Radiation protection of non-humans has recently been integrated into the ICRP (International Commission on Radiation Protection) framework using a reference animal and plant approach matching the anthropocentric 'reference human' approach. While this is simple to implement it has many drawbacks and is essentially focusing on measurements of uptake and transfer of radionuclides in individuals. This ignores the complexity and interdependence of natural ecosystems. It also ignores the biology involved in management of radiation damage in wild populations. To address these concerns international efforts are being made to develop a more ecocentric or holistic approach. Especially important is the recognition that ecosystems are very complex and that adverse emergent properties of these systems such as biodiversity collapse are not predictable from measurement of impacts on individuals. The paper discusses the limitations of current ICRP approaches and considers some promising new ideas, which may lead to more integrated protection systems involving the ecosystem as a central focus rather than the individual.
Exposure to radon and radon progeny within the home and at work constitutes one of the greatest hazards from radiation. Radon is continually generated from uranium and thorium, which occur in many rocks and soil. The concentration of 222Rn was measured in tap, natural spring and well water samples gathered from several places from the north-eastern area of Morocco. This work aims to determine any potential radiological hazard for the local population which might be due to an inevitable high concentration of radon in drinking water. We utilised an AlphaGUARD radon gas detector to perform our measurements. The results show reasonable radon concentrations when compared with international recommendations.
Twenty borehole (BH) and 15 hand-dug wells (HD) water samples were collected from Ifako-Ijaiye for this study. The samples were analysed using NaI (TI) detector for radioactivity and BUCK200 AAS for elemental concentrations. The Effective Dose Rates (EDR) and Excess Lifetime Cancer Risks (ELCR) were calculated from activity concentrations of 40K, 238U and 232Th. The activity and elemental concentrations were statistically correlated. The mean activity concentrations of 40K, 238U and 232Th in the BH water were 8.77±8.40 Bq/L, 1.03±0.19 Bq/L and 0.93±0.15 Bq/L, respectively; and 10.12±0.07 Bq/L, 0.94±0.34 Bq/L and 0.89±0.10 Bq/L, respectively in the HD water. The EDR and ELCR in the study were higher in the infant than either crèche or adult. The elemental concentrations in BH water were higher than the World Health Organisation (WHO) recommended limits. The ELCR in the study is higher than the USEPA limit; therefore, drinking untreated water from the area should be discouraged.
The purpose of this work is to estimate dose received in case of release of radionuclide into the atmosphere from the under-construction Rooppur Nuclear power plant (NPP) due to a hypothetical accident with the help of an atmospheric dispersion model. A generic source term code has also been developed using MATLAB by following NUREG-1228. The sensitivity analysis is based on variation of the received total effective dose equivalent (TEDE) corresponding to the variation of the uncertain input parameters. The sensitivity was seen to be higher at stable conditions with the change of high wind speed. Estimated TEDE dose results for Xe-133 at different downwind distances from Rooppur NPP site in different atmospheric stability classes. The maximum TEDE of 6.40E-06 Sv was estimated at maximum distance of 0.7 km from the site for stability class A, whereas, in case of unstable stability class B, it was 5.70E-05.
The aim in this present work is to determine the specific activities of 226Ra, 232Th and 40K in rock samples collected from Mounana in Gabon, to assess the contribution of natural radioactivity. A p-type high-purity germanium detector has been coupled with a multichannel analyser DSA-1000 to perform measurements and data processing. The energy resolution of the 1332 keV60Co line is still found to be 1.8 keV at FWHM, with a relative efficiency of 30%. The specific activities average values of 226Ra, 232Th and 40K are 6554±198 Bq/kg, 63±12 Bq/kg and 513±93 Bq/kg, respectively wet weight. To assess the radiological risks due to 226Ra, 232Th and 40K, many parameters were estimated. The average value of annual effective dose was 18.95 mSv from the studied area. Rock from Mounana presents a high radioactivity, and we are planning to measure radon in homes to assess the risks of living in Mounana.
The linear non-threshold (LNT) single-hit (SH) dose response model for cancer risk assessment is assessed with respect to its historical foundations. This paper examines and summarises how mistakes, ideological biases, and scientific misconduct by key scientists affected the acceptance, validity, and application of the LNT single-hit model for cancer risk assessment. This analysis concludes that the LNT single-hit model was inappropriately adopted for governmental risk assessment, regulatory policy and practices, and for risk communication.
This paper focuses on the relationship between radon concentration and lung cancer morbidity from the methodological point of view. Geographically aggregated data on cancer risk factors, collected for 3142 US counties and county-equivalents are discussed. Apart from the Least-Squares and Bayesian linear regression analysis, for the first time the Maximum Entropy Method (MEM) is used to investigate this type of correlation, where major confounding factors under considerations are altitude and ultraviolet (type B) radiation. First two methods of analysis show statistically significant decrease in the group with the high smoking prevalence. This trend did not depend on the sex of the subjects or their prevalence of smoking. The use of MEM provides a much richer picture of a clear trend of decreasing morbidity of lung cancer with increasing radon concentration level. Last but not least, it is shown that the data binning has to be made carefully as otherwise the conclusions based on the data can be dubious.
The present study aims to assess 222Rn concentration and its radiological hazard for agricultural soil samples collected from Wadi Al-Hussini and Tuban as agricultural areas. Forty agricultural soil samples were collected from Lahj Governorate, Yemen. AlphaGUARD was used to measure radon concentration, and radon exhalation rates and annual effective dose in the agricultural soil samples were calculated. The average 222Rn activity concentration, area radon exhalation rate, mass radon exhalation rate and annual effective dose outdoor are as follows: 5170 ± 1740 Bq m−3, (12.4 ± 4.18)×10−4 Bq m−2s−1, (20.3 ± 6.82)×10−6 Bq kg−1s−1 and 49.13 mSv y−1 for Wadi Al-Hussini, 7263±2061 Bq m−3, (17.4±4.95) × 10−4 Bq m−2s−1, (28.5±8.08)×10−6 Bq kg−1s−1 and 69.03 mSv y−1 for Wadi Tuban. The average value of 222Rn concentration in agricultural soil gas in Wadi Al-Hussini and Tuban is much higher than the value of United Nations Environment Programme (UNEP), which the recommended reference 100 Bq m−3.
Many experimental, ecological, and epidemiological studies have shown that low doses of ionising radiation may be beneficial to human health by causing an adaptive response, a process called 'hormesis'. The dual effect of radiation has been summarised by the qualitative dual-probability model, which estimates the resulting biological effect of the radiation by taking into account both (a) dose- and time-dependent damage and (b) dose- and time-dependent beneficial health effects (adaptive protection). We report here further development of the dual-probability model into a quantitative phenomenological model. Our main objective is to model the time-evolution response to radiation as a time-evolution of a damped oscillator in the critical damping regime. The model predicts that an organism's resistance to radiation stress can be considerably improved by 'radiation training'. If the model is verified by future experiments, it may prove valuable; for example, it could considerably improve the efficacy of radiation therapy by increasing therapeutic doses.
This study seeks to determine the concentrations of 238U, 232Th and 40K in water and sediments of the São Francisco River in Petrolina. For this purpose, high resolution gamma ray spectrometry with hyperpure germanium was performed. The levels of 238U, 232Th and 40K in the water samples were all under the detection limit. The concentrations of 238U, 232Th and 40K in the sediments varied from 5 to 76 Bq kg−1, from 11 to 521 Bq kg−1, and from 80 to 542 Bq kg−1, respectively. The results indicated an increase of availability of these radionuclides through the trophic chain in the São Francisco River.
For the radon map elaboration, radon measurements are generally performed in different seasons. Correction factors must be applied in order to represent comparable concentrations. The effects of environmental parameters have been investigated for the determination of these seasonal correction factors. Radon concentration measurements have been performed in several locations in Algiers over more than 17 seasonal periods. The average concentrations showed that the daily maximum appears in the early morning and the daily minimum in the late afternoon. Furthermore, the indoor radon concentration negatively correlates with both the indoor temperature and the relative humidity with correlation coefficients equal respectively to −0.22 and −0.31. The annual pattern features a maximum around December and a minimum around June.
The levels of natural radioactivity for 226Ra, 228Ra and 40K were measured for 28 water samples taken from Kufa River inside Governorate of Al-Najaf Al-Ashraf in Iraq. Measurements were performed using a HPGe gamma-ray spectrometer system. The activity concentration (mBq/l) varied from 17.70 ± 1.83 to 58.90 ± 3.34, 4.60 ± 0.86 to 37.10 ± 2.44 and 142.56 ± 07.96 to 652.67 ± 17.03 for 226Ra, 228Ra and 40K, respectively. The average values of activity concentration for 226Ra, 228Ra and 40K were 35.14 (mBq/l), 19.13 (mBq/l) and 352.84 (mBq/l), respectively. Annual effective dose in (nSv/y) was also calculated and all the annual effective dose values are much lower than the recommended values. So the water of Kufa River in Najaf Governorate, Iraq is safe to be used by humans either as drinking water or for daily routine activity.
This study aimed at measuring radioactivity in drinking water and to assess corresponding ingestion dose to the public and the uranium toxicity. Twenty samples were collected in the uranium bearing region of Poli, Cameroon. α- and γ-spectrometry were used for radioactivity measurements. The range of activity concentrations for each radionuclide is 0.7 ± 0.3-3.5 ± 0.5 mBq.l−1 for 238U, 0.07 ± 0.03-2.1 ± 0.9 mBq.l−1 for 235U, 0.6 ± 0.2-5.1 ± 0.6 mBq.l−1 for 234U, 10 ± 1 mBq.l−1 for 226Ra, 10 ± 2-16.8 ± 2.2 mBq.l−1 for 210Po. Ingestion dose due to intake of 238U, 235U, 234U, 226Ra and 210Po in water was assessed for six age groups. The mean ingestion dose ranges from 8.8 μSv.yr−1 for adult to 123 μSv.yr−1 for infant, higher than the reference level of the committed effective dose (100 μSv.yr−1) recommended by the World Health Organisation (WHO). The uranium mass ranges between 0.014 μg.l−1 and 0.18 μg.l−1, below the reference mass which is 30 μg.l−1 showing that the uranium toxicity is low. 234U/238U isotopic ratio in water was observed with values near the equilibrium on 70% of collected samples and far from equilibrium reaching 3.09 in a borehole.
Knowledge of accurate radio-isotopic signatures and chemical constituents is essential in assessing potential radiological hazards to the public and workers from exposure to NORM waste. For that reason, scale and sludge samples from Ghanaian oilfields were assessed using alpha spectrometry, gamma spectrometry, radon monitoring and scanning electron microscope techniques. Activity concentration of 238U, 232Th-series and 40K radionuclides for NORM residues have been evaluated. Fourteen trace elements were also identified and semi-qualitatively quantified. The obtained results clearly reflect that scale and sludge may present radiological risk for workers, public and environment.
Measurements of radon surface and mass exhalation rates were made for 35 types of building material samples frequently used in Morocco. In this survey, we used the Can technique, containing CR-39 detectors, to estimate the radon exposure from building materials. The surface and mass exhalation rates ranged from 37.92 mBq−2 h−1, 3.05 mBq kg−1 h−1 to 1545.60 mB q m−2 h−1, 43.14 mBq kg−1 h−1, with an average of 271.4192 mBq m−2 h−1 and 10.23 mBq kg−1 h−1, respectively. All the values of effective radium content and effective dose were calculated and they were within the safe limit in all samples studied.
