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.
Disclosure statement
No potential conflict of interest was reported by the author(s).
Additional information
Funding
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.