Geophagic clay around Uteh-Uzalla near Benin: mineral and trace elements compositions and possible health implications

摘要

Abstract Geophagic clay consumption, which is an age-long cultural practice by humans and animals in many parts of the world, and particularly in Nigeria, may have long time health effects on the consumers. This is particularly so because of the relatively high concentration of harmful minerals and toxic elements. This study sought to determine the mineralogical and trace element compositions of geophagic clay in Uteh-Uzalla area, which is underlain by the Benin Formation of Oligocene to Miocene age, in order to evaluate the potential health risk associated with the consumption of the clay. Sixteen clay samples were collected from mine face profiles of an open pit, analysed for mineral and trace element compositions, using x-ray diffraction technique and ultra-trace inductively coupled plasma mass spectrometry (ICP-MS) methods, respectively. The mean mineral concentration in % includes kaolinite, quartz and smectite (64.88, 19.98, and 9.54), respectively, among other minerals. And the mean concentrations in mg/kg for Cu (15.0), Pb (14.4), Zn (30.9), Co (8.9), Mn (39.4) and Th (10.5) among other elements were found in the clay. From the trace elements results when compared with health risk indices by Agency for Toxic Substances and Diseases Registry (ATSDR): Minimum Risk Level, recommended daily intake and estimated daily intake, it was found that the elements are far above the daily oral intake requirement. Also, considering the relatively low pH (acidic) values that were exhibited by the clays, harmful minerals and elements contained in the clay may be bioavailable in the internal system among those who are frequently involved in the consumption of the clay.