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Data File: MDB13A01

Data Files (2):

MDB13A01_d1 - Demographics

MDB13A01_d2 - Dose

Study Name: Mortality Among Mound Workers Exposed to Polonium-210 and Other Sources of Radiation, 1944–1979

Cohort Size: 7,269

Races: No data available.

Sexes: No data available.

Diseases: No data available.

Earliest Exposure: 01/15/1943

Latest Exposure: 12/31/1979

Follow-Up: 12/15/2009

Exposure Type: External and Internal Radiation Exposure

Exposure Agent: Polonium-210, Gamma Radiation, Plutonium-238, Tritium, and Neutrons

Covariate: Education, Year of Hire

Sites: Mound Plant

Description:
Polonium-210 is a naturally occurring radioactive element that decays by emitting an alpha particle. It is in the air we breathe and also a component of tobacco smoke. Polonium-210 is used as an anti-static device in printing presses and gained widespread notoriety in 2006 after the poisoning and subsequent death of a Russian citizen in London. More is known about the lethal effects of polonium-210 at high doses than about late effects from low doses. Cancer mortality was examined among 7,269 (MDB13A01_d1) workers at the Mound nuclear facility in Dayton, Ohio where polonium-210 was used (1944 to 1972) in combination with beryllium as a source of neutrons for triggering nuclear weapons. Other exposures included external gamma radiation and to a lesser extent plutonium-238, tritium, and neutrons. Vital status and cause of death was determined through 2009. Lifetime occupational doses from all places of employment were sought and incorporated into the analysis. Over 250,000 urine samples were analyzed to estimate radiation doses (MDB13A01_d2) to body organs from polonium and other internally deposited radionuclides in mSv. Vital status was determined for 98.7% of the workers of which 3,682 had died compared with 4,074.7 expected (SMR 0.90; 95% CI 0.88–0.93). The mean dose from external radiation was 26.0 mSv (maximum 1.4 Sv) and the mean lung dose from external and internal radiation combined was 88.4 mSv (maximum 17.5 Sv). Among the 4,958 radiation workers, all cancers taken together (SMR 0.86; 95% CI 0.79–0.93), lung cancer (SMR 0.85; 95% CI 0.74–0.97), and other types of cancer were not significantly elevated. Cox regression analysis revealed a significant positive dose-response trend for esophageal cancer [relative risk (RR) and 95% confidence interval at 100 mSv of 1.54 (1.15-2.07)] and a negative dose-response trend for liver cancer [RR (95% CI) at 100 mSv of 0.55 (0.23-1.32)]. For lung cancer the RR at 100 mSv was 1.00 (95% CI 0.96–1.04) and for all leukemias other than CLL it was 1.14 (95% CI 0.65–1.99). There was no evidence that heart disease was associated with exposures (RR at 100 mSv of 1.06). Assuming a relative biological effectiveness factor of either 10 or 20 for polonium and plutonium, alpha particle emissions had little effect on the dose-response analyses. Polonium was the largest contributor to lung dose, and a relative risk of 1.04 for lung cancer at 100 mSv could be excluded with 95% confidence. A dose-related increase in cancer of the esophagus was consistent with a radiation etiology but based on small numbers. A dose-related decrease in liver cancer suggests the presence of other modifying factors of risk and adds caution to interpretations. The absence of a detectable increase in total cancer deaths and lung cancer in particular associated with occupational exposures to polonium (mean lung dose 150 mSv), and to plutonium to a lesser extent (mean lung dose 14 mSv), is noteworthy. Nonetheless, larger combined studies of U.S. workers are needed to clarify radiation risks following prolonged exposures and radionuclide intakes.

Description:

Polonium-210 is a naturally occurring radioactive element that decays by emitting an alpha particle. It is in the air we breathe and also a component of tobacco smoke. Polonium-210 is used as an anti-static device in printing presses and gained widespread notoriety in 2006 after the poisoning and subsequent death of a Russian citizen in London. More is known about the lethal effects of polonium-210 at high doses than about late effects from low doses. Cancer mortality was examined among 7,269 (MDB13A01_d1) workers at the Mound nuclear facility in Dayton, Ohio where polonium-210 was used (1944 to 1972) in combination with beryllium as a source of neutrons for triggering nuclear weapons. Other exposures included external gamma radiation and to a lesser extent plutonium-238, tritium, and neutrons. Vital status and cause of death was determined through 2009. Lifetime occupational doses from all places of employment were sought and incorporated into the analysis. Over 250,000 urine samples were analyzed to estimate radiation doses (MDB13A01_d2) to body organs from polonium and other internally deposited radionuclides in mSv. Vital status was determined for 98.7% of the workers of which 3,682 had died compared with 4,074.7 expected (SMR 0.90; 95% CI 0.88–0.93). The mean dose from external radiation was 26.0 mSv (maximum 1.4 Sv) and the mean lung dose from external and internal radiation combined was 88.4 mSv (maximum 17.5 Sv). Among the 4,958 radiation workers, all cancers taken together (SMR 0.86; 95% CI 0.79–0.93), lung cancer (SMR 0.85; 95% CI 0.74–0.97), and other types of cancer were not significantly elevated. Cox regression analysis revealed a significant positive dose-response trend for esophageal cancer [relative risk (RR) and 95% confidence interval at 100 mSv of 1.54 (1.15-2.07)] and a negative dose-response trend for liver cancer [RR (95% CI) at 100 mSv of 0.55 (0.23-1.32)]. For lung cancer the RR at 100 mSv was 1.00 (95% CI 0.96–1.04) and for all leukemias other than CLL it was 1.14 (95% CI 0.65–1.99). There was no evidence that heart disease was associated with exposures (RR at 100 mSv of 1.06). Assuming a relative biological effectiveness factor of either 10 or 20 for polonium and plutonium, alpha particle emissions had little effect on the dose-response analyses. Polonium was the largest contributor to lung dose, and a relative risk of 1.04 for lung cancer at 100 mSv could be excluded with 95% confidence. A dose-related increase in cancer of the esophagus was consistent with a radiation etiology but based on small numbers. A dose-related decrease in liver cancer suggests the presence of other modifying factors of risk and adds caution to interpretations. The absence of a detectable increase in total cancer deaths and lung cancer in particular associated with occupational exposures to polonium (mean lung dose 150 mSv), and to plutonium to a lesser extent (mean lung dose 14 mSv), is noteworthy. Nonetheless, larger combined studies of U.S. workers are needed to clarify radiation risks following prolonged exposures and radionuclide intakes.

Citations Associated:
Boice, J. D., Cohen, S. S., Mumma, M. T., Ellis, E. D., Cragle, D. L., Eckerman, K. F., Wallace, P. W., Chadda, B., Sonderman, J. S., Wiggs, L. D., Richter, B. S., & Leggett, R. W. (2014). Mortality among mound workers exposed to polonium-210 and other sources of radiation, 1944-1979. Radiation Research. https://doi.org/10.1667/RR13395.1

Citations Associated:

Boice, J. D., Cohen, S. S., Mumma, M. T., Ellis, E. D., Cragle, D. L., Eckerman, K. F., Wallace, P. W., Chadda, B., Sonderman, J. S., Wiggs, L. D., Richter, B. S., & Leggett, R. W. (2014). Mortality among mound workers exposed to polonium-210 and other sources of radiation, 1944-1979. Radiation Research. https://doi.org/10.1667/RR13395.1