Radon concentrations and forecasting exposure risks to residents and workers in rare earth and copper mines containing radioactivity in northwest Vietnam

Abstract

Radon and its isotopes are inert gases as they do not interact with any chemical compounds. Compared with thoron (²²⁰Rn) and radon-219 (²¹⁹Rn), the risk of radioactive exposure of radon-222 (²²²Rn) is very high due to its long half-life of 3.8 d, while the half-life of ²²⁰Rn is 55 sec and of ²¹⁹Rn is 4 sec. As a gas, radon can escape from the surfaces of ore, minerals, and rocks, then dissolve into groundwater and move very far from the formation site. While all these radioisotopes emit alpha radiation, Rn-222 is the most important as it is the main factor behind dangerous doses to the respiratory tract that are harmful to human health. Survey results of radon concentration in the air and retrospective data (from 2017 to 2019) on the health of residents and workers near and in the rare earth mines Dong Pao and Muong Hum, as well as the Sin Quyen copper mine, illustrated the health characteristics of the people involved in the northwestern mineral mines (Lao Cai - Lai Chau) that are exposed to radon. At the Dong Pao and Muong Hum rare earth mines, as well as the Sin Quyen copper mine, residents and workers were exposed to high concentrations of radon gas and thus developed some related illnesses such as respiratory, urological, digestive, genetic, and neurological diseases. Assessing the risk of pulmonary tuberculosis and estimating the average death rate from lung cancer with radon exposure shows that, in the surveyed area, the risk value is high (0.046) compared to other regions of Vietnam. However, it is within the limits allowed by the United States Environmental Protection Agency (EPA).