Reciprocal translocations as an indicator for radiation exposures in the low dose range.

A few years back, the frequency of dicentrics was determined shortly after exposure in five accidentally exposed radiation workers. In all cases the observed dicentric yield was significantly higher in comparison with the background level, and the resulting estimated whole body doses lay between 0.2 and 0.3 Gy. Now, a number of years later (1 to 11 years), the frequency of translocations has been determined by means of the FISH technique. Chromosomes 2, 4 and 8 were painted. The measured translocation frequency lay, however, within the range of the spontaneous variation between individuals. No radiation exposure could, therefore, be proven. In two further cases, the dicentrics were determined by means of the conventional Giemsa staining technique, and the translocations by means of chromosome painting carried out on the same blood samples, which were taken about 3 and 10 years, respectively, after the radiation exposure. The dose estimates obtained on the basis of dicentric frequency using the Qdr method, and on the basis of FISH detected translocations, are compared.