Health implications of some geophagic clays on growth performance, haemato-biochemical profile and histology of female sprague dawley rats

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Geophagy is the purposeful or 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. The study was conducted to determine the health implications of some geophahic clays on growth performance, biochemical profile and histology of female Sprague dawley rats. Twenty-four female Sprague dawley rats were used for the experiment. They were divided into four groups of six and were housed in metal cages. Each group was weighed before commencement and at the end of the experiment. The powdered clay samples were dissolved in distilled water to form suspensions. Group 1 was used as the control and received 1ml of distilled water and feed ad libitum while test groups received varied doses of 0.1g, 0.3g, and 1.0g representing (0.2ml, 0.6ml and 1ml ) of 40g/1000ml per body weight of the rats. The clay doses were administered once daily for 28 days and the effects on body weigh, organ weight, haematology, histology and serum biochemical parameters were evaluated. X‟ray fluorescence (XRF) results showed that dominant elements in the clay were silicon, aluminum, iron potassium and magnesium oxides. Concentrations of Vanadium, Asernic and Barium in the clay samples was higher than the various RDAs but very negligible. It was also found that lead concentration in clay was 0.03mg (25ppm) higher than the RDA of 0.01ppm. These heavy metals present could be the cause of necrosis and other morphological changes in the histology results. The mineralogical composition of some geophagic clay samples was investigated using X‟ray diffractometry (XRD). The XRD results showed that geophagic clays consisted mainly quartz and kaolinite. With respect to growth performance, the control group gained mean weight of (39.89g), and test groups of 0.1g/kg/b.wt, 0.3g/kg/b.wt and 1.0g/kg/b.wt gained corresponding body weights of 159.75g, 34.86g and -69.96g which were significantly different from control more especially those fed on the highest dose of 1ml of the iv suspension.The values of liver, kidney, stomach, heart, lungs, spleen, ovaries and uterus were not statistically different (P> 0.05) between the controls and test groups. The mean values for Red blood cells (RBC), Haemoglobin (HB), Haematocrit (HCT), Mean corpuscular volume (MCV), Mean corpuscular Haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC) and White Blood Cells (WBC) were statistically similar but mean values of Lymphocytes and Neutrophils were statistically different among the treatment means. The Albumin, Globulin, Protein, ALT, AST, GGT, TBIL and DBIL were not affected by the treatments but ALP and INBIL were significantly influenced by the treatments. Significant differences were not observed for the Cholesterol, Triglycerides, HDL and VLDL levels recorded. Kidney function parameters considered were also not significantly different (P>0.05). Although some clay elements were slightly higher in concentrations than their RDAs this did not affect the biochemical parameters. However, some selected organs subjected to histology studies did show signs of defects which correlates well with the chemical results, hence eating clays which contain negligible anounts of heavy metals could be harmful to human in the long term.
A thesis submitted to the Department of Materials Engineering, College of Engineering in partial fulfillment of the requirements for the degree of MASTERS OF SCIENCE IN ENVIRONMENTAL RESOURCES MANAGEMENT.