Occupational radiation exposure and cancer incidence in a cohort of diagnostic medical radiation workers in South Korea

Abstract

ObjectivesWe investigated the association between protracted low-dose ionising radiation and the risk of cancer in medical radiation workers, the largest group of workers with occupational radiation exposures.MethodsData of all South Korean diagnostic medical radiation workers enrolled at the National Dose Registry during 1996–2011 were merged with the death and cancer incidence data until 31 December 2017. SIRs, relative risks and excess relative risks (ERRs) for cancer were calculated to quantify the radiation dose–response relationship using Poisson regression models.ResultsA total of 3392 first primary cancer cases were identified among 93 920 diagnostic medical radiation workers. The mean cumulative badge dose in the cohort was 7.20 mSv. The ERRs for solid cancer with a 5-year lag and haematopoietic cancers with a 2-year lag for all workers were 0.15 per 100 mGy (95% CI −0.20 to 0.51) and 0.09 per 100 mGy (95% CI −2.02 to 2.20), respectively. The ERRs for cancers did not significantly vary by job title, different lag years or after excluding thyroid and lung cancers. Sensitivity analyses restricted to workers employed for at least 1 year, or who were employed in or after 1996, or who had exposure to a cumulative badge dose of 1 mSv or more showed similar results.ConclusionsOccupational radiation doses were not significantly associated with cancer incidence among South Korean diagnostic medical radiation workers. However, cautious interpretation of ERRs is needed due to the limitations of short follow-up and low cumulative radiation doses.

Ionizing radiation exposure during adulthood and risk of developing central nervous system tumors: systematic review and meta-analysis

“…No statistically significant association was reported between cumulative radiation exposure (mean badge dose: 7.2 mSv, max: >20 mSv) and brain/CNS cancers among diagnostic medical radiation workers in South Korea (ERR per 100 mGy = − 0.29; 95% CI: − 3.14, 2.55; n deaths = 43) 36 . Similarly, no significant association was observed between cumulative occupational radiation exposure to the brain (cumulative mean absorbed brain dose: 12 mGy, max: 290 mGy) and mortality from malignant brain/CNS cancers in the US Radiologic Technologists (ERR per 100 mGy: 0.1; 95% CI: < − 0.30, 1.50; n deaths = 193) 17 .…”

“…We can note a lack of accurate dosimetry reconstruction for several studies, as those focusing on medical workers, and encourage future research to improve dose assessment in studies, including as much as possible homogenization of the dosimetric units used. Indeed, nine out of the twelve studies with dose-response analyses considered absorbed doses to the brain (in Gy) 14,17,18,28,30,32,36,37,39 , whereas the three other studies 29,31,38 used equivalent whole-body doses (in Sv) from external photons based on individual monitoring records . However, we calculated a pooled ERR/Gy using the numerical values of the estimated ERR/Sv as they are reported in the studies, assuming that the brain dose from external photons correlates with the whole-body equivalent dose, yet being aware that the absorbed dose to the brain is certainly lower than the equivalent whole-body dose 18,56 .…”

“…Several studies included in our work were limited to men only [32][33][34][38][39][40][41] , while the others included both men and women. Only six studies carried out analyses for men and women separately 14,17,28,[35][36][37] . However, women groups were much smaller compared to men groups, resulting in a low number of cancer cases and thus preventing robust results and conclusions.…”

“…A pooled ERR at 100 mGy was calculated using 12 studies 14,17,18,[28][29][30][31][32][36][37][38][39] , showing no dose-risk association (ERR pooled = − 0.01; 95% CI: − 0.05, 0.04) and no heterogeneity (Q = 11.62, p = 0.39 and I 2 = 5.35%), nor publication bias (p = 0.56). (Fig.…”

Low-Dose Radiation Can Cause Epigenetic Alterations Associated With Impairments in Both Male and Female Reproductive Cells

“…The dose we used in this study is considered a low-dose radiation because fetal absorbed about 4.9 cGy per procedure during abdominal CT scan, and for pelvis it was as high as 7.9 cGy ( Groen et al, 2012 ). A cohort study of diagnostic medical radiation workers in South Korea showed that the workers absorbed a mean cumulative badge dose of 7.20 mSv ( Lee et al, 2021 ). While the environmental level of ionizing radiation is about 3 mGy/year, high levels of background radiation was commonly reported in some areas around the world ( Hendry et al, 2009 ).…”