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Estimation of natural radioactivity in local and imported polished granite used as building materials in Saudi Arabia
Journal of Radiation Research and Applied Sciences xxx (2017) 1e5
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Estimation of natural radioactivity in local and imported polished granite used as building materials in Saudi Arabia J.H. Al-Zahrani Physics Department, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
a r t i c l e i n f o
a b s t r a c t
Article history: Received 18 April 2017 Received in revised form 3 May 2017 Accepted 3 May 2017 Available online xxx
Measurements of natural radioactivity in local and imported samples of commercial granites used in Saudi Arabia were carried out by using gamma-ray spectroscopy with hyper-pure germanium detector. The activity concentrations measured of granite samples were determined for 226Ra(from 1.53 to 77.16 Bq kg1), 232Th (from 0.51 to 89.82 Bq kg1) and 40K (from 19.47 to 1632.37 Bq kg1). The corresponding average activity concentrations for 226Ra,232Th and 40K were 28.82, 34.83 and 665.08 Bq kg1, respectively. The radiological hazard parameters (radium equivalent, gamma index, external index, internal index, absorbed dose and annual effective dose) were calculated to assess the radiation hazards associated with granite samples. The obtained results are lower than the recommended limits. The results were compared with the published data of other countries. The measurements will help in the development of standards and guidelines for the use and management of these materials. © 2017 The Egyptian Society of Radiation Sciences and Applications. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/ by-nc-nd/4.0/).
Keywords: Natural activity Gamma spectroscopy Building material Granite Effective dose Radium equivalent activity
1. Introduction Granite is a form of igneous rocks, consists mainly of quartz, mica, and feldspar, used for interior and exterior decorative as building and ornamental materials, these rocks, due to their composition contains some radionuclides. The radionuclides of 238 U and 232Th radioactive series are the sources of both external and internal exposures in building materials. Gamma-rays cause the external exposure from radionuclides of 238U and 232Th radioactive series and 40 K, while alpha particles mainly cause the internal exposure due to inhalation of radon and the short-lived products of the above radioactive series, which are deposited in the respiratory tract tissues (Ahmad, Jaafar, Bakhash & Rahim, 2015; Papadopoulos et al., 2013). Thus, the study of the natural radioactivity and the radon emissions from the granite materials is an essential subject to radiological environmental protection because it facilitates the possibility to assess any related health risk. Several studies refer to natural radioactivity levels along with radiation risks of polished granite which are both used as decorative building material, as: (Llope, 2011; Mittal, Guin, Sharma, & Sengupta, 2013;
E-mail address: [email protected]. Peer review under responsibility of The Egyptian Society of Radiation Sciences and Applications.
Hameed, Pillai, Satheeshkumar, & Mathiyarasu, 2014; Asaduzzaman, Khandaker, Amin, & Bradley, 2016). In Saudi Arabia, local and imported Polished Granites are used as building materials, decorating and expensive materials due to its hard, tough, elegant look and different colors. Therefore, it is important to measure the concentration of radionuclides in granite used in building materials, where the inhabitants spend about 80% of their time indoors. As a result, the objectives of this study are: 1) To determine the specific radioactivity concentrations of 238U, 232Th, and 40K in local and imported granites used as building materials in Saudi Arabia. 2) To assess the possible radiological risks to human health and compare the results with the recommended limits of UNSCEAR data. 2. Material and methods In this study, a total of 24 polished granite samples, local (11 samples) and imported (13 samples) are the most used as a decorative inner cover on walls and floors were collected from several commercial companies, construction sites and local suppliers in Saudi Arabia. The collected samples were crushed and milled to a fine powder, homogenized, oven dried at 110 C for 6 h, and then each sample packed in a cylindrical 1000-ml plastic Marinelli beaker, sealed for one month to achieve secular equilibrium between 226Ra and 232Th with their decay products (Ahmad, Jaafar, &
http://dx.doi.org/10.1016/j.jrras.2017.05.001 1687-8507/© 2017 The Egyptian Society of Radiation Sciences and Applications. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Please cite this article in press as: Al-Zahrani, J. H., Estimation of natural radioactivity in local and imported polished granite used as building materials in Saudi Arabia, Journal of Radiation Research and Applied Sciences (2017), http://dx.doi.org/10.1016/j.jrras.2017.05.001
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J.H. Al-Zahrani / Journal of Radiation Research and Applied Sciences xxx (2017) 1e5
Alsaffar, 2015). The activity concentrations of 226Ra,232Th and 40K for all homogenized and equilibrium samples were measured by a gamma ray spectrometry by using High purity Germanium (HPGe) detector (25% relative efficiency) with coaxial-type vertical dipstick cryostat. It is surrounded by lead and copper, which provides an efficient suppression of background gamma radiation present at the laboratory. The system has a resolution (FWHM) of (3.0e3.5 keV) for 1332.5 keV gamma-ray peak of 60Co and a peak to a Compton ratio of 41:1., and it was given high voltage through preamplifier which was then connected to amplifier to computer based Multi channel analyzer through ADC (analogue to digital converter). The spectra were analyzed by commercially available software GE- NIE-2000 obtained from Canberra, USA. For gammaray measurements, each prepared granite sample was placed directly over the detector and counted for a 36000sec period. Additionally, under the same conditions as for the samples, the background distribution in the environment around the detector was determined. The 226Ra specific activities were estimated from 214 Bi (609.3 keV) and 214Pb (295.2 and 352.0 keV), whereas, for 232 Th the specific activities of 228Ac (911.1 keV), 212Pb (583.1 keV) and 208Tl (238.6 keV) were used. The specific activity of 40K was determined directly from its gamma emission at 1460.83 keV (Ahmad, Jaafar, & Alsaffar, 2015). Table 1 presents the code number, origins, colors of the local and imported granite samples used in Saudi Arabia buildings (see Table 1). The activity concentrations of 238U, 232Th series, and 40K were calculated using the following equation:
A
Bq kg 1
from the three nuclides 226Ra, 232Th and 40K in the building materials, can be defined in units of nGyh1 using the formula proposed by (Asaduzzaman et al., 2016; UNSCEAR, 2000):
D
nGy h1 ¼ 0:0417 Ak þ 0:462 ARa þ 0:604 ATh
(6)
where ARa, ATh, and AK are the defining activities of 226Ra, 232Th, and 40K in Bqkg1 and their corresponding dose conversion factors. By using the standard room model with dimensions of 4 m 5 m 2.8 m, the average world value of the absorbed dose rate is 55 nGyh1 (Ahmad, Jaafar, & Alsaffar, 2015). The annual effective dose is calculated by applying the dose conversion factor of 0.7 SvGy1 with 0.8 as an indoor occupancy factor (Jibiri, Isinkaye, Bello, & Olaniyi, 2016; UNSCEAR, 2000):
Deff ðmSv=yÞ ¼ D nGyh1 ð0:7Sv=Gy 8760h=year 0:8Þ 106 (7) where, Deff ¼ 0.39 mSvy1 as the annual effective dose indoor for individuals, the recommended upper limit is one mSvy1 (ICRP, 1990), 8766 h is the number of hours in 1 year.
3. Results and discussions 3.1. Activity concentration
¼ N=ε bM
(1)
where: N is the net gamma counting rate (counts per second), ε is the detector efficiency of the specific geray, b is the absolute transition probability of Gammaedecay and M is the mass of the sample (kg). The radium equivalent activity (Req) is given as (Beretka & Mathew, 1985; UNSCEAR, 2000):
Req ¼ ARa þ 1:43ATh þ 0:077AK
(2)
where ARa, ATh and AK are the specific activities of 226Ra, 232Th and 40 K in Bqkg1, respectively. The estimated values of 1 Bqkg1 of 226 Ra, 0.7Bqkg1 of 232Th and 13Bqkg-1of 40K produce the same gamma-ray dose]. For safe use, the maximum value of Raeq in building materials must be less than 370 Bqkg1 to keep the external dose below 1.5 mSv.y1 (UNSCEAR, 2000). Representative level index (Ir) is used to estimate the standard of gamma radiation hazard associated with the natural radionuclides in specific building materials. It is calculated using the following formula (Asaduzzaman et al., 2016; UNSCEAR, 2000):
Ir ¼ CRa =300 þ CTh =200 þ CK =3000 1
(3)
where CRa, Seth and CK (in Bq/kg) are the concentration of 226Ra, 232 Th, and 40K, respectively. These two hazard indices were used to measure the external and internal hazards due to the emitted gamma radiation. For safe use of material in the construction of dwellings, Hex and Hin should be less than unity and can be defined as (Beretka & Mathew, 1985; UNSCEAR, 2000):
Hex ¼ ARa=370 þ ATh=259 þ AK=4810 1
(4)
Hin ¼ ARa=185 þ ATh=259 þ Ak=4810 1
(5)
The absorbed dose rate in the air is due to gamma-ray emission
Table 1 summarized the obtained activity concentrations of Ra, 232Th and 40K for the measured granite samples together with their corresponding total uncertainties. 226 Ra range varies from 1.53 Bqkg1 to 77.16 Bqkg1; 232Th varies from 0.51 Bqkg1 to 89.82Bqkg1. In most samples, 40K represents the highest radioactivity concentration; it varies from 19.47 Bqkg1 to 1632.37 Bqkg1. From all the samples measured in this study, the Iranian white sample(G1) presents the lowest activity concentrations for 226 Ra and 40K, whereas, the Indian green sample (G11) presents the lowest activity value for 232Th. The range activity concentrations of 226 Ra, 232Th and 40K were less than the typical ranges of activity concentration in building materials reported by (UNSCEAR, 2008) as 100e500 and 40e350 and 1200e1800 Bq kg1, respectively. As shown in Table 1, the radioactivity in granite samples varied from one sample to another; this depends on the nature of the region from which samples were collected (Harb, El-Kamel, El-Mageed, Abbady, & Rashed, 2014). The average values for all the three nuclides 226Ra, 232Th, and 40K were 28.82, 34.83 and 665.08Bqkg-1, respectively. 226Ra and 232Th values are lower than the world average value 50 Bq kg1 for building materials of 226Ra, 232Th, whereas, 40K is higher than the world average value 500 Bqkg1 (UNSCEAR, 2008). Fig. 1 shows the activity concentration of 226 Ra,232Th, and 40K in the present granite samples. Any granite rock could contain naturally occurring radioactive elements such as radium, thorium, and potassium. Some granite contains more of these items than others, depending on the chemical composition and the formation of the molten rock. Geologists provide an explanation of this behavior in the course of partial melting and fractional crystallization of magma, which enables U and Th to be concentrated in the liquid phase and become incorporated into the more silica-rich products. For that reason, igneous rocks of the granite composition are strongly enriched in U and Th with different concentrations (US-EPA, 1993). Table 1, showed that samples with dark colors (G: 4,6,7,14,19,24) for Ra and (G: 4,5,6,7,14,17,19,20,22,23,24) had high values of radiation. The 226Ra, 232 Th and 40K average concentrations of selected granite samples in 226
Please cite this article in press as: Al-Zahrani, J. H., Estimation of natural radioactivity in local and imported polished granite used as building materials in Saudi Arabia, Journal of Radiation Research and Applied Sciences (2017), http://dx.doi.org/10.1016/j.jrras.2017.05.001
J.H. Al-Zahrani / Journal of Radiation Research and Applied Sciences xxx (2017) 1e5 Table 1 226 Ra, 232Th and
40
3
K activity concentrations of the granite samples are used as the interior building materials in Saudi Arabia.
Sample code
Origin
Activity concentrations (Bqkg1)
Color
226
232
1.54 ± 0.4 3.17 ± 0.5 3.13 ± 0.86 77.16 ± 3.8 45.99 ± 4.1 72.94 ± 5.7 64.95 ± 8.5 7.89 ± 08 2.31 ± 0.5 1.53 ± 0.4 7.73 ± 1.8 3.71 ± 0.5 1.99 ± 0.9 54.87 ± 7.67 4.70 ± 1.3 9.95 ± 1.7 37.23 ± 4.9 15.18 ± 1.8 55.13 ± 6.9 43.36 ± 3.5 32.91 ± 3.1 45.76 ± 2.8 42.82 ± 3.4 55.63 ± 5.1 1.53e77.16 28.82 50
1.11 ± 0.3 0,85 ± 0,2 1.14 ± 0.4 77.82 ± 4.7 66.64 ± 1.9 61.53 ± 2.9 77.31 ± 2.5 3.77 ± 0.6 0.55 ± 0.1 L.D.L 1.18 ± 0.01 6.05 ± 0.7 0.51 ± 0.1 71.43 ± 3.33 2.32 ± 0.4 4.34 ± 0.9 53.77 ± 2.7 26.50 ± 1.7 73.26 ± 3.5 54.86 ± 5.5 43.83 ± 3.9 84.76 ± 3.9 63.63 ± 2.7 89.82 ± 4.6 0.51e89.82 34.83 50
Ra
G1 G2 G3 G4 G5 G6 G7 G8 G9 G10 G11 G12 G13 G14 G15 G16 G17 G18 G19 G20 G21 G22 G23 G24 Range Average UNSCEAEAR 2008
Iran Italy Egypt China China China Pakistan Pakistan Iran Italy India Italy Boringly Saudi Arabia Saudi Arabia Saudi Arabia Saudi Arabia Saudi Arabia Saudi Arabia Saudi Arabia Saudi Arabia Saudi Arabia Saudi Arabia Saudi Arabia
Fig. 1. The activity concentration of
White White White Brown with black Gray Black with red Ruby red color Brown Light color red White with gray Green Black Rosa Black with red Light Brown Fine Gray Gray Red Black Red with black Gray with black Gray with red Black with white Black eRed eGray
226
Ra,232Th, and
40
Th
40
K
19.47 ± 0.6 28.85 ± 0.6 33.17 ± 1.1 1152.30 ± 16.5 1130.73 ± 13.3 1114.4 ± 9.1 1272.98 ± 12.6 30.29 ± 0.9 L.D.L L.D.L L.D.L 21.63 ± 0.7 L.D.L 1632.37 ± 18.49 L.D.L L.D.L 824.25 ± 10.1 1437.66 ± 16.7 1469.46 ± 13.6 1281.83 ± 18.4 1196.08 ± 18.7 1157.41 ± 13.7 1123.57 ± 13.7 1035.85 ± 17.6 19.47e1632.37 665.08 500
K in the present granite samples used in Saudi Arabia as decorative materials.
this work are compared with the results from different countries of the world and the recommended values as given in Table 2. The Table shows that the average activity concentration values obtained in this work of 226Ra are comparable with those obtained in India and lower than the others while that average value obtained for 232 Th in all other countries are higher than the value gained in this work. The average present value of 40K activity concentration is lower than the obtained values in all countries, except India. As shown in this Table, the radioactivity in granite samples varied from one country to another, depend upon their geological conditions (UNSCEAR, 2008).
3.2. Radiation hazards The values of the hazard parameters in comparison with the world average are presented in Table 3. The results show that: 1- The highest value (277.17Bq/kg) of Req for all granite samples was observed in Chinese Granite (G4), while the lowest value (1.53 Bq/kg) was found in Italian granite (G10). It is apparent that there are significant variations in the Req values of the granite samples. This verity is essential in selecting the best granite samples for use in interior decoration in the homes.
Please cite this article in press as: Al-Zahrani, J. H., Estimation of natural radioactivity in local and imported polished granite used as building materials in Saudi Arabia, Journal of Radiation Research and Applied Sciences (2017), http://dx.doi.org/10.1016/j.jrras.2017.05.001
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J.H. Al-Zahrani / Journal of Radiation Research and Applied Sciences xxx (2017) 1e5
Table 2 Comparison of natural radioactivity concentration (Bq/kg) in present granite samples with the reported results for different countries of the world. Country
Average activity concentration (Bq/kg) 226
Saudi Arabia India Jordan Palestine Iran Greek Spain Turkey Egypt
Ra
28.82 25.88 41.52 71 77.4 74 84 80 137
232
References 40
Th
34.83 42.82 58.42 82 44.5 85 42 101 82
K
665.08 560.6 897 780 1017.2 881 1138 974 1082
Present study (Senthilkumar et al., 2014) (Sharaf & Hamideen, 2013) (Thabayneh, 2013) (Abbasi, 2013) (Papadopoulos et al., 2013) n, Tejado, Baeza, Corbacho, & Mun ~ oz, 2014) (Guille (Aykamıs¸, Turhan, Ugur, Baykan, & Kılıç, 2013) (Amin, 2012)
Table 3 The values of radium equivalent (Req), level index (Ig) and external hazard (Hex) absorbed dose, effective dose for granite samples. Sample code
G1 G2 G3 G4 G5 G6 G7 G8 G9 G10 G11 G12 G13 G14 G15 G16 G17 G18 G19 G20 G21 G22 G23 G24 Average UNSCEAR, 2008
Radical hazards Radium eqivalent Reaq (BqKg1)
Representative level index (Ig)
External index (Hex)
Internal index (Hin)
Absorbed dose D (nGyh1)
Annual effective dose Deff (mSvy1)
4.63 6.61 7.31 277.17 228.35 246.74 273.52 15.61 3.09 1.53 9.42 14.03 2.72 239.78 8.02 16.16 177.59 163.77 271.61 220.51 187.69 256.09 220.33 263.83 129.84 370
0.017 0.024 0.027 1.0304 0.863 0.922 1.027 0.055 0.011 0.005 0.032 0.049 0.009 0.934 0.027 0.055 0.668 0.662 1.035 0.846 0.728 0.962 0.835 0.980 0.492 1
0.012 0.018 0.019 0.749 0.617 0.667 0.739 0.042 0.008 0.004 0.025 0.038 0.007 0.648 0.022 0.044 0.479 0.442 0.733 0.595 0.507 0.692 0.595 0.713 0.351 1
0.017 0.026 0.028 0.957 0.741 0.864 0.914 0.064 0.015 0.008 0.046 0.048 0.013 0.796 0.0344 0.071 0.580 0.483 0.0167 0.026 0.028 0.957 0.741 0.864 0.914 1
2.19 3.12 3.47 130.98 109.78 117.40 130.64 7.02 1.33 0.65 4.04 6.28 1.17 119.42 3.45 6.95 84.84 84.81 131.75 107.81 92.79 122.11 106.24 124.25 62.60 84
0.011 0.015 0.017 0.643 0.539 0.575 0.641 0.034 0.007 0.003 0.020 0.031 0.006 0.586 0.017 0.034 0.416 0.416 0.646 0.529 0.455 0.599 0.521 0.609 0.307 0.48
All the radium equivalent activity levels obtained in this work are lower than the (370 Bq kg1) limit reported in (UNSCEAR, 2008) for building materials to be used for homes. 2- The values of the representative index ranged from 0.005(G10) to 1.035(G19) with an average value 0.49. All Iϫ values are lower than the value limit unit, except the two samples (G4and G19) exceed this limit. Therefore, the use of these two samples is unsuitable for interior decoration and can be used for exterior construction. 3- The average values of the external and internal hazard indices obtained in this study were 0.351 and 0.914 respectively, these values are lower than unity. Therefore, we can say that the radiation hazard is insignificant for the population. 4- The estimated absorbed dose rate ranged from 1.17 to 131.75 nGy h1, which is to be within the typical variety (10e200) nGyh1 reported by (Ahmad, Jaafar, & Alsaffar, 2015). The calculated average value of absorbed dose was 62.60 nGy h1, which is lower than the population-weighted value 84 nGy h1 (UNSCEAR, 2008). The contributions to the
total absorbed dose rate were 37% for 232Th, 36% for 40K and % 27 for 226Ra. A comparison of the absorbed dose rate (nGy/h) for granite samples under investigation, present in Fig. 2. 5- The annual effective dose values ranged from 0.003 in the sample (G10) to 0.646 mSvy1 in the sample (G19). The international upper limit annual effective dose of 1 mSvy1 is not exceeded. According to the obtained results, we can recommend that most of the granite samples are safe and can be used for building as interior decoration materials of the dwelling without any radiological complication. 4. Conclusion Twenty-four of granite samples used in Saudi Arabia considered as the most popular ones were measured for their natural radioactivity to assess the radiological impact when they are used as interior decorative building materials. The highest concentrations of 226Ra, 232Th and 40K were observed in the Chinese, Pakistani and local samples. The average values of 226Ra and 232Th concentrations are lower than the recommended limit 50 Bqkg1, whereas, the 40K average value is higher than the limit 500 Bqkg1. The obtained
Please cite this article in press as: Al-Zahrani, J. H., Estimation of natural radioactivity in local and imported polished granite used as building materials in Saudi Arabia, Journal of Radiation Research and Applied Sciences (2017), http://dx.doi.org/10.1016/j.jrras.2017.05.001
J.H. Al-Zahrani / Journal of Radiation Research and Applied Sciences xxx (2017) 1e5
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Fig. 2. The absorbed dose rate (nGy/h) of the studied granite samples used in Saudi Arabia.
radiological hazard indices for granites are acceptable for safe use as decorative materials according to the dose criteria limits proposed by UNSCEAR 2008. Therefore, the granite samples under investigation are within the recommended safety limit when used as an interior ornamental in the building except some samples can be used for exterior construction. Acknowledgement We would like to thank Deanship of Scientific Research (DSR), King Abdulaziz University, Jeddah, for their kind help and providing the necessary facilities for the preparation of the paper. This work would not have been possible without the generous assistance of DSR. References Amin, R. M. (2012). Gamma radiation measurements of naturally occurring radioactive samples from Egyptian commercial granites. Environmental Earth Sciences, 67(3), 771e775. Abbasi, A. (2013). Calculation of gamma radiation dose rate and radon concentration due to granites used as building materials in Iran. Radiation Protection Dosimetry, 155(3), 335e342. Ahmad, N., Jaafar, M., & Alsaffar, M. (2015). Natural radioactivity in virgin and agricultural soil and its environmental implications in Sungai Petani, Kedah, Malaysia. Pollution, 1(3), 305e313. Ahmad, N., Jaafar, M. S., Bakhash, M., & Rahim, M. (2015). An overview on measurements of natural radioactivity in Malaysia. Journal of Radiation Research and Applied Sciences, 8(1), 136e141. Asaduzzaman, K., Khandaker, M. U., Amin, Y. M., & Bradley, D. A. (2016). Natural radioactivity levels and radiological assessment of decorative building materials in Bangladesh. Indoor and Built Environment, 25(3), 541e550. Aykamıs¸, A.S¸., Turhan, S¸., Ugur, F. A., Baykan, U. N., & Kılıç, A. M. (2013). Natural radioactivity, radon exhalation rates and indoor radon concentration of some granite samples used a construction material in Turkey. Radiation Protection Dosimetry, nct110. Beretka, J., & Mathew, P. J. (1985). Natural radioactivity of Australian building materials, industrial wastes and by-products. Health Physics, 48(1), 87e95. n, J., Tejado, J. J., Baeza, A., Corbacho, J. A., & Mun ~ oz, J. G. (2014). Assessment of Guille
radiological hazard of commercial granites from Extremadura (Spain). Journal of Environmental Radioactivity, 132, 81e88. Hameed, P. S., Pillai, G. S., Satheeshkumar, G., & Mathiyarasu, R. (2014). Measurement of gamma radiation from rocks used as building material in Tiruchirappalli district, Tamil Nadu, India. Journal of Radioanalytical and Nuclear Chemistry, 300(3), 1081e1088. Harb, S., El-Kamel, A. H., El-Mageed, A. A., Abbady, A., & Rashed, W. (2014). Measurements of naturally occurring radioactive materials for some granite rocks samples in the Eastern Desert Egypt. IOSR Journal of Applied Physics, 6, 40e46. ICRP. (1990). Recommendations of ICRP, Publication 60. In ICRP (Ed.). Pergamon Press Oxford. Jibiri, N. N., Isinkaye, M. O., Bello, I. A., & Olaniyi, P. G. (2016). Dose assessments from the measured radioactivity in soil, rock, clay, sediment and food crop samples of an elevated radiation area in south -western Nigeria. Environmental Earth Sciences, 75(2), 107. Llope, W. J. (2011). Activity concentrations and dose rates from decorative granite countertops. Journal of Environmental Radioactivity, 102(6), 620e629. Mittal, S., Guin, R., Sharma, S. P., & Sengupta, D. (2013). Estimation of 238U, 232Th and 40K concentrations in rock and soil samples around South Purulia Shear Zone, India. International Journal of Low Radiation, 9(2), 110e118. Papadopoulos, A., Christofides, G., Koroneos, A., Papadopoulou, L., Papastefanou, C., & Stoulos, S. (2013). Natural radioactivity and radiation index of the major plutonic bodies in Greece. Journal of Environmental Radioactivity, 124, 227e238. Senthilkumar, G., Raghu, Y., Sivakumar, S., Chandrasekaran, A., Anand, D. P., & Ravisankar, R. (2014). Natural radioactivity measurement and evaluation of radiological hazards in some commercial flooring materials used in Thiruvannamalai, Tamilnadu, India. Journal of Radiation Research and Applied Sciences, 7(1), 116e122. Sharaf, J. M., & Hamideen, M. S. (2013). Measurement of natural radioactivity in Jordanian building materials and their contribution to the public indoor gamma dose rate. Applied Radiation and Isotopes, 80, 61e66. Thabayneh, K. M. (2013). Measurement of natural radioactivity and radon exhalation rate in granite samples used in Palestinian buildings. Arabian Journal for Science and Engineering, 1e7. UNSCEAR, United Nations, & Scientific Committee on the Effects of Atomic Radiation.. (2000). Sources and effects of ionizing radiation: Sources (Vol. 1). United Nations Publications. UNSCEAR, United Nations, & Scientific Committee on the Effects of Atomic Radiation.. (2008). Report of the united Nations scientific committee on the effects of atomic radiation: Fifty-sixth Session. United Nations Publications (10e18 July 2008) (No. 46). US-EPA. (1993). Carcinogenicity assessment. IRIS (inte- grated risk information system), 2003. Washington DC, USA: US Environ- mental Protection Agency. Internet www.epa.gov/iris.
Please cite this article in press as: Al-Zahrani, J. H., Estimation of natural radioactivity in local and imported polished granite used as building materials in Saudi Arabia, Journal of Radiation Research and Applied Sciences (2017), http://dx.doi.org/10.1016/j.jrras.2017.05.001
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H O S T E D BY
Journal of Radiation Research and Applied Sciences journal homepage: http://www.elsevier.com/locate/jrras
Estimation of natural radioactivity in local and imported polished granite used as building materials in Saudi Arabia J.H. Al-Zahrani Physics Department, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
a r t i c l e i n f o
a b s t r a c t
Article history: Received 18 April 2017 Received in revised form 3 May 2017 Accepted 3 May 2017 Available online xxx
Measurements of natural radioactivity in local and imported samples of commercial granites used in Saudi Arabia were carried out by using gamma-ray spectroscopy with hyper-pure germanium detector. The activity concentrations measured of granite samples were determined for 226Ra(from 1.53 to 77.16 Bq kg1), 232Th (from 0.51 to 89.82 Bq kg1) and 40K (from 19.47 to 1632.37 Bq kg1). The corresponding average activity concentrations for 226Ra,232Th and 40K were 28.82, 34.83 and 665.08 Bq kg1, respectively. The radiological hazard parameters (radium equivalent, gamma index, external index, internal index, absorbed dose and annual effective dose) were calculated to assess the radiation hazards associated with granite samples. The obtained results are lower than the recommended limits. The results were compared with the published data of other countries. The measurements will help in the development of standards and guidelines for the use and management of these materials. © 2017 The Egyptian Society of Radiation Sciences and Applications. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/ by-nc-nd/4.0/).
Keywords: Natural activity Gamma spectroscopy Building material Granite Effective dose Radium equivalent activity
1. Introduction Granite is a form of igneous rocks, consists mainly of quartz, mica, and feldspar, used for interior and exterior decorative as building and ornamental materials, these rocks, due to their composition contains some radionuclides. The radionuclides of 238 U and 232Th radioactive series are the sources of both external and internal exposures in building materials. Gamma-rays cause the external exposure from radionuclides of 238U and 232Th radioactive series and 40 K, while alpha particles mainly cause the internal exposure due to inhalation of radon and the short-lived products of the above radioactive series, which are deposited in the respiratory tract tissues (Ahmad, Jaafar, Bakhash & Rahim, 2015; Papadopoulos et al., 2013). Thus, the study of the natural radioactivity and the radon emissions from the granite materials is an essential subject to radiological environmental protection because it facilitates the possibility to assess any related health risk. Several studies refer to natural radioactivity levels along with radiation risks of polished granite which are both used as decorative building material, as: (Llope, 2011; Mittal, Guin, Sharma, & Sengupta, 2013;
E-mail address: [email protected]. Peer review under responsibility of The Egyptian Society of Radiation Sciences and Applications.
Hameed, Pillai, Satheeshkumar, & Mathiyarasu, 2014; Asaduzzaman, Khandaker, Amin, & Bradley, 2016). In Saudi Arabia, local and imported Polished Granites are used as building materials, decorating and expensive materials due to its hard, tough, elegant look and different colors. Therefore, it is important to measure the concentration of radionuclides in granite used in building materials, where the inhabitants spend about 80% of their time indoors. As a result, the objectives of this study are: 1) To determine the specific radioactivity concentrations of 238U, 232Th, and 40K in local and imported granites used as building materials in Saudi Arabia. 2) To assess the possible radiological risks to human health and compare the results with the recommended limits of UNSCEAR data. 2. Material and methods In this study, a total of 24 polished granite samples, local (11 samples) and imported (13 samples) are the most used as a decorative inner cover on walls and floors were collected from several commercial companies, construction sites and local suppliers in Saudi Arabia. The collected samples were crushed and milled to a fine powder, homogenized, oven dried at 110 C for 6 h, and then each sample packed in a cylindrical 1000-ml plastic Marinelli beaker, sealed for one month to achieve secular equilibrium between 226Ra and 232Th with their decay products (Ahmad, Jaafar, &
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Please cite this article in press as: Al-Zahrani, J. H., Estimation of natural radioactivity in local and imported polished granite used as building materials in Saudi Arabia, Journal of Radiation Research and Applied Sciences (2017), http://dx.doi.org/10.1016/j.jrras.2017.05.001
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Alsaffar, 2015). The activity concentrations of 226Ra,232Th and 40K for all homogenized and equilibrium samples were measured by a gamma ray spectrometry by using High purity Germanium (HPGe) detector (25% relative efficiency) with coaxial-type vertical dipstick cryostat. It is surrounded by lead and copper, which provides an efficient suppression of background gamma radiation present at the laboratory. The system has a resolution (FWHM) of (3.0e3.5 keV) for 1332.5 keV gamma-ray peak of 60Co and a peak to a Compton ratio of 41:1., and it was given high voltage through preamplifier which was then connected to amplifier to computer based Multi channel analyzer through ADC (analogue to digital converter). The spectra were analyzed by commercially available software GE- NIE-2000 obtained from Canberra, USA. For gammaray measurements, each prepared granite sample was placed directly over the detector and counted for a 36000sec period. Additionally, under the same conditions as for the samples, the background distribution in the environment around the detector was determined. The 226Ra specific activities were estimated from 214 Bi (609.3 keV) and 214Pb (295.2 and 352.0 keV), whereas, for 232 Th the specific activities of 228Ac (911.1 keV), 212Pb (583.1 keV) and 208Tl (238.6 keV) were used. The specific activity of 40K was determined directly from its gamma emission at 1460.83 keV (Ahmad, Jaafar, & Alsaffar, 2015). Table 1 presents the code number, origins, colors of the local and imported granite samples used in Saudi Arabia buildings (see Table 1). The activity concentrations of 238U, 232Th series, and 40K were calculated using the following equation:
A
Bq kg 1
from the three nuclides 226Ra, 232Th and 40K in the building materials, can be defined in units of nGyh1 using the formula proposed by (Asaduzzaman et al., 2016; UNSCEAR, 2000):
D
nGy h1 ¼ 0:0417 Ak þ 0:462 ARa þ 0:604 ATh
(6)
where ARa, ATh, and AK are the defining activities of 226Ra, 232Th, and 40K in Bqkg1 and their corresponding dose conversion factors. By using the standard room model with dimensions of 4 m 5 m 2.8 m, the average world value of the absorbed dose rate is 55 nGyh1 (Ahmad, Jaafar, & Alsaffar, 2015). The annual effective dose is calculated by applying the dose conversion factor of 0.7 SvGy1 with 0.8 as an indoor occupancy factor (Jibiri, Isinkaye, Bello, & Olaniyi, 2016; UNSCEAR, 2000):
Deff ðmSv=yÞ ¼ D nGyh1 ð0:7Sv=Gy 8760h=year 0:8Þ 106 (7) where, Deff ¼ 0.39 mSvy1 as the annual effective dose indoor for individuals, the recommended upper limit is one mSvy1 (ICRP, 1990), 8766 h is the number of hours in 1 year.
3. Results and discussions 3.1. Activity concentration
¼ N=ε bM
(1)
where: N is the net gamma counting rate (counts per second), ε is the detector efficiency of the specific geray, b is the absolute transition probability of Gammaedecay and M is the mass of the sample (kg). The radium equivalent activity (Req) is given as (Beretka & Mathew, 1985; UNSCEAR, 2000):
Req ¼ ARa þ 1:43ATh þ 0:077AK
(2)
where ARa, ATh and AK are the specific activities of 226Ra, 232Th and 40 K in Bqkg1, respectively. The estimated values of 1 Bqkg1 of 226 Ra, 0.7Bqkg1 of 232Th and 13Bqkg-1of 40K produce the same gamma-ray dose]. For safe use, the maximum value of Raeq in building materials must be less than 370 Bqkg1 to keep the external dose below 1.5 mSv.y1 (UNSCEAR, 2000). Representative level index (Ir) is used to estimate the standard of gamma radiation hazard associated with the natural radionuclides in specific building materials. It is calculated using the following formula (Asaduzzaman et al., 2016; UNSCEAR, 2000):
Ir ¼ CRa =300 þ CTh =200 þ CK =3000 1
(3)
where CRa, Seth and CK (in Bq/kg) are the concentration of 226Ra, 232 Th, and 40K, respectively. These two hazard indices were used to measure the external and internal hazards due to the emitted gamma radiation. For safe use of material in the construction of dwellings, Hex and Hin should be less than unity and can be defined as (Beretka & Mathew, 1985; UNSCEAR, 2000):
Hex ¼ ARa=370 þ ATh=259 þ AK=4810 1
(4)
Hin ¼ ARa=185 þ ATh=259 þ Ak=4810 1
(5)
The absorbed dose rate in the air is due to gamma-ray emission
Table 1 summarized the obtained activity concentrations of Ra, 232Th and 40K for the measured granite samples together with their corresponding total uncertainties. 226 Ra range varies from 1.53 Bqkg1 to 77.16 Bqkg1; 232Th varies from 0.51 Bqkg1 to 89.82Bqkg1. In most samples, 40K represents the highest radioactivity concentration; it varies from 19.47 Bqkg1 to 1632.37 Bqkg1. From all the samples measured in this study, the Iranian white sample(G1) presents the lowest activity concentrations for 226 Ra and 40K, whereas, the Indian green sample (G11) presents the lowest activity value for 232Th. The range activity concentrations of 226 Ra, 232Th and 40K were less than the typical ranges of activity concentration in building materials reported by (UNSCEAR, 2008) as 100e500 and 40e350 and 1200e1800 Bq kg1, respectively. As shown in Table 1, the radioactivity in granite samples varied from one sample to another; this depends on the nature of the region from which samples were collected (Harb, El-Kamel, El-Mageed, Abbady, & Rashed, 2014). The average values for all the three nuclides 226Ra, 232Th, and 40K were 28.82, 34.83 and 665.08Bqkg-1, respectively. 226Ra and 232Th values are lower than the world average value 50 Bq kg1 for building materials of 226Ra, 232Th, whereas, 40K is higher than the world average value 500 Bqkg1 (UNSCEAR, 2008). Fig. 1 shows the activity concentration of 226 Ra,232Th, and 40K in the present granite samples. Any granite rock could contain naturally occurring radioactive elements such as radium, thorium, and potassium. Some granite contains more of these items than others, depending on the chemical composition and the formation of the molten rock. Geologists provide an explanation of this behavior in the course of partial melting and fractional crystallization of magma, which enables U and Th to be concentrated in the liquid phase and become incorporated into the more silica-rich products. For that reason, igneous rocks of the granite composition are strongly enriched in U and Th with different concentrations (US-EPA, 1993). Table 1, showed that samples with dark colors (G: 4,6,7,14,19,24) for Ra and (G: 4,5,6,7,14,17,19,20,22,23,24) had high values of radiation. The 226Ra, 232 Th and 40K average concentrations of selected granite samples in 226
Please cite this article in press as: Al-Zahrani, J. H., Estimation of natural radioactivity in local and imported polished granite used as building materials in Saudi Arabia, Journal of Radiation Research and Applied Sciences (2017), http://dx.doi.org/10.1016/j.jrras.2017.05.001
J.H. Al-Zahrani / Journal of Radiation Research and Applied Sciences xxx (2017) 1e5 Table 1 226 Ra, 232Th and
40
3
K activity concentrations of the granite samples are used as the interior building materials in Saudi Arabia.
Sample code
Origin
Activity concentrations (Bqkg1)
Color
226
232
1.54 ± 0.4 3.17 ± 0.5 3.13 ± 0.86 77.16 ± 3.8 45.99 ± 4.1 72.94 ± 5.7 64.95 ± 8.5 7.89 ± 08 2.31 ± 0.5 1.53 ± 0.4 7.73 ± 1.8 3.71 ± 0.5 1.99 ± 0.9 54.87 ± 7.67 4.70 ± 1.3 9.95 ± 1.7 37.23 ± 4.9 15.18 ± 1.8 55.13 ± 6.9 43.36 ± 3.5 32.91 ± 3.1 45.76 ± 2.8 42.82 ± 3.4 55.63 ± 5.1 1.53e77.16 28.82 50
1.11 ± 0.3 0,85 ± 0,2 1.14 ± 0.4 77.82 ± 4.7 66.64 ± 1.9 61.53 ± 2.9 77.31 ± 2.5 3.77 ± 0.6 0.55 ± 0.1 L.D.L 1.18 ± 0.01 6.05 ± 0.7 0.51 ± 0.1 71.43 ± 3.33 2.32 ± 0.4 4.34 ± 0.9 53.77 ± 2.7 26.50 ± 1.7 73.26 ± 3.5 54.86 ± 5.5 43.83 ± 3.9 84.76 ± 3.9 63.63 ± 2.7 89.82 ± 4.6 0.51e89.82 34.83 50
Ra
G1 G2 G3 G4 G5 G6 G7 G8 G9 G10 G11 G12 G13 G14 G15 G16 G17 G18 G19 G20 G21 G22 G23 G24 Range Average UNSCEAEAR 2008
Iran Italy Egypt China China China Pakistan Pakistan Iran Italy India Italy Boringly Saudi Arabia Saudi Arabia Saudi Arabia Saudi Arabia Saudi Arabia Saudi Arabia Saudi Arabia Saudi Arabia Saudi Arabia Saudi Arabia Saudi Arabia
Fig. 1. The activity concentration of
White White White Brown with black Gray Black with red Ruby red color Brown Light color red White with gray Green Black Rosa Black with red Light Brown Fine Gray Gray Red Black Red with black Gray with black Gray with red Black with white Black eRed eGray
226
Ra,232Th, and
40
Th
40
K
19.47 ± 0.6 28.85 ± 0.6 33.17 ± 1.1 1152.30 ± 16.5 1130.73 ± 13.3 1114.4 ± 9.1 1272.98 ± 12.6 30.29 ± 0.9 L.D.L L.D.L L.D.L 21.63 ± 0.7 L.D.L 1632.37 ± 18.49 L.D.L L.D.L 824.25 ± 10.1 1437.66 ± 16.7 1469.46 ± 13.6 1281.83 ± 18.4 1196.08 ± 18.7 1157.41 ± 13.7 1123.57 ± 13.7 1035.85 ± 17.6 19.47e1632.37 665.08 500
K in the present granite samples used in Saudi Arabia as decorative materials.
this work are compared with the results from different countries of the world and the recommended values as given in Table 2. The Table shows that the average activity concentration values obtained in this work of 226Ra are comparable with those obtained in India and lower than the others while that average value obtained for 232 Th in all other countries are higher than the value gained in this work. The average present value of 40K activity concentration is lower than the obtained values in all countries, except India. As shown in this Table, the radioactivity in granite samples varied from one country to another, depend upon their geological conditions (UNSCEAR, 2008).
3.2. Radiation hazards The values of the hazard parameters in comparison with the world average are presented in Table 3. The results show that: 1- The highest value (277.17Bq/kg) of Req for all granite samples was observed in Chinese Granite (G4), while the lowest value (1.53 Bq/kg) was found in Italian granite (G10). It is apparent that there are significant variations in the Req values of the granite samples. This verity is essential in selecting the best granite samples for use in interior decoration in the homes.
Please cite this article in press as: Al-Zahrani, J. H., Estimation of natural radioactivity in local and imported polished granite used as building materials in Saudi Arabia, Journal of Radiation Research and Applied Sciences (2017), http://dx.doi.org/10.1016/j.jrras.2017.05.001
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J.H. Al-Zahrani / Journal of Radiation Research and Applied Sciences xxx (2017) 1e5
Table 2 Comparison of natural radioactivity concentration (Bq/kg) in present granite samples with the reported results for different countries of the world. Country
Average activity concentration (Bq/kg) 226
Saudi Arabia India Jordan Palestine Iran Greek Spain Turkey Egypt
Ra
28.82 25.88 41.52 71 77.4 74 84 80 137
232
References 40
Th
34.83 42.82 58.42 82 44.5 85 42 101 82
K
665.08 560.6 897 780 1017.2 881 1138 974 1082
Present study (Senthilkumar et al., 2014) (Sharaf & Hamideen, 2013) (Thabayneh, 2013) (Abbasi, 2013) (Papadopoulos et al., 2013) n, Tejado, Baeza, Corbacho, & Mun ~ oz, 2014) (Guille (Aykamıs¸, Turhan, Ugur, Baykan, & Kılıç, 2013) (Amin, 2012)
Table 3 The values of radium equivalent (Req), level index (Ig) and external hazard (Hex) absorbed dose, effective dose for granite samples. Sample code
G1 G2 G3 G4 G5 G6 G7 G8 G9 G10 G11 G12 G13 G14 G15 G16 G17 G18 G19 G20 G21 G22 G23 G24 Average UNSCEAR, 2008
Radical hazards Radium eqivalent Reaq (BqKg1)
Representative level index (Ig)
External index (Hex)
Internal index (Hin)
Absorbed dose D (nGyh1)
Annual effective dose Deff (mSvy1)
4.63 6.61 7.31 277.17 228.35 246.74 273.52 15.61 3.09 1.53 9.42 14.03 2.72 239.78 8.02 16.16 177.59 163.77 271.61 220.51 187.69 256.09 220.33 263.83 129.84 370
0.017 0.024 0.027 1.0304 0.863 0.922 1.027 0.055 0.011 0.005 0.032 0.049 0.009 0.934 0.027 0.055 0.668 0.662 1.035 0.846 0.728 0.962 0.835 0.980 0.492 1
0.012 0.018 0.019 0.749 0.617 0.667 0.739 0.042 0.008 0.004 0.025 0.038 0.007 0.648 0.022 0.044 0.479 0.442 0.733 0.595 0.507 0.692 0.595 0.713 0.351 1
0.017 0.026 0.028 0.957 0.741 0.864 0.914 0.064 0.015 0.008 0.046 0.048 0.013 0.796 0.0344 0.071 0.580 0.483 0.0167 0.026 0.028 0.957 0.741 0.864 0.914 1
2.19 3.12 3.47 130.98 109.78 117.40 130.64 7.02 1.33 0.65 4.04 6.28 1.17 119.42 3.45 6.95 84.84 84.81 131.75 107.81 92.79 122.11 106.24 124.25 62.60 84
0.011 0.015 0.017 0.643 0.539 0.575 0.641 0.034 0.007 0.003 0.020 0.031 0.006 0.586 0.017 0.034 0.416 0.416 0.646 0.529 0.455 0.599 0.521 0.609 0.307 0.48
All the radium equivalent activity levels obtained in this work are lower than the (370 Bq kg1) limit reported in (UNSCEAR, 2008) for building materials to be used for homes. 2- The values of the representative index ranged from 0.005(G10) to 1.035(G19) with an average value 0.49. All Iϫ values are lower than the value limit unit, except the two samples (G4and G19) exceed this limit. Therefore, the use of these two samples is unsuitable for interior decoration and can be used for exterior construction. 3- The average values of the external and internal hazard indices obtained in this study were 0.351 and 0.914 respectively, these values are lower than unity. Therefore, we can say that the radiation hazard is insignificant for the population. 4- The estimated absorbed dose rate ranged from 1.17 to 131.75 nGy h1, which is to be within the typical variety (10e200) nGyh1 reported by (Ahmad, Jaafar, & Alsaffar, 2015). The calculated average value of absorbed dose was 62.60 nGy h1, which is lower than the population-weighted value 84 nGy h1 (UNSCEAR, 2008). The contributions to the
total absorbed dose rate were 37% for 232Th, 36% for 40K and % 27 for 226Ra. A comparison of the absorbed dose rate (nGy/h) for granite samples under investigation, present in Fig. 2. 5- The annual effective dose values ranged from 0.003 in the sample (G10) to 0.646 mSvy1 in the sample (G19). The international upper limit annual effective dose of 1 mSvy1 is not exceeded. According to the obtained results, we can recommend that most of the granite samples are safe and can be used for building as interior decoration materials of the dwelling without any radiological complication. 4. Conclusion Twenty-four of granite samples used in Saudi Arabia considered as the most popular ones were measured for their natural radioactivity to assess the radiological impact when they are used as interior decorative building materials. The highest concentrations of 226Ra, 232Th and 40K were observed in the Chinese, Pakistani and local samples. The average values of 226Ra and 232Th concentrations are lower than the recommended limit 50 Bqkg1, whereas, the 40K average value is higher than the limit 500 Bqkg1. The obtained
Please cite this article in press as: Al-Zahrani, J. H., Estimation of natural radioactivity in local and imported polished granite used as building materials in Saudi Arabia, Journal of Radiation Research and Applied Sciences (2017), http://dx.doi.org/10.1016/j.jrras.2017.05.001
J.H. Al-Zahrani / Journal of Radiation Research and Applied Sciences xxx (2017) 1e5
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Fig. 2. The absorbed dose rate (nGy/h) of the studied granite samples used in Saudi Arabia.
radiological hazard indices for granites are acceptable for safe use as decorative materials according to the dose criteria limits proposed by UNSCEAR 2008. Therefore, the granite samples under investigation are within the recommended safety limit when used as an interior ornamental in the building except some samples can be used for exterior construction. Acknowledgement We would like to thank Deanship of Scientific Research (DSR), King Abdulaziz University, Jeddah, for their kind help and providing the necessary facilities for the preparation of the paper. This work would not have been possible without the generous assistance of DSR. References Amin, R. M. (2012). Gamma radiation measurements of naturally occurring radioactive samples from Egyptian commercial granites. Environmental Earth Sciences, 67(3), 771e775. Abbasi, A. (2013). Calculation of gamma radiation dose rate and radon concentration due to granites used as building materials in Iran. Radiation Protection Dosimetry, 155(3), 335e342. Ahmad, N., Jaafar, M., & Alsaffar, M. (2015). Natural radioactivity in virgin and agricultural soil and its environmental implications in Sungai Petani, Kedah, Malaysia. Pollution, 1(3), 305e313. Ahmad, N., Jaafar, M. S., Bakhash, M., & Rahim, M. (2015). An overview on measurements of natural radioactivity in Malaysia. Journal of Radiation Research and Applied Sciences, 8(1), 136e141. Asaduzzaman, K., Khandaker, M. U., Amin, Y. M., & Bradley, D. A. (2016). Natural radioactivity levels and radiological assessment of decorative building materials in Bangladesh. Indoor and Built Environment, 25(3), 541e550. Aykamıs¸, A.S¸., Turhan, S¸., Ugur, F. A., Baykan, U. N., & Kılıç, A. M. (2013). Natural radioactivity, radon exhalation rates and indoor radon concentration of some granite samples used a construction material in Turkey. Radiation Protection Dosimetry, nct110. Beretka, J., & Mathew, P. J. (1985). Natural radioactivity of Australian building materials, industrial wastes and by-products. Health Physics, 48(1), 87e95. n, J., Tejado, J. J., Baeza, A., Corbacho, J. A., & Mun ~ oz, J. G. (2014). Assessment of Guille
radiological hazard of commercial granites from Extremadura (Spain). Journal of Environmental Radioactivity, 132, 81e88. Hameed, P. S., Pillai, G. S., Satheeshkumar, G., & Mathiyarasu, R. (2014). Measurement of gamma radiation from rocks used as building material in Tiruchirappalli district, Tamil Nadu, India. Journal of Radioanalytical and Nuclear Chemistry, 300(3), 1081e1088. Harb, S., El-Kamel, A. H., El-Mageed, A. A., Abbady, A., & Rashed, W. (2014). Measurements of naturally occurring radioactive materials for some granite rocks samples in the Eastern Desert Egypt. IOSR Journal of Applied Physics, 6, 40e46. ICRP. (1990). Recommendations of ICRP, Publication 60. In ICRP (Ed.). Pergamon Press Oxford. Jibiri, N. N., Isinkaye, M. O., Bello, I. A., & Olaniyi, P. G. (2016). Dose assessments from the measured radioactivity in soil, rock, clay, sediment and food crop samples of an elevated radiation area in south -western Nigeria. Environmental Earth Sciences, 75(2), 107. Llope, W. J. (2011). Activity concentrations and dose rates from decorative granite countertops. Journal of Environmental Radioactivity, 102(6), 620e629. Mittal, S., Guin, R., Sharma, S. P., & Sengupta, D. (2013). Estimation of 238U, 232Th and 40K concentrations in rock and soil samples around South Purulia Shear Zone, India. International Journal of Low Radiation, 9(2), 110e118. Papadopoulos, A., Christofides, G., Koroneos, A., Papadopoulou, L., Papastefanou, C., & Stoulos, S. (2013). Natural radioactivity and radiation index of the major plutonic bodies in Greece. Journal of Environmental Radioactivity, 124, 227e238. Senthilkumar, G., Raghu, Y., Sivakumar, S., Chandrasekaran, A., Anand, D. P., & Ravisankar, R. (2014). Natural radioactivity measurement and evaluation of radiological hazards in some commercial flooring materials used in Thiruvannamalai, Tamilnadu, India. Journal of Radiation Research and Applied Sciences, 7(1), 116e122. Sharaf, J. M., & Hamideen, M. S. (2013). Measurement of natural radioactivity in Jordanian building materials and their contribution to the public indoor gamma dose rate. Applied Radiation and Isotopes, 80, 61e66. Thabayneh, K. M. (2013). Measurement of natural radioactivity and radon exhalation rate in granite samples used in Palestinian buildings. Arabian Journal for Science and Engineering, 1e7. UNSCEAR, United Nations, & Scientific Committee on the Effects of Atomic Radiation.. (2000). Sources and effects of ionizing radiation: Sources (Vol. 1). United Nations Publications. UNSCEAR, United Nations, & Scientific Committee on the Effects of Atomic Radiation.. (2008). Report of the united Nations scientific committee on the effects of atomic radiation: Fifty-sixth Session. United Nations Publications (10e18 July 2008) (No. 46). US-EPA. (1993). Carcinogenicity assessment. IRIS (inte- grated risk information system), 2003. Washington DC, USA: US Environ- mental Protection Agency. Internet www.epa.gov/iris.
Please cite this article in press as: Al-Zahrani, J. H., Estimation of natural radioactivity in local and imported polished granite used as building materials in Saudi Arabia, Journal of Radiation Research and Applied Sciences (2017), http://dx.doi.org/10.1016/j.jrras.2017.05.001