A meta-analysis of leukaemia risk from protracted exposure to low-dose gamma radiation

• Published in: Occupational and Environmental Medicine Vol. 68; no. 6; pp. 457 - 464
• Main Authors: Daniels, R D, Schubauer-Berigan, M K
• Format: Journal Article Book Review
• Language: English
• Published: London BMJ Publishing Group Ltd 01.06.2011; BMJ Publishing Group; BMJ Publishing Group LTD; BMJ Group
• Subjects: Analytical estimating; Atomic bombs; Bias; Biological and medical sciences; Biological effects of radiation; Confidence intervals; Dosimetry; Environmental studies; Epidemiology; Estimates; Estimation bias; Fundamental and applied biological sciences. Psychology; Gamma rays; Gamma Rays - adverse effects; health and safety; Hematologic and hematopoietic diseases; Humans; Ionizing radiation; Ionizing radiations; Leukaemia; Leukemia; Leukemia, Radiation-Induced - epidemiology; Leukemia, Radiation-Induced - etiology; Leukemias. Malignant lymphomas. Malignant reticulosis. Myelofibrosis; Mathematical models; Medical sciences; Meta analysis; Modeling; Models, Statistical; Mortality; Nuclear Reactors; Nuclear weapons; Occupational; Occupational Diseases - epidemiology; Occupational Diseases - etiology; Occupational exposure; Occupational Exposure - adverse effects; Occupational Exposure - analysis; Occupational Exposure - statistics & numerical data; Publication Bias; radiation; Radiation Dosage; Review; Risk; Standard error; Tissues, organs and organisms biophysics; Variance; United States; North America; America; Human; Low dose; Leukemia; Risk; Malignant hemopathy; Exposure; Occupational exposure; Epidemiology; Metaanalysis; Gamma radiation; Cohort study; Risk factor; Occupational medicine; Cancer
• ISSN: 1351-0711; 1470-7926
• DOI: 10.1136/oem.2009.054684

ContextMore than 400 000 workers annually receive a measurable radiation dose and may be at increased risk of radiation-induced leukaemia. It is unclear whether leukaemia risk is elevated with protracted, low-dose exposure.ObjectiveWe conducted a meta-analysis examining the relationship between protracted low-dose ionising radiation exposure and leukaemia.Data sourcesReviews by the National Academies and United Nations provided a summary of informative studies published before 2005. PubMed and Embase databases were searched for additional occupational and environmental studies published between 2005 and 2009.Study selectionWe selected 23 studies that: (1) examined the association between protracted exposures to ionising radiation and leukaemia excluding chronic lymphocytic subtype; (2) were a cohort or nested case–control design without major bias; (3) reported quantitative estimates of exposure; and (4) conducted exposure–response analyses using relative or excess RR per unit exposure.MethodsStudies were further screened to reduce information overlap. Random effects models were developed to summarise between-study variance and obtain an aggregate estimate of the excess RR at 100 mGy. Publication bias was assessed by trim and fill and Rosenthal's file drawer methods.ResultsWe found an ERR at 100 mGy of 0.19 (95% CI 0.07 to 0.32) by modelling results from 10 studies and adjusting for publication bias. Between-study variance was not evident (p=0.99).ConclusionsProtracted exposure to low-dose gamma radiation is significantly associated with leukaemia. Our estimate agreed well with the leukaemia risk observed among exposed adults in the Life Span Study (LSS) of atomic bomb survivors, providing increased confidence in the current understanding of leukaemia risk from ionising radiation. However, unlike the estimates obtained from the LSS, our model provides a precise, quantitative summary of the direct estimates of excess risk from studies of protracted radiation exposures.