Radiotoxicity risk assessments of ceramic tiles used in Nigeria: The Monte Carlo approach

This work reported the activity concentrations of 40K, 238U, 232Th, radiological impact assessment, the concentration of Cd, Cr, Zn, Cu, Pb, As, Mn, Ni, Co, and human risk assessment of the potentially toxic elements (PTEs) of commonly used tiles in Nigeria. The gamma-ray spectrometry was carried out by means of High Purity Germanium gamma detector, and the whole content of the PTEs in the sampled tiles were analyzed using ICP-MS instrument. The gamma-ray analysis reveals varying results that are higher than their corresponding global values in most cases. Similarly, the analysis of the PTEs reveals concentrations that are in some cases 100 times higher than the recommended limits. Surprisingly, for gamma dose rates, all the tiles (100%) have values greater than the recommended limit of 84.00 nGy/h provided by UNSCEAR. The radiological impact assessment reveals that Nigerians are at high risk of overexposure to indoor ionizing radiation for using these tiles for their building and construction purposes. The P 95% and mean cumulative probabilities from the Monte Carlo Simulation (MCS) indicates that the lifetime cancer risks for most of the sampled tiles exceed the recommended limit of 3.75 × 10−3 by UNSCEA i.e. the P 95% ranges between 5.00 × 10−3 and 20.60 × 10−3, and the mean cumulative probabilities ranges between 2.53 × 10−3 and 11.90 × 10−3. This high risk was confirmed by the MCS, which reveals that inhabitants using NISPRO verified tiles, Goodwill Verified, Virony Glazed, IDDRIS tiles, PNT Verified, and PNT Ceramic tiles are most likely to experience over-exposure to indoor ionizing radiation because even their lowest probable exposure risk, P 5% exceeds the limit recommended by UNSCEAR for indoor exposure. However, the Hazard Index (HI) and the Incremental Lifetime Cancer hazard (ILCR) of the PTEs reveals low cancer and non-cancer risks for all the tiles investigated