A study of markers of cosmic radiation exposure and effect among flight crew A biodosimetry study to assess cosmic radiation exposure compared the induction and persistence of chromosome aberrations by fluorescence in situ hybridization (FISH) among 83 pilots and 51 university faculty with minimal flying experience. The mean frequency of translocations did not differ between the airline pilots and a comparison group of university faculty, however there was a significant increasing trend among the pilots for number of years flying commercial aircraft and translocation frequency. In addition, radiation exposure from personal diagnostic procedures among the pilots was positively associated with translocation frequencies after adjustment for age and number of years flying. Cancer and Other Mortality Risks in a Cohort of U.S. Radiologic Technologists In 1982, the REB, initiated a nationwide cohort study of all cancer incidence and mortality among 146,022 U. S. radiologic technologists. The cohort with 73% females, and very high response rates offers a rare opportunity to study effects of occupational protracted low- to moderate-dose radiation exposure on breast and thyroid cancer, the two most sensitive organ sites for radiation carcinogenesis in women. All other cancer and non-cancer serious disease outcomes are also being evaluated in relation to protracted low-to-moderate dose exposures. Presently we are expanding the scope of the study to include a study of skin cancer in relation to radiation exposure and variation in levels of circulating vitamin D. Cancer Mortality in Russian Nuclear Workers Exposed to Plutonium and Protracted External Radiation A cohort of 26,000 Mayak nuclear facility workers (in the Russian Federation) is being studied because they comprise a unique occupational group for protracted exposure to external occupational radiation at high doses and exposure to plutonium. Improved dosimetry and updated mortality data confirm earlier findings of external dose-response relationships for leukemia and for all solid cancers. Mortality analyses have clearly demonstrated that internal exposure to plutonium results in excess risks for lung cancer, liver cancer and bone cancer. Dose-response analyses of lung, liver and bone cancer mortality indicated significant associations for both internal dose from plutonium and external dose. Dose-response analyses of cancer mortality in relation to in utero radiation exposure from maternal employment at the Mayak facility are underway. Germline Genetic Variation And Risk Of Chromosome Aberrations Among Mayak Nuclear Workers REB is elucidating the contribution of germline genetic variation to the frequency of chromosomal aberrations in a cohort of workers at the Mayak nuclear weapons facility. These workers were exposed to external gamma and internal plutonium radiation. Incidence of Breast Cancer and Other Cancers in Flight We are investigating the risk of breast cancer or other cancer incidence in a study of 9,631 female flight attendants due to cosmic radiation exposure. Surveys from living or proxy respondents have been collected from 6,341 female flight attendants. Confirmation of cancer diagnoses from death certificates or medical records is ongoing. Leukemia and Other Cancer Incidence in Chornobyl Clean-Up Workers All cancer incidence through 1998 was evaluated in two cohorts, comprising 10,000 clean-up workers, from Estonia and Latvia, who were sent to Chornobyl (Ukraine) following the reactor accident in 1986. Leukemia risk incidence was not significantly elevated in this group compared to the general population. Thyroid cancer incidence was increased, but this appeared to have been due, at least in part, to thyroid screening. The study is being extended to include a cohort of 7,000 clean-up workers from Lithuania and additional years of follow-up. NCI has recently completed a """"""""nested"""""""" case-control study of leukemia and other hematologic diseases among the approximately 110,000 Chornobyl clean-up workers in Ukraine and is continuing to accrue cases through record linkage with the Ukrainian National Cancer Registry. (Phase II) Studies of UV and cancer at various sites in the USRT cohort REB investigators also followed up suggestive inverse associations between vitamin D levels and colorectal cancer, using ultraviolet radiation (UVR) as a surrogate for vitamin D, and confirmed a protective association found only in women not using hormone replacement therapy. Thyroid Cancer among Chornobyl Clean-up Workers in Ukraine: Pilot Study We are conducting a pilot study to assess the feasibility of doing a full nested case-control study investigating the radiation-related risk of thyroid cancer among the 150,000 male clean-up workers in Ukraine. This pilot study will identify thyroid cancer cases occurring among the 150,000 Ukrainian clean-up workers through linkage to the National Cancer Registry of Ukraine;locate and interview a small sample of subjects (40-50) with thyroid cancer;obtain saliva buccal cell samples;and obtain information on availability of archival thyroid tumor specimens for future tumor-tissue collection.
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