Updated mortality analysis of the Mallinckrodt uranium processing workers, 1942–2012

Abstract

Purpose

Mallinckrodt Chemical Works (MCW) was the earliest uranium processing facility in the United States, and in 1942 produced the uranium oxide used for the first sustained and controlled nuclear fission chain-reaction at the University of Chicago. A second follow-up through 2012 was conducted of 2514 White male workers employed 1942–1966 at the MCW for dose-response analyses for selected causes of death.

Materials and methods

Organ/tissue-specific dose reconstruction included both external (12,686 MCW film badge records, 210 other facility film badge records, and 31,297 occupational chest x-rays) and internal sources of uranium and radium (39,451 urine bioassays, 2341 breath radon measurements, and 6846 ambient radon measurements). Dust measurements from pitchblende facilitated quantitative risk estimates for non-radiogenic effects on the lung and kidney. Vital status was determined from multiple sources including the National Death Index and the Social Security Administration. Cox regression models were used for dose response analyses.

Results

Vital status was determined for 99% of the workers, of whom 75% had died. The mean lung dose from all sources of external and internal radiation combined was 69.9 mGy (maximum 885 mGy; percent workers >100 mGy, 10%) and there was no evidence for a dose response for lung cancer (Hazard Ratio (HR) of 0.95 (95% CI = 0.81–1.12) at 100 mGy). A significant association with radiation was found for kidney cancer (HR of 1.73 (95% CI = 1.04–2.79) at 100 mGy) and suggested for nonmalignant kidney diseases (HR of 1.30 (95% CI = 0.96–1.76) at 100 mGy). A non-radiation etiology could not be discounted, however, because of the possible renal toxicities of uranium, a heavy metal, and silica, a component of pitchblende dust. Non-significant HRs at 100 mGy for other sites of a priori interest were 0.36 (0.06–2.03) for leukemia other than CLL, 0.68 (0.17–2.77) for liver cancer, and 1.23 (0.79–1.90) for non-Hodgkin lymphoma. The HR at 100 mGy was 1.09 (0.99–1.20) for ischemic heart disease. An association was seen between dust and combined malignant and non-malignant lung disease, HR at 10 mgm⁻³year⁻¹ of 1.01 (1.00–1.02).

Conclusions

A positive radiation dose response was observed for malignant and non-malignant kidney disease, and a negative dose response for malignant and non-malignant lung disease. Cumulative measures of dust were significantly associated with malignant and non-malignant lung disease and suggested for malignant and non-malignant kidney disease. Small numbers preclude definitive interpretations which will await the combination with similar studies of early uranium processing workers.

Keywords:

• Alpha emitters
• epidemiology
• kidney
• lung
• radiation

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported in part by a grant from the U.S. Nuclear Regulatory Commission (NRC-HQ-60-14-G-0011), a grant from the Centers for Disease Control and Prevention (5UE1EH000989), a grant from the National Aeronautics and Space Administration (Grant No. NNX15AU88G), and grants from the U.S. Department of Energy (Grant No. DE-SC0008944 and Grant No. DE-AU0000042 awarded to the National Council on Radiation Protection and Measurements, which included interagency support from the U.S. Nuclear Regulatory Commission, the U.S. Environmental Protection Agency and the National Aeronautics and Space Administration). Additional contract support was received by Oak Ridge National Laboratory from the Office of Radiation and Indoor Air, U.S. Environmental Protection Agency, under Interagency Agreement DOE No. 1824 S581‐A1, under contract No. DE-AC05‐00OR22725 with UT-Battelle; and contract support was received by Oak Ridge Associated Universities from the U.S. Department of Energy under contract No. DE-SC0014664.

Notes on contributors

Ashley P. Golden

Ashley P. Golden is a biostatistician and project manager at Oak Ridge Associated Universities were she conducts multi-disciplinary projects in occupational epidemiology, radiation exposure and dosimetry, medical surveillance, and environmental assessments. She has been a collaborator on the Million Person Study of Low-Dose Health Effects for nearly six years.

Elizabeth D. Ellis

Elizabeth (Betsy) Dupree Ellis currently works in the Health, Energy and the Environment Program, Oak Ridge Associated Universities. Dr. Ellis does research in Public Health, Occupational Health, and Epidemiology. A major project is contributing to the ‘Million Person Study’. She is also active in human subject protection in research.

Sarah S. Cohen

Sarah Cohen is a Principal Epidemiologist at EpidStat Institute and Adjunct Assistant Research Professor of Medicine in the Department of Medicine at Vanderbilt University School of Medicine. She has been a collaborator on the Million Person Study of Low-Dose Health Effects for nearly twenty years.

Michael T. Mumma

Michael Mumma is the Director of Information Technology at the International Epidemiology Institute and the International Epidemiology Field Station for Vanderbilt University Medical Center. He has over 20 years of experience in data analysis and conducting epidemiologic investigations.

Richard W. Leggett

Richard W. Leggett is a research scientist in the Environmental Sciences Division at Oak Ridge National Laboratory. His physiological systems models of the human circulation, skeleton, and gastrointestinal transfer and systemic biokinetic models for many elements are used by the International Commission on Radiological Protection as dosimetry and bioassay models.

Phillip W. Wallace

Phillip W. Wallace was Information Technology Manager at Oak Ridge Associated Universities where he contributed 10 years to the Million Person Study of Low-Dose Health Effects. He was also a developer of the DOE Comprehensive Epidemiologic Data Resource.

David Girardi

David Girardi is a scientific computer programmer at Oak Ridge Associated Universities and has been working with the Million Person Study of Low-Dose Health Effects for six years. He has been a certified Project Management Professional (PMP) for over 5 years.

Janice P. Watkins

Janice Watkins is a biostatistician with extensive experience working with data from a wide variety of areas including occupational epidemiology, radiation dosimetry and dose reconstruction, workplace violence and drugs/alcohol abuse. She worked extensively on the Mallinckrodt cohort study. She recently retired from Oak Ridge Associated Universities after 16 years of employment.

Roy E. Shore

Roy Shore is Professor Emeritus, New York University Langone School of Medicine; Chief of Research, Radiation Effects Research Foundation, Hiroshima, Japan (retired). Interests: radiation epidemiology of cancer and non-cancer, low doses and low dose rates. Has served as a member of the ICRP and NCRP and on UNSCEAR task groups.

John D. Boice

John Boice is Scientific Director of the National Council on Radiation Protection and Measurements and Professor of Medicine at Vanderbilt University. He served on the Main Commission of the International Commission on Radiological Protection and on the United Nations Scientific Committee on the Effects of Atomic Radiation.