Assessment of bio-availability of Cd, Pb, As and Tl via Gastric/Intestinal Digestion in Plants Collected From Different Kenyan Regions

Abstract

In this study, total and bio-available levels of cadmium (Cd), Lead (Pb), arsenic (As) and Thallium (Tl) in 19 Kenya plants from two study sites (Manga and Borabu) were evaluated. ICP-MS technique was used to determine total Cd, Pb, As and Tl contents, while ultra-filtration and physiological extraction tests evaluated bio-accessibility of these elements. The plants had low concentrations; Cd (0.27±0.02 and 0.26±0.02), As (0.32±0.02 and 0.48±0.04), Tl (0.07± 0.02 and 0.06±0.01) and Pb (1.23±0.11 and 1.16±0.10) mg/kg in Manga and Borabu sites. However, sequential ultra-filtration showed more than 70% high molecular weight species (>10 kDa) predominated with Pb, Cd and Tl. The physiological based tests showed Cd, Pb, As and Tl extracted enzymatically were significantly higher (0.45±0.11, 0.46±0.12, 0.37±0.10 and 0.81±0.19µg/g) than aquatically extracted (0.32±0.07, 0.34±0.11, 0.26±0.08 and 0.50±0.27) µg/g, (p<0.05). Low bio-accessibility levels of these elements in medicinal plants justifies their use therapeutically.