Revisiting some overlooked registered Thai traditional medicine preparations: an alert to a regulatory affair

Abstract

Abstract Objective This study evaluated the heavy metal identity and content of registered Thai Traditional medicine (TTM) preparations in Thailand to ensure consumer safety. Methods Both qualitative and quantitative information about the elemental composition of the heavy metal content in each TTM crude drug and the heavy metal content in some registered TTM preparations in Thailand was performed. Seven kinds of mineral-based TTM crude drugs, namely realgar, orpiment, Chinese powder, Sen, vermilion, natural vermilion, and cinnabar, were analyzed with X-ray diffraction and scanning electron microscopy and energy-dispersive spectroscopy techniques to determine the type of metal and elemental composition to confirm their chemical formulas. Furthermore, the number of heavy metals, such as arsenic (As), lead (Pb), and mercury (Hg), was in three samples of realgar-containing preparations; one sample of Sen-containing preparation, and eight samples of cinnabar-containing preparations. Heavy metals were determined with inductively coupled plasma-optical emission spectrometry. Results It was observed that realgar and orpiment consisted of arsenic sulfide (AsS) and arsenic trisulfide (As2S3), respectively. Both crude drugs contained approximately 50% of As. Vermilion, natural vermilion, and cinnabar consisted of mercuric sulfide (HgS), with Hg accounting for approximately 66%. Sen consisted of Pb (II, IV) oxide (Pb3O4) with an approximate Pb percentage of 80%. However, Pb was absent in Chinese powder and consisted mainly of calcium carbonate (CaCO3). A traditional detoxification procedure can reduce the amount of As and Hg in processed crude drugs by at least 20%. Conclusions Pb was higher in some TTM preparations, and no CaCO3 was detected in Chinese powder. Our results raise concerns on both safety and efficacy to consumers and alert public health policymakers that they should implement regulations so that the quality (authenticity) and quantity of elemental medicine used in traditional medicine are correctly labeled and within permissible limits to prevent threats to consumers.