Compositional Characteristics of Geophagic Clays in Parts of Southern Nigeria
Earth Science Research
Geophagy is the practice of deliberate consumption of soil and clay deposits by humans, birds and other animals in the wild. It is closely related to pica, a classified eating disorder characterized by abnormal cravings for non-food items. The focus of this work is to determine the compositional characteristics of the geophagic clays consumed around Asaba, Benin, Ibadan and Aramoko-Ekiti areas in southern Nigeria in order to get an insight into the role these clay constituents play in geophagy.
... s play in geophagy. This study includes XRD aided mineralogical determination, chemical analysis of major and trace elements using ICP-MS instrumentation, physical tests including determination of Atterberg limits. Biological parameters such as the bacteriological content and nutritional value were also determined from in situ samples of geophagic clays. X-ray diffraction analysis of ten representative samples collected from these areas show mineralogical composition of predominantly kaolinite with minor palygorskite, nontronite, illite, K-feldspar and halloysite, while the nonclay fraction is mainly quartz.. The relatively high percentage of fine grained kaolinite content in the geophagic clays is similar to that in kaolinite-based western medicines that are marketed for the purpose of alleviating gastrointestinal upsets. This characteristic is also revealed in the chemical analysis of the study samples which show average values of major elements such Si0 2 (50.9%), Al 2 O 3 (25.4%) and Fe 2 O 3 (2.9%); while MgO, P 2 O 5 and Ba are all below 0.5%. The bacteriological analysis shows high total bacteria count of 9.8 x 10 4 -11.4 x 10 4 cfu/gm for the Asaba samples while the Benin and Aramoko-Ekiti samples have an average total bacterial count of 2.1 x 10 4 . Cfu/gm The Ibadan samples have the lowest total bacteria count of 0.2 x 10 4 . cfu/gm. The low total bacteria count of the Ibadan sample may be due to the baking of the sample before consumption as against samples from Asaba, consumed fresh. Staphylococcus aureus and Micrococcus acidiophilus are the two micro-organisms common to all samples. Analysis for nutritional value indicates that geophagic clays have little or no nutritional value for humans. Results of this study show that the rich kaolinite content of these clays could serve as an antacid, while bacteriological and trace element content reveals the harmful effect of these clays on consumers.