Genomic Instability and Bystander Effect – Implications for Radiation Protection

The main results of the EC project ‘Genomic instability and radiation-induced cancer’ (RADINSTAB) are reviewed and the potential implications of genomic instability and bystander effect for risk assessment and radiation protection discussed. A basic paradigm in radiobiology is that, after exposure to ionising radiation, the deposition of energy in the cell nucleus and the resulting damage to DNA, the primary target, are responsible for the harmful biological effects of radiation. The radiation-induced changes are thought to be fixed already in the first cell division following the radiation exposure and health effects are considered to result as a consequence of clonal proliferation of cells carrying mutations in specific genes. These basic assumptions have recently been challenged by new research findings on radiation-induced genomic instability and bystander effects, which are also called non-targeted effects as it appears that DNA is not the primary target for their induction.