Natural radioactivity concentrations of 226Ra, 232Th, and 40K in commercial building materials and their lifetime cancer risk assessment in dwellers

Elevated radioactivity levels of 226Ra, 232Th, and 40K in building materials were measured using gamma-ray spectrometry and their associated lifetime cancer risks were also determined. The mean activity concentrations of 226Ra, 232Th, and 40K are 45.72 § 0.55, 65.90 § 8.89, and 487.32 § 15.20 Bq kg¡1, respectively. Statistically, the principal component (PC) analysis indicates that higher loadings were recorded in Principal Component One (PC1) with large contribution from 232Th and 40K. The leverage studies indicate that BN Ceramics (BNC) contributes more to the loadings in PC1 followed by Golden Crown Ceramic (GCC) sample and GC. The mean values of 0.399 mSv y¡1 for annual effective dose from the samples surpassed the world’s average value of 0.07 mSv y¡1 by a factor of 5.7. The mean gamma index from the measured samples is 0.644, whereas a mean value of 0.271 for alpha index is noted in the samples. The activity utilization index (AUI) from the samples satisfied the AUI <2, which corresponded with the annual effective dose of <0.3 mSv y¡1, except interlock Site 2 and Gomez Spain tiles. Significantly, the mean value of excess lifetime cancer risk of 0.0014 is slightly lower than the world average value of 0.29 £ 10¡3

The Background Dose Assessment of Highly Industrialized Area Used for Building and Construction Purposes in Ogun State, Nigeria

A highly industrialized and mining zone has been mapped to ensure the level of radiation exposure and environmental safety of the dwellers in the buildings within the vicinity. The highest values of238U and 232Th which are 48 ± 11 and 134 ± 9 BqKg-1 were found to be higher than the world average values of 30 and 40 BqKg-1 according to UNSCEAR. The mean value of radium equivalent (Raeq)activity of200.89±22.54BqKg-1lies within the limit of 370 BqKg-1 recommended by UNSCEAR. The meanabsorbed dose rate of 87.85 nGyh-1 is 4 % higher than the average world value according to UNSCAER 2000.The geospatial analysis revealed that the natural radionuclides in the region have a trend, NW-SE trending with significant re-deposition at the Southern part through diffusion which may be attributed the combinations of soil geology of Dahomey (Benin) Basin and human activities. 3D scatter and ribbon plots validates the strong positive correlation between the level of radioactivity distributions which is in the order of magnitudes 40K>232Th>238U in the study area. Significantly, the geospatial analysis of the background gamma dose rate has revealed the hot spot in the area that could pose high risk of contributing to indoor exposure if constructions are built for dweller

Radiation exposure to dwellers due to naturally occurring radionuclides found in selected commercial building materials sold in Nigeria

The activity concentration of 226Ra, 232Th and 40 K was measured in commonly building materials used in Nigeria from commercial supplier using High Purity Germanium Gamma (HPGe) detector. The mean activity concentrations in the samples were found to be 51.5 ± 9.3, 72.46 ± 17.65 and 217.05 ± 44.31 Bqkg-1 for 226Ra, 232Th and 40 K respectively. The highest radium equivalent (Raeq) of 273.9 Bqkg-1 was noted in Perfect Superfix White Cement (Nigeria) but found to be < 370 Bqkg-1 as the recommended dose limiting safe value for bulk media as presumed, the highest value of internal hazard index (Hin) and external hazard index (Hex) of 0.894 and 0.744 respectively were also < 1. The absorbed dose rate (DR) with a value of 122.52 nGyh-1 noted in ceramic tile sample is higher than the weighted population world average value of 80 nGyh-1 by a factor of 1.53. The highest annual effective dose rate (AEDR) of 0.601 mSvy-1 reported in PNT ceramics but was found to be less < 1 mSvy-1 . The investigated materials have the values of Hin, Hex and AEDR greater than 0.5 but less than1, showing that the dose impact exceeds the exemption dose level of 0.3 mSvy-1 for AEDR but complies to the upper limit of dose principle of 1 mSvy-1