Studies of Populations Exposed to Occupational Sources of Radiation

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Markers of Cosmic Radiation Exposure Among Flight Crew A biodosimetry study study was conducted to determine if there were differences in the frequency of chromosome aberrations by assess cosmic radiation exposure and frequency of chromosome aberrations by fluorescence in situ hybridization among 83 pilots (given their increased levels of cosmic radiation exposure) 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. Some diet and vitamin supplements were also associated with translocation frequency. 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 who were certified during 1926-1980. The cohort with 73% females. From work history data (collected 1983-89, 1994-98, 2003-2005, and beginning in 2012) along with tracing and matching with death information, we found significantly elevated incidence risks for breast cancer, leukemias other than chronic lymphocytic leukemia, basal cell carcinoma of the skin, melanoma and circulatory diseases among technologists first working before 1950, and a suggested increase in thyroid cancer in those first working before 1960. The , and very high response rates and development of the first comprehensive historical occupational dose reconstruction 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. Cancer Mortality in Russian Nuclear Workers A cohort of 26,000 Mayak nuclear facility workers is being studied because they comprise a unique occupational group for protracted exposure to external radiation at high doses and for 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 risks for lung cancer, liver cancer and bone cancer increase with increasing dose from plutonium. Dose-response analyses of cancer mortality in relation to in utero radiation exposure from maternal employment at the Mayak facility provide no evidence of an effect. Chernobyl Leukemia Study This is a joint US-Ukrainian case-control study of leukemia and other hematological diseases in a cohort of clean-up workers in Ukraine following the Chornobyl accident, carried out from 1986 to 2006 - one of the largest analytical studies performed in Chornobyl liquidators, taking into account the whole period of observation since the accident, cohort size (approximately 110,000) and collective dose. A total of137 cases of leukemia have been ascertained in the cohort. With a case-control ratio of 1:5, this number of cases provides adequate power to test the hypothesis of an association between radiation and leukemia risk. The study should also have adequate power to test the hypothesis that the risk is different from that seen in the atomic bomb survivors study if the previously pattern of CLL increases observed in the Chornobyl liquidators from Ukraine is confirmed. The study is conducted by scientists of the Ukrainian Research Center for Radiation Medicine (RCRM), scientists from the U.S. National Cancer Institute (NCI) and scientists and consultants from Columbia University, New York (through a contract with NCI). The field work for the study has been completed. A paper has been published, reporting a significant increase risk of both chronic lymphocytic leukemia and other types of leukemia. Dosimetry for Nuclear Medicine Patients Despite the growing use of nuclear medicine procedures in the United States, very little is known regarding patterns of exposure in medical radiation workers. 20% of radiologic technologists in the U.S. radiologic technologist (USRT) study have reported working as nuclear medicine technologists at some time in their job history. In November 2010, REB held a focus-group discussion in which 8 to 10 experts provided input on historical practices. Based on these findings, as well as the literature, we have developed a detailed interview work module for radiologic technologists working with nuclear medicine procedures. We plan to refine this module based on feedback from additional feedback from focus group attendees and other experts, and to perform extensive pilot testing of the new nuclear medicine module. Studies of UV and cancer at various sites in the USRT cohort This project is designed to facilitate study of the role of UV/ vitamin D in relation to several cancers. We recently completed an analysis in a USRT subpopulation of the UV and other determinants of circulating 25(OH)D, which is in press in AJE. An additional analysis of how well 25(OH)D tracks in individuals across seasons will soon be submitted to J Clin Endocrinology. Other analysis planned involve the relationship between 25(OH)D and telomere length. We also plan to examine the relationship between specific UV wavelengths and various skin and other cancers. Leukemia and Other Cancer Incidence in Baltic Clean-up Workers Workers received an average radiation dose of approximately 10 cGy. No clear evidence of increased risk was seen for leukemia, thyroid cancer or radiation-related cancer sites combined relative to incidence in the general population. An elevated risk was found for cancers of the pharynx, esophagus, central nervous system and a broad category of alcohol-related sites. Excess mortality was observed for cancer of the mouth and pharynx, alcohol-related sites taken together,and suicide. Twenty-five years of follow-up suggest that non-radiation determinants of cancer incidence and mortality predominate over direct effects of radiation in this cohort. Incidence of Cancers in Female Flight Attendants Flight attendants may be at increased risk of breast and other cancers due to work-place exposures including cosmic radiation and circadian rhythm disruption from traveling across multiple time zones. We are investigating the risk of breast and other cancers in 9,631 female flight attendants and whether the risk is cosmic radiation dose-related.