A Comparative Analyses of Granulometry, Mineral Composition and Major and Trace Element Concentrations in Soils Commonly Ingested by Humans

Veronica M. Ngole-Jeme and Georges-Ivo E. Ekosse
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Veronica M. Ngole-Jeme: Department of Crop Science, Faculty of Agriculture, Science and Technology, North West University, Private Bag X2046, Mmabatho 2735, South Africa
Georges-Ivo E. Ekosse: Directorate of Research and Innovation, University of Venda, Private Bag X5050, Thohoyandou, Limpopo Province 0950, South Africa

IJERPH, 2015, vol. 12, issue 8, 1-23

Abstract: This study compared the granulometric properties, mineralogical composition and concentrations of major and trace element oxides of commonly ingested soils (geophagic soil) collected from different countries with a view of understanding how varied they may be in these properties and to understand the possible health implications of ingesting them. Soil samples were collected from three different countries (South Africa, Swaziland and Democratic Republic of Congo (DRC)) and their granulometric properties, concentrations of major and trace element oxides as well as mineralogical composition determined. Differences were observed in the granulometric properties of geophagic soil from the three different countries with most of them having <20% clay content. The soils also showed varied degrees of weathering with values of Chemical Index of Alteration (CIA) and Chemical Index of Weathering (CIW) being between 60% and 99.9% respectively. The mineral assemblages of the soils from South Africa and Swaziland were dominated by the primary minerals quartz and feldspar whereas soils from DRC had more of kaolinite, a secondary mineral than primary minerals. Soils from DRC were associated with silt, clay, Al 2 O 3 , and CIA unlike most samples from South Africa which were associated with SiO 2 , sand, K 2 O, CaO, and MgO. The soils from Swaziland were closely associated with silt, H 2 O and Fe 2 O 3 (t). These associations reflect the mineralogy of the samples. These soils are not likely to serve as nutrient supplements because of the low concentrations of the nutrient elements contained. The coarse texture of the samples may also result in dental destruction during mastication. Sieving of the soils before ingestion to remove coarse particles is recommended to reduce the potential health threat associated with the ingestion of coarse-textured soils.

Keywords: geophagia; primary minerals; secondary minerals; chemical index of alteration; specific surface area/volume; Sauter Mean Diameter (search for similar items in EconPapers)
JEL-codes: I I1 I3 Q Q5 (search for similar items in EconPapers)
Date: 2015
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