Health effects from radiation exposure in former uranium production workers at Mallinckrodt studied

When data on one million workers is studied, numerous opportunities emerge that offer an the chance to find better methods for radiation protection and uncover answers to elusive questions like “what is the cancer and/or mortality risk when exposure is received gradually over time rather than briefly as for the atomic bomb survivors?”

These and many other radiation protection, occupational exposure, and radiation-induced cancer risk questions are being answered by a team of health physicists, epidemiologists, industrial hygienists and other experts leading research in the Million Worker Study (MWS). The MWS began nearly 25 years ago looking at exposure cohorts of workers from the U.S. Department of Energy (DOE), the U.S. Nuclear Regulatory Commission, the U.S. Department of Defense, and other workers from nuclear power plants; physicians and health professionals working with medical radiation; and even nuclear weapons test participants. ORISE has partnered with the National Council on Radiation Protection and Measurements, Oak Ridge National Laboratory, Vanderbilt University and other non-profit organizations to thoroughly examine individual cohorts for instances of cancer or death based on their occupational and other exposures received either acutely or over time.

The foundation of the DOE portion of the Million Worker Study is a data center, constructed by ORISE, that captures 70+ years of occupational radiation data, dating from 1942 to present. In addition to the data access and data management, ORISE provides historical knowledge of DOE operations, as well as subject matter expertise in occupational epidemiology, radiation dose assessment and biostatistical modelling.

In 2018, the team, which includes experts from ORISE, looked specifically at mortality among workers at Mallinckrodt Chemical Works (MCW), a key study group with complex exposures. In 1942, 40 tons of uranium oxide were used by Enrico Fermi to generate the first manmade nuclear reaction, which ushered in the atomic age. The uranium oxide was produced by workers at MCW. By studying mortality rates and reconstructed radiation organ doses on 2,500 MCW workers, the Million Worker Study team has been able to learn more about the effects of six different types of exposures to these workers. These exposures included external gamma ray exposures from uranium and radium; medical x-rays from occupationally required chest exams; and inhalation of uranium and silica dust from the work environment.

Even though these exposures at Mallinckrodt occurred more than 75 years ago, what we can learn from them continues to inform our understanding of radiation exposures and health outcomes and instructs our radiation protection measures.

From the Mallinckrodt study, and other groups like it, NASA is looking at how workers were exposed to radiation over time, and how that might correlate to astronauts’ exposures while traveling through space on Mars missions. An overview of the Million Worker Study involving the Mallinckrodt Chemical Works cohort was published in the April 2018 editon of Health Physics. ORISE experts Betsy Ellis, Ph.D., Ashley Golden, Ph.D., and David Girardi were contributing authors.

Additional References

  • Golden AP, Ellis E, Cohen S, Mumma M, Leggett R, Wallace P, Girardi D, Watkins J, Shore E, Boice J. 2019. Updated mortality analysis of the Mallinckrodt uranium processing workers, 1942-2012, International Journal of Radiation Biology. doi: 10.1080/09553002.2019.1569773
  • Ellis ED, Girardi D, Golden AP, Wallace PW, Phillips J, Cragle D. 2018. Historical perspective on the Department of Energy mortality studies:  focus on the collection and storage of individual worker data. Int J Radiat Biol. 2018 Oct 25: 1-9. doi.org/10.1080/09553002.2018.1547851
  • Mumma MT, Cohen SS, Sirko JL, Ellis ED, Boice JD Jr. Obtaining Vital Status and Cause of Death on a Million Persons. Int J Radiat Biol. 2018 Nov 9:1-21. doi: 10.1080/09553002.2018.1539884
  • Cohen SS, Mumma MT, Ellis ED, Boice JD Jr. Validating the Use of Census Data on Education as a Measure of Socioeconomic Status in an Occupational Cohort. Int J Radiat Biol. 2018 Nov 19:1-10. doi: 10.1080/09553002.2018.1549758
  • Golden AP, Cohen SS, Chen H, Ellis ED, Boice JD Jr. Evaluation of statistical modeling approaches for epidemiologic studies of low dose radiation health effects. Int J Radiat Biol. 2018 Nov 30:1-26. doi: 10.1080/09553002.2018.1554924
  • Dauer LT, Bouville A, Toohey RE, Boice JD Jr, Beck HL, Eckerman KF, Hagemeyer D, Leggett RW, Mumma MT, Napier B, Pryor KH, Rosenstein M, Schauer DA, Sherbini S, Stram DO, Thompson JL, Till JE, Yoder RC, Zeitlin C. Dosimetry uncertainty approaches for the million person study of low-dose radation health efects:  overview of the recommendations in NCRP Report No. 178. Int J Radiat Biol. 2018 Nov 19:1-10. doi: 10.1080/09553002.2018.1536299