Evaluation of Radiological Hazard Indices Due to Radioactivity in Quarry Sites in Itu, Akwa Ibom State, Nigeria

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2 International Journal of Scientific Research in Environmental Sciences, 4(3), pp , 2016 Available online at ISSN: ; 2016; Author(s) retain the copyright of this article Full Length Research Paper Evaluation of Radiological Hazard Indices Due to Radioactivity in Quarry Sites in Itu, Akwa Ibom State, Nigeria Imeh E. Essien*, Emmanuel N. Akpan Department of Physics, University of Physics, University of Uyo, Uyo, Nigeria *Corresponding Author: Received 04 February 2016; Accepted 13 April 2016 Abstract. The radiological hazard indices due to the radioactivity in soils at quarry sites in Ayadehe, Oku Iboku, Odiok Itam and Ntak Inyang villages in Itu Local Government Areas of Akwa Ibom State, Nigeria were evaluated. Soil samples were randomly collected at the depth of 30 cm in different locations from each of the quarry site. The radionuclide activity concentrations in the soil samples were measured using gamma spectroscopy method. The average values of 40 K, 238 U and 232 Th obtained is ( ) BqKg -1, ( ) BqKg -1 and ( ) BqKg -1 respectively for Ayadehe, ( ) Bqkg -1,( ) BqKg -1 and ( ) BqKg - 1 for Oku Iboku, ( ) BqKg -1, ( ) BqKg -1 and ( ) BqKg -1 for Odiok Itam and ( ) Bqkg -1, ( ) BqKg -1 and ( ) BqKg -1 for Ntak Inyang quarry sites. The average values obtained for radium equivalent, absorbed dose rate, annual effective dose equivalent, internal hazard index, external hazard index and excess lifetime cancer risk are BqKg -1, 9.80 ngyh -1, mSvy -1, , , and x10-3 respectively for Ayadehe and BqKg -1, 5.93 ngyh -1, msvy -1, , , and x10-3 respectively for Oku Iboku, BqKg -1, 7.22nGyh -1, msvy -1, , , and x10-3 respectively for Odiok Itam and BqKg -1, 7.61 ngyh -1, mSvy -1, , , and x10-3 respectively for Ntak Inyang quarry sites. The values for the indices obtained when compared with their corresponding world permissible limits were found to be below the standard limits for such environments. Therefore the level of exposure at the study areas presently poses no significant health threat; hence, the quarry products of these areas can be used as building material. Keywords: Activity concentrations, radionuclides, radiological hazard indices, quarry 1. INTRODUCTION Natural sources of radiation are known to be the most prominent means of exposing the public to radiation. The knowledge of radionuclides distribution in the environment is key for assessing the effect of radiation exposure due to both terrestrial and extraterrestrial sources. The primordial radionuclides are mainly the nuclides of uranium, thorium, and potassium known as naturally occurring radionuclides materials (NORMs) and their distributions depends primarily on the geological and geographical conditions of a place and appear at different levels in the soil. The presence of NORMs in a given geographical location on earth is most concentrated within the earth s crust, some distance beneath the earth s surface. Activities associated with the extraction, processing and the use of minerals from the soil have the potential to increase exposure to radiation to members of the general public and workers (Faanu et al., 2011). 71 Exposure of workers to naturally occurring radioactive materials (NORMs) continued to be an emerging industrial issue, for example in the extraction of rare earths, the zirconium industry, coalfired electricity generation and the phosphate industry. Environmental problems associated with NORMs in quarrying areas occurs in the process of quarrying, leaching, handling, storage, transportation of quarried products and the use of contaminated equipments without controls (Innocent et al., 2013). Today, we are witnessing the increasing demands for quarry products such as rocks, gravels, clays, stone sands, etc by governments, non-governmental organizations (NGOs) and individuals for buildings and other developmental purposes. Therefore, due to the economic values and high demands for the quarry products, some areas of Itu local Government Area of Akwa Ibom, Nigeria, which are naturally endowed with these resources in a large quantity, are now witnessing commercial quarries. The quarry activities which involve the digging of the ground soils to

3 Essien and Akpan Evaluation of Radiological Hazard Indices Due to Radioactivity in Quarry Sites in Itu, Akwa Ibom State, Nigeria certain depth in order to bring the natural resources to the top surfaces also bring the NORMs to the soil surface, thereby increasing the radiation exposure to the workers and environment. However, no adequate evaluation of the radiological effects due to the quarry activities in the area has been conducted before now. It is based on this background that this work is carried out to assess the level of radiological effects due to the quarry activities in the selected quarry sites. 2. MATERIALS AND METHODS 2.1. Study Area The study was carried out in different quarry locations of Ayadehe, Oku Iboku, Odiok Itam and Ntak Inyang communities of Itu Local Government Area of Akwa Ibom State, Nigeria. The study area is located between longitudes and E and latitudes and N. The major economic activities of the people are predominantly quarrying, fishing and farming 2.2. Sampling Procedure A total of 40 soil samples were randomly collected from the different selected quarry sites that made up the area of this study. Ten samples were collected from each of the quarry site. At each sampling location, the soil surface was cleared of stones, pebbles, vegetations and roots. A soil sample of 1.5kg was collected from each position with shovel and at a depth of 30cm and stored in black labeled polythene bags immediately after collection (Chad and Ohwekevwo, 2012) Samples Preparation and Analysis The collected soil samples were first dried and then crushed, grounded and passed through a sieve of 1.0mm mesh size. The fine-grained powder of each sample obtained were dried in an oven to about C for 2 hours to ensure total removal of moisture and 300g of each dried prepared sample was sealed in a cylindrical plastic container and properly labeled for easy identification. The prepared samples were stored for a period of 30 days to ensure secular radioactivity equilibrium between 226 Ra and its short lived progeny (EL-Arabic, 2005). In the laboratory, the activity concentrations of uranium 238, thorium 232 and potassium 40 were determined using gamma spectrometer coupled to NaI(TI) detector. The data acquisition and analysis of gamma spectra were made possible by a computer base multi-channel analyzer maestro program and the radionuclide activity concentration per unit mass (c) was calculated using equation (1) (Essiett et al., 2015) 72 N c t M 1 Where M is the mass of the samples measured in Kg, the detector energy dependent efficiency, t is the counting live time (s), is the gamma ray yield per disintegration of the nuclides and N is the net peak area of the nuclide Radiological Hazard Indices The radiological hazard indices considered for this work are radium equivalent activity, radioactivity level index, absorbed dose rate, annual effective dose equivalent, external and internal hazard indices as well as the excess lifetime cancer risk Radium Equivalent Activity The radium equivalent activity, Raeq is used to compare the specific activities of materials containing different quantities of U, Th and 40 K. The values of R could be obtained from (Bede et al., aeq 2015) BqKg C.43C C R u Th K aeq where, u C, C Th and 238 U K 2 C are the average activity 232 concentrations of, Th and 40 K respectively. In calculating Ra eq values, the average activity concentration of 370Bq/kg, 259Bq/Kg and 4810Bq/kg used for 238 U, 232 Th and 40 K radionuclide, respectively, were assumed to produce the same gamma dose rate (EL-Taher et al, 2004) Absorbed Dose Rate in Air The effects of gamma radiation, emanating from radioactive sources in the environment, are usually given in terms of the total gamma radiation absorbed dose rate in air, D. The values of D in air I.0 m above the ground level are calculated from the measured activity concentrations of 238 U, 232 Th and 40 K radionuclides into absorbed dose rate as proposed by UNSCEAR (Bede et al., 2015). D ( ngyh ) 0.427Cu 0.662CTh C K Annual Effective Dose Equivalent The annual effective dose equivalent (AEDE) received by individuals are generally obtained from the calculated values of D by applying the conversion factor of 0.7SvGy -1 and the occupancy factors of 0.2 and 0.8 for outdoors and indoors

4 International Journal of Scientific Research in Environmental Sciences, 4(3), pp , 2016 effective doses, respectively (UNSCEAR, 2000). The annual effective outdoor dose ( D ), the annual effective indoor dose, ( D, ) and the total annual in out effective doses ( D following relations. 6 D out ( msvyr ) D ( ngyh ) 24h days SvGy D in ( msvyr ) D ( ngyh ) 24h days SvGy 0 5 tot ), are obtained using the The total annual effective dose equivalent could be obtained from (Gbenu et al 2015) D msvyr 1 ( ) D D 6 Tot out External and internal hazards indices The external radiation hazard index, H ex, corresponding to 238 U, 232 Th and 40 K natural radionuclides are calculated using the relation below CK CTH CU H ext = Also, radon and its short-lived products are hazardous to the respiratory organs and as a result, the internal exposure to radon and its daughter products is quantified using the internal hazard index. The internal hazard index for 238 U, 232 Th and 40 K are obtained using the equation CK CTH CU H in = where C U, C Th and C K are the activity concentrations of 238 U, 232 Th and 40 K respectively and the numbers in the numerators of equations 5 and 6 are their respective conversion factors (Kocher and Sjoreen, 1985). These values for the external and internal hazard indices must be less than unity for the radiation hazard to be considered negligible (Beretka and Mathew, 1985) Radioactivity Level Index The radioactivity level index, I is usually employed to evaluate the hazardous level of radionuclides in the human body when exposed to an amount of external annual effective doses of gamma-radiations decayed from these radioactive nuclides in soils and values of I can be obtained using the following relations CK CTH CU I = where C u, C Th and C k are the activity concentrations of uranium, thorium and potassium respectively. The calculated values of I must be less than unity for the soil environment to be free from radiological health hazards. in Excess Lifetime Cancer Risk The excess lifetime cancer risk (ELCR) values are calculated using the equation given below. ELCR D D R 10 tot L F where D L is the duration of life (taken approximately as 70 years), D tot is the total annual effective dose equivalent and R F is the risk factor (Sv - 1 ), which reflects the fatal cancer risk per Sievert. For stochastic effects, ICRP 60 recommended a value of 0.05 for the public, (Taskin et al., 2009). 3. RESULTS AND DISCUSSIONS Tables 1and 2 present the activity concentration of the three ( 40 K 238 U and 232 Th) natural radionuclide materials in the four quarry study areas. Table 1 reports the NORM activity concentration for Ayadehe and Oku Iboku while Table 2 reports activity concentration for quarry sites at Odiok Itam and Ntak Inyang. It could be observed in the tables that some of the results were below detection limits (BDL) therefore results from quarry sites with insignificant activity concentrations, that is, where all the measured activity concentrations for the NORM were insignificant were not included in this report Radionuclides Concentration in the Soil of the Studied Quarry Sites Analysis of the reports in Tables 1 and 2 shows that the range values of 40 K are 79.91± 4.35 Bq/Kg to ±13.74 Bq/Kg with mean value of ±7.56 Bq/Kg, (23.32±1.26 to ±8.56) Bq/Kg with mean of 73.69±3.89 Bq/Kg, and (30.38±1.60 to ±5.35) Bg/Kg with mean of 63.77±3.34 Bq/Kg respectively for the four sites, then for 238 U the range (mean) for the four sites are respectively BDL- 8.71±0.90Bq/Kg (2.47±0.26 Bq/Kg), BDL- 5.80±0.63 Bq/Kg (2.04±0.32 Bq/Kg) and BDL-28.92±3.02 Bq/Kg (8.84±0.92 Bq/Kg) and for 232 Th the values obtained are BDL- 7.24±0.43Bq/Kg with mean value of 3.70±0.22 Bq/Kg, (0.71± ±0.31)Bq/Kg with mean 2.85±0.17 Bq/Kg and (0.54± ±0.21)Bq/Kg mean 2.31±0.14Bq/Kg. These radioactivity concentration values obtained in these quarry sites are below the world average value of

5 Essien and Akpan Evaluation of Radiological Hazard Indices Due to Radioactivity in Quarry Sites in Itu, Akwa Ibom State, Nigeria Bq/kg for 40 k, 35Bq/kg for 238 U and 30Bq/kg for 232 Th (UNSCEAR, 2000). Fig 1 is the graph showing the activity concentration of 40 K, 238 U, and 232 Th as well as the radium equivalent in the soil. It is observed from Fig. 1 that the percentage concentration of 40 K is the highest for all the studied sites making 40 K the dominant radionuclide in the study sites. This result agrees with the previous study elswhere within the South South zone of Nigeria (Iwetan et al., 2015, Bede et al., 2015). There is a high activity concentration of 238 U in soils at the Ntak Inyang quarry site with a maximum activity of 33.50±3.32 Bq/Kg while the activity concentration in some areas were below detection limit. Again Fig. 1 shows the low level of activity concentration of 232 Th in all the studied areas. The results of similar studies carried out in different local governments areas (LGA) of Akwa Ibom State are reported in Table 3. Analysis of the Table 3 shows that obtained radiological hazards indices for Itu local government Area are less than the values obtained from studies in other LGAs in the Akwa Ibom State except the activity concentration of 40 K in Itu local government are is greater than that in Ibeno and Uyo local government area. Table 1: Activity concentrations of 40 k, 238 U and 232 Th in the soil samples at the quarry sites at Ayadehe and Oku Iboku Location Sample Point K-40 (Bq/Kg) U-238 (Bq/Kg) Th-232 (Bq/Kg) ± ± ± ±4.35 BDL BDL ±7.36 BDL 4.37±0.26 OKU IBOKU AYADEHE ±7.24 BDL 4.19± ± ± ± ± ± ± ± ± ±0.27 Min 79.91±4.35 BDL BDL Max ± ± ±0.43 Mean ± ± ± ± ± ± ±8.56 BDL 5.31± ±1.26 BDL 1.96± ± ± ± ±2.56 BDL 0.71± ± ± ±0.11 Min 23.32±1.26 BDL 0.71±0.04 Max ± ± ±0.31 Mean 73.69± ± ± Radiological Hazard Indices in Soils of the Studied Areas In Tables 4 and 5 it is observed that the radium equivalent varies from 6.15Bq/kg to Bq/kg with a mean of Bq/kg for Ayadehe site, 4.6Bq/kg to 15.83Bq/kg with a mean of 11.78Bq/kg for Oku Iboku, Bq/Kg to 1.02 Bq/Kg and a mean value of Bq/Kg for Odiok Itam while the values for Ntak Inyang village was range between 37.26Bq/kg to 5.25 Bq/Kg and a mean value of Bq/Kg. These values are below the world standard of 370Bq/kg 74

6 International Journal of Scientific Research in Environmental Sciences, 4(3), pp , 2016 Table 2: Activity concentrations of 40 k, 238 U and 232 Th in the soil samples of the quarry sites at Odiok Itam and Ntak Inyang Location Sample Point K-40 (Bq/Kg) U-238 (Bq/Kg) Th-232 (Bq/Kg) ± ± ± ± ± ± BDL BDL 0.71±0.04 NTAK INYANG ODIOK ITAM ± ± ± ± ± ± ± ± ±0.13 Minimum BDL BDL 0.71±0.04 Maximum 75.85± ± ±0.28 Mean 33.96± ± ± ± ± ± ±1.60 BDL 2.04± ± ± ± ± ± ± ±5.35 BDL 2.74± ± ± ±0.03 Minimum 30.35±1.60 BDL 0.54±0.03 Maximum ± ± ±0.21 Mean 63.77± ± ±0.14 Table 3: Comparison of results for similar works within the State. L.G.A Raeq (Bq/Kg) 40 K (Bq/Kg) 238 U (Bq/Kg) 232 Th Bq/Kg) Reference Abak ± ± ±0.310 Chad umoren and Udoh, 2014 Eastern ± ± ±0.70 Bede, et al 2015 Obolo Eket ± ± ±0.62 Bede, et al 2015 Ibeno ± ± ±0.76 Bede, et al 2015 Ikot Abasi ± ± ±0.75 Bede, et al 2015 Uyo ± ± ±0.71 Bede, et al 2015 Itu ± ± ±0.18 Present Study Fig. 1: Mean activity concentrations for the radionuclides 75

7 Ntak Inyang Odiok Itam OKU IBOKU AYADEHE SITE Essien and Akpan Evaluation of Radiological Hazard Indices Due to Radioactivity in Quarry Sites in Itu, Akwa Ibom State, Nigeria Table 4: Calculated radiological hazard indices for the Ayadehe and Oku Iboku quarry sites Sample Raeq Absorbed Dose Total Annual Radioactivity Internal External points (Bq/Kg) Rate (ngyh -1 ) Effective Dose Level Index Hazard Hazard ELCR (X 10-3 (msvy -1 ) Index Index Mean Mean Sample point Table 5: Calculated radiological hazard indices for the Odiok Itam and Ntak Inyang quarry sites Raeq (Bq/Kg) Absorbed Dose Total Annual Radioactivity Internal External Rate (ngyh -1 ) Effective Dose Level Index Hazard Hazard ELCR (X 10-3 ) (msvy -1 ) Index Index Mean mean Standard Tables 4 and 5 show the results of the calculated radiological hazard indices for each of the quarry site. Absorbed dose rates vary from 4.30nGyh -1 to 18.67nGyh -1 with a mean of 9.80nGyh -1 for Ayadehe and 2.30nGyh -1 to 10.55nGyh -1 with a mean of 5.93nGyh -1 for Oku Iboku, 14.31nGyh -1 to 0.47nGyh -1 with mean value 7.22 ngyh -1 for Odiok Itam and absorbed dose rate range of ngyh -1 to 2.66 ngyh -1 and a mean value of 7.61nGyh -1 for Ntak Inyang. These values are below the world standard of 55.0nGyh -1. The mean total annual effective dose equivalent of mSvy -1 for Ayadehe site and a mean of mSvy -1 for Oku Iboku quarry site, mSvy -1 for Odiok Itam and mean value of mSvy -1 for Ntak Inyang quarry site. However, these values are within the msvy -1 range proposed by United Nations Scientific Committee on the Effect of Atomic Radiation (UNSCEAR). The calculated radioactivity level index values are below the world standard value of unity and the materials from these quarry site can be used for buidling construction without posing a health threat to the people (Tufail et. al, 2007). The calculated mean 76 internal and external hazard indices has a value range of and respectively. These values are below the world recommended standard of 1. This indicates that the values will not lead to respiratory diseases such as asthma and cancer and external diseases such as erythema, skin cancer and cataracts (Avwiri et al., 2012). The range mean excess lifetime cancer risk calculated for the studied area is between x x 10-3.These values are below the world standard of 0.29x10-3 implying that the probability of people in the quarry sites developing cancer cases is small (Taskin et al., 2009). 4. CONCLUSION The evaluation of radiological hazard indices and excess lifetime cancer risk in quarry sites in Itu Local Government Area of Akwa Ibom State, Nigerian have been conducted. This work saves as baseline for future radiological study of the quarry areas. The measured activity concentrations of 40 K, 238 U,and 232 Th in soil samples of the four quarry

8 International Journal of Scientific Research in Environmental Sciences, 4(3), pp , 2016 sites of were below their respective world recommended safety limit.the radionuclides are randomly distributed in the soil with a dorminant percentage of 40 K radionuclide.the calculated radiological hazard indices for the quarry sites are all below their respective world standards.the quarry activities nor the obtained building materials do not pose any significant health threat to the environment and it s residents. However, regular radiation monitoring and evaluation is recommended to checkmate the possible rise in radiation level due to the quarry activities in these areas. REFERENCES Avwiri GO, Osimobi JC, Agbalagba EO (2012). Evaluation of Radiation Hazard Indices and Excess Lifetime Cancer Risk Due to Natural Radioactivity in Soil profile of Udi and Ezeagu Local Government Area of Enugu State, Nigeria. Environmental and Earth Sciences. 1: 1-10 Bede MC, Essiett AA, Inam E (2015). An Assessment of Absorbed Dose and Radiation Hazard Index from Natural Radioactivity in Soils from Akwa Ibom State, Nigeria. International Journal of Science and Technology, 4(3): Beretka J, Mathew PJ (1985). Natural Radioactivity of Australian Building Materials, Industrial Waste and By-products. Health Physics, 48(75): Chad Umoren YE, Ohwekvwo E (2012). Influence of Crude Oil Spillage on the Gamma-Radiation status of Water and Soil in Ogba/ Egbema/ Ndoni Area. Nigeria. Energy and Environmental Research, 3(2):45-52 Chad Umoren YE, Umoh IJ (2014). Baseline Radionuclide Distribution Patterns in Soil and radiation hazards Indices for Abak, Nigeria. Advances in Physics Theories and Application, 32: Essiett AA, Essien IE, Bede MC (2015). Measurement of Surface Dose Rate of Nuclear Radiation in Coastal Areas of Akwa Ibom State, Nigeria. International Journal of Physics, 3(5): EL-Arabi AM (2005). Natural Radioactivity in Sand used in Thermal Therapy at the Red sea coast. Environmental Radioactivity, 81: El-Taher A, Uosif MA, Orabi AA (2004). Natural Radioactivity Level and Radiation Hazard Indices in Granites from Aswan to Wadi EL- Allaqi South Eastern Desert, Egypt. Radiation Physics and Protection Conference, 7: Fannu AE, Darko O, Ephraim JH (2011). Determination of Natural Radioactivity and Hazard in soils and Rocks samples in Mining Areas in Ghana. West African Journal of Applied Ecology, 19: Gbenu ST, Oladejo OF, Alayande O, Olukotun SF, Fasasi MK, Balogun FA (2015). Assessment of Radiological Hazard of quarry Products from Southwest Nigeria. Journal of Radiation Research and Applied Sciences, Innocent AJ, Onimisi MY, Jonah SA (2013). Evaluation of naturally Occurring Radionuclide Materials in Soils samples collected from some Mining Sites in Zamfara State. Nigeria. British Journal of Applied and Technology, 3(4): Iwetan CN, Fuwape IA, Arogunjo AM, Obor G (2015). Assessment of Activity Concentration of radionuclides in Sediment from Oil Producing communities of Delta State Nigeria. Journal of Environmental Protection, 6: Kocher DC, Sjoreen AL (1985). Dose rate Conversion Factors for External Exposure to Photon Emitters in Soil, Health Physics, 48: Taskin H, Karavus M, Topalloglu A, Hindroglu S, Karahan G (2009). Radionuclides Concentration in soils and Lifetime Cancer Risk of the Gamma Radioactivity in kirklareli, Turkey. Environmental Radioactivity, 100: Tufail M, Akhar N, Jaried SA, Hamid T (2007).natural Radiation Hazard in Building Bricks Fabrication from Soils of twodistricks of Pakistan,. Radiological Protection, 27: United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR, 2000): sources, Effects and Risks of Ionization Radiation. Report to the General Assembly, annexes B: exposures from natural Sources. New York, Pp

9 Essien and Akpan Evaluation of Radiological Hazard Indices Due to Radioactivity in Quarry Sites in Itu, Akwa Ibom State, Nigeria Dr. Imeh E. Essien holds a Ph.D in Applied Nuclear Physics, M. Sc in Nuclear Physics and a Bachelors of Science (B. Sc Hons) degree in Physics from University of Calabar, Nigeria. Dr Imeh Essien has 22 years of teaching and research experience at University level and 3 years in high school. He is presently holding the position of Senior Lecturer in the field of Physics at University of Uyo, Nigeria. His research area include, Radiation Protection Awareness, Radiation Dose Level due to Diagnostic X-ray Exposure in medical Diagnostic facilities, Radiation level due to Radioactivity in Soils, Shielding properties of local materials. Dr Essien has published research papers in reputable International and National Journals. He also supervised postgraduate works in the Departments of Physics and Engineering. Mr Emmanuel A. Akpan is a postgraduate student in the department of Physics of the University of Uyo awaiting to be awarded M. Sc in radiation/ health Physics. He is actively working on the area of environmental Physics as a part of his M.Sc. Project work.