Determination of cadmium bioaccessibility in herbal medicines and safety assessment by in vitro dissolution and ICP-AES

Abstract

A method was developed for in vitro dissolution and ICP-AES based determination of cadmium (Cd) for evaluating its bioaccessibility in herbal medicines to investigate the utility of this test for toxicological assessments. The bioaccessible Cd content of five commonly consumed and Cd-accumulating herbal medicines was determined by in vitro dissolution test with a biorelevant medium simulating gastric conditions. Cd levels were determined by a validated ICP-AES method. In all 5 herbal medicines, the total amount of Cd in herbal medicines was not proportional to the bioaccessible Cd content, which varied from 23.0% to 54.9%. The Cd tolerance limit was exceeded by four of the five herbal medicines in terms of total Cd content, but by only one of these in terms of bioaccessible Cd content. Assessments based on total content may overestimate the risk of Cd toxicity from herbal medicines. Assessing bioaccessibility by in vitro dissolution test coupled with ICP-AES method may be a more appropriate means of determining the safety of herbal medicines containing Cd.