The estimation of doses to the inhabitants arising from natural radiation source in the high background radiation area of Yangjiang, China
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Objective The purposes is to estimate the average annual effective dose of the inhabitants and absorbed dose in some human tissues and organs arising from natural radiation sources in the High Background Radiation Area(HBRA) of Yangjiang and in the neighboring Control Area(CA). In order to provide more effective evidence for analyzing the dose effect relationships among the cohort members in the investigated areas, we divided the local inhabitant into different dose groups. Methods We measured the environmental gamma external radiation levels and individual accumulated doses of 5?293 people in the investigated areas. The concentrations for 222 Rn, 220 Rn and their decay products in air were also surveyed. We estimated the internal doses of natural radionuclides based on the results obtained from measurements in food, in drinking water, in human teeth, in several human tissues, in human placenta, and in activity concentration of exhaled 222 Rn and 220 Rn of the residents living in the investigated areas. Results The estimation of average annual effective doses in HBRA and CA based on the data of environmental measurements of radiation level respectively are 2.12±0.29 mSv a -1 and 0.69±0.09 mSv a -1 . The sources of higher background radiation in HBRA are mainly contributed from terrestrial gamma radiation. The estimation of average annual effective doses to the residents arising from inhalation of 222 Rn, 220 Rn and their decay products was 3.28 mSv a -1 in HBRA, while that in CA was 1.03 mSv a -1 . The values of the absorbed dose of the residents in their trachea bronchial tree and lung in HBRA arising from inhalation of 222 Rn, 220 Rn and their decay products are 5.40 mGy a -1 and 1.08 mGy a -1 respectively, which are about four times of the values of the absorbed dose in CA. The estimation of average annual effective doses to the inhabitants caused by 226 Ra and 228 Ra in HBRA and CA were 281.88 μ Sv a -1 and 84.54 μ Sv a -1 respectively. The annual absorbed doses to red bone marrow and bone lining cells of the inhabitants in HBRA were estimated to be 25.54 μ Gy a -1 and 140.46 μ Gy a -1 respectively for 226 Ra and 228 Ra respectively, while in CA were estimated 7.68 μ Gy a -1 and 42.25 μ Gy a -1 respectively. Conclusion The values of the effective dose of the inhabitants arising from natural radiation sources in HBRA and CA are 5.9 mSv a -1 and 2.0 mSv a -1 respectively. The value of the effective dose of the inhabitants arising from natural radiation sources in HBRA is about three times of the value in CA. There are 23718 individuals whose effective dose is 7 mSv a -1 . The values of the effective dose caused by internal radiation and external radiation in HBRA are 3.76 mSv a -1 and 2.12 mSv a -1 respectively. The amount of the effective dose of the residents arising from inhalation of 222 Rn, 220 Rn and their decay products consists of about 88 percent of the total amount of the internal radiation dose of the residents in HBRA. The estimate of average annual effective dose the residents arising from inhalation of 222 Rn and its decay products in HBRA was 1.53 mSv a -1 . The average annual effective dose of the residents arising from 220 Rn and its decay products in HBRA is 17.5 mSv a -1 ,which is 17.5 times of the worldwide average value 0.10 mSv a -1 . Thus, the 220 Rn and its decay products are one of the main sources to cause the internal radiation dose of the inhabitants living in HBRA.Keywords:
Internal dose
Background radiation
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Introduction: Human beings are naturally exposed to ionizing radiation in any environment. There are two main contributors to radiation exposures from natural sources: cosmic rays, Cosmo genic radionuclides, and radioactive nuclides that originated in the earth's crust. According to the latest data provided by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), the estimated worldwide average annual exposure to natural radiation sources is 2.4 mSv, and the most exposures are in the range of 1–13 mSv/a. There are several small areas throughout the world where people are exposed to natural radiation sources that are in excess of those considered normal background”. However, there are no specific criteria in this regards, these areas are referred to as High Natural Radiation (HNRA) areas. Ramsar is one of these areas. The natural radioactivity of Ramsar is mainly due to the presence of Ra-226 along with its daughters. The aim of this study was to determine the internal and external exposures from natural radiation sources in Ramsar, and to estimate the total annual effective dose for the people in Ramsar. Materials and Methods: In this research, the all radiation sources and exposure pathways of people living in Ramsar were investigated. The concentration of 226Ra was measured by alpha spectrometry and radon emanation in different samples including foods and drinking water, and the internal dose was estimated. In addition, the annual effective dose of exposure to gamma rays and the annual effective dose due to inhalation of radon gas were calculated for residents. Results: The mean annual effective dose due to exposure to indoor gamma rays in Ramsar was 0.66 mSv, the range was 0.3 to 48 mSv, the mean annual effective dose due to exposure to outdoor gamma rays was 0.86 mSv, and the minimum was 0.1 mSv. The mean annual effective dose of internal exposure to radon gas was 10.3 mSv and its range was from 0.9 to 232 mSv. The mean annual effective dose due to ingestion of 226Ra was found 10 µSv and its range was 1 to 81 μSv. Conclusion: Based on the results of this study, the public annual effective dose of Ramsar from exposure to natural radiation sources was 1.25 to 281 mSv, with a mean value of 12 mSv. The results of this study show that the mean value (12 mSv) is approximately 5 times greater than the worldwide mean annual exposure to natural radiation sources reported by the UNSCAER (2.4 mSv). The results obtained could be used in determining the reference levels for controlling the exposure of people and in taking preventive measures to reduce the radiation exposure of the residents. In addition, the results of this research could be useful in the study of the effect of radiation on the public health.
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Background radiation
Environmental radioactivity
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A study to assess the Indoor and Outdoor Background Ionizing Radiation (BIR) of Sheda Science and Technology Complex, Abuja has been conducted. An in-situ measurement using a portable factory calibrated radiation dose rate meter, Radiagem 2000, was used to ascertain the radiation level. The measured radiation dose rates were used to evaluate the radiological health hazards and radiation effective doses to different body organs using well established radiological relations. The results shows that the total Dose Rate (indoor and outdoor), the Total Annual Equivalent Dose (indoor and outdoor), total Annual Effective Dose Equivalent (indoor and outdoor) and the total Excess Lifetime Cancer Risk (indoor and outdoor) are 0.113±0.022 (μSv/h), 0.071±0.016 (μSv/h), 0.794±0.155 mSv/y, 0.0.124±0.074 mSv/y, 0.556±0.109 mSv/y, 0.087±0.020 mSv/y, 1.945±0.379, 0.304±0.104 respectively for the three zones. The dosage to organs received shows that the testes have the highest dose while the liver has the lowest dose (indoor and outdoor) for the three zones. Generally the study shows that the Annual Effective Dose Equivalents were within the permissible limits of 1 mSv/y for general public exposure recommended by the (ICRP). Also, the effective doses to different body organs are all below the recommended limits of 1 mSv/y. The calculated Excess Lifetime Cancer Risk values indicates that the chance of contacting cancer by workers and residents of the study area is not probable hence the study area could be said to be radiologically safe.Keywords: Ionizing Radiation, Equivalent Dose, Effective Dose, Excess Lifetime Cancer Risk
Equivalent dose
Dose rate
Background radiation
Reference dose
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Dose rate
Background radiation
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From 1990 to 1998, estimations of the effective dose from external and internal irradiation due to 137Cs and 134Cs were carried out for inhabitants in rural villages in the Bryansk region, Russia, highly contaminated due to the Chernobyl accident in 1986. Yearly expeditions were conducted in autumn. The external effective dose was estimated from measurements with thermoluminescent (TL)- dosemeters worn by the participants during one month each year. The internal effective dose was estimated from measurements of the urinary concentration of caesium radionuclides, together with measurements of the body content using a portable detector. The mean effective dose from external and internal irradiation varied between 1.2 and 2.5 mSv per year between 1990 and 1998. The total mean effective dose decreased, on average, 7% per year, while the mean external dose decreased by 15% per year. The dose rate from internal irradiation decreased more slowly than the dose rate from external irradiation, showing large variations from year to year depending to a great extent on dietary habits. The contribution from the external dose to the total dose was between 50-70%, depending on the village. The cumulated effective dose for the 70-year period after the accident was calculated to be 100 mSv with the assumption that both internal and external dose will decrease by 2% per year.
Internal dose
Dose rate
External beam radiation
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Natural radioactivity
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In 1999 about 6208 radiation workers from 389 departments were monitored by CLOR in Poland. The distribution of annual personal doses shows that 85% of controlled workers received doses below the MDL (0.4 mSv) and about 97% controlled workers received doses below 5 mSv. Doses higher than 50 mSv were received by three operators of industrial radiography units. The radiation workers under control are divided into four main work sectors: nuclear industry, research and education, medicine, and general industry. The average annual dose for all workers in each particular sector was 0.22 mSv, 0.22 mSv, 0.30 mSv and 0.80 mSv, respectively. The average annual dose for the entire monitored population was 0.47 mSv. The average annual dose in each particular sector for number of workers receiving E > 0, i.e. Hp(10) > or = 0.4 mSv, amounted to 1.78 mSv, 2.03 mSv, 1.88 mSv and 4.85 mSv, respectively. The average annual dose for the full number of workers receiving E > 0 was 3.21 mSv. This paper contains the detailed analysis of occupational exposure. The distributions of annual occupational exposure in different work sectors are also given.
Collective dose
Equivalent dose
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The study of natural background radiation dose at thirty two locations of Kathmandu valley has been done successfully using the instrument Radalert 100. The average dose rates and annual effective dose were measured. From the measurements, the least value of average dose rate was found to be (22.3±3.9)×10-3 mR/hr for Sundhara and the greatest value of average dose rate was found to be (37.7±7)×10-3 mR/hr for Budhanilkantha 3. As per the annual effective dose, the least value was 0.391 mSv/yr for Sundhara and the greatest value was 0.661 mSv/yr for Budhanilkantha 3. The average annual effective dose of Kathmandu valley was 0.475 mSv/yr ranging from 0.391 mSv/yr to 0.661 mSv/yr. The values thus obtained were compared to the worldwide average value of annual effective dose, 0.48 mSv/yr. Also, the obtained values were compared to the legal dose limit (annual effective dose), 1 mSv/yr set by International Commission on Radiological Protection (ICRP) for non-radiation workers and members of public. Among these thirty two locations, eight locations were chosen such that they had larger range of the observed dose rates. Those eight locations were re-observed. Further, Chi-square test was carried out to test whether the observed dose rates were following normal distribution or not. From the calculation, it was observed that the observed dose rates were following the normal distribution.BIBECHANA 16 (2019) 187-195
Dose rate
Natural radioactivity
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As a part of the China-Japan cooperative research on natural radiation epidemiology, we have carried out a dose-assessment study to evaluate the external exposure to natural radiation in the high background radiation areas (HBRA) of Yangjiang in Guangdong province and in the control areas (CA) of Enping prefecture since 1991. Because of the difficulties in measuring the individual doses of all inhabitants directly by personal dosimeters, an indirect method was applied in which the exposed individual doses were estimated from the environmental radiation doses measured by survey meters and the occupancy factors of each hamlet. We analyzed the dose in the hamlets and the variation in the occupancy factors to obtain the parameters of dose estimation on the inhabitants in selected hamlets; Madi and several hamlets of different dose levels in HBRA and Hampizai hamlet in CA. With these parameters, we estimated individual dose rates and compared them with those obtained from direct measurement using dosimeters carried by selected individuals. The results obtained are as follows. 1) The environmental radiation doses are influenced by the natural radioactive nuclide concentrations in building materials, the age of the building and the arrangement of the houses in a hamlet. There existed a fairly large and heterogeneous distribution of indoor and outdoor environmental radiations. The indoor radiation doses were due to exposure from the natural radioactive nuclides in the building materials and were about two times as large as the outdoor radiation doses. The difference between indoor and outdoor doses was not observed in CA. 2) The occupancy factor was influenced by the age of individuals and by the season of the year. The occupancy factor was higher for infants and aged individuals than for other age groups. This lead to higher dose rates of exposure to those age groups. 3) A good correlation was observed between the dose assessed indirectly and that measured directly and the correlation factor was 0.97.
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Background radiation
Radiation monitoring
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Purpose : Environmental natural radiation measurement is of great importance and interest especially for human health. The induction of genetic disorder and cancer appears to be the most important in an exposed population. Method and Materials: Measurements of background gamma rays were performed using a mini‐rad environmental survey meter at 25 different locations around the city of Kermanshah (a city in the west of Iran). The measurements were also performed at two different time of day one in the morning and the other in the afternoon. At each location and time measurement were repeated for five times and the mean was considered as the background dose at that location. Results and Conclusion : Comparison between the measured results in the morning and afternoon have not shown any significant difference (P>0.95). The maximum and minimum obtained results were 2.63 mSv/y and 1.49 mSv/y respectively. From the total measurement at 25 sites mean and SD background radiation dose to the population is 2.24±0.25 mSv. It is about 2.5 times of the world average total external exposure cosmic rays and terrestrial gamma rays dose reported by UNSCEAR. Keywords: Background radiation, Ionizing radiation, low level radiation, Environment radiation.
Background radiation
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