This paper presents results of a collaborative experiment between six laboratories which examined the yields of unstable chromosomal aberrations in human lymphocytes induced in vitro by X-rays over the dose range 0-300 mGy. The work included data points of nominal doses of 0, 3, 5, 6, 10, 20, 30, 50 and 300 mGy. Cells from 24 donors were examined and a total of about 300 000 metaphases were scored. The work was undertaken to determine the limits of sensitivity of the system taking into account variations in scoring data due to interdonor sample and inter-laboratory effects. Despite the existence of these effects, aberration yields significantly in excess of control values were seen at doses > 20 mGy and these were consistent with a linear extrapolation from higher doses. Below 20 mGy the observed dicentric yields were generally lower than background, but not significantly so. Excess acentric aberrations, on the other hand, and centric rings, were higher than the controls but the increase was usually not significant. It is concluded that the statistical uncertainties are such that below 20 mGy this technique cannot distinguish between a linear or a threshold model.
Bibliographical noteFunding Information:
We wish to acknowledge Mr D . R . McClure of the UK National Radiological Protection Board for irradiating the blood samples and performing meticulous physical dosimetry. Five of the collaborating laboratories (Chilton, Essen, Leiden, Mol and Rome) were partly supported by grants from the Commission of the European Communities . We are indebted to Dr K . H . Chadwick of CEC for his encouragement and constructive comments during the course of this project .
Copyright 2014 Elsevier B.V., All rights reserved.