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Radionuclides and heavy metals
Published in Rym Salah-Tazdaït, Djaber Tazdaït, Phyto and Microbial Remediation of Heavy Metals and Radionuclides in the Environment, 2022
Rym Salah-Tazdaït, Djaber Tazdaït
222Rn (half-life of 3.8 days) is a naturally occurring radionuclide that decays sequentially over time by emitting α and β particles and produces a total of eight daughter radionuclides (218Po, 214Pb, 214Bi, 214Po, 210Pb, 210Bi, 210Po and 206Pb), of which the last-formed one (206Pb) is stable (Gillmore, Crockett, and Przylibski 2010, 2052). Radon-222 is generated in the form of gas by the decay of Uranium-238 in rocks and building materials; it is one of the most abundant natural radionuclides in the environment and represents roughly half of the total human exposure to radiation. For instance, its air levels range from 4 to 20 Bq/m3, while its concentration in naturally formed holes such as caves can reach 25,000 Bq/m3 (Ojovan, Lee, and Kalmykov 2019, 44). Thus, 222Rn can be a risk to human health at high levels. Furthermore, observations have demonstrated that gaseous 222Rn has been associated with deletion mutations due to alpha-particle emission. According to WHO (2006), among the known risk factors for developing lung cancer, 222Rn occupies the second place after smoking; it is responsible for tens of thousands of deaths worldwide every year. 222Rn is incorporated in the body mainly through inhalation, and it deposits on different parts of the respiratory system (nasal cavity, larynx, trachea, bronchi, bronchioles, and alveoli), where it decays and acts on the target cells. It was estimated that the radiation absorbed dose of human bronchial basal epithelial cells ranged from 5 to 25 nGy. On the other hand, and based on epidemiological studies and physical dosimetry, it was determined that the radiation dose equivalent values of 222Rn were ranging from 6 to 15 nSv (UNSCEAR 2000, 36). 222Rn has also been positively associated with other non-cancer diseases: cardiovascular disease (coronary heart disease) (Villeneuve and Morrison 1997, 221).
Monitoring and investigating the alpha emitter’s concentration in toothpaste and teeth, using CR-39 NTDs
Published in Radiation Effects and Defects in Solids, 2023
The natural radioactivity and environment are important since naturally occurring radionuclides are the major source of radiation exposure to humans. One of the main sources of public exposure to natural radioactivity is radium and radon, also its short-lived decay products (1). High concentrations of radon (222Rn) and its decay products are widely known to be dangerous to human health. The isotope Rn-222, produced from the decay of U-238, is the main source (approximately 55%) of internal radiation exposure to human life (2). It is commonly associated with different types of cancer, especially with lung cancer (2,3). Alpha particles are emitted when the radon decays. The alpha particles are suspected to include damage to the epithelial cell (3–5). Alpha particles are high Linear Energy Transfer (LET) radiation with a large amount of energy (3–7 MeV) (6). If alpha emission enters the body (upon being inhaled, ingested or injected) it becomes extremely dangerous. Because of this high mass and strong absorption, alpha particles are more damaging to living tissues because they are more massive and more highly charged than other types of ionizing radiation (7).
Radioactivity and dose assessment of naturally occurring radionuclides in terrestrial environments and foodstuffs: a review of Bahi district, Tanzania
Published in International Journal of Environmental Health Research, 2023
Dominic Parmena Sumary, Jofrey Raymond, Musa Chacha, Frimi Paul Banzi
Radon-222 is one of the radionuclides produced from the uranium-238 decay series. This gas is a normal constituent of soil gas and seeps into buildings. When radon is inhaled, some of its, alpha-emitting progeny, short-lived decay products such as 218Po and 210Po, half-lives 3.11 minutes and 138.4 days, respectively are retained in the lungs and irradiate cells in the respiratory tract. Some other progeny of radon contributes very little to internal exposure through inhalation. The worldwide annual average dose of inhaled radon gas is 1.26 mSv y−1. It is expected that the radon concentration in air to be 1–2 µBq m−3 with the assumption that a dust loading of 50 µg m−3 and the concentrations of 238U and 232Th in the soil are 25–50 Bq kg−1 (UNSCEAR 2008).
Isotope radon measurement method to identify spontaneous combustion regions in coal gangue hills: case study for a coal mine in China
Published in International Journal of Coal Preparation and Utilization, 2023
Songtai Wu, Bin Zhou, Junfeng Wang, Qifan Yang, Wenzhe Dong, Zhiyu Dong
Radon (222Rn) is an inert, naturally radioactive gas which is widely present in nature. A great number of experimental studies have shown that an increase in temperature will lead to increasing radon emissions from coal (Hassan et al. 2009; Zheng 2017). Hence, when spontaneous combustion occurs in underground coal seams or goafs, radon emissions will increase, resulting in a high radon concentration around the areas at high temperature. Under the action of the concentration gradient and high pressure induced by burning, radon present in the spontaneous combustion area will rapidly migrate to the surface, eventually forming an anomalous region of radon concentration on the upper surface. The radon measurement method therefore allows the location of underground fire sources to be measured through the measurement of the abnormal radon concentration areas. Unlike indicator gases, radon gas is an inert gas and is less affected by the underground chemical environment. Due to the external effect of diffusion and convection and the internal factor that radon gas and radon and its daughters form helium nuclei after α decay to form a cluster with buoyancy force greater than gravity, radon gas can migrate from deep underground to the surface. As a proven technique for measuring the location of concealed fire sources, the radon measurement method has the advantages of ease of operation, low cost, and no limitation of the detectable terrain. As a result, it has been widely applied in many mining areas in China and Australia (Deng et al. 2012; Tait et al. 2013; Wang 2015; Wen et al. 2020; Xue, Dickson, and Wu 2008).