Determination of Heavy Metal Contamination of Some Commercially Available Herbal Preparations in Nigeria

There has been reported increase in the use of herbal medicine preparations in the management of diseases in Africa over the past few decades. However, some of these preparations are contaminated with heavy metals which are toxic to both man and animals even at low concentration. Some of these heavy metals include cadmium, lead, zinc, chromium, arsenic and mercury. Availability of heavy metals in herbal medicine products may sometimes be due to plant materials used for production which are obtained from soils heavily contaminated or from the atmosphere. This study aimed to measure the levels of Pb, Cd, As, Cu and Hg in commercially available herbal products. Twenty products were purchased from traditional herbal medicine outlets in Lagos. The samples solutions were used to determine concentration of the heavy metals making use of Atomic Absorption Spectrophotometer (AAS). Results obtained indicated that some of the heavy metals were found in various percentages in the herbal products. Lead was found in 75% of the samples with concentrations range of 0.02 – 1.24ppm, cadmium (75%) with concentration range of 0.01 – 1.23ppm, arsenic (75%) with range between 0.01 – 0.08ppm, mercury (70%) with range between 0.08 – 1.32ppm and copper (80%) with range between 0.03 – 1.25ppm. The concentrations of heavy metals in few of the commercially available herbal remedies were well below the acceptable global recommendations, however our findings revealed that at present, the amount of heavy metals in most of the herbal preparations need to be reduced to acceptable limits so as to avoid heavy metal poisoning.