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Background: Health hazards associated with exposure due to the natural radioactivity which is a part of our physical environment are of great concern. In order to assess the risks associated with exposure due to the natural radioactivity in soil and building materials, extensive studies have been carried out all over the world. The most commonly encountered radionuclide’s are ²³⁸U, ²³²Th, their decay products and ⁴⁰K. Materials and Methods: In order to study the concentration of these radionuclides soil, sand, gravel aggregates, bricks and marble, samples were collected from different sites and local suppliers of the district Mirpur, Azad Kashmir (Pakistan). ²²⁶Ra, ²³²Th, and ⁴⁰K activities in the collected samples were measured using HPGe detector. The measured specific radioactivity concentration of ²²⁶Ra, ²³²Th and ⁴⁰K in the studied samples ranged from 10 ±1 to 47 ± 2, 18 ± 1 to 75 ± 4 and 40 ± 3 to 683 ±3 Bq.kg-1, respectively. Results: From the measured activity concentration, radium equivalent activity, external and internal hazard indices, gamma and alpha indices, terrestrial absorbed dose and annual effective dose were calculated. Maximum value of radium equivalent activity of 197.1 ± 9 Bq.kg-1 was observed in soil sample whereas minimum value of 45.9 ± 2 Bq.kg-1 was found in gravel aggregates. Relatively higher mean values of hazard indices were found in brick samples. Annual effective dose varied from 0.06 ± 0.01 to 0.47 ± 0.02 mSv.y-1. Conclusion: Current values of annual effective dose, radium equivalent activity and hazard indices have been found to be within the recommended limits. Iran. J. Radiat. Res., 2011 9(2): 77-87

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Background: The natural radionuclides are always present in soil and care needs to be taken to minimize the radiation dose to humans. These radionuclides are mostly gamma ray emitting radionuclides which contribute to the radiation dose in long term behavior of radionuclides in soil. Health hazards associated with natural radioactivity are of great concern and it is necessary to assess risk due to them. The most common radionuclides found are ²³⁸U, ²³²Th and ⁴⁰K. Materials and Methods: The activity concentration of natural radionuclides in the soil samples collected from South Konkan region of Maharashtra, India were analyzed using HPGe based gamma spectrometry. Results: The activity concentrations from the selected villages are found to be ranging from 24.78 ± 0.14 to 76.38 ± 0.31Bq kg-1 for 238U, 30.08 ± 0.14 to 96.18 ± 31Bq kg^-1 for ²³²Th and 105.34 ± 0.24Bq kg^-1 to 432.51 ± 0.48Bq kg^-1 for ⁴⁰K. The average absorbed dose rate in air was calculated as 66.89nGy h^-1.The annual effective dose rates were varied from 0.27mSv y^-1 to 0.85mSv y^-1 with an average of 0.49mSv y^-1. The mean radium equivalent activity value for soil samples of South Konkan was 144.84 Bq kg^-1 which is lower than 370Bqkg^-1 of world average. Conclusion: It is observed that the study area is free from hazards of Radium and its progeny nuclides like Radon. The external hazard index for all soil samples from South Konkan was lower than unity denoting that the villages from this study area are safe for human health.

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Background: Vegetation (food stuff) is grown in soil that contains many radioactive elements such as ²³⁸U (uranium), ²³²Th (thorium) and ⁴⁰K (potassium), which may get deposited either due to radioactive fallout or/and by absorption from the soil and can pose serious health hazards. Materials and Methods: Natural radioactivity, radiological hazards and annual effective dose assessment was carried out in vegetation samples (vegetables, cereals and fruits) collected from fields and market. Gamma spectrometry using HPGe detector was used. Results: The measured specific activity concentration of ²³⁸U (uranium), ²³²Th (thorium) and ⁴⁰K (potassium) varied from 10.25 ± 0.94 Bq/kg to 29.13 ± 0.69 Bq/kg, 22.20 ± 2.46 Bq/kg to 58.21 ± 1.15 Bq/kg, and 1158.4 ± 26.05 Bq/kg to 1962.2 ± 18.17 Bq/kg respectively in various vegetable and cereal samples and varied from 2.5 ± 0.16 Bq/kg to 9.8 ± 0.15 Bq/kg, 7.4 ± 1.24 Bq/kg to 18.4 ± 1.39 Bq/kg, and 287.13 ± 11.23 Bq/kg to 815.72 ± 12.50 Bq/kg respectively in various fruit samples studied in the present work. From these values, hazard indices, the minimum and maximum values of absorbed dose and indoor and outdoor annual effective doses were calculated for various samples used in the present investigation. Conclusion: The various values obtained were found to be within the recommended limits. The absorbed dose and annual effective dose for the vegetable and cereal samples in which fertilizers were used to enhance the crop yield were higher than that in fruit samples.

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To assess the environmental radioactivity levels and hence to determine the population exposure in Kutubdia Island, Bangladesh the sediment samples were analyzed by using gamma ray spectrometry. In those sediment samples the average activity concentration of natural radionuclides ²³⁸U, ²³²Th and ⁴⁰K were found 15.39±1.67, 38.35±0.76 and 475.51±21.15 Bq/kg respectively. The activity concentration of ²³⁸U and ²³²Th were less than the world average. But the activity concentration of ⁴⁰K was higher than the world average values. These results were used to calculate the radiological hazard parameters like radium equivalent activities (Ra_eq), representative level index (I_γr). Due to natural radionuclides in sediment, the effective annual outdoor dose in the study area was 0.07 mSv; which is within the accepted range of 0.07 mSv. The average value of radium equivalent activities (Ra_eq) and representative level index (Igr) were found to be 128.03±12.08 Bq/Kg and 0.96±0.09 Bq/Kg which were greater than the world average. The anthropogenic radionuclide ¹³⁷Cs was also found in few samples. The average activity concentration of ¹³⁷Cs was 1.64±0.20 Bq/kg which is lower than the world average. The obtained experimental data of this research work would be useful to assess the population exposure from radionuclides in sediment as well as base line data of natural radioactivity in this island.

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