- Summary:
- Establish a cohort from the more than 500,000 civilian nuclear power workers who have been primarily exposed to external radiation with estimated cumulative dose averages between 2.2 and 4.2 rem. This cohort would also present opportunities to contrast neutron exposures. Records have been collected on this cohort in support of the cooperative agreement with IARC on the International Collaborative Study of Nuclear Industry Workers.
- Summary:
- Several epidemiologic studies have suggested that time-related variables, including age at time of radiation exposure may have a significant effect on risk of cancer. Methods for statistically modeling this biological effect are not well defined. Following a literature review, a statement of work was prepared to create age-based analysis files and propose analytic approaches to these issues.
- Summary:
- Work environments with substantial neutron exposure records are being evaluated to develop methods for neutron exposure estimation and the appropriate incorporation of these estimates in epidemiologic studies. Additionally, numerous reports indicate that substantial uncertainties in estimating neutron exposure may have caused bias in the neutron dose estimates. Currently, risk estimates for neutron exposures are derived from animal studies.
- Summary:
- Documents that describe historical dosimetry practices at DOE facilities will be identified, collected, and summarized to better describe uncertainties in exposure estimates in epidemiology studies at those facilities. A list of key contacts with knowledge of historical dosimetry practices at each site is being developed.
![[Decontaminating a truck]](images/2001-133i-1.jpg)
Decontamination and monitoring of a truck. Idaho National Engineering and Environmental Laboratory, Idaho Falls, Idaho. 1975. Photo courtesy of the U.S. Department of Energy.
- Summary:
- Phase I of this research project is described in Ongoing Research. If the analysis of Phase I information indicates a need for further evaluation, Phase II would include visits to collect additional site information and develop hypotheses for further study based on priorities of hazards and exposures. Phase III would include studies to test the hypotheses.
- Summary:
- This facility engaged in operations with potential exposures to polonium-210, plutonium-238, and tritium. A mortality study through 1979 showed elevated lung cancer mortality in workers employed from 1943-1959 and a significant dose-response relationship between plutonium-238 exposure and lymphopoietic/hematopoietic cancers and leukemia. Because of these suggestive results, the health effects of tritium, polonium, and external radiation along with potential chemical exposures at the Mound plant should be further investigated. An update would allow an additional 20 years of followup and use of validated bioassay.
- Summary:
- The precision of occupational epidemiology studies will be improved by characterizing multiple exposure conditions. The potential effect of medical and off-site exposures to ionizing radiation in occupational epidemiologic studies has never been evaluated. Risk estimates from studies without characterization of these exposures could be biased. At K-25, an investigation has found that routine fluoroscopic chest x-ray examinations in the 1940s and 1950s may have resulted in substantial whole-body equivalent radiation exposures. This study will determine the feasibility of using medical and off-site records for workers and, if feasible, whole-body doses would be estimated using information from these additional sources of radiation.
- Summary:
- Mortality studies at Los Alamos, Oak Ridge, Y-12, and Rocky Flats have found nonsignificant excesses in brain cancer. Individually, these studies lacked sufficient power to evaluate exposure response associations because of the rarity of brain cancer and the relatively small size of the cohorts. Preliminary feasibility analysis indicates that sufficient brain cancer cases exist across the DOE complex to support a multisite case-control study that would evaluate any association of the disease with chemical and ionizing radiation exposures.
- Summary:
- Uranium and plutonium have well known tumorigenic potential. Worker cohort studies at sites with potential uranium or plutonium exposures have not demonstrated significant elevated risk for bone cancer primarily because of low statistical power to detect an excess. Bone cancer deaths from combined DOE cohorts should be reviewed to determine whether a multisite study is warranted where uranium or plutonium was present in the work environment. This study would provide the most sensitive evaluation of excess bone cancer in nuclear workers possible.
- Summary:
- When actual monitoring data on individual workers are absent, exposures may be estimated from facility, building, or job information through exposure matrices. Because of the extensive individual external radiation monitoring information at DOE sites, the reliability of grouped estimates for chemicals or internal sources may be evaluated when they are derived under various conditions from exposure matrices. A sensitivity analysis will be performed to determine "how much data is enough" to construct a reasonably accurate job exposure matrix. This study will: (1) identify a set of health physics monitoring data with known work histories and tasks; (2) use programming to remove various portions of the data (e.g., collapse job titles and reduce sample sizes within jobs) according to preset criteria; (3) determine indicators of instability or unreliability using various modeling techniques; and (4) determine the level of uncertainty of the estimates at each level of data completeness.
