Radiometric survey of sediments and health risk assessments from the southern coastal area of Delta State, Nigeria

Over the years, the release of potential radiological components around the oil exploration environment has increased with potential health implications.Yet; the mechanism and health associated assessment have remained fuzzy to most experimental scientists. The current study determines the activity concentration of radionuclides in sediments and the corresponding health risk assessments from the hydrocarbon exploration environment of the southern coastal area of Delta State, Nigeria. A Sodium-iodide NaI(Tl) detector, with a well-calibrated multichannel analyzer (MCA) to ensure efficiency and energy was utilized. A total of seventy-five sediment samples (Five sediment samples each per community) were collected from the southern coastal area of Delta State, Nigeria. The mean activity concentrations of 40K, 238U, and 232Th of the sediment samples were 3361.48 ± 194.26 Bqkg-1, 40.11 ± 16.17 Bqkg-1, and 45.73 ± 19.27 Bqkg-1 respectively. The obtained mean values exceeded the world standard limit of 400 Bqkg-1, 35 Bqkg-1, and 30 Bqkg-1 respectively. Also, the computed mean radiological health hazard risk of radium equivalent activity (Raeq), representative level index (Iyr), external hazard index (Hex), internal hazard index (Hin), absorbed gamma dose rate (D), annual effective dose equivalent outdoor and indoor (AEDE) and lifetime cancer risk (ELCR) values are 363.94 ± 32.37 Bkgl-1, 2.9657 Bkgl-1, 0.9839, 1.0919, 175.82 nGyh-1, 2.1556 mSvyr-1, 0.8625 mSvyr-1, and 7.5447 mSvyr-1 respectively. The values were found to be slightly higher than the world standard limit. Therefore, the residents that are using the sediments of the southern coastal area for the construction of buildings as well as dwelling in houses built with such sediments are exposed to these radiological materials. This may pose a radiological health risk concern. The obtained results will serve as radiation and radiological baseline data for sediments of the southern coastal area of Delta State, Nigeria.

Evaluation of radiological health risk caused by the use of fly ash in cement and concrete production and its storage

As a result of firing pulverized coal in thermal power plants, enormous amounts of fly ash (FA) are produced as industrial waste. The release into the atmosphere and storage of this industrial waste remains one of the major environmental problems that threaten human health by contributing to air, water, and soil pollution. The recovery and reuse of FA in the construction industry is the only economic solution to the existing problem. In this study, the potential radiological risk caused by the usage of FA in concrete and cement production as a main component and its storage in landfill sites was evaluated for people and works by estimating radiological parameters (activity concentration and alpha index, annual effective doses, and the corresponding excess lifetime cancer risks) based on activity concentrations of terrestrial radionuclides in FA. Also, the radiological risk to the workers working in the FA landfill site was evaluated using the Residual Radioactivity Onsite 7.2 code. The average activity concentrations of terrestrial radionuclides in FA samples from the Tunçbilek lignite coal-fired thermal power plant at Kütahya province of Turkey were measured as 417, 156 and 454 Bq kg-1 for 226Ra, 232Th and 40K, respectively. When using up to 35% by mass of FA in cement and concrete, the average values of the radiological parameters revealed that they were within the recommended safety limits. However, code estimations showed that a regular worker in FA storage would be exposed to a total effective dose rate greater than 3 mSv y-1.

Radioactivity concentration and radiological risk assessment of beach sand along the coastline in the Mediterranean Sea

A radiological baseline survey was conducted using a calculation analysis to assess the 226Ra, 232Th, 40K, and 137Cs distribution in beach sand samples collected from the coastal areas of the Mediterranean Sea. An analysis of the activity concentration of selected radionuclides was conducted. No evidence of recent migration of radiocaesium was found through precipitation, as well as indirect pathways, such as ocean runoff. The activity concentration of 226Ra, 232Th, 40K and 137Cs in beach sands ranged from 12 ± 1 to 37 ± 4 Bq kg- 1 (mean of 26 ± 3 Bq kg- 1); 18 ± 2 to 71 ± 8 Bq kg- 1 (mean of 40 ± 5 Bq kg- 1); 411 ± 10 to 720 ± 16 Bq kg- 1 (mean of 572 ± 12 Bq kg- 1); and 0.8 ± 0.1 to 3.1 ± 0.6 Bq kg- 1 (mean of 1.9 ± 0.3 Bq kg- 1), respectively. The radiological risk assessment showed that in all cases the values were lower than those that endanger life and safe work.

Assessment of radiation hazard indices due to naturally occurring long-life radionuclides in the coastal area of Barra de Valizas, Uruguay

The Uruguayan east coast has several mineral resources, which include black sand ores in the Barra de Valizas-Aguas Dulces area. Cancer in Uruguay shows non-homogeneous geographical distribution, with the highest standardized mortality ratio (SMR) in the northeast and east region, which includes the aforementioned area and the town of Barra de Valizas. The activity concentration of natural radionuclides (226Ra, 232Th and 40 K) in Barra de Valizas´soil was determined by gamma spectrometry in order to evaluate the radiological hazard for inhabitants and tourists. The outdoor annual effective dose (AEDE), excess lifetime cancer risk (ELCR), and annual gonadal dose equivalent (AGDE) were evaluated for inhabitants with a life expectancy of 77.7 years, a 0.2 and 0.5 occupancy factor, and using the conversion coefficients recommended by United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). The annual effective dose was also evaluated for both summer and fortnight tourists. The radiological hazard indices for Barra de Valizas inhabitants are higher than the worldwide mean and recommended values. This may contribute to Rocha's higher SRM value, although a direct correlation cannot be assured with the epidemiological information currently available. Social, medical and anthropological studies will be carried out in future to provide data and verify this correlation.

Evaluation of radiological risk associated with local building materials commonly used in Northwestern Nigeria

In this study, potential radiological risk due to the activity concentrations of primordial radionuclides (²²⁶Ra, ²³²Th, and ⁴⁰K) in commonly used local building materials (sand, clay, kaolin and gypsum) in Northwestern Nigeria were assessed using NaI (Tl) detector. The measured activity concentrations ranged from 47 to 63 Bq kg^-1 for ²²⁶Ra, 24-32 Bq kg^-1 for ²³²Th, and 219-257 Bq kg^-1 for ⁴⁰K respectively. The mean values of ²³²Th, and ⁴⁰K for all samples were below the respective world averages of 45 and 420 Bq kg^-1 with that of ²²⁶Ra for all the samples higher than the world average value of 32 Bq kg^-1. The potential radiological risks were assessed by determining radium equivalent activity (Ra_eq), internal and external hazard indices (H_in and H_ex), absorbed gamma dose rates (D_R), internal annual effective dose rates (IAED), and annual gonadal dose equivalent (AGDE) and activity utilization index (AUI). The assessed parameters were found to range between 104 and 125 Bq kg^-1, 0.99 to 1.15, 0.28 to 0.34, 48 to 58 nGyh^-1, 0.76 to 0.86 mSvy^-1, and 0.78 to 0.96 respectively. The Ra_eq and D_R for all the analyzed samples were found to be within International recommended limits of 370 Bq kg^-1 and 59 nGy h^-1 as recommended by UNSCEAR.

Radiological assessment of the disposal of bulk oil NORM waste: Case study from Brazil

The oil and gas industries are the largest producers of NORM wastes that are continuously generated during production and extraction activities. In addition, an increasing trend is observed in waste production worldwide due to the decommissioning of oil platforms. The problem is that most of these wastes are in activity concentration levels above the exemption and the clearance limits and are being accumulated in storage sites because no repositories exist in Brazil for NORM wastes generated by oil industries. There are regulations for radioactive wastes and for the licensing of repositories for managing wastes with low and intermediate levels of radiation but the current regulations apply only to packaged wastes. Therefore an initial radiological assessment was carried out with the RESRAD-OFFSITE code to show that bulk NORM wastes (not packaged wastes) could be disposed of in repositories near the surface without causing additional risk to the public above the criteria used. The results can also support decision-making by the Regulatory Authority to change the current regulations and allow for the disposal of wastes in bulk form.

Evolving radiological protection guidelines for exploration-class missions

International Space Station partner nations have yet to agree on career radiation dose constraints. This is of increasing concern for collaborative mission planning beyond low-Earth orbit, since it is likely that one or two long-duration missions will expose crew to a cumulative dose that approaches or exceeds their current respective limits. As with radiological effects, the cumulative health impact of the numerous other injuries and illnesses documented during spaceflight is inherently heightened with longer and farther missions, say to the Moon and Mars. This paper summarizes the origin of existing radiological constraints employed by the Canadian Space Agency and explores how to build upon these protection practices to address the challenges associated with beyond low-Earth orbit missions. The discussion then leads into a review of conventional risk metrics currently under evaluation by space-faring nations to quantify risk of radiation-induced cancer mortality. This paper concludes with a proposal for the application of an existing burden of disease model termed the Disability Adjusted Life Year, to space exploration. This model can accommodate the many health hazards of spaceflight, including ionizing radiation, on a common scale. It has the potential to serve as an intuitive communication tool for informing on the impact of spaceflight on crew health.

Artificial neural network modeling of meteorological and geological influences on indoor radon concentration in selected tertiary institutions in Southwestern Nigeria

Exposure to indoor radon, with no safe level, has been reported to bear the possible radiological risk to humans. The indoor radon level of a total of one hundred and thirty-two offices and sixty classrooms of tertiary institutions within different lithology and at varied meteorological values in southwestern Nigeria was measured using Electret Passive Environmental Radon Monitor (E-PERM). The meteorological parameters were obtained from the National Aeronautics and Space Administration (NASA) database. MATLAB scripts of code were used to develop the Artificial Neural Network (ANN) model. The measured parameters were subjected to both descriptive and inferential statistics. The highest mean radon concentration was observed in offices built on granitic bedrock with a value of 64.3 ± 1.7 Bq.m^-3 while the lowest was observed in alluvium bedrock with a value of 52.5 ± 1.4 Bq.m^-3. To enhance prediction involving erratic parametric patterns, the measured data were subjected to an optimized Artificial Neural Network architecture training, validation, and testing, leading to a model determined to have a Nash-Sutcliffe efficiency coefficient value of 0.997, Average Absolute Relative Error of 0.0115, and Mean Squared Error of 0.07. The predicted result was compared favorably with the measured data with 0.054 Average Validation Error, 0.027 Mean Absolute Error 3.64 Mean Absolute Percentage Error, and 83.7% Goodness-of-Prediction values. About 21.4% of the values were found to be higher than the 100 Bq.m^-3 limits specified by the World Health Organization. Measured radon concentration and predicted ANN data as obtained in this work, being novel in this study area is useful for immediate assessment of the level of risk associated with radon exposure as well as for future predictions. The ANN developed is effective and efficient in predicting indoor radon concentration.

Assessment of released natural radionuclides by waste rock pile and mining pit associated with a uranium mine at Caldas, Minas Gerais, Brazil

The Ore Treatment Unit was a uranium mining company that is currently being decommissioned. The local rainfall index makes it necessary to release effluents into the environment. After releasing, the wastewater is available for unrestricted use. Current study aims to use national and international recommendations to assess the radiological potability of released effluents at one of the three points of company's interface with the environment. Twenty-four samples of water were collected and activity concentrations (AC) were obtained by gross alpha count, gross beta count, and for arsenazo spectrophotometry. Statistical analysis techniques were applied to the data with the purpose of understanding the results for the soluble, particulate, and total fractions. The mean AC for effluents were 3.580, 0.082, 0.103, 0.063, and 0.090 Bq L^-1 for U_nat, ²²⁶Ra, ²¹⁰Pb, ²³²Th, and ²²⁸Ra, respectively, for the total fraction. The analysis of variance pointed to U_nat as a critical radionuclide, since it presented more than 90% of the total AC released into the environment. Pearson's R² pointed to soluble fraction as a major contributor to the total AC released. The guidance level proposed by WHO was used to assess the radiological potability of the effluents. The results obtained indicated the need for trigger other analyses. Committed effective dose was estimated due to the unrestricted use of effluents and the value obtained, 0.23 mSv year^-1, was below the maximum allowed limit. Finally, the radiotoxicity of the released effluent was evaluated and the value obtained was ~ 50% of the maximum allowed limit. In conclusion, the present study showed that the level of radioactivity released into the environment by the Ore Treatment Unit does not present a radiological risk to the surrounding population.

Radiological risks from 40 K, 226Ra and 232Th in urbanised and industrialised karstic coastal area (Kaštela Bay, Croatia)

Radiological risks associated with ⁴⁰ K, ²²⁶Ra and ²³²Th massic activities in limestones, marls, stream sediments and soils of the Kaštela Bay (Croatia) coastal area were assessed by calculating outdoor absorbed dose rates in air (D), annual outdoor effective dose rates (D_ef), radium equivalent activities (Ra_eq) and external hazard indices (H_ex). Radionuclides relative contributions to D and H_ex were determined for all four types of samples as well as their total contribution to H_ex in all samples. D, D_ef, Ra_eq and H_ex were the lowest in limestones and the highest in soils. Maximum Ra_eq and H_ex in soil were below the recommended values of 370 Bq/kg and 1.0. No adverse radiological effects were determined in the researched area. The most important contribution to D and H_ex in limestones was almost exclusively from ²²⁶Ra, in marls from ⁴⁰ K, in stream sediments from ²²⁶Ra and in soils from ²³²Th. The most significant total contribution to H_ex in all samples came from ²²⁶Ra and ²³²Th, and the lowest came from ⁴⁰ K. ²²⁶Ra showed the largest variability of its total contribution to H_ex, with tendency to higher values. Special attention should be given to ²²⁶Ra when studying radiological risks in typical karstic areas, irrespectively of other possible influences of geological background.

Radiological risk assessment to the public due to the presence of radon in water of Barnala district, Punjab, India

Various research studies have shown that exposure to radon gas is a cause of concern for health effects to the public. The present work has been carried out for the radiological risk assessment to the public due to the presence of radon isotopes in drinking water of Barnala district of Punjab, India, for the first time using scintillation-based radiation detector. A total of 100 samples were collected from different sources of water (canal and underground water) from 25 villages on grid pattern of 6 × 6 km² in the study area for uniform mapping. In situ measurements were carried out to find out Rn-222 concentration in water samples. The measured values have been found to vary from 0.17 ± 0.01 to 9.84 ± 0.59 BqL^-1 with an average value of 3.37 ± 0.29 BqL^-1, which is well below the recommended limit of 100 BqL^-1(WHO 2004). The annual effective dose due to ingestion and inhalation of radon has also been calculated for various age groups like infants, children and adults to understand the age-wise dose distribution. The calculated values suggest that there is no significant health risk to the general public from radon in water.

Radiation exposure of the operators in the preparation and administration of yttrium-90 microspheres in the treatment of malignant hepatic lesions: What is the risk?

Liver radioembolization is an emerging treatment against liver primary and secondary tumours. The whole procedure of radioembolization involves different health care specialists with different expertise. During the fractionation and infusion phases, the personnel manipulates high activities of ⁹⁰Y. In our centre, the number of radioembolization treatments per year is increasing; the aim of this study is to monitor the dose to the operators and to estimate the radiological risk for the operators involved in the RE. At present, two medical devices are approved: Sir-Sphere® and Therasphere™, both loaded with ⁹⁰Y. The dosimeters used were TLDs placed over the fingertips, for a total of 4 dosimeters for each phase; the selected dose descriptor was Hp_0.07. The study concerned 17 patients affected by malignant hepatic lesions, treated from September 2017 to March 2018. We performed 27 procedures: 10 fractionations (with Sir-Sphere®) and 17 infusions to the patients (10 with Sir-Spheres®, 7 with Theraspheres™). For fractionation phase, the average activity of each preparation was 3.34 GBq, the average value of Hp_0.07 was 0.50mSv. For infusion phase, the average activity was 1.51 GBq for Sir-Sphere® and 2.10 GBq for Theraspheres™, the average value of Hp_0.07 was 0.10mSv. No significant differences were found between senior (Hp_0.07 = 0.08mSv) and young operators (Hp_0.07 = 0.09mSv), respectively. Similarly, no significant differences were found between the right and left hand, with the same average value of Hp_0.07 (0.01mSv). In conclusion, the results are encouraging, since fingertips reported doses very low. The handling of ⁹⁰Y microspheres and the radioembolization procedure can be carried out under safe conditions.

Radiological and chemical risks by waste scales generated in the titanium dioxide industry

Along the industrial process devoted to the production of titanium dioxide pigments by using ilmenite as main raw material, small residues amounts are generated, remaining clearly enriched in natural radionuclides and chemical pollutants. Between them, we can remark the scales enriched in both radium isotopes and lead, which are formed in the internal walls of pipes and some equipment. These scales are radiological anomalies that demand its mineralogical, elemental and radiometric characterization as a basis for a detailed radiological and toxicological assessment from the occupational and public point of view. In this work, several scales collected in a TiO₂ pigment production plant in South of Spain have been mineralogically characterized by XRD, while information about their elemental composition and morphology have been obtained by applying the XRF and SEM techniques. In addition, radiometric determinations have been performed by gamma-ray and alpha-particle spectrometry. The performed study indicates that the radiological doses received due to the scales by the workers performing its conventional activities are clearly lower than 1 mSv/y. Special dosimetric and chemical controls could be needed for the workers in charge of the maintenance labours (which include the removal of the scales) if these workers belong to an external company devoted to perform maintenance operations in several NORM industries.

Radiation exposure of the operators in the preparation and administration of yttrium-90 microspheres in the treatment of malignant hepatic lesions: what is the risk?

Liver radioembolization (RE) is an emerging treatment against liver primary and secondary tumours. The whole procedure of RE involves different health care specialists with different expertise. During the fractionation and infusion phases, the personnel manipulates high activities of ⁹⁰Y. In our centre, the number of RE treatments per year is increasing; the aim of this study is to monitor the dose to the operators and to estimate the radiological risk for the operators involved in the RE. At present, two medical devices are approved: Sir-Sphere® and Therasphere™, both loaded with ⁹⁰Y. The dosimeters used were TLD placed over the fingertips, for a total of four dosimeters for each phase; the selected dose descriptor was Hp_0.07. The study concerned 17 patients affected by malignant hepatic lesions, treated from September 2017 to March 2018. We performed 27 procedures: 10 fractionations (with Sir-Sphere®) and 17 infusions to the patients (10 with Sir-Spheres®, seven with Theraspheres™). For fractionation phase, the average activity of each preparation was 3.34 GBq, the average value of Hp_0.07 was 0.50 mSv. For infusion phase, the average activity was 1.51 GBq for Sir-Sphere® and 2.10 GBq for Theraspheres™, the average value of Hp_0.07 was 0.10 mSv. No significant differences were found between senior (Hp_0.07 = 0.08 mSv) and young operators (Hp_0.07 = 0.09 mSv), respectively. Similarly, no significant differences were found between the right and left hand, with the same average value of Hp_0.07 (0.01 mSv). In conclusion, the results are encouraging, since fingertips reported doses very low. The handling of ⁹⁰Y microspheres and the RE procedure can be carried out under safe conditions.

Baseline levels of natural radionuclides concentration in sediments East coastline of North Cyprus

In this study, surface sediment samples from the North Cyprus East coast of the Mediterranean Sea were collected to determine the concentrations of three main natural radionuclides (²²⁶Ra, ²³²Th, and ⁴⁰K) using a high-resolution HPGe gamma-spectroscopy system. The activity concentrations of ²²⁶Ra, ²³²Th, and ⁴⁰K in the selected sediment samples ranged from 11.5 to 31.6, 11.8 to 24.9, and 391.7 to 1014 Bq kg^-1 dw (dry weight), respectively. The concentration distribution analysis showed that the kurtosis statistics parameter was negative, and the concentration distribution was less peaked than the normal curve. The mean activity concentrations of ⁴⁰K (628.1 Bq kg^-1) in the sediment samples was higher than the worldwide average (420 Bq kg^-1) concentration. The radium equivalent activity, external hazard, internal hazard and gamma activity concentration indexes were calculated to assess the pollution and risk level of radionuclides. The radiological risk assessment indicated that observed values were below the threshold values.

Cardiac arrhythmia catheter ablation procedures guided by x-ray imaging: N-acetylcysteine protection against radiation-induced cellular damage (CARAPACE study): study design

PURPOSE

Catheter ablation (CA) procedures are characterized by exposure to ionizing radiations (IR). IR can cause DNA damage and may lead to carcinogenesis if not efficiently repaired. The primary endpoint of this study is to investigate whether intravenous administration of N-acetylcysteine prior to CA procedure may prevent systemic oxidative stress and genomic DNA damage induced by exposure to IR.

METHODS

The "Cardiac Arrhythmia catheter ablation procedures guided by x-Ray imaging: N-Acetylcysteine Protection Against radiation induced Cellular damagE" (CARAPACE) study is a prospective, randomized, single-blinded, parallel-arm monocenter study enrolling 550 consecutive patients undergoing CA at the Arrhythmology Unit of Centro Cardiologico Monzino (CCM). Inclusion criteria are age ≥ 18, indication for CA procedure guided by IR imaging, and written informed consent. IR levels will be measured via fluoroscopy time, effective dose, and dose area product. Glutathione and glutathione disulfide concentrations will be measured, and urinary levels of 8-iso-prostaglandin-F_2α and 8-hydroxy-2-deoxyguanosine will be quantified. The enrolled patients will be randomized 1:1 to the N-acetylcysteine group or to the control group.

RESULTS

We expect that pre-operative administration of N-acetylcysteine will prevent IR-induced systemic oxidative stress. The study will provide data on oxidative DNA damage assessed by urinary 8-hydroxy-2-deoxyguanosine levels and direct evidence of genomic DNA damage in blood cells by comet assay.

CONCLUSION

Catheter ablation procedures can lead to IR exposure and subsequent DNA damage. N-acetylcysteine administration prior to the procedure may prevent them and therefore lead to less possible complications.

TRIAL REGISTRATION

www.clinicaltrials.gov (NCT04154982).

Uranium distribution in groundwater and assessment of age dependent radiation dose in Amritsar, Gurdaspur and Pathankot districts of Punjab, India

A comprehensive study of seasonal variation of uranium distribution in groundwater of Amritsar, Gurdaspur and Pathankot districts of Punjab, India and assessment of associated radiological risks, chemical risks and effective radiation dose for different age groups, was conducted to determine its health impact on humans residing in these regions. Physicochemical parameters such as pH, EC, TDS, total hardness and contents of various anions such as carbonates/bicarbonates, chlorides, fluorides, nitrates, sulphates and phosphates in groundwater were also analysed to determine correlation between groundwater chemistry and uranium distribution. The average values of uranium concentration in ground water samples of Amritsar, Gurdaspur and Pathankot districts were found to be 8.6 μg L^-1, 4.3 μg L^-1 and 3.0 μg L^-1, respectively, in pre-monsoon and 8.8 μg L^-1, 4.9 μg L^-1 and 3.4 μg L^-1, respectively, in post-monsoon. The uranium concentration in majority of the ground water samples was found to be below the permissible limit of 30 μg L^-1 recommended by World Health Organization (WHO, 2011). In all three districts, TDS, EC and bicarbonates were found to have positive correlation with observed uranium contents in both seasons. The annual effective dose due to ingestion of uranium through drinking water was found to be less than the prescribed limit of 100 μSv y^-1 given by WHO (2004). Radiological and chemical toxicity risk assessment of uranium in groundwater was also carried out and found to be within the permissible values of 1.67 × 10^-4 and 4.53 μg kg^-1 day^-1 respectively, recommended by Atomic Energy Regulatory Board (AERB, 2004).

Distribution and potential health risk of groundwater uranium in Korea

Chronic exposure even to extremely low specific radioactivity of natural uranium in groundwater results in kidney problems and potential toxicity in bones. This study was conducted to assess the potential health risk via intake of the groundwater containing uranium, based on the determination of the uranium occurrence in groundwater. The groundwater was investigated from a total of 4140 wells in Korea. Most of the groundwater samples showed neutral pH and (sub-)oxic condition that was influenced by the mixing with shallow groundwater due to long-screened (open) wells. High uranium contents exceeding the WHO guideline level of 30 μg L(-1) were observed in the 160 wells located mainly in the plutonic bedrock regions. The statistical analysis suggested that the uranium component was present in groundwater by desorption and re-dissolution processes. Predominant uranium phases were estimated to uranyl carbonates under the Korean groundwater circumstances. These mobile forms of uranium and oxic condition facilitate the increase of potential health risk downgradient. In particular, long-term intake of groundwater containing >200 μg U L(-1) may induce internal exposure to radiation as well as the effects of chemical toxicity. These high uranium concentrations were found in twenty four sampling wells of rural areas in this study, and they were mainly used for drinking. Therefore, the high-level uranium wells and neighboring areas must be properly managed and monitored to reduce the exposure risk for the residents by drinking groundwater.

Assessment of radiological risk for marine biota and human consumers of seafood in the coast of Qingdao, China

This paper reports the levels of (226)Ra, (232)Th, (40)K and (137)Cs in the edible parts of 11 different marine species collected from the Qingdao coast of China. The activities of (226)Ra, (232)Th and (40)K ranged from 0.08±0.03 to 1.65±0.60 Bq kg(-1) w.w., 0.09±0.02 to 1.44±0.10 Bq kg(-1) w.w., 26.89±1.25 to 219.25±5.61 Bq kg(-1) w.w., respectively. Artificial (137)Cs was undetectable or close to the detection limit in the biota sampled. To link radioactivity to possible impact on health, we calculated radiation doses to both the marine biota and human beings. We showed that doses in all cases were dominated by naturally occurring (40)K and that (137)Cs doses were negligible compared with (40)K-derived doses. The total doses to marine biota ranged between 16.55 and 62.41 nGy h(-1) among different biota species, which were below the benchmark level of aquatic organism. The committed effective dose to humans through seafood consumption varied from 10.55 to 36.17 μSv y(-1), and the associated lifetime cancer risks ranged from 5.93E-05 to 9.49E-05 for different age and gender groups. Both the dose and cancer risk to humans were at the acceptable range. Despite the significant amount of radionuclides released as a result of the Fukushima accident, their impact on the seafood in Qingdao coast appears to be negligible based on our measurements of concentrations of radionuclide activity and internal dose estimates.

Indoor radon measurements in the uranium regions of Poli and Lolodorf, Cameroon

The objective of this work is to carry out indoor radon measurements in the uranium regions of Poli and Lolodorf in which lie the uranium deposits of Kitongo and Lolodorf, prior to their impending exploitation. The indoor radon concentration was measured in 103 and 50 dwellings located respectively in Poli and Lolodorf using E-PERM electret chamber detectors. Indoor radon distributions in Poli and Lolodorf follow the lognormal law. Radon concentrations range respectively in Poli and Lolodorf between 29 and 2240 Bq m(-3) and 24-4390 Bq m(-3) with corresponding median values of 165 Bq m(-3) and 331 Bq m(-3). Corresponding arithmetic and geometric means are respectively 294 Bq m(-3) and 200 Bq m(-3) for the uranium region of Poli, 687 Bq m(-3) and 318 Bq m(-3) for the uranium region of Lolodorf. For the uranium region of Poli, 80% of dwellings have radon concentration above the reference level of 100 Bq m(-3) and 20% of dwellings show a radon concentration above 300 Bq m(-3). For the uranium region of Lolodorf, 80% of dwellings have radon concentration above 100 Bq m(-3) and 50% of dwellings show a radon concentration above 300 Bq m(-3). Thus radon monitoring and mitigation plan are required to better protect people against harmful effects of radon.

The measurement of gamma-emitting radionuclides in beach sand cores of coastal regions of Ramsar, Iran using HPGe detectors

Radionuclides which present in different beach sands are sources of external exposure that contribute to the total radiation exposure of human. (226)Ra, (235)U, (232)Th, (40)K and (137)Cs analysis has been carried out in sand samples collected at six depth levels, from eight locations of the northern coast of Iran, Ramsar, using high-resolution gamma-ray spectroscopy. The average Specific activities of natural radionuclides viz., (226)Ra, (235)U, (232)Th, (40)K and (137)Cs, in the 0-36 cm depth sand were found as: 19.2±0.04, 2.67±0.17, 17.9±0.06, 337.5±0.61 and 3.35±0.12 Bq kg(-1), respectively. The effects of organic matter content and pH value of sand samples on the natural radionuclide levels were also investigated. Finally, the measured radionuclide concentrations in the Ramsar beach were compared with the world average values, as reported by UNSCEAR (2000). None of the studied beaches were considered as a radiological risk.