Natural radionuclides distribution in quarry products from quarries in Osun and Oyo States, Southwestern Nigeria

Granites are one of the major quarry products that are widely used in building materials; thus, it is imperative to investigate their radiological safety with regard to human protection. This study, therefore, determines the concentrations of natural radionuclides of 40K, 238U, and 232Th in quarry products of three different sizes: Stone-Dust (< 2 mm), 3/4-Down (~10 mm) and 3/4-Up (≥ 15 mm), collected from quarries in Osun and Oyo States, Southwestern Nigeria, using the gamma-ray spectrometry technique. The average radioactivity concentrations of 232Th, 238U, and 40K for Stone-Dust samples are 8.92 ± 0.81, 15.70 ± 1.19, and 374.26 ± 12.74 Bq/kg, respectively; 2.78 ± 0.39, 3.99 ± 0.65, and 146.99 ± 2.55 Bq/kg respectively for 3/4-Up samples and 5.68 ± 0.64, 6.61 ± 0.57, and 250.78 ± 4.02 Bq/kg, respectively for 3/4-Down samples. The results of one-way analysis of variance (ANOVA-1) and Scheffe pair-wise comparisons tests showed that there exists a significant difference between the activity concentration of the quarry products (Fcal> Fva) at α = 0.05, but all the analyzed samples have lower activity concentrations when compared with the recommended limits. It can therefore be concluded that the activity concentrations of the radionuclides decrease as the sample size increases and that quarry processes play a significant role in the activity concentrations of quarry products. Thus, adequate ventilation is needed to ensure diffusion of natural radionuclides whenever these quarry products are used as part of building materials