A review of worker radiation doses from mining and processing radionuclide containing ore in Western Australia

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This study reviewed the radiation doses of mining and ore processing workers to naturally occurring radioactive material (NORM) in Western Australia. NORM is commonly encountered in mining and mineral operations in Western Australia. Worker exposure to NORM is routinely monitored as part of normal safety precautions. In this study the authors examined the radiation exposure of mining operation workers in 2018-19 and compared it to exposure in 2019-2020. They found that the mean effective dose reported increased by 32% from 0.71 mSv to 0.94 mSv, indicating that mean doses are approaching the 1 mSv annual dose estimate where regulatory intervention should be considered (Ralph and Cattani, 2022). In addition, there was a 36.4% increase in the maximum effective dose of workers from 4.4 mSv to 6.0 mSv. This was the first time in 10 years that an increase in the effective dose has been observed above 5 mSv; this is the threshold level where additional institutional controls and personal monitoring are required (Ralph and Cattani, 2022). The authors also noted that there has been a trend of decreased monitoring for internal exposure to NORM and that this should be reversed to provide increased confidence in the reported dose estimates.

https://pubmed.ncbi.nlm.nih.gov/34814129/

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This is the latest paper in a series (Ralph et al 2020a, 2020b) by the authors that have demonstrated that worker effective doses have increased due the revision of the dose coefficients for occupational intakes of radionuclides by International Commission for Radiological Protection (ICRP). The increase is observed because of the updates in how the dose from inhalation of radionuclides, particularly of the uranium-238 and thorium-232 and radon-222 and their progeny nuclides, are calculated. The updates to how ICRP now calculates doses can be found in the ICRP 130, 134, 137 & 141. 

To ensure workers are protected from the harmful effects of radiation and our guides reflect international best practice, ARPANSA is currently updating RPS 9 and RPS 9.1 to reflect the changes to the dose coefficients by the ICRP. Information on these updates can be found on ARPANSA’s NORM Dose conversion factor update webpage. Making these changes should provide an easy mechanism for implementation by State and Territory radiation regulators.

More information on worker exposure to ionising radiation and the controls in place to protect workers in the mining industry can be found in the ARPANSA factsheet Occupational exposure: Uranium mining and milling workers.