Review date
March 2024
Article publication date
11 January 2024
Summary
This prospective cohort study examined the association between primary central nervous system (CNS) tumours and chronic external occupational exposure to gamma radiation. The study included 22,377 workers from Mayak Production Association that had been hired to work at a facility with reactors, radiochemical production or plutonium production plants between 1948 and 1982. Radiation exposure was estimated based on ‘Mayak Worker Dosimetry System—2013’ (MWDS 2013). A total of 43 workers who were acutely exposed to radiation and developed acute radiation syndrome as well as 717 workers with missing medical records were excluded from the analysis. The authors examined the excess relative risk of all CNS, glioma and meningioma per Gray (Gy) of external gamma dose. They reported ERR per 1 Gy of external gamma brain dose was 0.05 (95% confidence interval (CI) −0.30 to 0.70) for all CNS tumours, −0.18 (95% CI 0 to 0.44) for gliomas, and 0.38 (95% CI −0.32 to 2.08) for meningiomas. The study concluded no statistically significant association between ionising radiation (IR) exposure and incidence of any CNS cancer type among the workers.
Published in
Radiation and Environmental Biophysics
Link to
ARPANSA commentary
The study found no association between low chronic external exposure to gamma radiation and CNS cancers. This is similar to a study by Kitahara et al (2017), which showed absence of association between low to moderate cumulative occupational radiation exposure and CNS cancers in radiation technologists (ERR per 100 mGy: 0.1; 95% CI: −0.30 to 1.50). Another study (Boice et al 2022) of medical radiation workers in the United States also found no significant association between cumulative absorbed doses of radiation ( 18.9 mGy - 1.08 Gy) and brain cancers (ERR at 100 mGy = 0.20; 95% CI: − 0.30 to 0.71). The United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) states that at low levels (less than 0.1 Gray) IR exposure, the possible increased risk of cancer is uncertain. However, it remains important to track doses of occupational radiation in workplaces as the doses of 100-1000 millisieverts can increase the risk of cancer.
ARPANSA publishes a series of evidence-based documents to guide Australian radiation protection principles and practices for radiation workers and the general public. For example,The Code for Radiation Protection in Planned Exposure Situations (2020)established a framework in Australia for the protection of occupationally exposed persons, the public and the environment in planned IR exposure situations. A planned exposure situation, is an exposure arising from the planned operation of a radiation source or facility that causes exposure to a radiation source is called a ‘planned exposure’ and in these planned exposure situations, some level of exposure can be expected to occur. The guideline applies the three main principles of radiation protection for planned exposure situations: i) justification (that any activity involving IR exposure should do more good than harm), ii) optimisation (that actual IR exposure, likelihood of exposures and number of exposed persons should be as low as reasonably achievable taking into account economic and societal factors), and iii) dose limits (levels of radiation dose that must not, under normal circumstances, be exceeded). ARPANSA will continue to update the latest science on human radiation protection, including cancer risk associated with IR exposure, in order to protect Australian general public and occupational populations.
