JavaScript is disabled for your browser. Some features of this site may not work without it.
| dc.contributor.supervisor | Eze, Peter N. | |
| dc.contributor.author | Molale, T.L.K. | |
| dc.date.accessioned | 2026-03-16T09:11:33Z | |
| dc.date.available | 2026-03-16T09:11:33Z | |
| dc.date.issued | 2025-08 | |
| dc.identifier.citation | Molale, T.L.K. (2025) Geochemical characterization, potential health risk assessment and indigenous knowledge of geophagic soils of Botswana, Master’s thesis, Botswana International University of Science and Technology: Palapye | en_US |
| dc.identifier.uri | https://repository.biust.ac.bw/handle/123456789/727 | |
| dc.description.abstract | Geophagy, the deliberate consumption of earth materials including soils, has been widely reported across the globe at different periods of human history. Although widely practiced in Botswana, especially among pregnant women and children, the nature and potential human health risks of geophagy is poorly documented. The overarching aim of this research therefore is to characterize geophagic soils of Botswana, assess the potential human health risk of their consumption through multiple pathways and to evaluate consumers’ traditional knowledge of geophagic soils. To achieve the research objectives, a mixed method of both qualitative and quantitative designs was used. The qualitative aspect focuses on evaluating the indigenous knowledge of geophagic soils in Botswana and their health impacts of consuming them while the quantitative aspect focuses on the characterization of these soils including mineralogical and geochemical properties. Using geochemical ratios of the United States Environmental Protection Agency (USEPA), human health risk indices such as carcinogenic risk (CR) and non-carcinogenic risks, hazard quotient (HQ), hazard Index (HI) were computed. The colours of the geophagic soils are dominantly various shades of brown ranging from reddish browns, yellowish browns, dark browns, pale browns and strong browns. The pH (H2O) ranges from 5.3 - 7.8 The electrical conductivity ranges from 43-1423.3 μS/cm. The soil organic matter is below 1.5 % for all the samples. Clay particles content ranges from 203g.kg-1 to 800g.kg-1, silt particles range from 60 g.kg-1 to 320g.kg-1 and sand particles content ranges from 0g.kg-1 to 697 g.kg-1. The clay-sized fractions contained kaolinite, illite, calcite, and muscovite. The essential elements order of concentration with respect to their means is: potassium (K) (14286 ppm) > calcium (Ca) (87723ppm) > magnesium (Mg) (4656 ppm) >phosphorus (P) (150 ppm). The order of mean concentrations for essential trace elements is iron (Fe) > copper (Cu) > chromium (Cr) > nickel (Ni) > zinc (Zn). For toxic elements (TEs), the order of concentration is: lead (Pb) > arsenic (As) > mercury (Hg) > cadmium (Cd) with Pb having a mean concentration of 15.2 mg/kg and As 1.9 mg/kg. The HIs of the potentially toxic elements (PTEs) for all the three exposure pathways are below 1 for both adults and children. Ni, Cr and As have the highest mean CR values which fall within the acceptable range of 1.00E-06 to 1.00E-04 for both adults and children for exposure through oral consumption and dermal contact while the mean CR values for exposure through inhalation are all below 1.00E-06. The most common reason for eating soil was cravings with 48% of the respondents followed by anti-stress effects (27%). Whereas 81% of the respondents reported that consume soil daily while 16% of the reported consuming soil weekly. The results demonstrate a good knowledge of the risks of geophagy by the study population. The most known and reported effect of soil consumption is constipation (46%) followed by worm transmission (39%). Implicitly, exposure to PTEs in the soils is less likely to have health risks, however, caution should be applied since aggregate exposure from other sources could cause a significant increase thereby resulting in negative health effects among practitioners. | en_US |
| dc.language.iso | en | en_US |
| dc.publisher | Botswana International University of Science and Technology | en_US |
| dc.subject | Iron supplements | en_US |
| dc.subject | Termite mounds | en_US |
| dc.subject | Oral ingestion | en_US |
| dc.subject | Potentially toxic elements | en_US |
| dc.subject | Health risk indices | en_US |
| dc.title | Geochemical characterization, potential health risk assessment and indigenous knowledge of geophagic soils of Botswana | en_US |
| dc.description.level | phd | en_US |
| dc.description.accessibility | unrestricted | en_US |
| dc.description.department | ees | en_US |
Files in this item
This item appears in the following Collection(s)
-
Faculty of Engineering and Technology
This collection is made up of electronic theses and dissertations produced by post graduate students from Faculty of Engineering and Technology