Specific activities of natural ( 40 K, 226 Ra, and 232 Th) and anthropogenic ( 137 Cs) radionuclides in 230 surface soil and beach sand samples collected from the densely populated areas of industrial activities in Rayong Province, Thailand, were analyzed. Experimental results were obtained using a high-purity germanium detector and gamma spectrometric analysis system. The frequency distributions of the four radionuclides were investigated and calculated as suitable medium values of all distributions. According to asymmetrical distribution, medium values of the specific activities of all required radionuclides should be median values. Furthermore, the median values of the three natural radionuclides were also used to evaluate absorbed dose rates in the air (D), radium equivalent (Ra eq ), external hazard index (H ex ), annual effective dose rate (AED out ), and excess lifetime cancer risk (ELCR) in the studied areas. The results were compared with data obtained from the annual report of Thailand's Office of Atoms for Peace, the global radioactivity measurements, and the evaluations and recommended values proposed by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). It was found that most of the results were significantly lower than the recommended values of UNSCEAR except for the median value of specific activity of 226 Ra. Moreover, the radioactive contour map for the investigated areas was constructed.
It is well known that Thai people and many other Asian countries consume rice as the main dish. Minor contamination of natural and anthropogenic radionuclides in rice dishes may cause illness, fever or unwell for no apparent reason. For this reason, the research team was interested in the measurement and analysis of the concentrations of natural and anthropogenic radionuclides in 28 samples of organic Sangyod rice from courtesy of rice farmers in the Don Pradu sub-district, Pak Phayun District, Songkhla province. In addition, the research team was also received courtesy of the National Institute of Nuclear Technology (Public Organization) or TINT to use semiconductor detector measuring instruments and gamma spectrometry analysis systems for this research. It was found that the mean specific activity values of 40K, 226Ra, 232Th and 137Cs were 24.11 ± 2.01, 0.28 ± 0.07, 0.17 ± 0.06 and 0.10 ± 0.03 Bq/kg, respectively. The four relevant radiological indices which were gamma-absorbed dose rate (D), radium equivalent activity (Raeq), external hazard index (Hex) and annual external effective dose rate (AEDout), were also calculated and presented. Furthermore, the excess lifetime cancer risk (ELCR(outdoor)) was also evaluated by using the AEDout value from the investigated area. The results of this research were taken to compare with the values measured by the Office of Atoms for Peace (OAP) and research groups that have been measured and analyzed both at home and abroad. In conclusion, the results in this study were found to be lower than the values recommended by some international organizations and is safe for consumers and farmers who produce organic Sang Yod rice in the study area.
Study on assessment of contamination of natural and artificial radionuclides in agricultural products samples are very important to all human being as a consumer. In the present study, we have measured and evaluated the specific activities of natural (40K, 226Ra and 232Th) and anthropogenic (137Cs) radionuclide in rice samples. The 30 rice samples were collected from general and department stores at Songkhla province in the south of Thailand. The high-purity germanium (HPGe) detector and gamma-ray spectrometry analysis system which was set-up in advanced laboratory in Thailand Institute of Nuclear Technology (public Organization) or TINT were employed to perform all of measurements and analysis for this study. The frequency distribution of specific activities of 40K, 226Ra, 232Th and 137Cs for this study were also studied and found to be asymmetrical distribution with the skewness of 1.29, 1.43, 2.32 and 0.82, respectively. For this reason, the median values of specific activities of 40K, 226Ra and 232Th which were 620.04 ± 44.30, 3.73 ±0.54 and 2.44 ±0.54 Bq/kg respectively, should be selected and also used to calculate some related radiological hazard indices in this study. Furthermore, the excess lifetime cancer risk (ELCR) would be also evaluated and presented. Moreover, the results of present study were taken to compare with some data and studies in Thailand and global measurement and calculations. It was found that the outcomes satisfied the standards of UNSCEAR and IAEA.
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