Measurement of NORM in Building Materials to Assess Radiological Hazards to Human Health and Develop the Standard Guidelines for Residents in Thailand: Case Study in Sand Samples Collected from Seven Northeastern Thailand Provinces

A total of 223 sand samples collected from seven provinces in Northeastern Thailand were analyzed for their gamma radioactivity from naturally occurring radioactive materials (NORMs), and the data were used to calculate the concentrations of Ra-226, Th-232, and K-40. Radiological safety indicators such as the indoor external dose rates (D-in), the annual indoor effective dose (E-in), the activity concentration index (I), the radium equivalent activity (Ra-eq), the external hazard index (H-ex), the internal haphazard index (H-in), and the excess lifetime cancer risk (ELCR) were calculated. The activity concentrations were found to be 36 +/- 10 Bq/kg for Ra-226, 2.64 +/- 0.58 Bq/kg for Th-232, and 323 +/- 168 Bq/kg for K-40. D-in is 62 +/- 23 nGy/h. The E-in is 0.30 +/- 0.11 mSv/y. The activity concentrations and other indicators were reported by each province and compared with the safety standards and are found to be within the safe limits in this study. The results can be used to develop the standard guideline levels for choosing building materials in Thailand.