=> DATA FILE SET-LEVEL: SSFL05A2
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=> indicates the hierarchical level of the current display Further description of the hierarchical organization of CEDR Structured Documentation
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Description:
This set of three files contains demographic and radiation monitoring and dosimetry data on 5,801 Atomics International-Boeing-Rocketdyne employees who were monitored for either external or internal radiation from 1948 until 1999. The 3 analytic files contain data on: 1) employee demographics 2) external radiation (including neutron) dose, and 3) internal radiation dose. All three datasets can be linked using the ID variable. The principal investigator for this study is John D. Boice, Jr.
The demographics file contains key demographic (but not personally identifiable) information on all 5,801 radiation workers. Each record represents one employee. Variables include sex, race, year of birth, year of hire and termination, whether the employee was monitored for external, internal and/or neutron radiation, occupational variables indicating whether the employee was primarily a factory worker, the primary pay type (hourly versus salary), and if the employees ever worked an a test stand mechanic or related position. The vital status, as of December 31, 1999, is also included. If worker was found to be dead, the year of death, along with the cause of death coded in the International Classification of Diseases (ICD) revision in effect at the time of death are included.
The two dose files contain dosimetry data. The external file contains annual total external (gamma and x-rays) and neutron doses for 5,743 workers monitored for external radiation. Each record represents one employee (n=5,743), with variables for id, total external dose in 1940 to 1999 (texd1940-texd1999), and total neutron dose in 1948 to 1999 (tned1948-tned1999). The internal file contains 15 annual committed equivalent internal organ doses (in millirem) for 285 workers who had committed equivalent doses to any organ expected to be greater than 10 mSv. Each record represents one year of organ dose for each employee (n=8,760). Variables include the id, year, and organ doses, including bladder, bone surface, brain, breast, colon, esophagus, kidney, liver, lung, respiratory lymph node, red marrow, stomach, testes, thyroid, and the remainder dose.
A retrospective cohort mortality study was conducted of workers engaged in nuclear technology development and employed for at least 6 months at Rocketdyne-Atomics International-Boeing Facilities in California, from 1948-1999. The entire workforce of 46,970 Rocketdyne-AI employees was identified from 35,042 Kardex work histories cards, 26,136 electronic personnel listings, and 14,189 radiation folders containing individual exposure histories. Overall, 5,801 workers were monitored for radiation at Rocketdyne-AI: 5,743 for external exposure and 2,232 for internal intakes of radionuclides, 41,169 workers were not monitored for radiation.
Because incomplete radiation exposure histories, inadequate treatment of internally deposited radionuclides, and failure to account for neutron exposures can be important uncertainties in epidemiologic studies of radiation workers, the lifetime occupational doses, including radiation received prior to and subsequent to work at Rocketdyne, were obtained from both company records and linkages with national dosimetry data sets. To obtain prior and subsequent occupational exposure information, the roster of all workers was matched against nationwide dosimetry files from the Department of Energy, the Nuclear Regulatory Commission, the Landauer dosimetry company, the U.S. Army, and the U.S. Air Force. Dosimetry files of other worker studies were also accessed.
Detailed internal exposure scenarios were developed and annual internal doses were derived on a case-by-case basis for 292 workers with committed equivalent doses indicated by screening criteria to be greater than 10 mSv to the organ with the highest internal dose. Computation of organ doses from radionuclide intakes was complicated by the diversity of bioassay data collected over a 40 year period (urine and fecal samples, lung counts, whole-body counts, nasal smears, and wound and incident reports) and the variety of radionuclides with documented intake including isotopes of uranium, plutonium, americium, calcium, cesium, cerium, zirconium, thorium, polonium, promethium, iodine, zinc, strontium, and hydrogen (tritium). Over 30,000 individual bioassay measurements, recorded on 11 different bioassay forms, were abstracted. The bioassay data were evaluated using International Commission on Radiological Protection (ICRP) biokinetics models recommended in current or upcoming ICRP documents (modified for one inhaled material to reflect site-specific information) to estimate annual doses for 16 organs or tissues taking into account time of exposure, type of radionuclide, and excretion patterns.
Vital status was determined for 97.6% of the monitored workers of whom 25.3% (n=1,468) had died. The average period of observation was 27.9 years. Standardized mortality ratios (SMRs) compared the observed numbers of deaths with those expected in the general population of California. Cox proportional hazards models were used to evaluate dose-response trends over categories of cumulative radiation dose, combining external and internal organ-specific doses.
The mean dose from external radiation was 13.5 mSv. However, the mean cumulative external dose based on Rocketdyne-AI records alone was 10.0 mSv, and the dose distribution was highly skewed with most workers experiencing low cumulative doses and only a few with high doses (maximum 500 mSv). Only 45 workers received greater than 200 mSv while employed at Rocketdyne-AI. However, nearly 32% (or 1,833) of the Rocketdyne-AI workers had been monitored for radiation at other nuclear facilities and incorporation of these doses increased the mean dose to 13.5 mSv (maximum 1,005 mSv) and the number of workers with >200 mSv to 69. The mean lung dose from external and internal radiation combined was 19.0 mSv (maximum 3.6 Sv). However, for a small number of workers (n=292), lung doses from internal radionuclide intakes were relatively high (mean 106 mSv, maximum 3,560 mSv) and increased the overall population mean dose to 19.0 mSv and the number of workers with lung dose >200 mSv to 109.
Although nearly 12% of the radiation workers were monitored for neutron exposures (mean 1.2 mSv, 10% at Rocketdyne-AI, 2% elsewhere), the cumulative dose levels were small in comparison with other external and internal exposure. Interestingly, 1,477 workers not monitored for radiation at Rocketdyne-AI (3.6%) were found to have worn dosimeters at other nuclear facilities (mean external dose of 2.6 mSv, maximum 188 mSv). Without considering all sources of occupational exposure, an incorrect characterization of worker exposure would have occurred with the potential to bias epidemiologic results. For these pioneering workers in the nuclear industry, 26.5% of their total occupational dose (collective dose) was received at other facilities both prior to and after employment at Rocketdyne-AI. In addition, a small number of workers monitored for internal radionuclides contributed disproportionately to the number of workers with high lung doses.
Overall, this study showed: 1) radiation exposure has not caused a detectable increase in cancer deaths in this population, but results are limited by small numbers and relatively low career doses, and 2) risk estimates based on nuclear worker data must be interpreted cautiously if internally deposited radionuclides and occupational doses received elsewhere are not considered.
Number of data files: 3
Cohort Size: 5,801
Cause of Death Summary Table
Exposure Type: external and internal radiation
Exposure Agent: gamma, x-rays and neutron
Method: The methods of measuring external dose changed over the years, from film badge to TLD to OSL (optically stimulated luminescence). Bioassays (urine and fecal samples, lung counts, whole-body counts, nasal smears)
incident reports were used to monitor for internal dose.
Notes: October 12th, 2007. DATA PROVIDER: Early in the course of the project, 292 workers were deemed to have internal radiation levels sufficiently high enough to warrant detailed organ dose determination. Over the course of these workers were found to be misidentified and the reconstructed doses were not subsequently included in the doses used for the radiation cohort analyses. We have provided you with the doses for the 285 workers whose internal dos our analyses.
Contact Information:
Mumma, Michael
International Epidemiology Institute
1455 Research Blvd Suite 550
Rockville, MD 20850
(301) 424-1054, ext 4264
Fax: (301)424-1053
Email: Mike@ieixmail.com
Boice, Jr. John D.
Principal investigator
International Epidemiology Institute
Scientific Director
1455 Research Boulevard Suite 550
Rockville, MD 20850
(301) 424-1054
Fax: 301-424-1053
Email: john.boice@vanderbilt.edu