The influence of age, sex and smoking habits on the background level of fish-detected translocations

Chromosomal aberrations have been used for biological dosimetry for many ye ars but dicentric yield decreases with time after irradiation. Since transl ocation yields should persist in peripheral lymphocytes with time they shou ld prove to be a better indicator in the detection of old and chronic expos ures to ionising radiations. The precondition, however, is knowledge of the control level in healthy subjects exposed only to normal background and al so knowledge of confounding factors. From 42 healthy subjects, aged between 21 and 73 years, about 120,000 FISH-painted cells were scored using DNA pr obes for chromosomes 2, 4 and 8, and an all-human centromere probe. The sta tistical analyses revealed no influence of gender on the translocation freq uency. Smoking habits-even a daily consumption of > 30 cigarettes-seem to h ave only a marginal impact on the translocation yield, whereas an age-depen dence has been established. Because of the high background level of translo cations and the variation in the frequency between subjects, the lowest det ectable limit for radiation exposures should be between 0.3 and 0.5 Gy, ass uming that blood stem cells have a similar radiation sensitivity to that of peripheral lymphocytes for the induction of translocations. (C) 1999 Elsev ier Science B.V. All rights reserved.