Adjusting External Doses from the ORNL and Y-12 Facilities for the Oak Ridge Nuclear Facilities Mortality Study
A Supplemental Report to Data Collection, Validation, and Description for the Oak Ridge Nuclear Facilities Mortality Study
J. P. Watkins (1), D. L. Cragle (1), E. L. Frome (2), C. M. West (1), D. J. Crawford-Brown (3), and W. G. Tankersley (1)
(1) Oak Ridge Institute for Science and Education, Environmental and Health Sciences Division, Center for Epidemiologic Research, Oak Ridge, TN 37831-0117.
(2) Oak Ridge National Laboratory, Oak Ridge, TN 37830.
(3) School of Public Health, University of North Carolina, Chapel Hill, NC 27599-7400.
This report concerns work undertaken as part of the Health and Mortality Study of Department of Energy workers being conducted by Oak Ridge Associated Universities with the collaboration of the School of Public Health, University of North Carolina at Chapel Hill under Contract No. DE-AC05-76OR00033 between the Department of Energy, Office of Energy Research, and Oak Ridge Associated Universities.
The complete text of Adjusting External Doses from the ORNL and Y-12 Facilities for the Oak Ridge Nuclear Facilities Mortality Study is available. Below is the report's Executive Summary.
An earlier report, Data Collection, Validation, and Description for the Oak Ridge Nuclear Facilities Mortality Study (Watkins et al., 1993), described demographic and radiation exposure data characteristics, and the effect of monitoring policies and practices on annual recorded external radiation doses and internal radiation exposure indicators for workers employed in nuclear facilities in Oak Ridge, Tennessee, through 1984. Investigations of changing monitoring policies and practices from the Oak Ridge National Laboratory (ORNL) and the Y-12 site indicated that certain annual recorded doses were likely to be biased downward. To evaluate the effect of this bias on dose-response coefficients, the report concluded that adjusted annual external doses should be calculated as replacements.
As a supplement to the earlier report, this report details specific procedures used for adjusting doses from ORNL and the Y-12. Comparisons of unadjusted and adjusted cumulative external doses for both facilities are also presented. For ORNL, the only major change in dose distribution was percent of workers with a cumulative dose of zero through 1956; this percent decreased from 31.9% to 11.7%. The mean cumulative dose increased from 1.08 to 1.63 cSv, and the median increased from 0.13 to 0.46 cSv. For Y-12, the decrease in percent of workers with a cumulative dose of zero was much more significant because few workers were monitored before 1961. As a result of the adjustment process, this percentage decreased from 74.3% to 10.1%. However, most Y-12 workers still had cumulative doses through 1960 of less than 1 cSv, with 50% having less than 0.2 cSv. The results of the dose-response analysis using unadjusted and adjusted doses will appear in a separate publication.
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