Determination of Heavy Metal Concentrations on some Selected Herbal Medicinal Preparations Marketed in Kano State, Nigeria

Abstract

Herbs are extensively consumed in Nigeria, for their medicinal properties and availability. This study aimed at determining the concentration of heavy metals residues in some selected traditional medicinal herbs consumed in Kano State, Nigeria. This is to assess their relative safety and potential health risks to local inhabitants based on the World Health Organization standard limit. A total of ten (10) powdered samples of medicinal preparations were purchased from local markets in Kano metropolis and analyzed for the presence of lead, chromium, cadmium, and mercury contents. The samples underwent digestion, and heavy metal concentrations were determined using Atomic Absorption Spectrometry (AAS). The metals found to be present varied in different concentrations in the herbal samples. The presence of heavy metal ranges as follows: 0.6-6.5mg/kg for chromium, 3.10-22.10mg/kg for lead, 0.08-0.60mg/kg for cadmium, and 0.09-0.30mg/kg for mercury. However, mercury content was not detected in some samples. The study's findings conclude that the lead (Pb) values were found to be the highest in concentration, exceeding the W.H.O limits in sample J, which is used as a remedy for cough. This indicates that the sample is highly contaminated compared to others. Mercury was not detected in four of the samples, and when present, it was below the limits set by the World Health Organization, making all the samples free from mercury contamination.