Assessment of Natural Radioactivity and Associated Radiological Hazards in Cement Used as A Building Material in Rajasthan, India

Assessment of natural radioactivity and radiological hazards in building materials used in the Tiruvannamalai District, Tamilnadu, India, using a statistical approach

The naturally occurring 40 K, 232 Th and 238 U radionuclide contents in the soil used as building materials in Ondo West Local Government, Southwest Nigeria were determined using gamma spectrometric technique. The radiological hazards were estimated by employing several indices consisting of radium equivalent (Ra eq ), representative level index (RLI), activity utilization index (AUI), absorbed dose (D), annual effective dose, external hazard index (H ex ), internal hazard index (H in ) and gamma index (Iᵧ). The average activity concentrations of 238 U, 40 K, 232 Th and Ra eq were 171.8, 146.2, 19.8 and 211. 3 Bqkg -1 while the average values of H in , H ex , RLI, D, AED, ELCR, AUI and Iᵧ were, 1.0, 0.6, 0.2, 97.4, 0.5, 3.9 x 10 -3 , 1.8 and 0.7, respectively. The multivariate statistical analysis was employed to identify the relationships between the radionuclides and the estimated radiological hazard parameters. The estimated radiological indices were within the internationally acceptable limits confirming the safe use of these soil for building construction for human dwelling without any radiological implications.

Naturally occurring radioactive materials (NORMs) in building materials can elevate background gamma radiation and pose potential health risks. Establishing baseline radiation levels in historically significant areas is therefore important for both public health and heritage conservation. This study aimed to assess the activity concentration of radionuclides (²²⁶Ra, ²³²Th, and ⁴⁰K) and associated radiological hazards in two historical monuments located in Narnaul, Haryana, India—Jal Mahal and Chor Ghumbad and the survey initiated in April 2024. Samples of building materials such as marble, soapstone, brick, and lime were collected from both sites. Each sample was dried, powdered, homogenized, and sealed prior to analysis. Gamma spectrometry using a NaI(Tl) detector was employed to measure activity concentrations, and radiological indices including radium equivalent activity (Raeq), absorbed dose rate (ADR), annual effective dose (AED), excess lifetime cancer risk (ELCR), activity utilization index (AUI), gamma index (Iγ), and annual gonadal dose equivalent (AGDE) were calculated.The mean activity concentration of NORMs was 518.08 Bq/kg in Jal Mahal and 632.99 Bq/kg in Chor Ghumbad, both higher than the world average of 420 Bq/kg (UNSCEAR). The mean Raeq values were 130.78 Bq/kg and 149.87 Bq/kg for Jal Mahal and Chor Ghumbad, respectively, well below the recommended safety limit of 370 Bq/kg. Similarly, the mean ADR values (60.63 nGy/h and 69.57 nGy/h) were slightly above the global average of 59 nGy/h, while the AED, ELCR, and other indices remained below international safety thresholds. In conclusion, although both monuments exhibit higher NORM activity concentrations than the global average, For some values the radiological risk indices confirm that the sites are not so hazardous. Continuous monitoring is recommended to ensure long-term safety and preservation of these cultural heritage structures.

The activity concentration of Ra, Th and K in brick samples used in Tiruvannamalai District of Tamilnadu has been determined using gamma ray spectrometry. The activity concentration ranges from BDL to 16.02 Bq kg, 17.86 to 120.19 Bq kg, 240.09 to 481.35 Bq kg for Ra, Th, and K, respectively. The concentration of these radionuclides is compared with reported data from other countries. The radium equivalent activity (Raeq), absorbed gamma dose rate (DR), annual effective dose rate (HR), annual gonadal dose equivalent (AGDE), criteria formula (CF), representative level index (RLI), activity utilization index (AUI), gamma index (Iγ), alpha index (Iα), the external hazard (Hex), and internal hazard (Hin) indices are calculated for the measured samples to assess the radiation hazards due to the use of these materials in the construction of dwellings. Multivariate statistical techniques (Pearson correlation, principal component analysis and cluster analysis) are used to study the relation between radionuclides and radiation hazards. The treatment of 14 radioactive variables sampled at 32 bricks by the factor and cluster analyses provided a possible interpretation of the collective data. The spatial distribution pattern of radionuclides has been depicted through the Kriging method using MapInfo software.

The natural radioactivity of 15 ceramic samples imported from Italy, China, and Egypt to the local market of Benghazi city-Libya, was measured by the means of a gamma-ray spectroscopy system with an HPG detector. The activity concentrations of 226Ra, 232Th and 40K were ranged from 75.75 to 85.63 Bq.kg-1, 44.10to 65.20 Bq.kg-1 and 819.52 to 959.27 Bq.kg-1, respectively. The radium equivalent, external hazard index, gamma radiation index, absorbed dose rate, annual effective dose, and cancer risk factor were calculated using the above measurements in order to assess the radiological hazard associated with the studied ceramic samples. The average values of these radiological indices for the ceramic samples were found to be; 232.29 Bq.kg-1, 0.63, 1.71, 107.11 nGy.h-1, 0.13 mSv.y-1 and 0.43, respectively. In general, the average value of radium equivalent for ceramic samples is not exceeded the recommended value of 370 Bq.kg-1, the external hazard index is lower than unity, and for all samples the annual effective dose below the recommended world limits. On the other hand, some radiological hazard indices were reported to be higher than the recommended world limits. The ceramic samples concerned in this study might be recommended to be utilized as building materials for dwelling construction. Keywords: Natural radioactivity; Radiological hazard; Absorbed dose rate; HPGe detector; Ceramic

This study presents an investigation into the natural radioactivity levels of 238U, 232Th, and 40K using a thallium-doped sodium iodide (NaI(TI)) detector and associated radiological hazards in river sediments, specifically sand, which serves as a crucial building material in the KwaZulu-Natal Province of South Africa. The assessment aims to provide insights into potential radiological risks posed by the utilization of these sediments in construction activities. The mean activity concentrations of 238U, 232Th, and 40K are 145.33, 38.67, and 362.67 Bq kg–1, 124.64, 60.60, and 353.00 Bq kg–1, 144.00, 48.80, and 371.00 Bq kg–1, 92.95, 52.00, and 368.75 Bq kg–1, 133.55, 45.60, and 324.40 Bq kg–1, and 109.50, 52.50, 381.50 Bq kg–1 for Umngeni River, Umsunduzi River, Ashburton Sarupen, Hammersdale, Kwanjobekazi, and Cator Ridge, respectively. The obtained values of the radiological hazard indices (radium equivalent activity, external hazard index, internal hazard index, and activity utilization index) were below the world average values reported for building materials. Therefore, the studied samples are radiologically safe for use as building materials in the study area because they may not constitute any severe radiological hazards to residents.

The concentration of natural radionuclides in commonly used building materials collected from Yan'an, China, was determined using gamma ray spectroscopy with a NaI(Tl) detector. The activity concentration of ²²⁶Ra, ²³²Th, and ⁴⁰K in the studied building materials ranges from 9.4-73.1, 11.5-86.9, and 258.9-1,055.1 Bq kg⁻¹, respectively. The concentrations for these natural radionuclides were compared with the reported data of other countries and the world mean values for soil. The radium equivalent activity (Raeq), external hazard index (Hex), internal hazard index (Hin), indoor air absorbed dose rate, and annual effective dose rate due to natural radionuclides in samples were estimated to assess radiological hazards for people living in dwellings made of the studied building materials. The calculated Raeq values of all building materials (75.7-222.1 Bq kg⁻¹) are lower than the limit of 370 Bq kg⁻¹. The values of Hex and Hin are less than unity. The mean values of indoor air absorbed dose rates of all building materials (101.0 ± 14.1-177.0 ± 6.8 nGy h⁻¹) are higher than the world population-weighted average of 84 nGy h⁻¹, while the mean values of annual effective dose range from 0.50 ± 0.07-0.87 ± 0.03 mSv y⁻¹, which are lower than the recommended limit of 1 mSv y⁻¹. It is found that these materials may be used safely as construction materials and do not pose significant radiation hazards to inhabitants.

In this study, the activity concentrations of 226Ra, 232Th and 40K in twenty cement samples of four types (CEM, CEM II, CEM III, and CEM IV) collected from building material suppliers in Senegal were measured using a low-background digital gamma-ray spectrometer equipped with broad energy germanium detector. The activity concentrations of 226Ra, 232Th and 40K varied from 7.1–150.3 Bq kg−1, 3.7–16.1 Bq kg−1, and 48.7–133.9 Bq kg−1, respectively. Also, possible radiological risks from the usage of these materials were assessed by estimating external and internal index, indoor absorbed gamma dose rate and the corresponding annual effective dose, effective dose rate to different body organs and tissus, and excess lifetime cancer risk. The estimated radiological hazard indices were revised in light of the relevant national and international legislation and guidance. The values of the radiological hazard indices were found to be within relevant all limit values for structural building materials.

ABSTRACTThe specific activities of 226Ra, 232Th and 40K of 26 samples of granite produced in Xinjiang of China were measured by a high-purity germanium detector, and their radiological hazards of radium equivalent, external hazard index, internal hazard index, absorbed dose rate, annual effective dose rate, gamma index and alpha index were evaluated. The results indicate that the overall average specific activities of 226Ra, 232Th and 40K obtained in the investigated samples are below the world’s average granite values. The average radium equivalent is within the recommended limit of 370 Bq kg−1. The results obtained further show that the mean values of external hazard index, internal hazard index, absorbed dose rate, annual effective dose rate, gamma index and alpha index are 0.65, 0.77, 111.7 nGy h−1, 0.55 mSv y−1, 0.89 and 0.23, respectively. These mean values established that radiological hazards are also found to be below the international recommended values. The results are compared with granite samples from other countries or China-Taiwan province. It can be noticed that the specific activity values of granite samples produced in China are lower or similar to that of other countries or China-Taiwan province, however there are higher specific activity values for 226Ra and 232Th in individual samples, which need to provide proper radiation monitoring before use considering the long term health effect.

Natural radioactivity measurements and dose rate assessment of selected ceramic and cement types used in Riyadh, Saudi Arabia

Human populations are being exposed to a wide spectrum of radiation from soils as a result of the availability of radiation sources. Assessing the ecological and health effects of radionuclides in soils is crucial to support the optimal soil management practices but large-scale studies are limited. This study compiled data on radionuclides (226Ra, 232Th, 40K, 238U, and 137Cs) in soils located across the world (44 countries and 159 places) between 2008 and 2022 and applied radiological hazards indices and several multivariate statistical approaches. The average activity concentration (Bq/kg) of 226Ra, 232Th, 40K, 238U, and 137Cs were 408.56, 144.80, 508.78, 532.78, and 83.12, respectively, whereas 226Ra, 232Th, 40K, and 238U exceeded the standard limits. The principal component analysis explained more than 91% of variation in soils. Based on the geoaccumulation index, 40K posed moderately to heavy contamination whereas 238U and 226Ra posed moderate contamination in soils. Moreover, the mean values of radiological hazards evaluation such as radium equivalent activity (487.17Bq/kg), external radiation hazard indices (1.32), internal hazard indices (2.15), absorbed dose rate (247.86 nGyh-1), annual effective dose rate (1.82 mSvy-1), activity utilization index (4.54) and excess lifetime cancer risk (63.84 × 10-4) were higher than recommended limit suggesting significant radiological risks in study region soils. The findings indicated that the study area soils were contaminated by radionuclides and unsafe for hazards in terms of the health risks linked with studied radioactive contents. The study is valuable for mapping radioactivity across the globe to determine the level of radioactivity hazards.

The vertical distribution of 226Ra was investigated in soils from the cultivated and undisturbed areas in Rudovci, municipality Lazarevac, Serbia. There were three profiles, each profile divided on four horizons, what gives 12 soil samples. The specific activity of 226Ra in soil and sediment samples was determined by using the gamma-spectrometric method. Analysis of the vertical soil profiles indicated that the activity of 226Ra was not extremely changed with depth. To evaluate the radiological hazards of 226Ra in the samples, the absorbed dose rate, the annual effective dose rate, the radium equivalent activity, and the external hazards index were calculated according to the UNSCEAR 2000 report.

Assessment of natural radioactivity is very important from different points of view, especially for assessment of radiation exposure to human. In the present study, natural radionuclide concentrations of 238U, 232Th, and 40K were measured by gamma spectrometry using HPGe detector in soil samples collected from Southwest coast of Kanyakumari district, Tamil Nadu. The radiological index parameters due to natural radionuclides such as radium equivalent activity, absorbed dose rate, annual effective dose rate, external hazard index, internal hazard index, and gamma index were calculated for the soil samples. All the calculated radiological index values are higher than world average values and the recommended safety limits. Multivariate statistical techniques such as Pearson correlation, principal component analysis, and cluster analysis were applied to know the relation between radionuclides and radiological parameters and to study the spatial distribution of radionuclides.

The Higher and Tethys Himalayan region of NW-Himalaya is less explored from the natural radioactivity mapping assessment, though geologically and tectonically, this region is still active. The concentration of primordial radionuclides (226Ra, 232Th, and 40K) in rock samples of the Manali-Leh Highway region of the Himalayas is determined in the present study using the HPGe detector. The radiological hazard parameters are also estimated in terms of radium equivalent activity (Raeq), annual effective dose (Ein and Eout), hazard indices (Hin, Hex, Hα, and Hγ), and gamma absorbed dose rate. SEM-EDS analysis was used to understand the mineralogical composition of the rocks. The activity concentration of 226Ra, 232Th, and 40K radionuclides varies from 1.4 ± 0.9 to 25.3 ± 1.2, 0.7 ± 0.5 to 59.6 ± 1.6, and BDL (below detection limit) to 830.3 ± 45.7Bqkg-1, with an average value of 13.0 ± 1.0, 21.7 ± 1.0, and 243.7 ± 25.2Bqkg-1, respectively. The average of Raeq in the study region lies within the safe limit of 370Bqkg-1. The hazard indices have values < 1, indicating no radiological hazards to the population from the rocks. The annual effective dose also has values less than the global average value. This study revealed that the rocks of the Higher Himalayan region have a higher concentration of natural radioactivity, while the Tethys Himalayan rocks have lower concentrations of 226Ra, 232Th, and 40K radionuclides. The origin of rocks from different lithologies may be the reason for the natural radioactivity variation. The average concentrations of primordial radionuclides in the region are within the world average indicating that the rocks of the region are safe to be used for different purposes.

A global meta-analysis of radiological contamination in soils and Monte Carlo simulation-oriented hazards evaluation