Chapter 12. Status of soil pollution in sub-Saharan Africa
Knowledge gaps in sub-Saharan Africa
12.7.1. Science gaps
An important gap in the availability of scientific data is the determination of the nature and extent of soil pollution as a result of armed conflicts in sub-Saharan Africa. Despite the region’s history of armed conflicts, no quantitative studies on their impact on soil contamination have been found (Demarest and Langer, 2018). Similarly, even though landmines have been used widely in these conflicts, their impact has not yet been investigated as either point or diffuse sources of soil pollution. Research originating from outside the region has shown that historical explosion of landmines have enriched forest soils in Croatia with cadmium, nickel and zinc (Mesić Kiš et al., 2016). The deliberate detonation of landmines as part of demining programmes has also caused soil contamination by trace metals in Iraq (Hamad, Balzter and Kolo, 2019).
The scientific knowledge gap on this topic is highlighted by the information on the extent of landmine presence in the region. Both Chad and Angola each has more than a 100 square kilometres that are still affected by the presence of landmines (ICBL-CMC, 2019). Eritrea, Ethiopia, Somalia, South Sudan and Zimbabwe each have between 20 and 99 square kilometres affected by landmines. Several other countries of the region have smaller affected areas or have yet to undertake an assessment. Whether the landmines are triggered or detonated through demining actions, they are likely to cause soil contamination.
Although innovative studies provide important insights on the harmful environmental effects of soil contamination, some of them are lacking in detailed characterization of the contaminants present. The drastic reduction in biodiversity as a result of soil contamination by petroleum products in Nigeria was illustrated without the identification of the specific petroleum contaminants or their concentrations (Akande, Ogunkunle and Ajayi, 2018).
A lack of scientific solutions for malaria control under local conditions are currently contributing to soil pollution with DDT. The position statement issued by WHO allows the use of DDT for Indoor Residual Spraying (IRS) against malaria due to the compound’s effectiveness (World Health Organization, 2011). While the importance of malaria eradication cannot be overemphasized, the long-term negative health implications of DDT pollution of soil should not be ignored. IRS has already been linked to soil pollution in South Africa (Van Dyk et al., 2010) and Kenya (Sun et al., 2016). DDT concentrations found in the eggs and meat of chicken in a village that is sprayed to eradicate malaria mosquitoes, are a hundred times that of the allowable limit. This is attributed to the ingestion of polluted soil by chickens as part of their feeding pattern (Bouwman et al., undated). The WHO position statement emphasized that it should only be used until “locally-appropriate and cost-effective alternatives are available” (World Health Organization, 2011). Although progress has been made in identifying alternative strategies to manage malaria, DDT use is still considered an important element in many countries’ strategies.
The information on soil pollution from published literature and academic research tends to be specific to particular sectors and pollutants. These sources do not provide an integrated picture of the situation. Water is considered a scarce resource in Africa and is often managed by dedicated government departments. Soil, on the other hand, is considered to be present everywhere and its governance is distributed between the departments responsible for each economic sector, such as agriculture and mining. Several institutions or regional chapters of international organizations such as the Society of Environmental Toxicology and Chemistry, provide platforms for information sharing on soil pollution in the region. However, each of these address singular aspects of soil pollution such as environmental toxicology or pesticide regulation as opposed to the complex topic in its entirety.
12.7.2. Science to policy gaps
One of the greatest problems of soil pollution is the scarcity of official data and monitoring systems. The data on soil pollution levels comes mostly from scientific research limited to small areas, or from NGO or international agency remediation projects that are, likewise, concentrated in specific areas. This often means that governments are not aware of the risks and do not take the necessary prevention and remediation measures. Examples of cases, where scientific evidence of soil pollution risks has not yet been addressed by appropriate policies, are presented below.
Radon gas occurs naturally in soil and geological formations. It migrates from soil into air with a half-life of 3.8 days (Pule and Speelman, 2016; World Health Organization, 2009). The contribution of radon gas to incidence of lung cancer has been investigated for several decades and it is now known to be the second largest contributor after smoking (World Health Organization, 2009). While radon gas transfers into the atmosphere, it tends to concentrate in cavities such as buildings and underground mining workings. Thus, both mine workers and the general public are at risk of exposure if they work or reside in areas where radon is present. In South Africa, a study report of 2008 identified approximately two thousand houses in Paarl in the Western Cape that had high radon concentrations. The radon was linked to high soil concentrations of radium in soil west of the Berg River (Lindsay, Newman and Speelman, 2008). The recommendation of this study was that building regulations should be adapted to provide guidelines that will make buildings less prone to the accumulation of radon gas.
However, South Africa does not regulate radon exposure (Pule and Speelman, 2016). Two other examples that illustrate the potential for exposure to high levels of radon are:
- the use of abandoned uranium ore stockpiles to build the foundation of a farmhouse in the Beaufort West area; and
- the construction of houses in an area prone to radon gas exposure in the Tshepisong residential area of Soweto.
Environmental and other policies that have been developed subsequent to these cases did not include measures to prevent exposure to radon. There are no regulations that prevent building in areas of high risk or screening procedures for existing residential areas where people are already exposed. The average radon concentrations at both these sites are more than double that of the WHO recommended limit of 100 Bq/m3. In their report, Pule and Speelman (2016) documented these incidences, highlighted that the lack of legal instruments and recommended that radon gas should be included in the South African environmental regulatory framework.
A report on the global status of e-waste management, illustrated that, even though countries in sub-Saharan Africa are increasingly aware of the pollution effect of e-waste, the lack of legislation and policy is still a major issue. In 2017, the only countries to have enacted legislation on e-waste were Ghana, Kenya and Madagascar (Baldé et al., 2017). In 2020, Cameroon, Nigeria, South Africa and Zambia were in the process of drafting legislation to regulate e-waste. The Ministry of Environmental Affairs in South Africa previously indicated that the absence of legislation on e-waste, was one of the key factors that enabled its negative impacts (Department of Environmental Affairs, 2019b).