Assessment of human health risks through the consumption of mercury contaminated fish from gold and platinum mining areas

ABSTRACT

Mining activities can pollute freshwater systems with toxic contaminants that can damage the environment and cause risks to human health. In South Africa, mercury is a contaminant of major concern due to it being released into the environment through artisanal gold mining and the coal combustion process at power stations. Mercury accumulates in the liver and more importantly the muscle tissue of fish. Mercury can then be transferred to humans through the consumption of contaminated fish and can affect the nervous system and cause permanent damage. Although South Africa is a major contributor to global mercury emissions, there are very few papers published on mercury concentrations and the risks to human health associated with consuming contaminated fish. This study aimed to determine the mercury concentrations in environmental matrices (water, sediment and two fish species (Cyprinus carpio and Clarias gariepinus)) from five sites and determine the risks to human health associated with the consumption of these fish. The mercury concentrations in muscle and liver tissues of C. carpio (1.2 and 0.8 mg/kg) and C. gariepinus (1.6 and 0.9 mg/kg) from Boskop Dam were the highest across all sites. Clarias gariepinus had higher mercury concentrations and a higher risk to human health compared to C. carpio across all sites. Both species from Boskop Dam and the Vaal River, while C. gariepinus from Olifantsnek and Modder Dam all had a hazard quotient of > 1 which shows these fish had a high possibility for adverse health effects to humans.

KEYWORDS:

• Adverse human health effects
• bioaccumulation
• biomagnification
• Clarias gariepinus
• Cyprinus carpio
• mining pollution

Acknowledgments

We would like to thank the following people and organisations for their assistance and involvement on different levels for the duration of the project. We would like to thank the North-West University (NWU) and the Water Research Group (WRG) for the use of the necessary facilities and equipment needed for the project. We would also like to thank the members of the WRG for all the support and guidance during the study.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/03067319.2023.2290217.

Additional information

Funding

This work is based on the research supported in part by the National Research Foundation (NRF) of South Africa (grant 138544; JH Erasmus). Metal data for the Hex River system formed part of a project that was supported by the NRF (NRF Project GERM160623173784; grant 105875; NJ Smit, PI) and BMBF/PT-DLR (Federal Ministry of Education and Research, Germany, grant 01DG17022; B. Sures, PI). Opinions, findings, conclusions and recommendations expressed in this publication are that of the authors, and the NRF, NWU, and BMBF accepts no liability whatsoever in this regard. E.L. Stevens would like to thank Richards Bay Minerals (RBM) for the opportunity to complete her honours year and this project through their student support bursary. The support from the employees and the funding received was truly appreciated. This is contribution number 835 from the WRG-NWU.