Background: Occupational medical examinations of permanent mine employees include one biennial postero-anterior (PA) chest X-ray (CXR) for pulmonary evaluation. Similar testing is required for contracted employees who could, however, have more than one annual PA CXR, which is required for entrance, periodic and exit medical examinations. Furthermore, employees may be contracted by more than one mine in a year, resulting in additional CXRs.
Objectives: To determine baseline diagnostic reference levels (DRLs) for four occupational health clinics, to optimise contracted mine employees' radiation doses.
Methods: Radiological and demographic data were collected for 400 contracted employees from four clinics in the Northern Cape province of South Africa, in 2019/2020. Technical parameters were used to calculate the CXR entrance surface dose (ESD) for each employee, i.e. the radiation dose absorbed by the skin. The ESDs were used to determine a diagnostic reference level (DRL) for each clinic.
Results: Of the 400 participants, 217 (54.3%) had one CXR, 89 (22.3%) had two, and 34 (8.5%) had three CXRs in the one-year study period; one employee had 10 CXRs. The DRLs for the four clinics ranged from 0.144 to 0.391 mGy.
Conclusion: The baseline DRLs determined in this study can be used to optimise contracted mine employees' ionising radiation doses, and can be reviewed regularly, using the methods described. The clinics in the Northern Cape province should develop a central database of mine workers' CXR examinations to reduce the number of X-ray examinations performed. The mines should implement strategies to limit the number of annual CXRs to one, to further minimise employees' radiation exposure.biennial postero-anterior (PA) chest X-ray (CXR) for pulmonary evaluation. Similar testing is required for contracted employees who could, however, have more than one annual PA CXR, which is required for entrance, periodic and exit medical examinations. Furthermore, employees may be contracted by more than one mine in a year, resulting in additional CXRs.

This century, we have experienced pandemics of numerous novel and re-emerging infectious agents. Each of these pandemics has taught us, to a greater or lesser extent, that the public health threat becomes an occupational threat when health and other workers are exposed to infected people through contact or vectors. The first necessity for infection prevention and control in the workplace is a global and national political commitment. The hierarchy of control may be difficult to apply in infectious disease outbreaks, and prevention and control of workplace infection cannot be considered in isolation. Prevention is largely dependent on measures such as immunisation and chemoprophylaxis, when applicable, and personal protective equipment (PPE). A One Health model should also be considered in addressing pandemics.