Biological Dosimetry of Radiation Workers at the Sellafield Nuclear Facility

Abstract

The British Nuclear Fuels plc facility at Sellafield performs a range of nuclear-related activities. The site has been in operation since 1950 and has, in general, employed a stable work force, many of whom have accumulated relatively high occupational exposures to ionizing radiation. This paper compares the physical dosimetry with two biological end points for evaluating radiation exposure: fluorescence in situ hybridization with whole-chromosome painting probes to quantify stable chromosome aberrations (translocations and insertions), and glycophorin A (GPA) analysis of variant erythrocytes. For the cytogenetic analyses, 81 workers were evaluated in five dose categories, including 23 with minimal radiation exposure (< or = 50 mSv) and 58 with exposures ranging from 173 to 1108 mSv, all but 3 being > 500 mSv. In a univariate analysis, the mean stable chromosome aberration frequencies showed a significant increase with dose category (P = 0.032), and with cumulative dose when dose is treated as a continuous variable (P = 0.015). The slope of the dose response for stable aberrations is 0.79 +/- 0.22 aberrations per 100 cells per sievert (adjusted for smoking status), which is less than that observed among atomic bomb survivors, and suggests a dose and dose-rate effectiveness factor for chronic exposure of about 6. Analyses of the data for GPA N/O and N/N variants from 36 workers revealed no correlation with dose. Neither was there a correlation between the frequencies of N/O GPA variants and stable aberrations, although a weak negative association was observed between N/N variant frequency and stable aberrations (r = -0.38, P = 0.05). These results provide clear evidence for the accumulation of stable aberrations under conditions of chronic occupational exposure to ionizing radiation and show that stable chromosome aberrations are a more sensitive indicator for chronic radiation exposure than GPA variants. In comparison with human studies of brief exposure, chronic low-dose exposures appear substantially less effective for producing somatic effects as reflected by stable chromosome aberrations.

Clustered DNA damages induced in isolated DNA and in human cells by low doses of ionizing radiation

“…Humans are exposed to low doses of radiation-during air travel, from radon in homes, during space travel, or in areas of low-level contamination, including former sites of nuclear weapon production-and can encounter much higher radiation doses in contaminated areas such as Chernobyl or during radiotherapy (1)(2)(3)(4)(5). However, ionizing radiation induces a plethora of types of DNA damages (6), and the identity of specific lesions responsible for the biological effects of radiation remains uncertain.…”

BiodosEPR-2006 consensus committee report on biodosimetric methods to evaluate radiation doses at long times after exposure

“…To evaluate the utility of GPA as a biodosimeter of radiation doses accumulated over a long period of time, the GPA assay was applied to 36 radiation workers at the Sellafield Nuclear Facility who had received > 50 mGy cumulative dose based on previously recorded doses. No correlation was evident between variant frequency measured by GPA and radiation dose (Tucker et al, 1997b;. GPA ]N variant frequencies, but not NN V f , were only slightly elevated among the population living near the Semipalatinsk nuclear test site, but were not significantly greater compared with matched controls living in a non-contaminated area .…”

Molecular Cytogenetics in metaphase and interphase cells for diagnosis and prognosis in cancer and genetic research

“…FISH has been one of the latest methodologies used in the field of radiation biology, bringing many new insights into the study of mechanism of aberration production including initial chromosome damage and the repair systems involved (Cornforth et al, 1989;Mühlmann-Díaz and Bedford, 1993Folle et al, 1998), radiobiodosimetry (Edwards, 1997Tucker et al, 1997) eters analyzed after nuclear accidents. In this way, it is possible to estimate the risk that the victims will have to confront and to take preventive measures accordingly.…”