Estimation of Inhaled Effective Doses of Uranium and Thorium for Workers in Bayan Obo Ore and the Surrounding Public, Inner Mongolia, China

Abstract

Uranium and thorium are two common natural radioactive elements with high concentrations in Earth’s crust. The main aim of this study is to estimate the inhaled effective dose of uranium and thorium caused by a typical radioactive rare earth ore to the occupational population and the surrounding public. The particulate matter (PM) concentrations in the atmosphere of four typical workplaces and one surrounding living area were obtained by a high-flow sampling equipment with a natural cellulose filter membrane. The critical parameter for the inhaled effective dose estimation—the activity median aerodynamic diameter (AMAD)—was determined. The AMAD values of uranium and thorium in the atmosphere PM were 3.36 and 3.64 μm, respectively. The estimated median effective dose caused by inhalation thorium among the occupational population ranged from 15.3 to 269.0 μSv/a, and the corresponding value for the surrounding public was 2.3 μSv/a. All values for the effective dose caused by the inhalation of uranium were in the nSv magnitude.

Thorium Alters Lung Surfactant Protein Expression in Alveolar Epithelial Cells: In Vitro and In Vivo Investigation

“…Inhalation, the most likely route of exposure with Th compounds//Th-containing dust and observed health effects such as pneumoconiosis 17 and lung fibrosis 18,19 in Th workers, rationalizes the present study investigating the impact of Th exposure on expression of various SPs in type-I and type-II human alveolar epithelial cells (WI26 and A549). Since these proteins are crucial to maintain tissue elasticity for lung function and innate immune defense, 33 this study would be helpful to explore (i) the feasibility of using SPs as a biomarker of Th exposure in nuclear workers; (ii) mechanistic role of SPs in the inflammation-associated lung disease; and (iii) the development of rational therapeutic approaches for mitigation of Th-toxicity in the respiratory system.…”

“…However, inhalation has been observed to be the predominant route (∼44% of total cases) of internal contamination with actinides, which has occurred in French CEA-AREWA centers during 1970–2003 . Notably, the long-term inhalation of Th-dust was found to cause pneumoconiosis and lung carcinogenesis in Chinese miners (average Th in lung, 0.4 mg). − Moreover, a significant level of Th has been reported in the blood (370–3000 ng/L), hair (19–2388 ng/g), and urine (18–906 ng/L) of Th-workers of several countries as compared to nonoccupationally exposed populations. − Indeed, the level of Th in hair of Iraq and Chinese women were found to be associated with the risk of congenital anomalies in their offspring. − Thus, these reports suggested significant adverse health effects of Th in humans after exposure to Th-containing dust. Lungs being the primary target organ of exposure, understanding the effect of Th on human lung alveolar epithelial cells is extremely important.…”

Thorium Removal, Recovery and Recycling: A Membrane Challenge for Urban Mining

“…We can conclude that thorium, although radioactive, can be found in the aerospace industry, automobile industry, chemical and metallurgical industry, electrotechnical industry, electronics industry, dentistry (cements for dentistry, optical and surgical instruments, manufacturing), and in art objects (alloys, jewelry, sculptures, statues) [ 26 , 27 ], which leads to thorium being an environmental pollutant [ 28 , 29 , 30 ].…”

“…We can conclude that thorium, although radioactive, can be found in the aerospace industry, automobile industry, chemical and metallurgical industry, electrotechnical industry, electronics industry, dentistry (cements for dentistry, optical and surgical instruments, manufacturing), and in art objects (alloys, jewelry, sculptures, statues) [26,27], which leads to thorium being an environmental pollutant [28][29][30]. In addition to its surprising use in toothpaste, in the dating of hominids, as a contrast agent in certain radiological examinations or as a filament in incandescent light bulbs, lamps, lanterns, and thorium mantles [23], it is also used for technical applications in which it is practically irreplaceable: crucibles for high temperatures, welding electrodes and alloys (aluminum, magnesium, steel), lamps for special electronic equipment, mantles in the metallurgical industry, industrial catalysts (ammonia, sulfuric acid, cracking hydrocarbons), the manufacture of thorium-mixed oxide tablets and uranium, oxygen detectors, and lenses for various optical and opto-electronic devices (having excellent wavelength dispersion and high refractive index) [24,25].…”