Health Risk Assessment of Exposure to Heavy Metals in Soils Near Mine Dumps

Abstract

Introduction Heavy metals present a significant global threat, and South Africa's mining industry exacerbates this issue due to its considerable contribution to environmental pollution. Toxic heavy metals such as Lead, Arsenic, Chromium, mercury, and Cadmium are not only hazardous but also carcinogenic when inhaled or ingested. This highlights the urgent need to assess the levels of specific heavy metals in soils near mine dumps and to quantify the associated health risks for children aged 1 to 12 years in Kagiso, West Rand. The study aimed to evaluate the risk of heavy metal exposure among children within this age group living in Kagiso, a township located in South Africa's West Rand District. Method A cross-sectional study was carried out in Kagiso involving the collection of 14 soil samples in a zigzag pattern to reduce variability. These samples were analysed at an independent and SANS 17025-accredited laboratory, ensuring the objectivity of the results. The data analysis utilized the Kruskal-Wallis and Wilcoxon rank-sum tests, both non-parametric methods. The main variables examined included concentrations of heavy metals and their respective collection sites. For this study, the researcher employed Stata 18.0. And a health risk assessment was conducted using the framework for Health Risk Assessment developed by the United States Environmental Protection Agency. Results The study revealed soil contamination, with variations in heavy metal concentration across collection sites. Cadmium (Cd), Chromium (Cr), and Nickel (Ni) were found in higher concentrations at the community site, soccer fields, excavation land and clinics, compared to the tailing dam. Chromium (Cr) levels exceeded South African and international reference values in all locations, and lifetime cancer risk from Cr exposure (1.04 E-05 to 1.93 E-05) was above the US-EPA reference threshold. In addition, worst-case scenarios indicate significant risks from heavy metals (As, Ni and Cr) for young children. For those under 2 years, Chromium exposure was 2.35 E-05, and Nickel exposure is 1.36 E-05. For children aged 2 to 6, Arsenic exposure is 1.4 E-05, Chromium is 3.64 E-05, and Nickel is 2.10 E-05. v Conclusion Heavy metal stressors, including As, Cd, Cr, Ni, and Pb, possibly originating from tailing dam facilities, cause soil contamination and pose significant health risks, particularly cancer due to Cr exposure, in children in Kagiso. However, no correlation was found between Cd, Cr, Ni, and Pb concentrations and distance from the tailing dam sites except for As that showed distance-related patterns. These findings highlight the need for further research and interventions to reduce these health risks.