Assessment of Heavy Metal Contents in Selected Herbal Medicines in Nigeria

The use of herbal medicines, despite the advancement in production of orthodox ones, has been on the increase, both in underdeveloped, developed and developing countries like Nigeria in particular. The approval of these herbal remedies by regulatory bodies like the National Agency for Food and Drug Administration Control, (NAFDAC) in Nigeria has further encouraged the use of herbal remedies by almost everybody. This research targets the estimation of the concentration of‘heavy metals’ in some samples of herbal medicinal products, branded and registered with NAFDAC Nigeria Ten(10) brands of herbal medicines were selected for the analysis of heavy metals content using  ‘Atomic Absorption Spectrometer, AAS’. The samples were prepared for analysis by ‘wet digestion method’ using nitric acid  HNO3 and perchloric acid, HClO4 treatment.  To determine levels of contamination of eight (8) metals, an analysis method using anatomic absorption spectrometer was validated after obtaining the most appropriate destructive tools and processes. The heavy metals of targets were; Lead(Pb), Cadmium(Cd), Cupper(Cu), Nickel(Ni), Manganese(Mn), Zinc(Zn), Iron(Fe) and Chromium(Cr) and the herbal medicines selected are Omo Osun herbal mixture, Dr. Nwakor Cleanser, Origin bitters, japata herbal mixture, olekoko,maisansanchi, wildfire ginger herbal mixture, Basir Zalla, action bitters and Lamjib herbal mixture. All the herbal mixtures have high content of Fe that ranges between 116.26ug/L to 330.51ug/L. 30% of all the herbal medicines contain Lead beyond the WHO limit of 10mg/g 40% of the samples contain cadmium beyond the 0.3ug/g tolerable limit, respectively, Fe, Cd, Pb, Ni, Zn, Cu, Mn, and Cr have their minimum values of 116.26ug/L, 0.04ug/L, 0.14ug/L, 9.18ug/L, 4.94ug/L, 2.81ug/L, 3.21ug/L, and 0.09ug/L  in Omo Osun herbal mixture, In order to ensure the safety, potency and quality of herbal medicines, it is helpful to estimate the level of metal contamination. It is sacrosanct that consumers are informed that “natural” or ‘‘traditional’’ does not necessarily mean ‘free from risk’ or ‘100% safe’ and that the adverse effects as a result of the administration of herbal medicine are undeniable reality due to heavy toxic metal contamination. Further research is needed to determine the levels of metals in many other herbal medicines consumed locally in Nigeria as a means of periodic assessment. The National Agency for Food and Drug Administration and Control (NAFDAC) must also promulgate and enforce strictly the law guiding the safety and use of herbal products in Nigeria, as individuals should be more aware of the risk of heavy metal accumulation in the body.