In parallel with sub-Saharan Africa’s rapid population growth, the estimated number of people living on less than USD 1.90/day has almost doubled between 1990 (278 million people) and 2015 (416 million people) (World Bank, 2019b). Such poverty tends to make people turn to the land either to produce their own food through subsistence or small-scale farming or for foraging wild vegetables, herbs and fruit. In a similar fashion, artisanal miners are exposed to soil contaminants while working on abandoned mine dumps. However, these people are seldom aware of the health risks associated with soil pollution of these areas.
In South Africa, vegetable gardens at schools took off as an initiative to relieve food insecurity and nutrient deficiencies amongst school children. Unfortunately, elevated levels of lead, mercury and arsenic were detected in produce from gardens that were located in close proximity to gold-mine tailings. Analysis of soil samples taken from these gardens indicated high concentrations of arsenic, lead and mercury (Kootbodien et al., 2012). Even the garden soil in four neighbourhoods in Johannesburg, South Africa, may pose harm to the health of the citizens living there (Mathee et al., 2018). Analysis of soil from the four neighbourhoods indicated extensive arsenic and lead contamination. In one neighbourhood, the high concentration of lead in soil correlates with the level of lead in the blood of children in their first school year (Mathee et al., 2018).
Unable to afford commercial fertilizer, some small-scale farmers perceive waste dump areas as fertile soil with high organic carbon content and have cultivated crops there (Yabe, Ishizuka and Umemura, 2010). A case study on the correlation between trace element content of waste dump soil and bioaccumulation indicated that the vegetables produced there, contain much higher levels cadmium and lead than that recommended by WHO/FAO guidelines of 1989 (Odai et al., 2008). Manure and sewage sludge are widely applied as a source of fertilizer. While the soil contamination risks of this practice have been identified, many small-scale farmers remain unaware and continue to use such materials.
The artisanal extraction of metals from e-waste can have far-reaching health implications. The methods used to retrieve the metals from the electronics, expose the workers, and the surrounding population and environment to contaminants. Faced with the lack of other economic opportunities, the e-waste workers will continue to scavenge waste dumps in search of discarded electronic equipment.
At its inception the Basel Convention was criticized by leaders of the region as the creation of a legal instrument that regulated shipment of waste to poor, underdeveloped countries rather than preventing it. This concern led to the development of the Bamako Convention (Ovink, 1995). The Bamako Convention aimed to provide stronger protection to the region by banning importation of hazardous waste for both recycling and disposal. Unfortunately countries were slow to ratify and translate the Convention into national legislation (Agbor, 2016).
Several publications have identified that, although e-waste processing at the Agbogbloshie site in Ghana has serious human health and environmental impacts, it is a source of income to many people (Cao et al., 2020), which lead to minor interventions by the Accra’s municipal authority to address the issue (Daum, Stoler and Grant, 2017). For example, after a previous flood resulted in 200 fatalities in the Korle Lagoon, experts indicated that land within 100 m of the riverbank should be cleared to improve water flow during floods. This included informal housing structures cleared with bulldozers. However, the Accra Metropolitan Assembly decided to reduce the clearance zone to maintain intact the e-waste dumps within the 100 m clearance zone. This was seen as an attempt by the authorities to avoid retaliation by the e-waste processors in the area (Daum, Stoler and Grant, 2017).
Concern about the health impacts of exposure to asbestos has led to the closure of all asbestos mines in South Africa. In 2020, the country was in the process of addressing the asbestos problems through management approaches such as eviction of residents from areas polluted with asbestos. In sharp contrast, contemporaneously Zimbabwe was in the process of reopening their asbestos mines (McCormack and Schüz, 2012).
Analytical capacity for some contaminants, especially the emerging contaminants, is only available in one country in the region, South Africa. The only other option is to send samples to laboratories outside the region. This is problematic as the cost of exporting samples is high and the process of obtaining export permits and special permissions for soil samples is complex. The region only has a limited number of laboratories that have the capacity to analyse samples for a wide range of contaminants. The majority of the laboratories in the region are restricted to analyses for elements and trace elements. This leads to either inconclusive results or otherwise complicated and costly logistical arrangements to split samples for dispatch to multiple laboratories.
While the Bamako Convention is clear on the prohibition of hazardous waste trade and transport across country boundaries, it leaves a gap on waste management technologies. The development and implementation of these technologies are further limited by the financial constraints experienced by most countries in the region (Agbor, 2016).
The lack of regional analytical capacity and high cost of analysis abroad are major barriers to building a comprehensive understanding of soil pollution in sub-Saharan Africa. Mining and industrial companies are sometimes directed by government departments to conduct routine soil analysis as part of their environmental monitoring. Unfortunately the high cost of soil sample analysis can be a driver to minimize number of samples to be analysed. The cost of soil analysis is often unaffordable for individuals concerned about the possible health risk posed by their soil.