Beryllium as an Effect Modifier of Radiation Mortality Risk at the Rocky Flats Plants

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Beryllium is a lightweight metal with physical properties that make it indispensable across various industries, including nuclear and aerospace. Despite its industrial utility, beryllium poses significant occupational health risks, including chronic beryllium disease (CBD), beryllium sensitization (BeS), and its classification as a human carcinogen. In many workplaces, workers are frequently exposed to beryllium alongside other hazardous substances, creating complex co-exposure scenarios that may influence long-term health outcomes. Historically, beryllium exposure has been a notable health concern at several U.S. Department of Energy (DOE) facilities, including the Rocky Flats Plant (RF), which fabricated components for weapons productions. At RF, workers were routinely rotated between radiological and beryllium work areas, resulting in concurrent exposures to beryllium and ionizing radiation from plutonium, americium, and uranium.

The Million Person Study (MPS), a comprehensive investigation of chronic low-dose radiation exposure among 1 million U.S. workers and veterans, recently assessed mortality risks among RF workers. As part of this analysis, the MPS incorporated beryllium exposure data from the Beryllium Health Surveillance Program, categorizing workers into three groups: (1) no indication of beryllium surveillance, (2) beryllium surveillance without disease, and (3) indication of CBD or BeS. Statistical methods employed included Cox proportional hazard models, excess relative risk (ERR) models, and Spearman correlation coefficients.

The study cohort comprised 9,397 RF workers first employed between 1951 and 1989 for at least 30 days. Approximately 90% of the cohort underwent radiation monitoring, with a mean lung dose of 59.0 mGy. Over 40% of workers had indications of beryllium surveillance, and 6% showed evidence of BeS or CBD. A slightly positive correlation (rho = 0.25, p < 0.001) was observed between absorbed lung dose and beryllium surveillance.…