Occupational Radiation Dose Trends in U.S. Radiologic Technologists Assisting with Fluoroscopically Guided Interventional Procedures, 1980-2020.

PURPOSE: To summarize dose trends from 1980 to 2020 for 19,651 U.S. Radiologic Technologists who reported assisting with fluoroscopically guided interventional procedures (FGIPs), overall and by work history characteristics. MATERIALS AND METHODS: A total of 762,310 annual personal dose equivalents at a 10-mm reference depth (doses) during 1980-2020 for 43,823 participants of the U.S. Radiologic Technologists (USRT) cohort who responded to work history questionnaires administered during 2012-2014 were summarized. This population included 19,651 technologists who reported assisting with FGIP (≥1 time per month for ≥12 consecutive months) at any time during the study period. Doses corresponding to assistance with FGIP were estimated in terms of proximity to patients, monthly procedure frequency, and procedure type. Box plots and summary statistics (eg, medians and percentiles) were used to describe annual doses and dose trends. RESULTS: Median annual dose corresponding to assistance with FGIP was 0.65 mSv (interquartile range [IQR], 0.60-1.40 mSv; 95th percentile, 6.80). Higher occupational doses with wider variability were associated with close proximity to patients during assistance with FGIP (median, 1.20 mSv [IQR, 0.60-4.18 mSv]; 95th percentile, 12.66), performing ≥20 FGIPs per month (median, 0.75 mSv [IQR, 0.60-2.40 mSv]; 95th percentile, 9.44), and assisting with high-dose FGIP (median, 0.70 mSv [IQR, 0.60-1.90 mSv]; 95th percentile, 8.30). CONCLUSIONS: Occupational doses corresponding to assistance with FGIP were generally low but varied with exposure frequency, procedure type, and proximity to patients. These results highlight the need for vigilant dose monitoring, radiation safety training, and proper protective equipment.

Third mortality follow-up of the Mallinckrodt uranium processing workers, 1942-2019.

INTRODUCTION: Mallinckrodt Chemical Works was a uranium processing facility during the Manhattan Project from 1942 to 1966. Thousands of workers were exposed to low-dose-rates of ionizing radiation from external and internal sources. This third follow-up of 2514 White male employees updates cancer and noncancer mortality potentially associated with radiation and silica dust. MATERIALS AND METHODS: Individual, annualized organ doses were estimated from film badge records (n monitored = 2514), occupational chest x-rays (n = 2514), uranium urinalysis (n = 1868), radium intake through radon breath measurements (n = 487), and radon ambient measurements (n = 1356). Silica dust exposure from pitchblende processing was estimated (n = 1317). Vital status and cause of death determination through 2019 relied upon the National Death Index and Social Security Administration Epidemiological Vital Status Service. The analysis included standardized mortality ratios (SMRs), Cox proportional hazards, and Poisson regression models. RESULTS: Vital status was confirmed for 99.4% of workers (84.0% deceased). For a dose weighting factor of 1 for intakes of uranium, radium, and radon decay products, the mean and median lung doses were 65.6 and 29.9 mGy, respectively. SMRs indicated a difference in health outcomes between salaried and hourly workers, and more brain cancer deaths than expected [SMR: 1.79; 95% confidence interval (CI): 1.14, 2.70]. No association was seen between radiation and lung cancer [hazard ratio (HR) at 100 mGy: 0.93; 95%CI: 0.78, 1.11]. The relationship between radiation and kidney cancer observed in the previous follow-up was maintained (HR at 100 mGy: 2.07; 95%CI: 1.12, 3.79). Cardiovascular disease (CVD) also increased significantly with heart dose (HR at 100 mGy: 1.11; 95%CI: 1.02, 1.21). Exposures to dust ≥23.6 mg/m3-year were associated with nonmalignant kidney disease (NMKD) (HR: 3.02; 95%CI: 1.12, 8.16) and kidney cancer combined with NMKD (HR: 2.46; 95%CI: 1.04, 5.81), though without evidence of a dose-response per 100 mg/m3-year. CONCLUSIONS: This third follow-up of Mallinckrodt uranium processors reinforced the results of the previous studies. There was an excess of brain cancers compared with the US population, although no radiation dose-response was detected. The association between radiation and kidney cancer remained, though potentially due to few cases at higher doses. The association between levels of silica dust ≥23.6 mg/m3-year and NMKD also remained. No association was observed between radiation and lung cancer. A positive dose-response was observed between radiation and CVD; however, this association may be confounded by smoking, which was unmeasured. Future work will pool these data with other uranium processing worker cohorts within the Million Person Study.

Racial Disparities in Lung Cancer Stage of Diagnosis Among Adults Living in the Southeastern United States.

BACKGROUND: Black Americans receive a diagnosis at later stage of lung cancer more often than White Americans. We undertook a population-based study to identify factors contributing to racial disparities in lung cancer stage of diagnosis among low-income adults. RESEARCH QUESTION: Which multilevel factors contribute to racial disparities in stage of lung cancer at diagnosis? STUDY DESIGN AND METHODS: Cases of incident lung cancer from the prospective observational Southern Community Cohort Study were identified by linkage with state cancer registries in 12 southeastern states. Logistic regression shrinkage techniques were implemented to identify individual-level and area-level factors associated with distant stage diagnosis. A subset of participants who responded to psychosocial questions (eg, racial discrimination experiences) were evaluated to determine if model predictive power improved. RESULTS: We identified 1,572 patients with incident lung cancer with available lung cancer stage (64% self-identified as Black and 36% self-identified as White). Overall, Black participants with lung cancer showed greater unadjusted odds of distant stage diagnosis compared with White participants (OR,1.29; 95% CI, 1.05-1.59). Greater neighborhood area deprivation was associated with distant stage diagnosis (OR, 1.58; 95% CI, 1.19-2.11). After controlling for individual- and area-level factors, no significant difference were found in distant stage disease for Black vs White participants. However, participants with COPD showed lower odds of distant stage diagnosis in the primary model (OR, 0.72; 95% CI, 0.53-0.98). Interesting and complex interactions were observed. The subset analysis model with additional variables for racial discrimination experiences showed slightly greater predictive power than the primary model. INTERPRETATION: Reducing racial disparities in lung cancer stage at presentation will require interventions on both structural and individual-level factors.

Deep Breaths: A Systematic Review of the Potential Effects of Employment in the Nuclear Industry on Mortality from Non-Malignant Respiratory Disease.

Ionizing radiation is an established carcinogen, but its effects on non-malignant respiratory disease (NMRD) are less clear. Cohorts exposed to multiple risk factors including radiation and toxic dusts conflate these relationships, and there is a need for clarity in previous findings. This systematic review was conducted to survey the body of existing evidence for radiation effects on NMRD in global nuclear worker cohorts. A PubMed search was conducted for studies with terms relating to radiation or uranium and noncancer respiratory outcomes. Papers were limited to the most recent report within a single cohort published between January 2000 and December 2020. Publication quality was assessed based upon UNSCEAR 2017 criteria. In total, 31 papers were reviewed. Studies included 29 retrospective cohorts, one prospective cohort, and one longitudinal cohort primarily comprising White men from the U.S., Canada and Western Europe. Ten studies contained subpopulations of uranium miners or millers. Papers reported standardized mortality ratio (SMR) analyses, regression analyses, or both. Neither SMR nor regression analyses consistently showed a relationship between radiation exposure and NMRD. A meta-analysis of excess relative risks (ERRs) for NMRD did not present evidence for a dose-response (overall ERR/Sv: 0.07; 95% CI: -0.07, 0.21), and results for more specific outcomes were inconsistent. Significantly elevated SMRs for NMRD overall were observed in two studies among the subpopulation of uranium miners and millers (combined n = 4229; SMR 1.42-1.43), indicating this association may be limited to mining and milling populations and may not extend to other nuclear workers. A quality review showed limited capacity of 17 out of 31 studies conducted to provide evidence for a causal relationship between radiation and NMRD; the higher-quality studies showed no consistent relationship. All elevated NMRD SMRs were among mining and milling cohorts, indicating different exposure profiles between mining and non-mining cohorts; future pooled cohorts should adjust for mining exposures or address mining cohorts separately.

Cohort profile: four early uranium processing facilities in the US and Canada.

PURPOSE: Pooling of individual-level data for workers involved in uranium refining and processing (excluding enrichment) may provide valuable insights into risks from occupational uranium and external ionizing radiation exposures. METHODS: Data were pooled for workers from four uranium processing facilities (Fernald, Mallinckrodt and Middlesex from the U.S.; and Port Hope, Canada). Employment began as early as the 1930s and follow-up was as late as 2017. Workers were exposed to high concentrations of uranium, radium, and their decay products, as well as gamma radiation and ambient radon decay products. Exposure and outcome data were harmonized using similar definitions and dose reconstruction methods. Standardized mortality ratios (SMR) were estimated. RESULTS: In total, 560 deaths from lung cancer, 503 non-malignant respiratory diseases, 67 renal diseases, 1,596 ischemic heart diseases, and 101 dementia and Alzheimer's disease (AD) were detected in the pooled cohort of over 12,400 workers (∼1,300 females). Mean cumulative doses were 45 millisievert for whole-body external ionizing radiation exposure and 172 milligray for lung dose from radon decay products. Only SMR for dementia and AD among males was statistically significant (SMR=1.29; 95% confidence interval: 1.04, 1.54). CONCLUSIONS: This is the largest study to date to examine long-term health risks of uranium processing workers.