Assessment of radiological hazards arising from natural radioactivity in Bayburt stones used in buildings and possible effects on public health

Background – Since ancient times, natural stones have served as essential materials in construction, landscaping, and artistic applications. Bayburt stone is one of the most important stones used in and around Bayburt, in the Eastern Black Sea region of Türkiye. It has been frequently used in buildings (castle, house, etc.), street flooring, fountains, and places of worship from ancient times to the present day. Due to their underground origin, natural stones contain natural radioisotopes in various concentrations, making the assessment of their radioactivity levels important for public health. Objective – This study aims to determine the natural radioactivity levels of Bayburt stones used in buildings and to assess the potential radiological hazards and possible effects on public health. Methods – Natural radioactivity levels (226Ra, 232Th and 40K) were determined in a total of 36 Bayburt stone samples, 30 from five different quarries and 6 from a natural stone factory in Bayburt province. High-purity germanium (HPGe) spectrometry was employed to measure radioactivity concentrations. Additionally, several radiological hazard indices (Raeq, Hin, Iγ, D, AEDE, AGDE, and ELCR) were calculated and compared with reference limits proposed by international organizations. Results – The radioactivity concentrations in the Bayburt stone samples ranged from 1.56 to 23.54 Bq/kg for 226Ra, from 0.53 to 23.69 Bq/kg for 232Th, and from 10.31 to 505.35 Bq/kg for 40K. The average activity concentrations were found to be 5.56 ± 0.90 Bq/kg for 226Ra, 4.62 ± 0.65 Bq/kg for 232Th, and 179.12 ± 9.88 Bq/kg for 40K. The average values of Raeq, Hin, Iγ, D, AEDE, AGDE, and ELCR were found to be 18.68 Bq/kg, 0.07, 0.14, 8.91 nGy/h, 43, 72 μSv/y, 63.06 μSv/y, and 17.07 × 10−5, respectively. All calculated radiological hazard indices were below the recommended safety limits. Conclusion – The findings indicate that the Bayburt stone samples investigated are suitable for construction purposes and do not pose significant radiological hazards to human health when used in building environments.