Characterization Of The Geophagic Materials And Their Overlying Rocks And Soils From Anfoega, Ghana

Abstract

Geophagy is the deliberate consumption of earth and clay deposits by animals, including man. It is a special type of pica, which is defined as the craving and subsequent consumption of non-food substances. This study was conducted to examine the physical, chemical and mineralogical properties of the geophagic materials and their overlying rocks and soils from four sites at Anfoega in order to determine possible relationships among them and the potential human health risk associated with the consumption of the geophagic materials. The four sites were Tokorme 1, Tokorme 2, Tokorme 3 and Wuve. Soil samples and geophagic materials from the selected sites were subjected to the following laboratory analyses: colour, particle size distribution, pH, electrical conductivity, cation exchange capacity, organic carbon content and X-ray defractometry. The rock samples and geophagic materials were also subjected to petrographic and x-ray analysis. Whereas the pH of the soils from Tokorme 1, Tokorme 3 and Wuve ranged from slightly acidic to moderately acidic, that of Tokorme 2 was moderately acidic in the surface soils but strongly acidic in the lower layers. The pH of the geophagic materials was strongly acidic. While the soil samples generally contained high amounts of sand, the geophagic materials contained high amounts of clay. With higher amounts of clay, the CEC of the geophagic materials ranged from 18.0 to 23.2 cmolc kg-1 which was higher than that of the soil samples (5.3 to 22.6 cmolc kg-1). The thin sections of the rocks showed very high amounts of quartz and small amounts of feldspars and sericite. The thin sections of the geophagic materials on the other hand, revealed the presence of large amounts clay and some quartz, feldspars and sericite. The x-ray diffractograms showed that the soils, rocks, and geophagic materials were dominated by SIALIC minerals mainly quartz, kaolinite, muscovite and http://ugspace.ug.edu.gh/ iii feldspar. The mineralogy of the soils indicated that they were derived in-situ from the underlying sandstones. The results also showed that the high amounts of SIALIC minerals in the geophagic materials was accumulated through leaching of the overlying sandstone. The health risk index analysis of the geophagic materials calculated based on consumption of 70 g of clay per day were all less than 1.0. This result indicates that the geophagic materials were safe for human consumption. Also, the microbial analysis of the geophagic materials showed high levels of bacteria load in the processed fresh, processed dry, powdered and smoked samples. However, no coliform group was detected. The microbial results showed that although the geophagic materials were naturally safe for consumption, processing them could introduce harmful micro-organisms.