Assessment of artisan's exposure to heavy metals from tantalite ore mining sites in Oke-Ogun, Oyo State, Nigeria

Abstract

Mining activities cause disequilibrium in the bound states of heavy metals in rocks, soils and mineral ore. These heavy and toxic metals find their ways into the food chain thereby posing health risks along the chain. Furthermore, the work scenarios in mining activities have exposure pathways such as inadvertent ingestion and inhalation of dust and materials from the sites . The dose levels due to heavy metals in tantalite samples from Oke-Ogun, Oyo State have been estimated. Twelve samples of tantalite ore [(Fe, Mn) Ta2O6], were obtained from the mining sites. 500mg of the pulverized samples were pelletized for their elemental analysis using proton Induced X-ray Emission technique. Hazard indices due to exposure to carcinogenic elements in Tantalite were estimated based on United State Environmental Protection Agency (USEPA) dose model. Chromium, Lead and Arsenic are the only carcinogenic elements found in the samples and average concentrations 311.05, 2533.26 and 127.35 ppm respectively and are higher than permissible limit recommended by Abundance elements in average crustal rock (AEACR) (100, 10.1 and 2-0 ppm respectively). The summation of hazard indices values estimated for carcinogenic elements are greater than unity. The estimated Life time average daily dose for the carcinogenic elements is 6.86E-06 mg/kg. The cancer risk estimated for the carcinogenic elements in Komu and Eluku is of the order Cr (1.32E-05) > Pb (5.83E-08). The total risk for these elements is 1.32E-05 and this value is within the permissible limit range of 10-4 - 10-6 recommended by USEPA, 1998.

Keywords

• Artisan
• exposure
• heavy metals