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

Xianzhang Shao,Yanqin Ji,Yao Zhang,Liangliang Yin

doi:10.3390/ijerph18030987

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.

Highlights

Radiological hazards in industries involving naturally occurring radioactive material are a widespread radioactive problem and have attracted the attention of many researchers [1,2]
The knowledge of uranium and thorium concentrations in the atmosphere is important for evaluation of inhaled effective doses, which can predict their radiological hazard to the population [5]
The annual effective doses caused by inhaling uranium and thorium from typical radioactive rare earth (RE) ore were in the nSv and μSv magnitudes according to its concentrations in the atmosphere, respectively

Summary

Introduction

Radiological hazards in industries involving naturally occurring radioactive material are a widespread radioactive problem and have attracted the attention of many researchers [1,2]. Uranium and thorium are both radioactive and chemical toxicants and can cause leukemia, renal and nervous system diseases, cancer, and so on [3,4]. The knowledge of uranium and thorium concentrations in the atmosphere is important for evaluation of inhaled effective doses, which can predict their radiological hazard to the population [5]. The inhaled uranium and thorium continue to decay until a stable nuclide is formed. In this process, ionizing radiation that induces biological damage in human organs is emitted [5]. The main biological effects for such ionizing radiation were heritable diseases and cancer [6,7]. A 30-year follow-up study consisting of 995 workers from a uranium-processing facility revealed a significant increase in death due to various causes [9]

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