Exposure and Health Risks Posed by Potentially Toxic Elements in Soils of Metal Fabrication Workshops in Mbarara City, Uganda

Eunice Nuwamanya; Denis Byamugisha; Caroline K Nakiguli; Christopher Angiro; Alice V Khanakwa; Timothy Omara; Simon Ocakacon; Patrick Onen; Daniel Omoding; Boniface Opio; Daniel Nimusiima; Emmanuel Ntambi

doi:10.3390/jox14010011

Exposure and Health Risks Posed by Potentially Toxic Elements in Soils of Metal Fabrication Workshops in Mbarara City, Uganda

J Xenobiot. 2024 Jan 30;14(1):176-192. doi: 10.3390/jox14010011.

Authors

Affiliations

¹ Department of Chemistry, Faculty of Science, Mbarara University of Science and Technology, Mbarara P.O. Box 1410, Uganda.
² Centre for Water, Environment and Development, School of Water, Energy and Environment, Cranfield University, Cranfield MK43 0AL, UK.
³ Department of Environmental Health and Disease Prevention, Faculty of Public Health, Lira University, Lira P.O. Box 1035, Uganda.
⁴ Department of Chemistry, College of Natural Sciences, Makerere University, Kampala P.O. Box 7062, Uganda.
⁵ Department of Civil and Environmental Engineering, College of Engineering, Design, Art and Technology, Makerere University, Kampala P.O. Box 7062, Uganda.
⁶ Department of Chemistry, University of Kerala, Thiruvananthapuram 695581, India.
⁷ Department of Chemistry, Faculty of Science, University of Lucknow, Lucknow 226007, India.
⁸ Department of Science and Vocational Education, Lira University, Lira P.O. Box 1035, Uganda.
⁹ Department of Chemistry, Faculty of Science and Technology, Andhra University, Visakhapatnam 530003, India.

Abstract

Metal fabrication workshops (MFWs) are common businesses in Ugandan cities, and especially those producing metallic security gates, window and door frames (burglar-proof), and balcony and staircase rails. The objective of this study was to comparatively assess the pollution levels and potential health risks of manganese (Mn), chromium (Cr), cadmium (Cd), lead (Pd) and nickel (Ni) in pooled surface soil samples from four 5-, 7-, 8-, and 10-year-old MFWs (n = 28) and a control site (n = 8) in Mbarara City, Uganda. The concentration of the potentially toxic elements (PTEs) was determined using inductively coupled plasma-optical emission spectrometry. Contamination, ecological, and human health risk assessment indices and models were used to identify any risks that the PTEs could pose to the pristine environment and humans. Our results showed that PTE pollution of soils is occuring in the MFWs than at the control site. The mean concentrations of the PTEs (mg kg^-1) in the samples were: Mn (2012.75 ± 0.23-3377.14 ± 0.31), Cr (237.55 ± 0.29-424.93 ± 0.31), Cd (0.73 ± 0.13-1.29 ± 0.02), Pb (107.80 ± 0.23-262.01 ± 0.19), and Ni (74.85 ± 0.25-211.37 ± 0.14). These results indicate that the PTEs could plausibly derive from the fabrication activities in these workshops, which is supported by the high values of contamination factors, index of geoaccumulation, and the overall increase in pollution load indices with the number of years of operation of the MFWs. Human health risk assessment showed that there are non-carcinogenic health risks that could be experienced by children who ingest PTEs in the soils from the 7-, 8- and 10-year-old MFWs. The incremental life cancer risk assessment suggested that there are potential cancerous health effects of Cd and Ni that could be experienced in children (who ingest soils from all the four MFWs) and adults (ingesting soils from the 8- and 10-year-old MFWs). This study underscores the need to implement regulatory guidelines on the operation and location of MFWs in Uganda. Further research should be undertaken to investigate the emission of the PTEs during welding operations in the MFWs.

Keywords: average daily doses; carcinogenic risk; hazard index; health risks; metal fabrication workshops; soil pollution; toxic metals.

Grants and funding

The article processing charge for this article was in part supported by Cranfield University through its Institutional Open Access Program (No. 2750397).