Towards resolving conflicting reports of radiation-induced genomic instability in populations exposed to ionizing radiation: Implications for the hibakusha

Radiation-induced genomic instability has been demonstrated in numerous in vitro model systems. This instability can manifest as chromosomal changes, gene amplifications and mutations, micronuclei formation, transformation, and reduced plating efficiency and occurs in the progeny of an irradiated cell generations after the initial insult. However, reports of induced genomic instability in humans exposed to ionizing radiation are contradictory. We will review the evidence for and against induced chromosomal instability in radiation exposed human populations. In an attempt to reconcile these conflicting observations, we propose that analysis of potential chromosomal instability in blood samples from normal healthy individuals, irrespective of their radiation history, is unlikely to reveal evidence of induced instability because observable dynamic genomic changes would be inconsistent with a normal healthy phenotype.