Concentration, Source, and Health Risk of Trace Metals in Some Liquid Herbal Medicine Sold in Nigeria

The ingestion of toxic metals through liquid herbal medicine over a long period of time, and in excessive dose, may result in chronic accumulation that could cause disorder to several organs of the body. This study evaluated the concentration, source, and probable health risk of 8 trace metals in liquid herbal medicines sold in Nigeria. Triplicate samples of 10 different brands of liquid herbal formulations were analyzed using flame atomic absorption spectrophotometer. Elemental concentrations (mg L^-1) ranged as < 0.00120 (nickel), 0.329-1.23 (zinc), < 0.00150-0.0750 (chromium), 0.565-6.94 (manganese), 1.75-19.4 (iron), < 0.00150-0.266 (cobalt),  < 0.0018-3.01 (lead), and < 0.00900-0.0281 (copper). The estimated hazard quotient (HQ) and hazard index (HI) of trace metals (zinc, chromium, manganese, iron, cobalt, lead, and copper) were < 1.00, except for one of the herbal products which depicted a value of < 1.50, an indication that there is no major probable health effect due to exposure. Carcinogenic risks were lower than the threshold level of 10.0^-6-10.0^-4; this probably reflects non-existent carcinogenic risk in both age groups. The principal component analysis revealed the likelihood of geogenic and anthropogenic activities as indirect sources of trace metals in the herbs. Using hierarchical cluster analysis, AAB and AHM herbal mixtures showed strong similarities in cluster 1, while the remaining herbs reflected identical association within cluster 2. Based on the results of this study, there is need to periodically monitor levels of toxic metals in herbal medicine in order to ensure regulatory compliance and safeguard the health of its consumers.