| This analytic data file set consists of three files supporting the 1989 combined cohort mortality study by Ethel Gilbert, et al. of white males employed at the Hanford, Oak Ridge, and Rocky Flats sites and three additional files supporting the updated 1993 study of workers at these sites. |
| An important objective of studies of workers exposed occupationally to chronic low doses of ionizing radiation is to provide a direct assessment of health risks resulting from this exposure. This objective is most effectively accomplished by conducting analyses that allow evaluation of the totality of evidence from multiple study populations. |
| The 1989 combined study of males employed at Hanford, Oak Ridge, and Rocky Flats provides no evidence of a correlation between external radiation exposure and mortality from all cancers or from leukemia. Of 11 other specific types of cancer analyzed, multiple myeloma was the only cancer found to exhibit a statistically significant correlation with exposure. Estimates of the excess risk of all cancers and of leukemia, based on the combined data, were negative. Upper confidence limits based on the combined data were lower than for any single population and were similar to estimates obtained from recent analyses of A-bomb survivor data. These results strengthen support for the conclusion that estimates obtained through extrapolation from high-dose data do not seriously underestimate risks of low-dose exposure but leave open the possibility that extrapolation may overestimate risks. |
| Each of the 1989 study files in the HFMULA02 data file set represent a particular site. The study population at each site consists of white males monitored for external radiation and employed for at least 6 months. |
| HFMULA02_d1 (HFMUL_HF) has one record for each of 25,241 white male candidates in the study period of 1944 to 1981. This file contains demographic, work history, vital status, and external dosimetry data. HFMULA02_d2 (HFMUL_OR) has one record for each of 8,375 white male candidates in the study period of 1943 to 1977. This file contains demographic, work history, vital status, and external dosimetry data. HFMULA02_d3 (HFMUL_RF) has one record for each of 7,616 white male candidates in the study period of 1952 to 1979. This file contains demographic, work history, vital status, external dosimetry, and internal deposition data. |
| Updated 1993 analyses of mortality data on workers at the Hanford Site, ORNL, and Rocky Flats Weapons Plant were performed with the objective of providing a direct assessment of health risks resulting from protracted low-dose exposure to ionizing radiation. For leukemia, the combined excess relative risk estimate was negative (-1.0 per Sv), and confidence limits excluded risks that were more than slightly larger than those forming the basis of International Commission of Radiological Protection (ICRP) recommendations. For all cancer except leukemia, the excess relative risk estimate was 0.0 per Sv, but confidence limits indicated consistency with estimates several times those forming the basis of ICRP recommendations. Of 24 cancer types tested, 12 showed positive correlations with radiation dose and 12 showed negative correlations, as would be expected by chance fluctuation. Cancer of the esophagus, cancer of the larynx, and Hodgkin's disease showed statistically significant correlations with radiation dose (P < 0.05), but these correlations were interpreted as likely to have resulted from bias or chance fluctuation. Evidence of an increase in the excessive relative risk with increasing age at risk was found for all cancers at both Hanford and ORNL, and both populations showed significant correlations of all cancers with radiation dose among those 75 years and older. Although this age effect may have resulted from bias in the data, its presence suggests that risk estimates based on nuclear worker data be interpreted cautiously. |
| Each of the three updated 1993 study files in the HFMULA02 data file set represents a particular site. The study population at each site includes white males monitored for external radiation and employed for at least 6 months. In addition, female workers and a small number of non-white workers are included in the Hanford study population. |
| HFMULA02_d4 (HFMUP_HF) has one record for each of 44,156 candidates in the study period of 1944 to 1986. This file contains demographic, work history, vital status, internal deposition, and external radiation exposure data. External radiation estimates are provided by type of work: onsite operations, onsite construction, or offsite. HFMULA02_d5 (HFMUP_OR) has one record for each of 8,318 white male candidates in the study period of 1943 to 1984. This file contains demographic, work history, vital status, internal deposition, and external dosimetry data. HFMULA02_d6 (HFMUP_RF) has one record for each of 7,616 white male candidates in the study period of 1952 to 1983. This file contains demographic, work history, vital status, external dosimetry, and internal deposition data. |
| Workers at the Hanford Site were involved in a variety of activities that resulted in their exposure to radiation, including reactor operations, chemical separation of reactor fuel to obtain plutonium, treatment and storage of hazardous waste, and biological and engineering research. |
| Personal dosimeters (film or thermoluminescent) have been used at Hanford since 1944. Annual whole-body doses from penetrating external radiation are presented in units of millisieverts. Quality factors of 10 for fast neutrons, 3 for slow neutrons, and 1 for photons and electrons were used in the conversion of exposure to dose. |
| ORNL began monitoring personnel for exposure to external penetrating radiation, primarily gamma rays, in 1943. Pocket chambers were used until June of 1944. At this time, film dosimeters (film badges) became the primary type of dosimeter. In 1975, film badges were replaced with thermoluminescent dosimeters (TLDs). |
| Until the early 1950s, the usual practice at ORNL was to provide personal dosimeters to only those workers entering designated areas where there was a potential for exposure. After that time, all workers were monitored. |
| The Rocky Flats Plant has been a weapons facility since 1952. Sources of occupational exposure include external radiation, both gamma and neutron, and potential for internal deposition of plutonium-239. Personal film dosimeters and, subsequently TLDs were used to monitor external exposure to workers. Formal bioassay programs to monitor for internal radiation were initiated in 1952. Results of both types of monitoring programs reflect technological improvements and changes in concepts and models over time. |
