Environmental Pollution by Heavy Metals in Sub-Saharan Africa

Introduction

The rise in urbanization and industrial revolution for the growing global population has resulted to extensive pollution. Technology advancements in contemporary society have improved the living standards of the global population but consequently, unwanted substances have been released into the environment inducing public health concerns (Anyamwu et al., 2018). The ineffective regulation of the pollutants and their release owing to the anthropic activities has exposed humans to health etiology. Regions such as Sub-Saharan Africa (SSA) have been affected by environmental pollution sourced from the substances including chemicals and heavy metals gravely (Fasinu & Orisakwe, 2013). The toxicity by heavy metals extends to soils, water, animals, plants and humans once the pollutants enter in food chains (Nyika & Dinka, 2022). In SSA region, the situation is likely to worsen since economic growth has taken precedence over environmental conservation. Consequently, environmental pollution has become common in the region. According to Tindwa and Singh (2023), out of 80 world’s most polluted countries, 36 of this total are from SSA region. Some of the countries include South Sudan, Democratic Republic of Congo, Seychelles, Somalia, Zambia, South Africa, Nigeria, Namibia, Sierra Leone, Mauritania, Malawi, Madagascar, Kenya, Lesotho, Ghana, Gabon and Eswatini among others (Nkonya et al., 2016). The region is also the least prepared to deal with pollution among other environmental challenges due to its economic and technological limitations.

Heavy metals exposure occurs via food, air, water, soil (as a result of geophagia) and during occupational exposure. The ecological importance of the pollutants is their toxicity even in minute concentrations, their translocation in food chains and their non-biodegradable nature, which is attributable to their persistence and bioaccumulation in the environment (Oruko et al., 2021). Activities such as industrial processes resulting to emissions and effluents, unscientific handling of solid waste, illegal refining, mining, smelting and foundry all lead to exposure to heavy metals (Ghane et al., 2022; Xu et al., 2022). Once the pollutants are introduced to environmental compartments, they are transferred through food chains to different environmental components increasing the risk of human exposure. Consequently, heavy metals have evolved to be a significant problem in dietary, natural and evolutionary perspectives and their insufficient reclamation and remediation has further exacerbated their unplanned exposure and negative effects to the environment (Jan et al., 2015; Anyamwu et al., 2018).

Public health concerns of heavy metals are affiliated to their ubiquitous nature from both natural and mainly anthropogenic sources. Although global industrialization induces most of the negative health effects of heavy metals, the severity of the outcomes is influenced by individual susceptibility defined by their immunity, age, exposure method and duration, dosage and specific metal one is exposed to (Kinuthia et al., 2020; Oruko et al., 2021). Voluntary or involuntary exposure to the pollutants especially Cd, Hg and Pb has increased due to industrialization and their ubiquity (Kinuthia et al., 2020). In this respect, it is essential to understand the specific sources and occurrence of heavy metals, which varies spatially and temporally. Such information is key in identifying pollution hotspots, assaying trends of pollutant distribution and sources and in planning for remediation and reclamation measures to avert extensive environmental pollution. The current book chapter provides an assessment of the drivers, status and extent of heavy metal exposure in different environmental compartments (soil, air and water) of SSA and with a focus on industrial-sourced pollution to soils of the region.