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Physico Chemical Investigations and Health Implications of Geophagial Clays of Edo State, Mid-Western Nigeria

Eigbike CO, Nfor BN and Imasuen IO

Geophagy is the habitual and intentional consumption of earth and clay deposits by animals and humans. This research investigates the physical, chemical and the mineralogical composition of some selected clay samples collected across the three political zones of Edo state, in order to ascertain claims about their effectiveness in curing certain ailments. Among the properties investigated are: texture, pH, Electrical Conductivity (EC), Water Retention Capacity (WRC), Organic Matter Content (OM) and Cation Exchange Capacity (CEC). Results show that the pH values range from 5.22 to 6.46. EC values are generally high but those of OM are low (0.13 to 0.75%). The WRC values are generally very high (above 50%) except for the Auchi-Jattu clay whose value is 42.83.The samples were observed to have low CEC, ranging from 2.76 to 3.07. Results of the AAS analysis show that major and minor elements range from 1.0 mg to the limit of delectability 0.0001mg/g. Results of XRD analysis for mineralogical investigation reveal that the samples are dominantly composed of quartz, kaolinite, halloysite, illite, mica and feldspar. SiO2 values range between 54.85 and 63.1wt%, whereas Al2O3 values range from 12.63 to 26.78%. The present studies have shown that the high clay content and the high water retention capacity may help to alleviate the symptoms of diarrhea because of its absorption ability. The acidity of the soil impacts sour taste on the soil hence its effectiveness in overcoming nausea and excessive salivation. Because of the low CEC of the soils, adsorption of cations from the gastrointestinal tract may not be possible. But from results of available elements, there is tendency for some of the cations to be released and absorbed into the gastrointestinal tract. Possible human health shortcoming in the ingestion of the geophagic clayey soils would include dental enamel damage and perforation of the sigmoid colon.