Determination of Arsenic, Cadmium and Lead Elements in Chewing Sticks (Miswak) Using ICP-MS

Salvadorapersica (Miswak) is used in many parts of the world as a tool for the cleaning of teeth and general oral hygiene. This material is imported into the United Kingdom, from countries in Africa, Asia and the Middle East, and is sold in ethnic shops. They are popular amongst members of certain ethnic communities. Very little is known about the trace elements content of chewing sticks and their possible impact on human health. Therefore, in the current study, a survey of trace elements composition of chewing sticks, sold in ethnic shops (in Leicester, Birmingham, Luton, London) and some Libyan cities was carried out using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). We determined the content of arsenic (As), cadmium (Cd) and lead (Pb) in both the bark (which is often removed before chewing) and the flesh components of twigs fromSalvadorapersica. After cleaning, the samples were dried and digested using a microwave digester and the content of heavy metals analysed by ICP-MS. Concentrations of As, Cd and Pb were0.038, 0.15 and 2.18 (mg/kg, mean value) for the flesh and 0.11, 0.28 and 3.88 (mg/kg) for the bark, respectively. The content of As was found to be the lowest whereas the content Pb was highest for both the flesh and the bark components.Concentrations of these elements in the bark were significantly higher compared to the flesh. The precise reason for this is not clear although it could partly be due to air pollution or contact with soil. It is therefore recommended that users take extra care to fully remove the bark before using the chewing stick. Further studies are in progress to identify the role of environmental and processing conditions on the content of heavy metals in chewing sticks. Keyword: Miswak, Chewing sticks, Arsenic, Cadmium, Lead.