Radiological hazards due to naturally occurring radionuclides in the selected building materials used for the construction of dwellings in four districts of the Punjab Province, Pakistan

STATISTICAL ESTIMATION OF RADIOLOGICAL HAZARDS FROM RADIONUCLIDE CONTENTS IN BUILDING MATERIALS

Thirteen (13) types of building tiles and Sharp sand commonly used for building purposes were collected for their radionuclide contents analysis using gamma ray spectrometry. The average value of the Radium equivalent activity is 208.81 Bq/kg for all samples considered was found to be lower than the recommended safe limit of 370 Bq/kg. Similarly, both external and internal hazard indices (Hex and Hin) were noted to have mean values of 0.57 and 0.73, respectively, which were lower than the recommended safe standard of 1. More so, the average absorbed gamma dose rate was observed to be 94.31 nGy/h, much higher than the recommended safe limit of 59 nGy/h.

An overview of radioactivity measurement studies in Pakistan

In our environment, various naturally occurring radionuclides are present (both underground and overground) in several places, which results in lifelong human exposure. The radiation dose received by human beings from the radiation emitted by these naturally occurring radionuclides is approximately 87%. Exposure to radiation poses radiological health hazards. To assess the human health hazards from radiation, the concentration of these naturally occurring radionuclides are measured in soil (used for cultivation), building materials (soil, bricks, sand, marble, etc.), water and dietary items, worldwide. The available literature revealed that numerous studies related to the subject have been carried out in Pakistan. Most of these studies measured the radioactivity concentrations of primordial [uranium (238U), thorium (232Th), radium (226Ra) and potassium (40K)] and anthropogenic [cesium (137Cs)] radionuclide in soil samples (used for cultivation), fertilizers, building materials (i.e. bricks, rocks, sand, soil, marble, etc.), as well as water and dietary items, using a sodium iodide detector or high purity germanium. An effort was made in 2008 to compile these studies as a review article. However, since then, considerable studies have been undertaken and reported in the literature. Therefore, the main objective of the present article is to provide a countrywide baseline data on radionuclide levels, by overviewing and compiling the relevant studies carried out in Pakistan.

A STUDY OF NATURAL RADIOACTIVITY IN SOME BUILDING MATERIALS IN NIGERIA

Building materials of different brands were assessed for the concentrations of 226Ra, 232Th and 40K using HPGe detector. The activity concentrations in the measured samples ranged from 27 ± 8 to 82 ± 8 Bq kg-1 for 226Ra, 41 ± 4 to 101 ± 8 Bq kg-1 for 232Th and 140 ± 8 to 940 ± 19 Bq kg-1 for 40K, respectively. The Radium equivalent (Raeq) activity from the samples was found to be <370 Bq kg-1 as the recommended value for construction materials. This study will set a baseline data for significant standards on radiation exposure of the measured radionuclides in the selected building materials used in Nigeria.

ASSESSMENT OF RADIATION DOSE AND EXCESSIVE LIFE-TIME CANCER RISK FROM THE BUNAIR GRANITE, NORTHERN PAKISTAN

Natural radioactivity was measured in Bunair Granite using high purity germanium gamma-ray spectrometer and compared to world's granites and building materials to access its suitability for the construction purpose. Average gamma-activities of 226Ra, 232Th and 40K were found to be 52.41, 58.41 and 1130.12 Bq kg-1, respectively. The Indoor and outdoor radiation indices including excessive life-time cancer risk (ELCR) were calculated. The average indoor ELCR was estimated as 3.49 × 10-3. The average outdoor ELCR was assessed as 0.46 × 10-3. As a basic building material Bunair Granite should be on low propriety. For flooring, facing the buildings and as Table tops, in kitchens and other utilities it is safe.

Assessment of Natural Radioactivity Levels and Potential Radiological Risks of Common Building Materials Used in Bangladeshi Dwellings

The concentrations of primordial radionuclides (226Ra, 232Th and 40K) in commonly used building materials (brick, cement and sand), the raw materials of cement and the by-products of coal-fired power plants (fly ash) collected from various manufacturers and suppliers in Bangladesh were determined via gamma-ray spectrometry using an HPGe detector. The results showed that the mean concentrations of 226Ra, 232Th and 40K in all studied samples slightly exceeded the typical world average values of 50 Bq kg(-1), 50 Bq kg(-1) and 500 Bq kg(-1), respectively. The activity concentrations (especially 226Ra) of fly-ash-containing cement in this study were found to be higher than those of fly-ash-free cement. To evaluate the potential radiological risk to individuals associated with these building materials, various radiological hazard indicators were calculated. The radium equivalent activity values for all samples were found to be lower than the recommended limit for building materials of 370 Bq kg(-1), with the exception of the fly ash. For most samples, the values of the alpha index and the radiological hazard (external and internal) indices were found to be within the safe limit of 1. The mean indoor absorbed dose rate was observed to be higher than the population-weighted world average of 84 nGy h(-1), and the corresponding annual effective dose for most samples fell below the recommended upper dose limit of 1 mSv y(-1). For all investigated materials, the values of the gamma index were found to be greater than 0.5 but less than 1, indicating that the gamma dose contribution from the studied building materials exceeds the exemption dose criterion of 0.3 mSv y(-1) but complies with the upper dose principle of 1 mSv y(-1).