Mortality follow-up of Fernald Feed Materials Production Center workers exposed to uranium from 1951 to 1985.

OBJECTIVE: This follow-up study of uranium processing workers at the Fernald Feed Materials Production Center examines the relationship between radiation exposure and cancer and non-cancer mortality among 6403 workers employed for at least 30 days between 1951 and 1985. METHODS: We estimated cumulative, individual, annualised doses to 15 organs/tissues from external, internal and radon exposures. Vital status and cause of death were ascertained in 2017. The analysis employed standardised mortality ratios, Cox proportional hazards and Poisson regression models. Competing risk analysis was conducted for cardiovascular disease (CVD) mortality risk given several assumptions about risk independent of competing outcomes. Emphysema was examined to assess the potential for confounding by smoking. RESULTS: Vital status was confirmed for 98.1% of workers, with 65.1% deceased. All-cause mortality was less than expected in salaried but not hourly workers when compared with the US population. A statistically significant dose response was observed between external (but not total or internal) lung dose and lung cancer mortality (HR at 100 mGy adjusted for internal dose=1.45; 95% CI=1.05 to 2.01). Significantly increased HRs at 100 mGy dose to heart were observed for CVD (1.27; 95% CI=1.07 to 1.50) and ischaemic heart disease (1.30; 95% CI=1.07 to 1.58). CVD risk remained elevated regardless of competing risk assumptions. Both external and internal radiation were associated with emphysema. CONCLUSIONS: Lung cancer was associated with external dose, though positive dose responses for emphysema imply residual confounding by smoking. Novel use of competing risk analysis for CVD demonstrates leveraging retrospective data for future risk prediction.

Variation in the Diagnostic Evaluation among Persons with Hematuria: Influence of Gender, Race and Risk Factors for Bladder Cancer.

PURPOSE: We sought to determine whether race, gender and number of bladder cancer risk factors are significant predictors of hematuria evaluation. MATERIALS AND METHODS: We used self-reported data from SCCS (Southern Community Cohort Study) linked to Medicare claims data. Evaluation of subjects diagnosed with incident hematuria was considered complete if imaging and cystoscopy were performed within 180 days of diagnosis. Exposures of interest were race, gender and risk factors for bladder cancer. RESULTS: Of the 1,412 patients evaluation was complete in 261 (18%). On our adjusted analyses African American patients were less likely than Caucasian patients to undergo any aspect of evaluation, including urology referral (OR 0.72, 95% CI 0.56-0.93), cystoscopy (OR 0.67, 95% CI 0.50-0.89) and imaging (OR 0.75, 95% CI 0.59-0.95). Women were less likely than men to be referred to a urologist (OR 0.59, 95% CI 0.46-0.76). Also, although all patients with 2 or 3 risk factors had 31% higher odds of urology referral (OR 1.31, 95% CI 1.02-1.69), adjusted analyses indicated that this effect was only apparent among men. CONCLUSIONS: Only 18% of patients with an incident hematuria diagnosis underwent complete hematuria evaluation. Gender had a substantial effect on referral to urology when controlling for socioeconomic factors but otherwise it had an unclear role on the quality of evaluation. African American patients had markedly lower rates of thorough evaluation than Caucasian patients. Number of risk factors predicted referral to urology among men but it was otherwise a poor predictor of evaluation. There is opportunity for improvement by increasing the completion of hematuria evaluations, particularly in patients at high risk and those who are vulnerable.

Mortality among military participants at the 1957 PLUMBBOB nuclear weapons test series and from leukemia among participants at the SMOKY test.

Health effects following low doses of ionizing radiation are uncertain. Military veterans at the Nevada test site (NTS) during the SMOKY atmospheric nuclear weapons test in 1957 were reported to be at increased risk for leukemia in 1979, but this increase was not evaluated with respect to radiation dose. The SMOKY test was one of 30 tests in 1957 within the PLUMBBOB test series. These early studies led to public laws where atomic veterans could qualify for compensation for presumptive radiogenic diseases. A retrospective cohort study was conducted of 12219 veterans at the PLUMBBOB test series, including 3020 at the SMOKY nuclear test. Mortality follow-up was through 2010 and observed causes of death were compared with expected causes based on general population rates. Radiation dose to red bone marrow was based on individual dose reconstructions, and Cox proportional hazards models were used to evaluate dose response for all leukemias other than chronic lymphocytic leukemia (non-CLL leukemia). Vital status was determined for 95.3% of the 12 219 veterans. The dose to red bone marrow was low (mean 3.2 mGy, maximum 500 mGy). Military participants at the PLUMBBOB nuclear test series remained relatively healthy after 53 years and died at a lower rate than the general population. In contrast, and in comparison with national rates, the SMOKY participants showed significant increases in all causes of death, respiratory cancer, leukemia, nephritis and nephrosis, and accidents, possibly related in part to lifestyle factors common to enlisted men who made up 81% of the SMOKY cohort. Compared with national rates, a statistically significant excess of non-CLL leukemia was observed among SMOKY participants (Standardized Mortality Ratio = 1.89, 95% 1.24-2.75, n = 27) but not among PLUMBBOB participants after excluding SMOKY (SMR = 0.87, 95% 0.64-1.51, n = 47). Leukemia risk, initially reported to be significantly increased among SMOKY participants, remained elevated, but this risk diminished over time. Despite an intense dose reconstruction, the risk for leukemia was not found to increase with increasing levels of radiation dose to the red bone marrow. Based on a linear model, the estimated excess relative risk per mGy is -0.05 (95% CI -0.14, 0.04). An explanation for the observed excess of leukemia remains unresolved but conceivably could be related to chance due to small numbers, subtle biases in the study design and/or high tobacco use among enlisted men. Larger studies should elucidate further the possible relationship between fallout radiation, leukemia and cancer among atomic veterans.

Associations of Long-term Sleep Duration Trajectories with Overall and Cause-Specific Mortality Among Middle-to-older Aged Black and White Adults.

Background: Both short and long sleep durations are adversely associated with numerous chronic conditions, including cardiovascular disease (CVD), diabetes, hypertension, and mortality. The American Academy of Sleep Medicine recommends adults in the United States sleep at least 7 hours and less than 9 hours per night to maintain optimal health. It remains unclear how sleep duration trajectories over time are associated with mortality. Methods: This observational cohort study includes 46,928 Black and White adults (mean age: 53 ± 9 years) who enrolled in the Southern Community Cohort Study between 2002-2009 and completed a follow-up survey in 2008-2013. Participants were categorized into nine sleep duration trajectory categories based on the reported average sleep duration between study enrollment and at follow-up. Participant vital status and date and cause of death were ascertained via linkage to the National Death Index through 2022. Cox regression analysis was performed to estimate hazard ratios (HR) and 95% confidence intervals (CI) for the association between sleep duration trajectory and all-cause and cause-specific mortality (CVD, cancer, and neurodegenerative disease) after adjustment for sociodemographic characteristics, health behaviors, and clinical factors. Results: During a median 12.6 years of follow-up, we documented 13,579 deaths, including 4,135 from CVD, 3,067 from cancer, and 544 from neurodegenerative diseases. Compared to the optimal sleep duration trajectory (maintaining 7-9 hours), all sub-optimal trajectories were associated with significant 6 to 33% greater risk of all-cause mortality in fully adjusted models. Compared to the optimal sleep trajectory, three of the sub-optimal trajectories were associated with increased CVD mortality, with HRs ranging from 1.20 to 1.34. The short-long trajectory was associated with the greatest risk of all-cause mortality (HR:1.33; 95%CI: 1.21, 1.46) and the long-short trajectory was associated with the greatest CVD mortality risk (HR:1.34; 95%CI: 1.10, 1.65). The healthy-long trajectory was associated with the greatest risk of cancer mortality (HR: 1.19; 95%CI:1.00, 1.41). None of the sub-optimal trajectories was associated with neurodegenerative disease mortality. Conclusions: Suboptimal sleep duration trajectories were associated with increased risk of all-cause mortality as well as CVD mortality. Findings highlight the importance of maintaining healthy sleep duration throughout midlife to reduce mortality risk.

Moon, Mars and Minds: Evaluating Parkinson's disease mortality among U.S. radiation workers and veterans in the million person study of low-dose effects.

BACKGROUND: Radiation is one of the most important stressors related to missions in space beyond Earth's orbit. Epidemiologic studies of exposed workers have reported elevated rates of Parkinson's disease. The importance of cognitive dysfunction related to low-dose rate radiation in humans is not defined. A meta-analysis was conducted of six cohorts in the Million Person Study (MPS) of low-dose health effects to learn whether there is consistent evidence that Parkinson's disease is associated with radiation dose to brain. MATERIALS AND METHODS: The MPS evaluates all causes of death among U.S. radiation workers and veterans, including Parkinson's disease. Systematic and consistent methods are applied to study all categories of workers including medical radiation workers, industrial radiographers, nuclear power plant workers, atomic veterans, and Manhattan Projects workers at the Los Alamos National Laboratory and at Rocky Flats. Consistent methods for all cohorts are used to estimate organ-specific doses and to obtain vital status and cause of death. RESULTS: The meta-analysis include 6 cohorts within the MPS, consisting of 517,608 workers and 17,219,001 person-years of observation. The mean dose to brain ranged from 6.9 to 47.6 mGy and the maximum dose from 0.76 to 2.7 Gy. Five of the 6 cohorts revealed positive associations with Parkinson's disease. The overall summary estimate from the meta-analysis was statistically significant based on 1573 deaths due to Parkinson's disease. The summary excess relative risk at 100 mGy was 0.17 (95% CI: 0.05; 0.29). CONCLUSIONS: Parkinson's disease was positively associated with radiation in the MPS cohorts indicating the need for careful evaluation as to causality in other studies, delineation of possible mechanisms, and assessing possible implications for space travel as well as radiation protection guidance for terrestrial workers.

Impacts of Poverty and Lifestyles on Mortality: A Cohort Study in Predominantly Low-Income Americans.

INTRODUCTION: Low socioeconomic status has been linked to increased mortality. However, the impacts of poverty, alone or combined with health behaviors, on mortality and life expectancy have not been adequately investigated. METHODS: Data from the Southern Community Cohort Study was used, including nearly 86,000 participants recruited during 2002-2009 across 12 US southeastern states. Analysis was conducted from February 2022 to January 2023. RESULTS: During a median follow-up of 12.1 years, 19,749 deaths were identified. A strong dose-response relationship was found between household incomes and mortality, with a 3.3-fold (95%CI=3.1-3.6) increased all-cause mortality observed for individuals in the lowest income group (<$15,000/year) compared with those in the highest group (≥$50,000/year). Within each income group, mortality monotonically increased with declining healthy lifestyle score. Risk was significantly lower among those in the lowest income but healthiest lifestyle group, compared to those with the highest income but unhealthiest lifestyle (HR=0.82, 95%CI=0.69-0.97). Poor White participants appeared to experience higher all-cause mortality than poor Black participants. Life expectancy was more than 10.0 years shorter for those in the lowest income group compared with those in the highest income group. CONCLUSIONS: Poverty is strongly associated with increased risk of death, but the risks could be modestly abated by a healthier lifestyle. These findings call for a comprehensive strategy for enhancing a healthy lifestyle and improving income equality to reduce death risks, particularly among those experiencing health disparities due to poverty.

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.

A Million Person Study Innovation: Evaluating Cognitive Impairment and other Morbidity Outcomes from Chronic Radiation Exposure Through Linkages with the Centers for Medicaid and Medicare Services Assessment and Claims Data.

The study of One Million U.S. Radiation Workers and Veterans, the Million Person Study (MPS), examines the health consequences, both cancer and non-cancer, of exposure to ionizing radiation received gradually over time. Recently the MPS has focused on mortality patterns from neurological and behavioral conditions, e.g., Parkinson's disease, Alzheimer's disease, dementia, and motor neuron disease such as amyotrophic lateral sclerosis. A fuller picture of radiation-related late effects comes from studying both mortality and the occurrence (incidence) of conditions not leading to death. Accordingly, the MPS is identifying neurocognitive diagnoses from fee-for-service insurance claims from the Centers for Medicare and Medicaid Services (CMS), among Medicare beneficiaries beginning in 1999 (the earliest date claims data are available). Linkages to date have identified ∼540,000 workers with available health information. Such linkages provide individual information on important co-factor and confounding variables such as smoking, alcohol consumption, blood pressure, obesity, diabetes and many other health and demographic characteristics. The total person-level set of time-dependent variables, outcomes, organ-specific dose measures, co-factors, and demographics will be massive and much too large to be evaluated with standard software. Thus, development of specialized open-source software designed for large datasets (Colossus) is nearly complete. The wealth of information available from CMS claims data, coupled with individual dose reconstructions, will thus greatly enhance the quality and precision of health evaluations for this new field of low-dose radiation and neurocognitive effects.

Association of Rurality With Risk of Heart Failure.

Importance: Rural populations experience an increased burden of heart failure (HF) mortality compared with urban populations. Whether HF incidence is greater among rural individuals is less known. Additionally, the intersection between racial and rural health inequities is understudied. Objective: To determine whether rurality is associated with increased risk of HF, independent of cardiovascular (CV) disease and socioeconomic status (SES), and whether rurality-associated HF risk varies by race and sex. Design, Setting, and Participants: This prospective cohort study analyzed data for Black and White participants of the Southern Community Cohort Study (SCCS) without HF at enrollment who receive care via Centers for Medicare & Medicaid Services (CMS). The SCCS is a population-based cohort of low-income, underserved participants from 12 states across the southeastern United States. Participants were enrolled between 2002 and 2009 and followed up until December 31, 2016. Data were analyzed from October 2021 to November 2022. Exposures: Rurality as defined by Rural-Urban Commuting Area codes at the census-tract level. Main Outcomes and Measures: Heart failure was defined using diagnosis codes via CMS linkage through 2016. Incidence of HF was calculated by person-years of follow-up and age-standardized. Sequentially adjusted Cox proportional hazards regression models tested the association between rurality and incident HF. Results: Among 27 115 participants, the median (IQR) age was 54 years (47-65), 18 647 (68.8%) were Black, and 8468 (32.3%) were White; 5556 participants (20%) resided in rural areas. Over a median 13-year follow-up, age-adjusted HF incidence was 29.6 (95% CI, 28.9-30.5) per 1000 person-years for urban participants and 36.5 (95% CI, 34.9-38.3) per 1000 person-years for rural participants (P < .001). After adjustment for demographic information, CV risk factors, health behaviors, and SES, rural participants had a 19% greater risk of incident HF (hazard ratio [HR], 1.19; 95% CI, 1.13-1.26) compared with their urban counterparts. The rurality-associated risk of HF varied across race and sex and was greatest among Black men (HR, 1.34; 95% CI, 1.19-1.51), followed by White women (HR, 1.22; 95% CI, 1.07-1.39) and Black women (HR, 1.18; 95% CI, 1.08-1.28). Among White men, rurality was not associated with greater risk of incident HF (HR, 0.97; 95% CI, 0.81-1.16). Conclusions and Relevance: Among predominantly low-income individuals in the southeastern United States, rurality was associated with an increased risk of HF among women and Black men, which persisted after adjustment for CV risk factors and SES. This inequity points to a need for additional emphasis on primary prevention of HF among rural populations.

Mortality among medical radiation workers in the United States, 1965-2016.

BACKGROUND: Estimates of radiation risks following prolonged exposures at low doses and low-dose rates are uncertain. Medical radiation workers are a major component of the Million Person Study (MPS) of low-dose health effects. Annual personal dose equivalents, HP(10), for individual workers are available to facilitate dose-response analyses for lung cancer, leukemia, ischemic heart disease (IHD) and other causes of death. MATERIALS AND METHODS: The Landauer, Inc. dosimetry database identified 109,019 medical and associated radiation workers first monitored 1965-1994. Vital status and cause of death were determined through 2016. Mean absorbed doses to red bone marrow (RBM), lung, heart, and other organs were estimated by adjusting the recorded HP(10) for each worker by scaling factors, accounting for exposure geometry, the energy of the incident photon radiation, sex of the worker and whether an apron was worn. There were 4 exposure scenarios: general radiology characterized by low-energy x-ray exposure with no lead apron use, interventional radiologists/cardiologists who wore aprons, nuclear medicine personnel and radiation oncologists exposed to high-energy photon radiation, and other workers. Standardized mortality ratio (SMR) analyses were performed. Cox proportional hazards models were used to estimate organ-specific radiation risks. RESULTS: Overall, 11,433 deaths occurred (SMR 0.60; 95%CI 0.59,0.61), 126 from leukemia other than chronic lymphocytic leukemia (CLL), 850 from lung cancer, and 1654 from IHD. The mean duration of monitoring was 23.7 y. The excess relative rate (ERR) per 100 mGy was estimated as 0.10 (95% CI -0.34, 0.54) for leukemia other than CLL, 0.15 (0.02, 0.27) for lung cancer, and -0.10 (-0.27, 0.06) for IHD. The ERR for lung cancer was 0.16 (0.01, 0.32) among the 55,218 male workers and 0.09 (-0.19, 0.36) among the 53,801 female workers; a difference that was not statistically significant (p-value = 0.23). CONCLUSIONS: Medical radiation workers were at increased risk for lung cancer that was higher among men than women, although this difference was not statistically significant. In contrast, the study of Japanese atomic bomb survivors exposed briefly to radiation in 1945 found females to be nearly 3 times the radiation risk of lung cancer compared with males on a relative scale. For medical workers, there were no statistically significant radiation associations with leukemia excluding CLL, IHD or other specific causes of death. Combining these data with other cohorts within the MPS, such as nuclear power plant workers and nuclear submariners, will enable more precise estimates of radiation risks at relatively low cumulative doses.

The association between cardiovascular disease and breast and gynecologic cancers among black female patients.

INTRODUCTION: Little is known about whether a breast or gynecologic cancer diagnosis increases long-term cardiovascular disease (CVD) risk among Black females. The purpose of this study was to determine whether a breast or gynecologic cancer diagnosis is associated with CVD risk and identify determinants of subsequent CVD risk among Black females with an incident breast or gynecologic cancer diagnosis. METHODS: Using the Southern Community Cohort Study data from 2002-2016, this study was designed to analyze CVD incidence among Black females without cancer or CVD at enrollment. Cox proportional hazards regression models with or without covariates were used to explore the relationship between a breast or gynecologic cancer diagnosis and CVD risk among women without cancer as well as without CVD at enrollment (N=11,486). In addition, Cox proportional hazards regression models, excluding those who developed CVD before breast and gynecologic cancer diagnosis and those with other types of cancers, were used to assess determinants of CVD risk among breast and gynecologic cancer survivors. RESULTS: Of 11,486 Black females, 531 developed a breast or gynecological cancer (4.6%) over a median follow-up of 140 months (interquartile range: 123-159 months). Compared to women without cancer, women with a breast or gynecological cancers had greater than 20% higher risk of incident CVD during the follow-up period. Without adjusting for covariates, positive association between CVD risk and breast cancer was observed (hazard ratio (HR) = 1.24; 95% confidence interval (CI) = 1.11 - 1.39; p < 0.001); as well as between CVD risk and a gynecological cancer (HR = 1.23; 95% CI = 1.03 - 1.46; p = 0.021). Yet, after adjusting for covariates, CVD risk was only significantly associated with breast cancer (p = 0.001) but not gynecologic cancer. In cancer case-only analyses, CVD risk was significantly increasing with age (p < 0.05). CONCLUSIONS: Like study populations of predominantly White females, our results suggest that, adjusting for covariates, Black females possess a higher risk of CVD following a breast cancer diagnosis compared to women who did not develop breast cancer. Our results suggest a need for active CVD surveillance in the cancer survivorship phase.

Mortality among Tennessee Eastman Corporation (TEC) uranium processing workers, 1943-2019.

BACKGROUND: There are few occupational studies of women exposed to ionizing radiation. During World War II, the Tennessee Eastman Corporation (TEC) operated an electromagnetic field separation facility of 1152 calutrons to obtain enriched uranium (235U) used for the Hiroshima atomic bomb. Thousands of women were involved in these operations. MATERIALS AND METHODS: A new study was conducted of 13,951 women and 12,699 men employed at TEC between 1943 and 1947 for at least 90 days. Comprehensive dose reconstruction techniques were used to estimate lung doses from the inhalation of uranium dust based on airborne measurements. Vital status through 2018/2019 was obtained from the National Death Index, Social Security Death Index, Tennessee death records and online public record databases. Analyses included standardized mortality ratios (SMRs) and Cox proportional hazards models. RESULTS: Most workers were hourly (77.7%), white (95.6%), born before 1920 (58.3%), worked in dusty environments (57.0%), and had died (94.9%). Vital status was confirmed for 97.4% of the workers. Women were younger than men when first employed: mean ages 25.0 years and 33.0 years, respectively. The estimated mean absorbed dose to the lung was 32.7 mGy (max 1048 mGy) for women and 18.9 mGy (max 501 mGy) for men. The mean dose to thoracic lymph nodes (TLNs) was 127 mGy. Statistically significant SMRs were observed for lung cancer (SMR 1.25; 95% CI 1.19, 1.31; n = 1654), nonmalignant respiratory diseases (NMRDs) (1.23; 95% CI 1.19, 1.28; n = 2585), and cerebrovascular disease (CeVD) (1.13; 95% CI 1.08, 1.18; n = 1945). For lung cancer, the excess relative rate (ERR) at 100 mGy (95% CI) was 0.01 (-0.10, 0.12; n = 652) among women, and -0.15 (-0.38, 0.07; n = 1002) among men based on a preferred model for men with lung doses <300 mGy. NMRD and non-Hodgkin lymphoma were not associated with estimated absorbed dose to the lung or TLN. CONCLUSIONS: There was little evidence that radiation increased the risk of lung cancer, suggesting that inhalation of uranium dust and the associated high-LET alpha particle exposure to lung tissue experienced over a few years is less effective in causing lung cancer than other types of exposures. There was no statistically significant difference in the lung cancer risk estimates between men and women. The elevation of certain causes of death such as CeVD is unexplained and will require additional scrutiny of workplace or lifestyle factors given that radiation is an unlikely contributor since only the lung and lymph nodes received appreciable dose.

Radiation and CNS effects: summary of evidence from a recent symposium of the Radiation Research Society.

This article summarizes a Symposium on 'Radiation risks of the central nervous system' held virtually at the 67th Annual Meeting of the Radiation Research Society, 3-6 October 2021. Repeated low-dose radiation exposure over a certain period could lead to reduced neuronal proliferation, altered neurogenesis, neuroinflammation and various neurological complications, including psychological consequences, necessitating further research in these areas. Four speakers from radiation biology, genetics and epidemiology presented the latest data from their studies seeking insights into this important topic. This symposium highlighted new and important directions for further research on mental health disorders, neurodegenerative conditions and cognitive impairment. Future studies will examine risks of mental and behavioral disorders and neurodegenerative diseases following protracted radiation exposures to better understand risks of occupational exposures as well as provide insights into risks from exposures to galactic cosmic rays.

50 Years of the Radiation Exposure Information and Reporting System.

PURPOSE: As the Radiation Exposure Information and Reporting System (REIRS) celebrates 50 years of existence, this is an appropriate time to reflect on the innovative and novel system and how it has shaped the study of occupational radiation exposure. It is also fitting to appreciate the vision and initiative of the individuals who recognized the future value of the collection and analysis of this information to better inform regulations, policies, and epidemiologic studies, and thus contribute to the protection of workers and the public from the adverse health effects of radiation exposure. CONCLUSIONS: REIRS has evolved and expanded over its 50-year history and has played a central role in providing the radiation exposure monitoring records for the Million Person Study for individuals monitored as NRC licensees and at DOE facilities. REIRS has played two major functions in epidemiologic studies. First, it has provided dosimetry information on individual workers in occupational studies to ensure nearly complete ascertainment of career doses. Second, REIRS was used as the primary data source for large cohorts within the Million Person Study: nuclear power plant workers (n∼140,000) and industrial radiographers (n∼130,000). The legacy that REIRS continues to uphold is a model for creating and maintaining a successful tool throughout decades of political, technological, and demographic change.

Obtaining vital status and cause of death on a million persons.

PURPOSE: To present the methodology used to determine vital status and obtain cause of death (COD) within the Million Person Study of Low-Dose Health Effects (MPS). Data sources and vital status tracing techniques used to obtain vital status and COD for six (n = 424,238 subjects) of the ∼20+ cohorts under study are described. METHODS AND MATERIALS: A multistage approach using multiple sources of vital status information was used to determine vital status (or 'trace') study participants from as early as 1940 to the present. Mortality records from state departments of vital statistics and the Social Security Administration Death Master File (SSA-DMF) were matched to study participants by Social Security Number (SSN), full name, date of birth (DOB), and/or sex using deterministic and probabilistic algorithms. The National Death Index (NDI) and SSA Service for Epidemiological Researchers (SSA-SER) were used to obtain COD (after 1978) and verification of alive status, respectively. Online public records and ancestry services, death certificates, and specialized mortality sources were also utilized. RESULTS: For the MPS cohorts traced to date (nuclear power plant workers, industrial radiographers, atomic veterans, and workers at Rocketdyne/Atomics International, Mound nuclear facility, and Mallinckrodt Chemical Works), vital status was confirmed for over 90% of all study subjects in all but one cohort (88%). The ascertainment of COD was over 96% for all cohorts. CONCLUSIONS: A hallmark of a high-quality epidemiologic cohort mortality study is a low percentage of subjects with unknown vital status and a low percentage of deaths without a COD. The sources and methods used for vital status tracing and COD determination for the MPS have been successful and should be useful for other investigators tracing large, historic study populations. Some of the approaches would be applicable for use in all cohort studies using regional-specific mortality data or modifications to the approach.

Validating the use of census data on education as a measure of socioeconomic status in an occupational cohort.

PURPOSE: Adjusting for smoking status or a reliable surrogate [such as socioeconomic status (SES)] is critically important in occupational epidemiology studies when any smoking-related cancer or cardiovascular disease is an outcome of interest. Sometimes, however, data on smoking patterns or individual-level smoking surrogates such as job title, education, pay scale or other measures of SES are not readily available in occupational cohorts. METHODS AND MATERIALS: To obtain a surrogate measure for missing smoking or individual-level SES data, we demonstrate a method used to obtain and geocode residential address histories which were then linked to area-level SES measures from the United States Census in three test samples and then in a full cohort of workers from the Mound nuclear weapons facility in Dayton, Ohio, USA. The mean educational attainment of the Census Block Group was used to derive a categorical estimate of educational attainment which was compared to self-reported (SR) education available from Mound worker histories using Kappa statistics. Lung cancer mortality patterns between area-derived (AD) and SR education were investigated using Standardized Mortality Ratios (SMR) and Cox Proportional Hazards models with stratification or adjustment by either SR or AD education. RESULTS: Home address histories were obtained from linkages of individual worker data to online resources. In the test cohorts, mean educational attainment was the Census Block Group measure found to have the largest magnitude association with individual-level SES measures. Among 7251 Mound workers, 5685 (78.4%) had at least one residential address match (mean 4.9 addresses) identified. The SR and AD educational attainment measures were highly correlated (weighted Kappa coefficient 0.10, p < .0001). SMR patterns by SR and AD educational attainment were similar, with steadily decreasing mortality with increased educational attainment by either measure. Cox models for lung cancer using AD education produced similar results as those using SR education as an adjustment factor. CONCLUSION: When individual-level SES indicators are not available for statistical adjustment, area-level SES measures can serve as a reliable surrogate when investigating outcomes that are affected by lifestyle factors such as smoking.

The Million Person Study, whence it came and why.

PURPOSE: The study of low dose and low-dose rate exposure is of immeasurable value in understanding the possible range of health effects from prolonged exposures to radiation. The Million Person Study (MPS) of low-dose health effects was designed to evaluate radiation risks among healthy American workers and veterans who are more representative of today's populations than are the Japanese atomic bomb survivors exposed briefly to high-dose radiation in 1945. A million persons were needed for statistical reasons to evaluate low-dose and dose-rate effects, rare cancers, intakes of radioactive elements, and differences in risks between women and men. METHODS AND MATERIALS: The MPS consists of five categories of workers and veterans exposed to radiation from 1939 to the present. The U.S. Department of Energy (DOE) Health and Mortality study began over 40 years ago and is the source of ∼360,000 workers. Over 25 years ago, the National Cancer Institute (NCI) collaborated with the U.S. Nuclear Regulatory Commission (NRC) to effectively create a cohort of nuclear power plant workers (∼150,000) and industrial radiographers (∼130,000). For over 30 years, the Department of Defense (DoD) collected data on aboveground nuclear weapons test participants (∼115,000). At the request of NCI in 1978, Landauer, Inc., (Glenwood, IL) saved their dosimetry databases which became the source of a cohort of ∼250,000 medical and other workers. RESULTS: Overall, 29 individual cohorts comprise the MPS of which 21 have been or are under active study (∼810,000 persons). The remaining eight cohorts (∼190,000 persons) will be studied as resources become available. The MPS is a national effort with critical support from the NRC, DOE, National Aeronautics and Space Administration (NASA), DoD, NCI, the Centers for Disease Control and Prevention (CDC), the Environmental Protection Agency (EPA), Landauer, Inc., and national laboratories. CONCLUSIONS: The MPS is designed to address the major unanswered question in radiation risk understanding: What is the level of health effects when exposure is gradual over time and not delivered briefly. The MPS will provide scientific understandings of prolonged exposure which will improve guidelines to protect workers and the public; improve compensation schemes for workers, veterans and the public; provide guidance for policy and decision makers; and provide evidence for or against the continued use of the linear nonthreshold dose-response model in radiation protection.

Mesothelioma mortality within two radiation monitored occupational cohorts.

PURPOSE: The risk of mesothelioma, including cancers of the pleura and peritoneum, was examined within two large cohorts of workers monitored for exposure to ionizing radiation. METHODS AND MATERIALS: Mortality was assessed among 253,632 workers routinely monitored for external radiation, including 30,724 industrial radiographers (IR) at shipyards, 142,583 workers at nuclear power plants (NPP), and 83,441 IR who had not worked at an NPP or shipyard. Follow-up was from 1969 through 2011. Standardized mortality ratios (SMRs) and 95% confidence intervals (CIs) were computed; observed numbers of deaths from mesothelioma (including cancers of the pleura and peritoneum) and asbestosis were compared with numbers expected based on age-, sex-, and calendar year-specific national mortality rates. Job history and quantitative asbestos exposure data were unavailable, but work at a shipyard was taken as a surrogate for the likelihood of exposure. Cox proportional hazards models were used to estimate hazard ratios (HRs) for mesothelioma in relation to estimated cumulative radiation exposure to the lung. RESULTS: The mean duration of follow-up was 25.3 years (max 42 years). The mean cumulative lung dose was 28.6 mGy (7.3% > 250 mGy). Nearly 20% of the workers had died by 2011. A total of 421 mesothelioma deaths were found (75% occurring after 1999) with increased SMRs among workers monitored in shipyards (SMR 9.97; 95% CI 8.50-11.63) and for NPP workers (SMR 5.55; 95% CI 4.88-6.29), but not for IR who had not worked in shipyards (SMR 1.15; 95% CI 0.53-2.19). Likewise, deaths from asbestosis (n = 189) were also increased for shipyard and NPP workers (SMR = 18.1 and 9.2, respectively), but not among workers who never worked at a shipyard or NPP (SMR = 0.70; n = 1). Radiation dose to the lung was not associated with a statistically meaningful dose-response trend for mesothelioma in the combined cohorts (HR at 100 mGy = 1.10; 95% CI 0.96-1.27; p = .18), nor was mesothelioma risk associated with radiation exposure among IR who had not worked in a shipyard and assumed minimally exposed to asbestos. CONCLUSIONS: An elevated rate of death from mesothelioma was observed in two radiation-exposed occupational groups with potential for asbestos exposure. The increased risk of death from asbestosis, combined with little evidence of a rising trend in mesothelioma mortality with increasing radiation exposure, suggests that the mesothelioma (and asbestosis) excess in these workers was due to asbestos exposure in shipyards and power plants and not to occupational low-dose radiation.

Asbestos exposure and mesothelioma mortality among atomic veterans.

BACKGROUND: The United States (U.S.) conducted 230 above-ground atmospheric nuclear weapons tests between 1945 and 1962 involving over 250,000 military personnel. This is the first quantitative assessment of asbestos-related mesothelioma, including cancers of the pleura and peritoneum, among military personnel who participated in above-ground nuclear weapons testing. METHODS: Approximately 114,000 atomic veterans were selected for an epidemiological study because they were in one of eight series of weapons tests that were associated with somewhat higher personnel exposures than the other tests and because they have been previously studied. We were able to categorize specific jobs into potential for asbestos exposure based on a detailed database of the military activities of the atomic veterans. Standardized mortality ratios (SMR) were calculated by service, rank (officer/enlisted) and ratings (occupation code and work location aboard ship) after 65 years of follow-up. RESULTS: Mesothelioma deaths were significantly increased overall (SMR 1.56; 95% CI 1.32-1.82; n = 153). This increase was seen only among those serving in the PPG (SMR 1.97; 95% CI 1.65-2.34; n = 134), enlisted men (SMR 1.81; 95% CI 1.53-2.13; n = 145), and the 70,309 navy personnel (SMR 2.15; 95% CI 1.80-2.56; n = 130). No increased mortality rates were seen among the other services: army (SMR 0.45), air force (SMR 0.85), or marines (SMR 0.75). Job categories with the highest potential for asbestos exposure (machinist's mates, boiler technicians, water tender, pipe fitters, and fireman) had an of SMR 6.47. Job categories with lower potential (SMR =1.35) or no potential (SMR =1.28) for asbestos exposure had non-significantly elevated mesothelioma mortality. CONCLUSIONS: The large excess of mesothelioma deaths seen among atomic veterans was explained by asbestos exposure among enlisted naval personnel. The sources of exposure were determined to be on navy ships in areas (or with materials) with known asbestos content. No excess of mesothelioma was observed in other services or among naval personnel with minimal exposure to asbestos in this low-dose radiation exposed cohort.

Sex-specific lung cancer risk among radiation workers in the million-person study and patients TB-Fluoroscopy.

BACKGROUND: The study of Japanese atomic bomb survivors, exposed briefly to radiation, finds the risk of radiation-induced lung cancer to be nearly three times greater for women than for men. Because protection standards for astronauts are based on individual lifetime risk projections, this sex-specific difference limits the time women can spend in space. Populations exposed to chronic or fractionated radiation were evaluated to learn whether similar differences exist when exposures occur gradually over years. METHODS AND MATERIALS: Five occupational cohorts within the Million Person Study of Low-Dose Health Effects (MPS) and a Canadian Fluoroscopy Cohort Study (CFCS) of tuberculosis patients who underwent frequent chest fluoroscopic examinations are evaluated. Included are male and female workers at the Mound nuclear facility, nuclear power plants (NPP), and industrial radiographers (IR). Workers at the Mallinckrodt Chemical Works and military participants at aboveground nuclear weapons tests provide information on the risk among males. Cox proportional hazards and Poisson regression models were used to estimate sex-specific radiation risks for lung cancer and to compare any differences. RESULTS: Overall, 15,065 lung cancers occurred among the 443,684 subjects studied: 50,111 women and 395,573 men. The mean cumulative dose to the lung was 166.3 mGy (range 6 to 1,055 mGy) with the highest among the TB-fluoroscopy patients (mean 1,055 mGy). Mean lung dose for women in the worker cohorts was generally 4 times lower than for men. Of the 12 estimates of radiation-related risk, only one, for male IRs, showed a significant elevation (ERR 0.09; 95% CI 0.02-0.16, at 100 mGy). In contrast, the dose response for male NPP workers was negative (ERR -0.05; 95% CI -0.10, 0.01, at 100 mGy). Combined, these two cohorts provided little evidence for a radiation effect among males (ERR 0.01; 95% CI -0.04, 0.06, at 100 mGy). There was no significant dose-response among females within any cohort. There was no difference in the sex-specific estimates of lung cancer risk. CONCLUSIONS: There was little evidence that chronic or fractionated exposures increased the risk of lung cancer. There were no differences in the risks of lung cancer between men and women. However, the sex-specific analyses are limited because of small numbers of women and relatively low doses. A more definitive study is ongoing of medical radiation workers which include 85,000 women and 85,000 men (overall mean dose 82 mGy, max 1,140 mGy). Additional understanding will come from the ongoing follow-up of the CFCS.