Mineralogy and geochemical characterization of geophagic clays consumed in parts of southern Nigeria

Abstract

This study seeks to determine health risk associated with consumption of clay in different areas in southern Nigeria. Different clay samples sold for consumption were purchased from Mowe, Ikorodu and Onitsha Markets in southern Nigeria. The clays were subjected to mineralogical and geochemical characterization using X-Ray Diffractometry (XRD), Fourier Transform Infrared (FTIR) and Inductively Coupled Plasma-Atomic EmissionSpectrometry. Potential health risk assessment was calculated using a standardized Hazard Quotient (HQ) and Total Hazard Index (THI). XRD and FTIR results revealed the clay contains varying percentage of quartz, kaolinite, anatase, halite, pyrite, goethite, smectite and palygorskite while geochemical analysis result revealed wide range of elemental concentration (ppm). Mean concentration (ppm) of Cu, Pb, Zn, Cr, Ni and Co from the markets are 5.8 – 8; 17.4 – 29.6; 32.4 – 95.8;111.6 – 103.4; 18.6 – 39.4 and 4 – 16.6 respectively while As was below detection limit in most of the samples. HQ values were used to calculate the THI. THI values for children and adults for Mowe market samples range from 0.9 to 2.1 and 0.5–1.1 respectively, for Ikorodu market samples, THI for children and adult ranges from 1.0- 1.8 and 0.6–1.0 respectively, while THI for children and adults for Onitsha market samples ranges from 1.5 to 2.6 and 0.8–1.84 respectively. In conclusion, children that consume clay from the markets are more exposed to non-carcinogenic risks than adults. It is therefore advisable that the clays should not be consumed for a long period of time to avoid health problems.