Abstract
Background Community consumption of herbal plants in developing countries is a common practice, however, scarcity of information on their physiochemical composition is a major public health concern. In Uganda, Vernonia amygdalina is of interest in rural communities due to its therapeutical action on both bacterial and protozoal parasites, however no studies have been conducted to assess the heavy metal concentrations in traditional plants used in alternative medicine. The aim of the study was to establish concentrations of heavy metals in Vernonia amygdalina, model the estimated daily intake (EDI), and assess both the non-cancer-related health risk using the target hazard quotient (THQ), and the risk related to cancer through the incremental lifetime cancer risk (ILCR) for the Ugandan population. Methods Leaves of Vernonia amygdalina were collected from 20 georeferenced villages and processed into powder in the laboratory using standard methods. These were then analyzed in the laboratory using an atomic absorption spectrometer for lead (Pb), chromium (Cr), copper (Cu), zinc (Zn), cobalt (Co), iron (Fe), cadmium (Cd), and nickel (Ni). Concentrations were compared against the World Health Organization (WHO) limits. The EDI, THQ, and ILCR were modelled and significance was measured at 95% confidence. Results The study showed that mean ± SEM concentrations of heavy metals were highest in the order of Cr, 121.8 ± 4.291 ppm > Ni, 84.09 ± 2.725 ppm > Zn, 53.87 ± 2.277 ppm > Pb, 40.61 ± 3.891 ppm > Cu, 28.75 ± 2.202 ppm > Fe, 14.15 ± 0.7271 ppm > Co, 7.923 ± 0.7674 ppm > Cd, 0.1163 ± 0.005714 ppm. Concentrations of Pb, Cr, Zn, Co, and Ni were significantly higher than the WHO limits. The EDI was significantly higher in children than in adults, demonstrating an increased risk of toxicity in children. The THQ and ILCR were over 1000 times higher in all Ugandans, demonstrating the undesirable health risks following oral consumption of Vernonia amygdalina due to very high Cr and Ni toxicities, respectively. Conclusion Consumption of raw Vernonia amygdalina was associated with a high carcinogenic risk, demonstrating a need to enact policies to promote physiochemical screening of herbal medicines used in developing countries against toxic compounds.
Highlights
Herbal medicines are currently used widely in complementary and alternative medicine for the management of various forms of ailments, and their diversity is important in developing communities [1]
Most herbal medicines are only used with the application of basic indigenous knowledge by the local community who lack pharmacological knowledge and this predisposes locals to toxic effects arising from unknown harmful elements in the plants [2]. e traditional plant Vernonia amygdalina is widely used in local communities of Africa for home-based treatment of noncancer health conditions against bacterial and protozoal infections [3, 4], but detailed pharmacological knowledge and information on the presence of elements that could be toxic to humans is scarce. e most notable elements present in most medicinal herbs and vegetables are heavy metals such as lead (Pb), copper (Cu), nickel (Ni), iron (Fe), cobalt (Co), zinc (Zn), chromium (Cr), and cadmium (Cd) [5]
Concentrations of Heavy Metals in Vernonia amygdalina in Uganda. e study showed that mean ± SEM levels of heavy metals were highest in the order of Cr > Ni > Zn > Pb > Cu > Fe > Co > Cd, i.e., 121.8 ± 4.291 ppm, 84.09 ± 2.725 ppm, 53.87 ± 2.277 ppm, 40.61 ± 3.891 ppm, 28.75 ± 2.202 ppm, 14.15 ± 0.7271 ppm, 7.923 ± 0.7674 ppm, and 0.1163 ± 0.005714 ppm, respectively
Summary
Herbal medicines are currently used widely in complementary and alternative medicine for the management of various forms of ailments, and their diversity is important in developing communities [1]. Fe is required for the production of red blood cells and forms part of hemoglobin, helping in the binding and transportation of oxygen in the body [8] Both Fe and Cu are important in oxygen and electron transport [9], demonstrating their synergistic effect in body physiology [10]. Cu is an essential trace element playing an important role in human metabolism, primarily as a cofactor of many metalloenzymes helping the body to form red blood cells and maintain healthy bones, blood vessels, nerves, immune function, and it contributes to iron absorption and spermatogenesis [12,13,14]. Results. e study showed that mean ± SEM concentrations of heavy metals were highest in the order of Cr, 121.8 ± 4.291 ppm > Ni, 84.09 ± 2.725 ppm > Zn, 53.87 ± 2.277 ppm > Pb, Journal of Environmental and Public Health
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