Abstract
Discovery of new geophagic clayey deposit in the locality of Meka'a contributed to the apparition of new species of geophagic clay materials in the local market. Due to the fact that positive or negative effects of geophagia are conditioned by physico-chemical, mineralogical and geochemical properties of the clay soil ingested, it is therefore necessary to mineralogically and physico-chemically characterize these clayey materials in order to ascertain their health implications. X ray diffractometry (XRD), X ray fluorescence (XRF), particles size distribution, pH and cation exchance capacity (CEC) are the main analyses carried out with these materials. The results show that the clayey materials of Meka’a are extremely weathered and maybe as a result of the weathering of ignimbritic flows. Two main species (yellow and red) of this clay soil are identified on the basis of their colour, mineralogy and physico-chemical characteristic. Analysis of samples of these two types of materials shows that Meka’a clayey materials are mainly made up of kaolinite (64-87%) and goethite (6-25%). These two minerals greatly influence the properties of these materials. Abundance of kaolinite in this clayey mineral assemblage could be of benefit in the protection of gastro intestinal tract resulting from ingestion of soils with high clay content. These clayey soils have a lower CEC and cannot cause cations deficiency in the digestive tract. Their acidic pH makes them suitable for use as remedy for relief of nausea and to curb salivation associated with pregnancy. No dental enamel or gastro-intestinal tract damage was to be feared when ingesting Meka’a clayey soils and their great abundance in Zn could be of benefit to geophagic individuals. However, possibility of Fe supplementation of the clayey soils of Meka’a may be very low considering low ferric hydroxide content and the fact that only a part of Fe present in the clayey soil can be released in the digestive tract.
Highlights
The term geophagia designate the deliberate ingestion of non-food lithospheric substances, notably clay soil [1, 2, 3]
Some clay materials sold in West African markets for medicinal preparation have a similar mineral composition to the clays used in the pharmaceutical KaopectateTM and ingestion of at least certain soils may, provide medicinal benefits similar to commercially produced pharmaceuticals for general gastrointestinal ailments [8]
Despite the risk associated with geophagia, around the world, several differents types of clayey soil with differents colour continues incessantly to be ingested by geophagic practitioners [2, 6, 35, 24]
Summary
The term geophagia designate the deliberate ingestion of non-food lithospheric substances, notably clay soil [1, 2, 3]. Clayey soil have been reported to be medicinal [14, 15, 16, 17] and has been perceived as a mean of supplementing essential mineral nutrients [18, 19, 20]. The discovery in the beginning of this century of a new geophagic clayey deposit in the locality of Meka'a (Cameroon) contributed to the apparition of new species of geophagic clay materials in the local market in addition with the mythical clay varieties of Calabar (Nigeria) and Balengou (Nde Division) [12]. According to references [9, 38] and [45], positive or negative effects of geophagia are conditioned by physico-chemical, mineralogical and geochemical properties of the clay soil ingested. It’s necessary to characterize all geophagic materials in order to ascertain their health implications
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