DNA CONTENT PROPORTIONALITY AND PERSISTENCE OF RADIATION-INDUCED CHROMOSOMAL-ABERRATIONS STUDIED BY FISH

Chromosome aberrations induced by radiation have been used for the pur pose of dosimetry for a long time. Translocations are especially usefu l for retrospective dosimetry, since they are assumed to be stable. Th e method of chromosome painting (FISH) has facilitated objective scori ng of aberrations considerably. Translocation frequencies, obtained by FISH, for retrospective dosimetry rely on the main assumptions of neu tral selection value and that the distribution of aberrations over the chromosomes is a known function of the DNA content of the chromosomes . Data scrutinising the two above-mentioned assumptions indicate devia tions from both. Other factors potentially causing problems for retros pective dosimetry, such as inter-individual variations in background a nd induction patterns, are discussed, Finally, a brief analysis of the statistical power of dosimetry studies shows that establishing low do ses (approximate to 0.25 Gy) with good precision requires a great effo rt, which is probably unrealistic for individual dose estimates in epi demiological studies.