Determination of natural radionuclides content in some building materials in Nigeria by gamma-ray spectrometry

Evaluation of radiological risk associated with local building materials commonly used in Northwestern Nigeria

In this study, potential radiological risk due to the activity concentrations of primordial radionuclides (²²⁶Ra, ²³²Th, and ⁴⁰K) in commonly used local building materials (sand, clay, kaolin and gypsum) in Northwestern Nigeria were assessed using NaI (Tl) detector. The measured activity concentrations ranged from 47 to 63 Bq kg^-1 for ²²⁶Ra, 24-32 Bq kg^-1 for ²³²Th, and 219-257 Bq kg^-1 for ⁴⁰K respectively. The mean values of ²³²Th, and ⁴⁰K for all samples were below the respective world averages of 45 and 420 Bq kg^-1 with that of ²²⁶Ra for all the samples higher than the world average value of 32 Bq kg^-1. The potential radiological risks were assessed by determining radium equivalent activity (Ra_eq), internal and external hazard indices (H_in and H_ex), absorbed gamma dose rates (D_R), internal annual effective dose rates (IAED), and annual gonadal dose equivalent (AGDE) and activity utilization index (AUI). The assessed parameters were found to range between 104 and 125 Bq kg^-1, 0.99 to 1.15, 0.28 to 0.34, 48 to 58 nGyh^-1, 0.76 to 0.86 mSvy^-1, and 0.78 to 0.96 respectively. The Ra_eq and D_R for all the analyzed samples were found to be within International recommended limits of 370 Bq kg^-1 and 59 nGy h^-1 as recommended by UNSCEAR.

Evaluation of Radiological Health Risks in Popularly Consumed Brands of Sachet Water in Nigeria

Radiological investigation of 35 brands of most popularly used sachet drinking water in Ondo state, Nigeria has been carried out using a spectrometric method for evaluating the concomitant health risks to the members of the public. Activity concentrations of the investigated radionuclides ⁴⁰K, ²²⁶R, and ²²⁸Ra were in the range from 16.35 ± 4.10 to 199.94 ± 38.40 Bq L⁻¹ with an arithmetic mean (AM) of 66.22 ± 54.99 Bq L⁻¹, from 1.35± 0.79 to 17.06 ± 5.13 Bq L⁻¹ with an AM of 6.88 ± 3.66 Bq L⁻¹, and from 1.95 ± 0.08 to 17.22 ± 3.87 Bq L⁻¹ with an AM of 9.49 ± 4.98 Bq L⁻¹, respectively. The determined annual effective doses and the corresponding excess lifetime cancer risks due to ²²⁶Ra and ²²⁸Ra were found to exceed the acceptable limits of 0.1 mSv y⁻¹ and 10⁻³ respectively, as suggested by the World Health Organization (WHO). This implies a non-negligible carcinogenic health hazard due to the intake of the surveyed drinking water, especially for the lactating babies (0–1) y and teenagers (12–17) y. The data from this research may form an invaluable component of radiometric values of the database in Nigeria, as well as the world for setting up guidelines and control policies for the use of sachet water.

DETERMINATION OF NATURAL RADIOACTIVITY AND RADIOLOGICAL HAZARD ASSOCIATED WITH SEDIMENTS SOURCED FROM OGUNPA RIVER CHANNELS, IBADAN, NIGERIA

The natural radionuclides content and radiological assessment of sediments of the Ogunpa waste-water channel were evaluated to ascertain the radiological safety of the sediments as a building material. The mean activity concentrations of 40K, 226Ra and 232Th in Bq kg-1 were found to be 171 ± 69, 11 ± 5 and 10 ± 4, respectively. The overall mean radium equivalent 29 ± 13 Bq kg-1 was <370 Bq kg-1 that can give the maximum recommended dose of 1 mSv to the general public. The activity concentrations of the radionuclides were all less than world average for soils and sediments. Thus, the use of the sediments from the Ogunpa water channel as building material is safe and would not pose any significant radiological health hazards.

Using Geiger Dosimetry EKO-C Device to Detect Ionizing Radiation Emissions from Building Materials

The purpose of the article is to check and assess what radiation is emitted by particular building materials with the passage of time. The analysis was performed with the EKO-C dosimetry device from Polon-Ekolab. The scope of the work included research on sixteen selected construction materials, divided into five groups. The analysis of the results showed that samples such as bricks (first group) and hollow blocks (second group) emit the highest radiation in the tested objects. When comparing these materials, the highest value was recorded when measuring the ceramic block of 15.76 mSv·yr⁻¹. Taking into account the bricks, the highest value of radiation was shown by a full clinker brick, 11.3 mSv·yr⁻¹. Insulation materials and finishing boards are two other groups of building materials that have been measured. They are characterised by a low level of radiation. In the case of materials for thermal insulation, the highest condition was demonstrated by graphite polystyrene of 4.463 mSv·yr⁻¹, while among finishing boards, the highest value of radiation was recorded for the measurement of gypsum board of 3.76 mSv·yr⁻¹. Comparing the obtained test results to the requirements of the Regulation of the Council of Ministers on ionizing radiation dose limits applicable in Poland, it can be noted that the samples examined individually do not pose a radiation risk to humans. When working with all types of samples, the radiation doses are added up. According to the guidelines of the regulation, the total radiation dose does not exceed 50 mSv·yr⁻¹ and does not constitute a threat to human health.

ASSESSMENT OF NATURAL RADIOACTIVITY LEVELS AND RADIOLOGICAL HAZARDS IN BUILDING MATERIALS

Radioactivity of 226Ra, 232Th, and 40K were measured in a total of 92 samples, including eight commonly used types of building materials that were obtained from local manufacturers and suppliers in Beijing. Concentrations were determined using high-purity germanium gamma-ray spectrometry. The 226Ra, 232Th, and 40K activity concentrations in all samples varied from 10.1 to 661, 3.3 to 555 and 3.2 to 2945 Bq per kg with an average of 127.8, 114.8, and 701.5 Bq per kg, respectively. The potential radiological hazards were estimated by calculating the absorbed dose rate (D), radium equivalent activity (Raeq), external hazard (Hex), and internal hazard (Hin) indices. The investigated building materials were classified into different types according to the radioactivity levels. Results from this research will provide a reference for the acquisition, sales, and use of building materials. Attention should be paid to the use of coal cinder brick, ceramic, and granite in the construction of dwellings.

EXHALATION OF RADON FROM NATURALLY OCCURRING RADIOACTIVE MATERIALS (NORM) IN NIGERIA

Radon-222 mass exhalation rate, EM, and surface exhalation rate, EA, have been determined for some building materials and fertilizers in Nigeria by accumulation method using AlphaGUARD radon monitor. The building materials include granite, cement, tile, white marble, brick, concrete and sand. The mean EM of the building materials varied from 0.06 ± 0.03 for white marble to 0.23 ± 0.15 Bq kg-1 h-1 for brick. The mean EA ranged between 1.06 ± 0.56 Bq kg-1 h-1 and 3.15 ± 1.52 Bq m-2 h-1 for white marble and brick, respectively. Most of the EM and EA of the building materials were higher than those of other countries. For the fertilizers, the EM and EA ranged from 0.13 ± 0.01 to 0.42 ± 0.03 Bq kg-1 h-1 and 2.11 ± 0.56 to 4.81 ± 1.24 Bq m-2 h-1 with mean values of 0.25 ± 0.07 Bq kg-1 h-1 and 3.24 ± 0.93 Bq m-2 h-1, respectively. The radon mass and surface exhalation rates of the fertilizers were higher than those of the building materials.

Comparison of Natural Radioactivity of Commonly Used Fertilizer Materials in Egypt and Japan

Specific activities of 238U, 232Th, and 40K in the environment have been redistributed by the use of fertilizers in agriculture so their concentrations in fertilizer materials should be measured to identify the safe utilization of fertilizers. In the present work, the specific activities of these radionuclides in five commonly used fertilizers in Egypt and five fertilizers used in Japan were measured by HPGe and γ-ray spectrometry. The average values of 238U, 232Th, and 40K in Japanese fertilizers were less than their values in Egyptian fertilizers but both had some samples with specific activities greater than the recommended limiting values. The radiological hazards of radium equivalent activity (Raeq), external (Hex) and internal (Hin) indexes, alpha and gamma indexes, and annual effective dose, due to the presence of these radionuclides, were calculated and compared with each other.

Evaluation of radionuclide concentrations and associated radiological hazard indexes in building materials used in Egypt

Radionuclide concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K in different types of building materials used in Egypt were measured using gamma-ray spectroscopy. The results showed relatively moderate radionuclide concentrations for all samples except granite, which showed extremely high concentrations of 78.75 ± 2.36, 2.82 ± 0.11 and 2.37 ± 0.07 kBq kg⁻¹ for ²²⁶Ra, ²³²Th and ⁴⁰K, respectively. The radiological hazard indexes of radium equivalent activity (Raeq), external hazard index (Hex) and internal hazard index (Hin), due to the presence of those radionuclides in the investigated building materials, were calculated. The released radon from the selected samples was measured using the AlphaGUARD radon monitor in order to use its value to calculate the radon emanation coefficient and the radon exhalation rate. The alpha equivalent dose (dose from indoor radon generated from building materials) was calculated using the measured values of the radium concentration and the radon emanation coefficient.

Radioactivity measurement of primordial radionuclides in and dose evaluation from marble and glazed tiles used as covering building materials in Turkey

Measurements of the natural radioactivity arising from primordial radionuclides ((226)Ra, (232)Th and (40)K) in marble and glazed tile samples used covering building materials in Turkey were carried out by gamma-ray spectrometer with a high purity germanium detector. The mean activity concentrations of the (226)Ra, (232)Th and (40)K in marble and glazed tile samples were found as 8.2, 5.5 and 58.1 Bq kg(-1) and 81.2, 65.4 and 450.1 Bq kg(-1), respectively. The radiation doses received by occupants of buildings in which the sample marble and glazed tiles might be used are estimated using measured activity concentrations of constituent primordial radionuclides and dose conversion factors evaluated by the European Commission from models of tile use. Results obtained are presented for each radionuclide, analysed and compared with relevant national and international legislation, guidance and report, and with the results obtained from other studies. Results show that the use of such decorative building materials in the construction of domestic homes or workplaces in Turkey is unlikely to lead to any significant radiation exposure to the occupants.

Radiation hazard assessment in Egyptian painting oxides. A comparative study

Building materials are potential sources of radiation, which represents a risk factor for human disease including cancer. In this work, the natural radioactivity due to the presence of (238)U, (226)Ra, (232)Th and (40)K in different painting oxides has been measured using gamma spectrometry with a Hyper Pure germanium detector. The concentrations of the heavy metals (Cd, Co, Mn, Pb, Ni, Sr, Rb, Cr, Cu and Zn) were determined by atomic absorption spectrometry in order to investigate their possible correlation with radioactive elements. The activity concentrations of (238)U, (226)Ra, (232)Th and (40)K ranged from 15 ± 0.75 to 126 ± 14, 2.35 ± 0.09 to 72.96 ± 1.96, 1.76 ± 0.31 to 12.88 ± 0.7 and 2.26 ± 0.09 to 200 ± 3.34 Bq kg(-1), respectively. The calculated radium-equivalents were lower than values recommended for construction materials (370 Bq kg(-1)). The absorbed dose rates due to the natural radioactivity of the investigated samples ranged from 8.11 ± 0.24 to 68.46 ± 4.20 nGy/h. Also, the results revealed that some heavy metals (Cd, Co, Mn and Rb) were correlated with (238)U, (226)Ra, (232)Th or (40)K.

Radiation exposure levels within timber industries in Calabar, Nigeria

The UNSCEAR (2000) observed that there could be some exposure at work which would require regulatory control but is not really considered. This study was, therefore, set up to evaluate the effective dose in timber industries in Calabar, Nigeria to determine if the evaluated dose levels could lead to any radiological health effect in the workers, and also determine if the industries require regulatory control. The gamma ray exposure at four timber industries measured using an exposure meter were converted to effective dose and compared with the public and occupational values. The evaluated effective dose values in the timber industries were below public and occupational exposure limits and may not necessarily result in any radiological health hazard. Therefore, they may not require regulatory control.