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Mortality follow-up of Fernald Feed Materials Production Center workers exposed to uranium from 1951 to 1985
  1. Cato M Milder1,2,
  2. Michael B Bellamy3,
  3. Sara C Howard4,
  4. Elizabeth D Ellis4,
  5. Ashley P Golden4,
  6. Sarah S Cohen5,
  7. Michael T Mumma6,7,
  8. Benjamin French8,
  9. Lydia B Zablotska9,
  10. John D Boice1,10
  1. 1 Division of Epidemiology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
  2. 2 Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, Maryland, USA
  3. 3 Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York City, New York, USA
  4. 4 ORISE Health Studies Program, Oak Ridge Associated Universities, Oak Ridge, Tennessee, USA
  5. 5 Social & Scientific Systems, a DLH Holdings Corporation, Durham, North Carolina, USA
  6. 6 International Epidemiology Institute, Rockville, Maryland, USA
  7. 7 International Epidemiology Field Station, Vanderbilt University Medical Center, Nashville, Tennessee, USA
  8. 8 Department of Biostatistics, Vanderbilt University Medical Center, Nashville, Tennessee, USA
  9. 9 Department of Epidemiology and Biostatistics, School of Medicine, University of California San Francisco, San Francisco, California, USA
  10. 10 National Council on Radiation Protection and Measurements, Bethesda, Maryland, USA
  1. Correspondence to Dr Cato M Milder; cato.milder{at}hq.doe.gov

Abstract

Objective This follow-up study of uranium processing workers at the Fernald Feed Materials Production Center examines the relationship between radiation exposure and cancer and non-cancer mortality among 6403 workers employed for at least 30 days between 1951 and 1985.

Methods We estimated cumulative, individual, annualised doses to 15 organs/tissues from external, internal and radon exposures. Vital status and cause of death were ascertained in 2017. The analysis employed standardised mortality ratios, Cox proportional hazards and Poisson regression models. Competing risk analysis was conducted for cardiovascular disease (CVD) mortality risk given several assumptions about risk independent of competing outcomes. Emphysema was examined to assess the potential for confounding by smoking.

Results Vital status was confirmed for 98.1% of workers, with 65.1% deceased. All-cause mortality was less than expected in salaried but not hourly workers when compared with the US population. A statistically significant dose response was observed between external (but not total or internal) lung dose and lung cancer mortality (HR at 100 mGy adjusted for internal dose=1.45; 95% CI=1.05 to 2.01). Significantly increased HRs at 100 mGy dose to heart were observed for CVD (1.27; 95% CI=1.07 to 1.50) and ischaemic heart disease (1.30; 95% CI=1.07 to 1.58). CVD risk remained elevated regardless of competing risk assumptions. Both external and internal radiation were associated with emphysema.

Conclusions Lung cancer was associated with external dose, though positive dose responses for emphysema imply residual confounding by smoking. Novel use of competing risk analysis for CVD demonstrates leveraging retrospective data for future risk prediction.

  • Radiation
  • Epidemiology
  • Radiation, Ionizing
  • Occupational Health

Data availability statement

Data are available in a public, open access repository. The datasets generated during and/or analysed during the current study are available in the Comprehensive Epidemiologic Data Resource (CEDR) repository, https://oriseapps.orau.gov/CEDR/search_results.aspx?DataSet=FMM23A01.

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Data availability statement

Data are available in a public, open access repository. The datasets generated during and/or analysed during the current study are available in the Comprehensive Epidemiologic Data Resource (CEDR) repository, https://oriseapps.orau.gov/CEDR/search_results.aspx?DataSet=FMM23A01.

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Footnotes

  • Contributors All authors contributed to study design and analytical plan. MTM completed vital status and cause of death determination. MBB conducted the dosimetric update for the present follow-up. CMM completed data cleaning in consultation with SCH, EDE, APG and SSC. CMM conducted statistical analyses in consultation with BF, LBZ and JDB. CMM and MBB composed the first draft of this paper. CMM acted as guarantor for for the overall content of the paper. All authors edited the manuscript and provided feedback prior to manuscript finalisation.

  • Funding This work was supported in part by grants awarded to the National Council on Radiation Protection and Measurements from the US Department of Energy (grant numbers DE-AU0000042 and DE-AU0000046). Contract support was additionally received by Oak Ridge National Laboratory from the Office of Radiation and Indoor Air, US Environmental Protection Agency through Interagency Agreement DOE No. 1824 S581-A1, under contract number DE-AC05-00OR22725 with UT-Battelle. Contract support was also received by Oak Ridge Associated Universities from the US Department of Energy through contract number DE-SC0014664. LBZ’s work was funded by National Institute for Occupational Safety and Health and National Institutes of Health award (5R21OH011452) (principal investigator: LBZ).

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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