Determination of in vitro bioaccessibility of Pb, As, Cd and Hg in selected traditional Indian medicines

Abstract

In vitro bioaccessibility of Pb, As, Cd and Hg in five traditional Indian medicine samples was measured as a determinant of bioavailability. The method is based on simulation of human digestion in the passage of material from the gastric to intestinal portions of the gastrointestinal tract. Total concentration and concentration in extracts from gastric and intestinal phases were analyzed for Pb, As and Cd by dynamic reaction cell inductively coupled plasma mass spectrometry (DRC-ICP-MS) and for Hg by direct mercury analyzer (DMA). Total lead ranged from 1.9 to 36000 μg g⁻¹. In each of the samples bioaccessibility of lead was significantly higher (range 28–88%) in the gastric phase than in the intestinal phase (range 1.4–75.4%). Only Ekangvir Ras had measurable arsenic (304 μg g⁻¹). Its bioaccessibility in the gastric phase and intestinal phase was 82.6% and 78.1%, respectively. Only Ayu-Nephro-Tone had measurable cadmium (14.4 μg g⁻¹). Its bioaccessibility in the gastric phase and intestinal phase was 80.5% and 2.2%, respectively. Three samples had measurable mercury (range 37 μg g⁻¹–10000 μg g⁻¹). Mercury in these samples was not bioaccessible. For the samples with measurable amount of metal, the estimated daily amount of bioaccessible (EDAB) metal was calculated. When compared with the most liberal published safety guideline, EDAB-Pb in Mahayograj Guggulu and Ekangvir Ras were 37 and 45 fold greater. When compared with the most conservative published safety guideline, all samples had higher EDAB-Pb or EDAB-As than the suggested limits. The EDAB-Cd and EDAB-Hg were acceptably below published safety limits.