Risk of leukaemia mortality from exposure to ionising radiation in US nuclear workers: a pooled case-control study

• Published in: Occupational and environmental medicine (London, England) Vol. 70; no. 1; pp. 41 - 48
• Main Authors: Daniels, Robert D, Bertke, Stephen, Waters, Kathleen M, Schubauer-Berigan, Mary K
• Format: Journal Article
• Language: English
• Published: London BMJ Publishing Group Ltd 01.01.2013; BMJ Publishing Group; BMJ Publishing Group LTD
• Subjects: Biological and medical sciences; Biological effects of radiation; Case-Control Studies; Chronic lymphocytic leukemia; Dose response relationship; Dosimetry; Estimates; Fundamental and applied biological sciences. Psychology; Health risk assessment; Hematologic and hematopoietic diseases; Human subjects; Humans; Industry; Ionizing radiation; Ionizing radiations; Laboratories; Leukemia; Leukemia - mortality; Leukemias. Malignant lymphomas. Malignant reticulosis. Myelofibrosis; Medical sciences; Modeling; Mortality; Myeloid leukemia; Neoplasms, Radiation-Induced - mortality; Nuclear Reactors; Occupational Diseases - mortality; Occupational Exposure - adverse effects; Radiation Dosage; Radiation dose response relationship; Radiation, Ionizing; Risk Factors; Studies; Tissues, organs and organisms biophysics; United States - epidemiology; Workers; Workplace; United States; North America; America; Human; Nuclear industry; Leukemia; Mortality; Malignant hemopathy; Case control study; Occupational exposure; Epidemiology; Ionizing radiation; Risk factor; Worker; Pool; Occupational medicine; Cancer
• ISSN: 1351-0711; 1470-7926; 1470-7926
• DOI: 10.1136/oemed-2012-100906

Objective To follow-up on earlier studies of the leukaemogenicity of occupational ionising radiation exposure. Methods We conducted a nested case-control analysis of leukaemia mortality in a pooled cohort of US nuclear workers followed through 2005. Each case was matched to four controls on attained age. Exposures were estimated from available records. General relative risk models were used to estimate the excess relative risk (ERR) of leukaemia, excluding chronic lymphocytic (CLL), acute myeloid leukaemia, chronic myeloid leukaemia and CLL while controlling for potential confounders. Preferred exposure lags and time-windows of risks were calculated using joint maximum likelihood. Dose-response was also examined using linear, linear-quadratic, categorical and restricted cubic spline models. Results There were 369 leukaemia deaths in 105 245 US nuclear workers. The adjusted ERR for non-CLL leukaemia was 0.09 (95% CI −0.17 to 0.65) per 100 mGy. Elevated non-CLL risks were observed from exposures occurring 6–14 years prior to attained age of cases (ERR per 100 mGy=1.9; 95% CI <0 to 8.0). Lagged models indicated non-linearity of risk at very low (<10 mGy) and high (>100 mGy) doses, which contributed to the imprecision of results in linear models. Similar risk attenuation was not evident in time-windows-based models. Conclusions Risk estimates were in reasonable agreement with previous estimates, with the temporality of non-CLL leukaemia risk as a dominant factor in dose-response analyses. Future research should focus on methods that improve evaluations of the dose-response, particularly in the low-dose range.