Contamination levels of toxic metals in selected traditional plants incense (gum)

Gums are polysaccharides, proteins, and minerals that occur naturally in seed coverings and as exudative resinous substance from woody plants. It is reported to have antibacterial, anticancer, blood sugar regulation, and immune system boosting properties. However, the presence of toxic metals in gum is caused for caution as these metals can be harmful if taken in high quantities. The purpose of this study was to determine the amounts of toxic metals in gums collected from the local market, as many consumers tend to use them daily for incense or food ingredients. Gum samples were extracted from several parts of 10 selected medicinal plants (bark, sap, root, latex, leaf glue, and gum). Two fractions of each sample were produced using nitric acid (NHO₃), followed by hydrochloric acid (HCl) at first and then hydrogen peroxide (H₂ O₂). The presence of toxic metals in the solutions was determined using an Inductively Coupled Plasma Atomic Emission Spectrometer (ICP OES). The results showed that most of the elements were detected in high concentrations in Commiphora myrrha (Cd, Cu, Fe, K, Mn, Ni, Pb, and Zn) followed by Benzoin resin (Jawi Oud) and Paeonia officinalis. The most prevalent elements detected in all of the herbal gums were potassium (K) and iron (Fe). Fortunately, the sampled herbal gums were found to be within the WHO/FAO permitted range. This study may provide insights about the safety of the selected gums to be used for food applications. Further in vitro and in vivo toxicity studies should be performed to identify the safe dose.