Working in a uranium mine could affect workers’ health in several ways:
Exposure to radiation from radioactive elements: Mineralized rock containing uranium emits radiation. Such rock will also contain other radioactive elements, which are produced when uranium decays, or breaks down. The severity of health impacts depends on the type of radiation, the level of radioactivity and the way in which you are exposed. You will be required to wear a device called a dosimeter, which monitors your level of exposure to radioactive material.
External exposure to alpha and beta radiation can be reduced by wearing personal protective equipment (PPE) (e.g: gloves, work clothing, safety glasses, etc.) or using light-weight shielding, and by employing careful work practices to ensure radioactive dust is not spread around. Protection from gamma radiation is more difficult to achieve as it penetrates protective equipment and can only be stopped by 40 centimetres of heavy shielding like lead. You will rely on your dosimeter to inform you of your accumulated radiation exposure. There is a regulatory limit for exposure for mine workers. Once/if these are reached, you can no longer work in the mine for a certain time. For workers in the mine, exposure will largely depend on the concentration of radioactive elements in the ore and the amount of time spent in the mine near the ore. For workers at the mill plant, exposure to gamma radiation is more constant, while exposure to radioactive dust may occur from ore handling.
You may also be exposed internally, if you ingest dust containing radioactive elements, for example, by consuming food with dust-covered hands, by breathing in the dust or through an open cut in the skin. In fact, dust inhalation is the most frequent route for absorption of radioactive elements. Dust suppression and respiratory protection are therefore also very important.
Exposure to heavy metals and other chemicals: Uranium and other metals contained in the ore are also dangerous because of their chemical toxicity, much like lead, cadmium or arsenic. These can harm you through ingestion, inhalation or absorption by the skin. For uranium, its chemical toxicity is more important than its radiation danger. Other hazardous chemicals are also present on site, such as those used in the extraction process, water treatment and for fueling equipment.
Exposure to radiation from radon gas: Radon gas is released from the ore constantly. It has a short half-life of 3.8 days, releasing alpha and gamma radiation. Its decay products are also radioactive. The danger lies in breathing in the gas if it becomes concentrated in the air. Wherever a borehole, pocket, mine shaft or mine gallery exists in mineralized rock, the air will fill with radon gas unless it is ventilated. A mine’s ventilation system keeps air circulating to avoid such accumulation. There are regulatory limits as to what is considered a safe level of radon. Monitoring radon levels in the mine and exposure of miners through the use of a dosimeter is critical. The reliability and effectiveness of the mine ventilation system is therefore very important.
Combined risk factors: Mining of all sorts can result in the inhalation of silica dust and diesel fumes, both of which increase lung cancer risk. The inhalation of radon gas on top of these increases that risk significantly, as does smoking.
Technological failure at the mine: A failure of a mine’s ventilation system could expose mine workers to unsafe concentrations of radon gas.
Technological failure at the mill: The mill takes mineralized rock, grinds it into sand then extracts the uranium through various chemical processes. The usual risks involved in handling chemical reagents are present, as well as the potential for an equipment failure or accident. Any such failure could not only release volumes of chemical reagents, but also radioactive dust or slurry into the environment.
Level of exposure:
The impact of the risks described above on your health will depend on your exposure. All mine workers are exposed to low levels of radiation under normal working conditions.
Studies have shown increased lung cancer levels in uranium mine workers and these are most commonly associated with the inhalation of radon gas. The studies relate to mining practices of past decades. Improved ventilation in modern mines decreases exposure to radon and may have decreased this heightened risk. However, because such technological improvements are relatively recent, it is too soon for studies to confirm whether this has made a difference.