Radioactivity Levels Research Articles

Determine the hazards of radioactive elements and radon gas manufacturing processes in an Egyptian fertilizer factory

This study investigated the levels of radioactivity in soil surrounding a phosphate fertilizer factory in Egypt, aiming to assess potential risks to the population exposed to radiation. Concentrations of 238U, 226Ra, 232Th, and 40K were measured in soil samples collected from two subsites: one near the factory (subsite 1) and another further away (subsite 2). Two different systems were used for measuring radioactivity, a high-purity gamma ray spectroscopy system with an HPGe detector for gamma-emitting isotopes and a CR-39 solid nuclear track detector for alpha-emitting radon gas. Subsite 1, located close to the factory, displayed significantly elevated levels of 226Ra compared to global background levels (514 and 456 Bq/kg vs. 35 Bq/kg). Additionally, the concentrations of 238U (241.06 Bq/kg vs. global average 35 Bq/kg), 232Th (16.15 Bq/kg vs. global average 30 Bq/kg), and 40K (146.36 Bq/kg vs. global average 400 Bq/kg) were all above global averages. Furthermore, a high concentration of radon gas (337.06 μSv/y) was measured at subsite 1. The strong positive correlation observed between 226Ra and 238U (0.96256) provides further evidence of potentially elevated radioactivity levels near the factory. In contrast, subsite 2, situated farther from the factory, exhibited natural radioactive background levels within international limits. Quantitative analysis revealed that gamma ray absorbed doses for 226Ra and 232Th exceeded global averages in some samples. Specifically, 226Ra doses ranged from 7.8 to 46.26 ppm (exceeding the 20 ppm global average in some cases), and 232Th doses ranged from 1.98 to 9.14 ppm (exceeding the 10 ppm global average in some cases). The concentration of 40K, however, remained within the global range (0.07%–0.69 %). The observed imbalances in the ratios of Th/U (0.17–0.24 Bq/kg and 0.73–0.24 ppm) and U/Ra (0.81–0.73 Bq/kg and 0.73–0.17 ppm), both of which are significantly lower than their respective global averages of 4 and 2.4, point towards the presence of fertilizer-derived contamination. This conclusion is further supported by the high phosphate concentrations detected in the samples. Overall, this study suggests that radioactive contamination near the phosphate fertilizer factory significantly exceeds global background levels and international limits in some cases. This raises concerns about potential risks posed to surrounding agricultural land and crops.

Assessment of natural radioactivity levels and potential radiological risks of commonly used building materials in Uttara Kannada District, Karnataka, India.

The main goal of this study is to evaluate the natural radioactivity and potential radiological risks of frequently used building materials in Uttara Kannada district. Using an High purity Germanium Detector (HPGe) detector-based gamma-ray spectrometer, the activity concentration of 226Ra, 232Th and 40K was determined. The activity concentration of 226Ra, 232Th and 40K in the construction materials vary from 13.78±0.90 to 151.9±1.85, 14.21±0.80 to 207.72±2.9 and 55.26±1.20 to 1298.24±25Bqkg-1 with an average value of 40.57±1.37,60.13±1.70 and 425.38±4.75Bqkg-1 having a geometric mean of 33.07, 46.49 and 290.20Bqkg-1, respectively. The mean annual effective dose equivalent was found to be 0.68mSv y-1 and is less than the International Commission on Radiological Protection proposed acceptable limit of 1mSv y-1. The estimated radiological hazard parameters show that these building materials are safe to use in the construction of homes and do not offer a substantial source of radiation hazard.

Effects of Radioactive 56MnO2 Particle Inhalation on Mouse Lungs: A Comparison between C57BL and BALB/c.

The effects of residual radiation from atomic bombs have been considered to be minimal because of its low levels of external radioactivity. However, studies involving atomic bomb survivors exposed to only residual radiation in Hiroshima and Nagasaki have indicated possible adverse health effects. Thus, we investigated the biological effects of radioactive dust of manganese dioxide 56 (56MnO2), a major radioisotope formed in soil by neutron beams from a bomb. Previously, we investigated C57BL mice exposed to 56MnO2 and found pulmonary gene expression changes despite low radiation doses. In this study, we examined the effects in a radiation-sensitive strain of mice, BALB/c, and compared them with those in C57BL mice. The animals were exposed to 56MnO2 particles at two radioactivity levels and examined 3 and 65 days after exposure. The mRNA expression of pulmonary pathophysiology markers, including Aqp1, Aqp5, and Smad7, and radiation-sensitive genes, including Bax, Phlda3, and Faim3, was determined in the lungs. The radiation doses absorbed in the lungs ranged from 110 to 380 mGy; no significant difference was observed between the two strains. No exposure-related pathological changes were observed in the lungs of any group. However, the mRNA expression of Aqp1 was significantly elevated in C57BL mice but not in BALB/c mice 65 days after exposure, whereas no changes were observed in external γ-rays (2 Gy) in either strain. In contrast, Faim3, a radiation-dependently downregulated gene, was reduced by 56MnO2 exposure in BALB/c mice but not in C57BL mice. These data demonstrate that inhalation exposure to 56MnO2 affected the expression of pulmonary genes at doses <380 mGy, which is comparable to 2 Gy of external γ-irradiation, whereas the responses differed between the two mouse strains.

Novel environmental monitoring detector for discriminating fallout and airborne radioactivity

Early warning networks are used for detecting abnormal radioactivity levels in the environment. State-of-the-art networks are equipped with both dose rate detectors and spectrometric stations. Current networks don’t automatically discriminate between radioactivity on the ground and in the air. A novel directional sensing gamma radiation detector utilizing a collimated phoswich scintillator was developed. The signals from the two scintillator materials are separated using a pulse shape discrimination. The separated signals are employed to determine the radioactivity concentrations on the ground and in the air assuming specific concentration distributions. Limitations related to imperfect directional sensing and dead time are discussed.

The Rise and Fall of Radioactive Carbon in the Atmosphere

The level of radioactive carbon dioxide in the atmosphere has shifted dramatically since the middle of the twentieth century. At that time, nuclear weapons tests resulted in considerably raised levels of the radioactive molecule. The impact peaked in the early 1960s and, since then, the radioactive level has come back almost to where it was before the nuclear test period. The ambition here is to discuss the character of the carbon dioxide curve in its different phases with an emphasis on what has happened after the atmospheric tests stopped. The curve’s behaviour seems to raise an interesting question for climate change theory.

Pre-clinical evaluation of biomarkers for the early detection of nephrotoxicity following alpha-particle radioligand therapy.

Cancer treatment with alpha-emitter-based radioligand therapies (α-RLTs) demonstrates promising tumor responses. Radiolabeled peptides are filtered through glomeruli, followed by potential reabsorption of a fraction by proximal tubules, which may cause acute kidney injury (AKI) and chronic kidney disease (CKD). Because tubular cells are considered the primary site of radiopeptides' renal reabsorption and potential injury, the current use of kidney biomarkers of glomerular functional loss limits the evaluation of possible nephrotoxicity and its early detection. This study aimed to investigate whether urinary secretion of tubular injury biomarkers could be used as an additional non-invasive sensitive diagnostic tool to identify unrecognizable tubular damage and risk of long-term α-RLT nephrotoxicity. A bifunctional cyclic peptide, melanocortin 1 ligand (MC1L), labeled with [203Pb]Pb-MC1L, was used for [212Pb]Pb-MC1L biodistribution and absorbed dose measurements in CD-1 Elite mice. Mice were treated with [212Pb]Pb-MC1L in a dose-escalation study up to levels of radioactivity intended to induce kidney injury. The approach enabled prospective kidney functional and injury biomarker evaluation and late kidney histological analysis to validate these biomarkers. Biodistribution analysis identified [212Pb]Pb-MC1L reabsorption in kidneys with a dose deposition of 2.8, 8.9, and 20 Gy for 0.9, 3.0, and 6.7 MBq injected [212Pb]Pb-MC1L doses, respectively. As expected, mice receiving 6.7 MBq had significant weight loss and CKD evidence based on serum creatinine, cystatin C, and kidney histological alterations 28 weeks after treatment. A dose-dependent urinary neutrophil gelatinase-associated lipocalin (NGAL, tubular injury biomarker) urinary excretion the day after [212Pb]Pb-MC1L treatment highly correlated with the severity of late tubulointerstitial injury and histological findings. Urine NGAL secretion could be a potential early diagnostic tool to identify unrecognized tubular damage and predict long-term α-RLT-related nephrotoxicity.

Assessment of natural radioactivity levels in widely used food spices in the Iraqi Kurdistan region and their associated radiological risks

Assessment of natural radioactivity levels in widely used food spices in the Iraqi Kurdistan region and their associated radiological risks

Determination of natural and artificial radioactivity levels and radiation hazard indices for soil samples in Kırşehir

Abstract The aim of this study is to create a radiological map of Kırşehir province in Turkey by analyzing the radioactivity levels of soil samples and environmental radiation measurements. 226Ra, 232Th, 40K and 137Cs radionuclides were analysed in soil samples collected from 47 locations using gamma spectrometry with an HPGe detector. According to the results obtained, gamma radioactivity concentration ranges and mean values for 226Ra, 232Th, 40K and 137Cs were determined as 133 ± 15–1515 ± 128 Bq/kg (599.40 Bq/kg), 0.3 ± 0.09–21.1 ± 1.7 Bq/kg (4.61 Bq/kg), 8.7 ± 0.9–128.5 ± 8.5 Bq/kg (29.66 Bq/kg) and 11.6 ± 8.6–273.8 ± 19.9 Bq/kg (48.80 Bq/kg) respectively. Average radioactivity levels for 40K and 232Th are above the world average. The mean radium equivalent activity (Raeq), gamma dose rate (D), annual effective dose equivalent (AEDE), external hazard index (H ex ), and the excess lifetime cancer risk (ELCR) were calculated as 145.45 Bq/kg, 122.13 nGy/h, 0.15 mSv/h, 0.39 and 0.29 × 10−3 respectively.

Assessment of the potential radiation hazards posed by Nubian sandstone, Egypt

The study found that the activity concentrations of the radionuclides 238U, 232Th and 40K in the sandstone are 32 ± 13, 29.6 ± 12.2, and 132.6 ± 86.4 Bq kg−1, respectively. These values are lower than the reported worldwide limits of 33, 45, and 412 Bq kg−1. According to the present study, the absorbed dose rate (Dair), the annual effective dose, and the excess life time cancer were all found to be below the worldwide mean. Pearson correlation, PCA, and HCA were used to analyze the data and identify patterns in the relationship between radionuclides and radiological hazards. A statistical analysis of the sandstones showed that the radioactive elements 238U, 232Th and 40K are the main contributors to the radioactive risk. The study suggests that the sandstone is safe to use. The levels of radioactivity are not high enough to pose a risk to human health.

Still potentially deadly after all these years: how to safely handle and display radioactive dinosaurs and other fossils

Most curators and collection managers responsible for a geological collection will be aware of the risk posed by rocks and minerals which emit ionising radiation and will have put measures in place to reduce this risk to collection users. However, fewer people are aware that fossils, ranging from fish to dinosaurs, and even coprolites can be radioactive too. A fossil may be radioactive if it has been exposed to uranium-bearing fluids during diagenesis and fossilisation processes. Any uranium-enriched groundwater moving through nearby porous deposit can contaminate the rocks and fossils with radioactive elements. Over time the skeletons or other remains being fossilised incorporate these elements into their min- eral structure, such that the concentration of radioactive elements in fossils may be greater than that in the host rock. The greater the volume of fossil material, e.g. a large dinosaur bone, the greater the potential for higher levels of radioactivity, and a greater risk to hu- mans (although some small specimens can be highly radioactive). Whilst most radioactive fossils may not present a danger to health through direct absorption of radiation, unless there is prolonged exposure at close quarters (e.g. hundreds of hours), a risk is posed by the ingestion or inhalation of small radioactive particles derived from the specimen. Here, we describe what measures can be taken to reduce these risks and also provide a list of locations around the world known to yield radioactive fossils, which we hope can be augmented by others. The general principles discussed here are widely applicable, but it is recommended that specialist advice is sought to comply with national regulations in each instance. In ad- dition to the health risks posed by these specimens, there are also legal penalties for failing to comply with regulations.

Natural radioactivity level in graphite samples from the Cătălinul deposit, Parâng Mountains, Romania: sources identification and radiological risk assessment

Twenty graphite samples (amorphous and crystalline flake types of graphite) were collected from the ore storage of the Catalinul deposit and, the 238U, 232Th, 40K naturally occurring radionuclides have been investigated by gamma-ray spectrometry. The mineral contents of selected graphite samples were examined using a scanning electron microscope (SEM). The radiological hazard parameters: radium equivalent activity (Raeq), absorbed gamma dose rates in air (DR), and external hazard index (Hex) were calculated and compared with international safety limits. Radiometric data showed average specific activities for 238U, 232Th and, 40K of 80.40, 49.69 and, 124.21 Bq kg–1 for amorphous graphite respectively, 38.53, 76.25 and, 241.12 Bq kg–1 for flake graphite. Zircon, rutile, uraninite, coffinite, urano-thorite, and monazite are the main radioactive element bearing minerals. The mean of the radiological hazard parameters: Raeq – 262.22 (Bq kg–1), DR – 123.72 (nGy/h), and 0.7 – Hex do not exceed the recommended values by UNSCEAR.

Pierwiastki radioaktywne stwierdzone w ropie naftowej z obszarów wulkanicznych

In the geological structures containing crude oil and associated gases and located in areas where volcanic activity has been detected, radioactive substances and minerals are contained both in the structure of the reservoir waters and in the impurities related to the composition of the extracted crude oil. They are present during the extraction of crude oil and associated gases and affect human health and environmental safety. Radioactive elements have been detected in reservoir waters, in impurities associated with crude oil, and especially during the processing of drilling fluids (the separation of detritus sourced from geological strata from the used drilling fluid). Other radioactive elements were also detected in the areas polluted with oil and drilling waste. In order to determine the radioactivity level of crude oil originating from the area of volcanic activity of the Romanian Mountains, crude oil samples were collected from the oil field in a one-year analysis. The collected samples were analysed to determine their physical-chemical structure. The reservoir water associated with these samples and the minerals separated from the crude oil following their solvent extraction were also analysed. Radioactive elements were detected using X-ray spectrometry, and their chemical structures are also discussed.

Assessment of Background and Soil Dumpsites Radioactivity in Plateau State, Nigeria

Assessment of background and dumpsites radioactivity level plays a significant role in the protection of man from excessive radiation exposure. Exposure to high radiation levels causes a wide range of health problems such as cancer of the lung, bone and skin, kidney ailments and blood infections. The background radiation levels of 51 selected dumpsites (3 in each LGA) were obtained at 1m above it using a well-calibrated International Medcom CRM-100 Digital Radiation Monitor. Soil samples were also collected, packed, prepared and analysed with Gamma ray Spectrometer [NaI (Tl) detector]. The mean activity concentrations of 226Ra, 232Th and 40K in this study are 61.93±5.90Bq kg-1,123.37±34.05 Bq kg-1 and 276.54±62.44 Bq kg-1 respectively. The mean absorbed dose, AEDE (outdoor) and ELCR in the state have the value of 111 nGyh-1, 0.13 mSv/hr and 0.45 x 10-3 respectively, which are greater than the world average value of 58 nGy h-1, 0.07 mSv/hr and 0.29 x 10-3 respectively. The mean background radiation of the dumpsites recorded in Plateau State was 204 nGy h-1 with the outdoor AEDE of 0.25 mSv/yr and ELCR of 0.88 x 10-3 . These values are greater than the world average. The results obtained for the background radiation are higher than those from the radionuclides analysis. The study revealed that the health risks associated with the radionuclide concentrations of soil dumpsites and the background radiation are relatively high, and the use of dumps as manure and other re-cycling processes therefore raises radiological concern.

Assessment of radioactivity levels and radiation hazards in building materials in Egypt

Different degrees of natural radioactivity found in quartz can have negative consequences on health. Quartz vein along the investigated Abu Ramad area, Egypt, had its natural radioactivity assessed. The HPGe spectrometer was used to determine the role played by the radionuclides 238U, 232Th, and 40K in the gamma radiation that was emitted, and the results showed that these concentrations are 484.64 ± 288.4, 36.8 ± 13.1 and 772.2 ± 134.6 Bq kg−1 were higher than the corresponding reported global limits of 33, 45, and 412 Bq kg−1 for each radionuclide (238U, 232Th, and 40K). Among the radiological hazard parameters, the excess lifetime cancer risk (ELCR) is estimated and it's mean value of ELCR (1.2) is higher than the permissible limit of 0.00029. The relationship between the radionuclides and the associated radiological hazard characteristics was investigated based on multivariate statistical methods including Pearson correlation, principal component analysis (PCA), and hierarchical cluster analysis (HCA). According to statistical research, the radioactive risk of quartz is primarily caused by the 238U, 232Thand 40K. Finally, applying quartz to building materials would pose a significant risk to the public.

Assessment of radioactivity levels and radiological hazard indices in phosphate and phosphate mine waste samples from Algeria.

Phosphate ore is the starting raw material for production of all phosphate products including fertilisers phosphate waste. It can be of sedimentary, volcanic or biological origin. Like any other geological material found in nature, it contains various amounts of naturally occurring primordial radionuclides, such as 238U series, 232Th series and 40K. Gamma-ray spectrometry was used to assess natural radioactivity levels and radiological hazard indices in phosphate samples. In this paper, the specific activity concentrations of 226Ra, 232Th and 40K of phosphate ores, merchant and mine waste samples were determined. Based on the activity concentrations, the radiation hazard indices (Raeq, Hex, Hin and I𝛾𝑟), and the radiation doses (D, AED and ELCR) were calculated. The results were discussed and compared with those from other studies as well as recommended safety limit values.

Investigation of environmental radioactivity levels and human health risk around San'ao Nuclear Power Plant (China) before operation

Baseline study on environmental radioactivity levels and public health conditions are crucial before the operation of nuclear facilities. Our goal is to establish a baseline database before the operation of San'ao Nuclear Power Plant (SNPP). To achieve this, water and food samples collection was carried out around the SNPP from 2021 to 2022 for laboratory analysis to determine the radioactivity levels. Thereafter, annual effective dose (AED) to local residents were evaluated by the analysis results and cancer incidence rates were analyzed by health data of local residents. Our results showed that the gross α and β activity concentrations in water varied within < 0.016–0.023 Bq/L and 0.031–0.080 Bq/L, respectively. The 90Sr and 137Cs activity concentrations range from 3.1 to 9.7 mBq/L and 0.11–0.42 mBqg/L in water, and range from 0.037 to 0.95 Bq/kg and 0.015–0.38 Bq/kg in food. All obtained results of gross α and β, 90Sr and 137Cs were below the thresholds of World Health Organization (WHO) and Chinese national standard. The AED induced by ingestion of food or drinking water were below the thresholds of WHO or Chinese national standard, indicating that radiation exposure was at a safe level. The incidence rate of all cancer sites combined among the residents around the SNPP was slightly higher than other regions, but still remained at the same scale. However, the incidence rate of thyroid cancer stood out to be significantly higher than the national average value in China, presumably due to excessive iodine intake in the study region.

Quantification of radiological hazards associated with natural radionuclides in soil, granite and charnockite rocks at selected fields in Ekiti State, Nigeria

Assessment of activity levels of radionuclides that exist in soil, granite, and charnockite rock samples is very crucial because it exhibits an enhanced elemental concentration of uranium (U) and thorium (Th) contributing higher natural background activity than usual in the environment and it may cause health risk to human health through the external and internal exposure. This study determined the radioactivity levels of 238U, 232Th, and 40K radionuclides in soil, granite, and charnockite rock samples collected from selected fields in Ekiti State, Nigeria using Caesium iodide CsI(Tl) scintillation gamma spectrometer. It also evaluated indices of the radiological parameters consisting of radium equivalent activity (Raeq), absorbed dose rate (DR), annual effective dose equivalent (AEDE), internal hazard index (Hin), and excess lifetime cancer risk (ELCR). The calculated average activity concentrations of 238U, 232Th, and 40K are 30.40 ± 0.71 Bq kg−1, 3.31 ± 0.05 Bq kg−1, and 222.25 ± 14.72 Bq kg−1, respectively, which were lower than their respective world average values. Comparatively, potassium concentrations in these collected samples have a higher value than concentrations of uranium and thorium (40K > 238U > 232Th). All the evaluated values of the radiological parameters (except DR) of the appraised radionuclides were below the global permissible limits. The granite rocks, charnockite rocks, and soils from Ekiti State in Nigeria do not pose any hazardous risk to humans, but continued monitoring is necessary when these materials are used as building materials, which cause long-term radiation exposure.

Radiological risk assessment of beaches from volcanic oceanic islands: A case study of the Eastern Canary Islands (Spain)

This work constitutes the first survey that allows the establishment of baseline levels of environmental radioactivity in beach sands from the volcanic oceanic islands of La Graciosa, Lanzarote, Fuerteventura and Gran Canaria. Activity concentration values of 226Ra, 232Th and 40K were measured by gamma spectroscopy in 108 samples, collected from 39 beaches across the whole study region. The radiological hazard risks associated with these sands were studied. The mean absorbed dose rate in the study region was 20 nGy h−1, which is below the world average value. The mean outdoor annual effective dose for the beaches studied was 0.025 mSv y−1, which is within the internationally accepted safe limit. Additionally, the assessment of the radium equivalent showed that all samples from the Eastern Canary Islands are below the safe limit of 370 Bq kg−1. Despite not posing any radiological risk to the human population, the radiological hazard indices obtained in Gran Canaria were significantly higher than those of other islands. These significant differences seem to be related to the presence of sediments in the beaches of Gran Canaria that have their origin in lithologies with higher activity concentration values of 226Ra, 232Th and 40K that are not present in the rest of the islands.

Assessment of natural and anthropogenic radioactivity levels and their radiological hazards in surface soil samples around oil refinery, Little Aden City, Yemen

The activity concentration of global fallout of 137Cs and naturally- occurring radioactive materials (NORM), which primarily due to the geological and geographical condition of soil. and maybe occur from oil and gas burring processes and consequently accumulate on surface soil around the oil refinery in Aden Assoghra city, Yemen were studied by use the gamma-ray spectrometer equipped with a high purity germanium (HPGe) detector and specially designed shield. The average concentrations of 226Ra, 232Th, and 40K expressed in (Bq kg−1) of the studied samples were (13 ± 0.44) Bq kg−1, (22.1 ± 0.64) Bq kg−1 and (509 ± 9) Bq kg−1, respectively. Low concentrations of 137Cs were noted from some sample in the study area, where ranged from (0.3 ± 0.2) to (1.7 ± 0.2) Bq kg-1. The average values of calculated radiological hazard indices were 40.6 nGy h−1 (absorbed dose rate outdoors), 0.05 mSv y−1 (annual effective dose outdoors), 0.279 mSv y−1 (annual effective dose indoors), 83.7 Bq kg−1 (radium equivalent), 0.23 (external hazard index), 0.26 (internal hazard index), 0.65 (representative level index), 0.174×10-3 (the excess lifetime cancer risk ELCR) and 0.292mSv y−1 (annual gonadal equivalent dose, AGED).

Measurements of some radionuclides in coffee samples using gamma-ray spectrometry and evaluating radiological health risk to the Turkish public

ABSTRACT The current research aims to assess the radioactivity levels and radiological health risks of 28 coffee samples from 21 assorted brands obtained from different provinces of Turkey. The activity concentrations of natural radionuclides (226Ra, 232Th and 40K) and artificial radionuclide 137Cs in the samples were quantified using the high-resolution gamma ray spectroscopy technique with an HPGe detector. 137Cs could not be found in any of the samples. The activity concentrations in all coffee samples were found in the range of <MDA–2.93 Bq kg−1 with an average of 1.24 Bq kg−1 for 226Ra, <MDA–3.06 Bq kg−1 with an average of 1.51 Bq kg−1 for 232Th and 433.67–538.69 Bq kg−1 with an average of 496.24 Bq kg−1 for 40K. Radiological parameters such as annual intake of radioactivity (Yint), committed effective dose (Deff), threshold consumption rate (DIthresh), and excess lifetime cancer risk (ELCR) were evaluated to estimate human radiological risk in the coffee samples. The total committed effective dose to an individual due to the consumption of each coffee sample was less than the dose limit of 290 μSv y−1 suggested by UNSCEAR. The lowest threshold consumption rate (kg y−1 or g d−1) calculated in all coffee samples was higher than the amount of coffee consumed per year (kg y−1) and the amount of coffee consumed at the daily normal level (g d−1, cups d−1). The total lifetime cancer risks from ingestion of the sampled coffees were estimated to be less than the advised safety limit (10−3). Based on the obtained results, none of the coffee samples analysed in the present study constitute a possible radiological risk for public health. Pearson’s correlation coefficient analysis (PCCA) and discriminant analysis (DA) were used to present the relationships between the radionuclides and distinguish the group members, respectively.