Analysis of some selected toxic metals in registered herbal products manufactured in Nigeria

The use of herbal medicine has been on the increase in many developing and industrialized countries and Nigerians in particular has been using herbal medicine for many centuries. The approval of these herbal remedies by regulatory bodies has further encouraged the use of herbal remedies. The safety of these herbal remedies is however poorly understood. This study investigated the concentration of arsenic, cadmium, lead and mercury in twenty registered ready to use herbal products. Twenty brands of herbal remedies were purchased randomly from the Pharmacy shops in Lagos, digested with aquaregia (3:1 HCl: HNO3) and were analysed using atomic absorption spectroscopy (Buck 205 Atomic Absorption Spectrophotometer). There was no detectable lead in any of the 20 herbal samples; however, all the samples contained a detectable amount of one or more of the other metals of interest. The Oral Component Limit (OCL) for arsenic, cadmium and mercury as stated by USP are 1.5, 0.5 and 1.5 μg/g, respectively. All the samples contained arsenic and mercury below the USP OCL, while sixtyfive percent contained cadmium out of which fifty-five percent were above USP OCL. The results obtained from this study suggest a significant risk to consumers’ health considering the toxicity of these heavy metals