title: Association of chromosome translocation rate with low dose occupational radiation exposures in U.S. radiologic technologists.
abstract: Chromosome translocations are a well-recognized biological marker of radiation exposure and cancer risk. However, there is uncertainty about the lowest dose at which excess translocations can be detected, and whether there is temporal decay of induced translocations in radiation-exposed populations. Dosimetric uncertainties can substantially alter the shape of dose-response relationships; although regression-calibration methods have been used in some datasets, these have not been applied in radio-occupational studies, where there are also complex patterns of shared and unshared errors that these methods do not account for. In this article we evaluated the relationship between estimated occupational ionizing radiation doses and chromosome translocation rates using fluorescent in situ hybridization in 238 U.S. radiologic technologists selected from a large cohort. Estimated cumulative red bone marrow doses (mean 29.3 mGy, range 0-135.7 mGy) were based on available badge-dose measurement data and on questionnaire-reported work history factors. Dosimetric assessment uncertainties were evaluated using regression calibration, Bayesian and Monte Carlo maximum likelihood methods, taking account of shared and unshared error and adjusted for overdispersion. There was a significant dose response for estimated occupational radiation exposure, adjusted for questionnaire-based personal diagnostic radiation, age, sex and study group (5.7 translocations per 100 whole genome cell equivalents per Gy, 95% CI 0.2, 11.3, P = 0.0440). A significant increasing trend with dose continued to be observed for individuals with estimated doses <100 mGy. For combined estimated occupational and personal-diagnostic-medical radiation exposures, there was a borderline-significant modifying effect of age (P = 0.0704), but little evidence (P > 0.5) of temporal decay of induced translocations. The three methods of analysis to adjust for dose uncertainty gave similar results. In summary, chromosome translocation dose-response slopes were detectable down to <100 mGy and were compatible with those observed in other radiation-exposed populations. However, there are substantial uncertainties in both occupational and other (personal-diagnostic-medical) doses that may be imperfectly taken into account in our analysis.
authors.affiliation: a  Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, Maryland 20892;
authors.forename: Mark P
authors.initials: MP
authors.lastname: Little
authors.forename: Deukwoo
authors.initials: D
authors.lastname: Kwon
authors.forename: Kazataka
authors.initials: K
authors.lastname: Doi
authors.forename: Steven L
authors.initials: SL
authors.lastname: Simon
authors.forename: Dale L
authors.initials: DL
authors.lastname: Preston
authors.forename: Michele M
authors.initials: MM
authors.lastname: Doody
authors.forename: Terrence
authors.initials: T
authors.lastname: Lee
authors.forename: Jeremy S
authors.initials: JS
authors.lastname: Miller
authors.forename: Diane M
authors.initials: DM
authors.lastname: Kampa
authors.forename: Parveen
authors.initials: P
authors.lastname: Bhatti
authors.forename: James D
authors.initials: JD
authors.lastname: Tucker
authors.forename: Martha S
authors.initials: MS
authors.lastname: Linet
authors.forename: Alice J
authors.initials: AJ
authors.lastname: Sigurdson
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D008875:Middle Aged; D009010:Monte Carlo Method; D016273:Occupational Exposure / Q000009:adverse effects* / Q000706:statistics & numerical data; D011336:Probability; D012306:Risk; D013679:Technology, Radiologic / Q000706:statistics & numerical data*; D013997:Time Factors; D014178:Translocation, Genetic / Q000528:radiation effects*