Geochemical and mineralogical composition of geophagic materials from Baringo town, Kenyan Rift Valley and their possible health effects on the consumers

Abstract

Consumption of geophagic materials can be detrimental to human health. These materials, which are harvested from the natural environment, can contain high concentrations of potentially harmful elements and minerals. In this study, mineralogical and geochemical investigation of geophagic rock materials consumed by the local population in Baringo town, in Kenya, was conducted to assess its possible health effects. Twelve representative samples were purchased from an open market in Baringo town for this investigation. Optical and scanning electron microscope as well as X-ray diffractometer was used to determine the mineralogy as well as the morphology of the minerals present in the studied samples. The material is composed of about 10 to 20% coarse to very coarse (0.38-3.00 mm) and semi-rounded to angular crystals of quartz, feldspars, and amphiboles, together with lithic fragments occurring in a fine-grained matrix. X-ray fluorescence and inductively coupled plasma mass spectrometry were used to determine the major and trace elements composition, respectively. The analyses show that elements such as Si, Fe, Mn, Al, Hg, Cr, Cd, and Pb are particularly above their recommended daily allowances. This study assumes 100% bioavailability of elements in the geophagic materials, in the absence of a bioaccessibility test. Therefore, the consumption of some of the revealed elements, based on this assumption, can be detrimental due to possible short- and/or long-term health effects. From a mineralogical point of view, the presence of feldspar and quartz with Moh's hardness of 6 and 7, respectively, and their coarse and angular morphology may cause damage to the dental enamel and the gastrointestinal tract. From a geochemical point of view, the high concentrations of the revealed chemical elements can have various health effects including, but not limited to neurotoxic effects, which are critical in prenatal exposure, neurodegenerative diseases, and cancer amongst other serious diseases.

Keywords: Geochemistry; Geophagic rock materials; Health risk; Mineralogy; Potentially toxic elements.