TOXICOLOGICAL STUDY OF VERNONIA AMYGDALINA ON A SOIL CONTAMINATED WITH DIFFERENT CONCENTRATIONS OF LEAD AND CADMIUM AND ITS INTERACTION IN THE TRANSFER OF ESSENTIAL TRACE MINERALS

Abstract

Vernonia amygdalina is a vegetable widely used in nutrition and phytotherapy. Its toxicological quality poses real concerns for its use. Greenhouse cultivation is carried out with twelve batches of six vegetative vases in order to evaluate the soil-plant transfer. Atomic Absorption Spectrophotometry analysis allowed an investigation of the lead, cadmium and bivalent iron, magnesium, calcium, manganese, zinc and copper contents of the different plant organs. Lead and cadmium concentrations vary according to the concentration of the two metals in the crop soil. The lowest concentrations of lead and cadmium are found in the leaves, that are the most consumed part of the plant. In the leaves, cadmium (0.937-33.004ppm); lead (0.945-31.701ppm). Lead concentration is positively correlated with the trace elements iron (r = 0.465), manganese (r = 0.342), magnesium (r = 0.349); there is a weak correlation between cadmium and trace elements in leaves. In the stem, cadmium (0.145- 96.680ppm); lead (0.050-288.364ppm). Lead and cadmium correlate respectively with zinc (r = 0.552; r = 0.547), manganese (r = 0.741; r = 0.708); iron (r = 0.432; r = 0.452). There is a strong negative correlation between cadmium-calcium r = -0.341. At root level cadmium (0.572- 237.043); lead (2.594-151.358ppm). The following correlations can be observed: cadmium-copper r = 0.648; cadmium-zinc r = -0.379; cadmium-iron r = -0.412; lead-magnesium r = 0.369; lead-calcium r = 0.410. This study permits to orient the cultivation of this vegetable in order to guarantee its virtues and protect the consumers.