ASSESSMENT OF SELECTED TOXIC TRACE ELEMENTS IN GEOPHAGIC CLAYS FROM VHEMBE DISTRICT, SOUTH AFRICA

Geophagic clays are earth materials that are deliberately consumed by human beings and other members of the animal kingdom. Up till now, there exist limited toxicological data on safety of these clays. The focus of this study was to determine the bioaccessible toxic trace elements in geophagic clays in the Vhembe District and their potential implications on human health. A two-stage physiologically based extraction test simulating the human stomach and intestine was used to estimate the human bioaccessibility of selected toxic trace elements in geophagic clays. Extractants were analysed by inductively coupled plasma mass spectrometry (ICP-MS). The element concentration extracted from geophagic clays within the human stomach and intestines were on average; 5.59 and 102.87 ppm Ni; 2.22 and 3.23 ppm As; 29.50 and 35.91 ppm V. Cadmium and Pb were not bioaccessible in the gastric phase. Nickel, As and V showed higher bioaccessibility under intestinal conditions. The correlation between As in the stomach and intestinal phase was strong. Lead and As are the toxic elements of greatest health concern in this locality.