Assessment of Natural Radioactivity Levels of (226Ra, 232Th, 40K) in Rice Samples Collected from the Provinces of Phatthalung, Surat Thani, Phang Nga, Krabi, Chumphon and Narathiwat
Abstract
This study investigated the concentrations of natural radionuclides—226Ra, 232Th, and 40K—in 10 samples from three rice varieties: fragrant rice, brown rice, and riceberry rice. The samples were collected from the provinces of Phatthalung, Surat-Thani, Phang Nga, Krabi, Chumphon, and Narathiwat. Analysis was performed using a high-purity germanium (HPGe) detector and gamma spectrometry system at the Nuclear Physics Laboratory, Faculty of Science and Technology, Suratthani Rajabhat University. Calibration was conducted with the IAEA RGU-1 standard reference material, and each sample underwent measurement for 18,000 seconds. The results indicated that the specific activity concentrations of the natural radionuclides 226Ra, 232Th, and 40K ranged from 1.48±0.07 to 4.81±0.62 Bq/kg, less than the minimum detectable activity (MDA) by 4.81±1.13 Bq/kg, and 6.85±0.02 to 63.51±0.18 Bq/kg, respectively. The average concentrations were 3.01±0.97 Bq/kg for 226Ra, 2.76±2.06 Bq/kg for 232Th, and 29.46±22.22 Bq/kg for 40K. When assessing the annual effective dose from rice consumption, the total mean value was found to be 84.66±8.24 µSv/y. The annual radiation dose from rice consumption found in this research is below the safety limit established by the United Nations Scientific Committee on the Effects of Atomic Radiation (290 µSv/y; UNSCEAR, 2000). Therefore, it can be concluded that the radiation exposure from consuming rice in this study is within safe limits.
