Carcinogenic and Noncarcinogenic Health Risk Assessment of Heavy Metals on Some Selected Traditional Herbal Drugs
Résumé
Herbal drugs have gained significant popularity as alternative medicines among residents in the northern region of Nigeria, capitalizing on the abundant medicinal plants available in the area. This study aimed to investigate the levels of five selected heavy metals (Cd), (Hg), (Ni), (Pb), and (Zn) in five herbal drugs sold in Andaza Town, Kiyawa Local Government Area of Jigawa State. The preparation of the samples was carried out using a wet digestion method with nitric acid (HNO₃) and perchloric acid (HClO₄), and the heavy metals were quantified using an Atomic
Absorption Spectrophotometer (AAS). The health risk assessment (HRA) was performed for both
adults and children using metrics such as estimated daily intake (EDI), target hazard quotient
(THQ), hazard index (HI), and target cancer risk (TCR). On a dry weight (dw) basis, the concentrations of heavy metals were as follows (mean ± SD, mg/kg dw): Cd (0.156-0.312, 0.221
± 0.065), Hg (8.58-16.7, 12.7 ± 3.78), Ni (0.960-2.74, 1.67 ± 0.698), Zn (4.26-10.1, 6.17 ± 2.34),
and Pb (0.876-1.91). Lead was not detected in two out of the five samples, and therefore, the mean ± SD for Pb was not computed. A comparison with the WHO maximum permissible limits revealed that Hg levels were consistently above the recommended limits, while two samples exceeded the Cd limit. However, the concentrations of Ni, Zn, and Pb were within the permissible limits established by WHO. The HRA results indicated that the THQ values for all metals, except Hg, were below 1 for both adults (70 kg body weight) and children (24 kg body weight), suggesting that the metals themselves do not present a significant non-carcinogenic risk. However, Hg had relatively high THQ values for both demographics, potentially posing health risks. The percentage non-carcinogenic risk (NCR) analysis showed that Hg was responsible for more than 95% of the HI, highlighting its dominant role in the overall non-carcinogenic risk. Additionally, the TCR analysis indicated that Pb exposure could lead to a moderate to high cancer risk, whereas Cd poses a high to very high cancer risk if the herbal medicines are consumed over extended periods.In conclusion, it is crucial to monitor and regulate the consumption of these herbal medicines to prevent potential health issues for consumers. Strengthening regulatory frameworks and ensuring safe practices in the cultivation and processing of herbal medicines are essential for safeguarding public health.
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