants cultivated in contaminated soil, and the effects were more significant with increasing concentrations of heavy metal in the soil. Both synergistic and antagonistic effects were observed depending upon type of vegetables, concentration of pollutants in the soil and metal mixture used. Among the selected vegetables, the effects were more prominent on lettuce. The projected daily dietary intake of chromium, nickel and zinc was higher for vegetables grown in metals-contaminated soil than control. The contribution to recommended dietary allowance was significant for copper and nickel and less significant for zinc, although great variations were observed in recommended dietary allowance for different treatment levels. Food quality and elemental composition of vegetables cultivated in metals-contaminated soil were significantly affected, and their consumption may result in over and/or under nutrition affecting human health.