Changing views on ionising radiation-induced cellular effects

Low dose and low dose-rate effects of ionising radiation (IR) are important issues in radiation protection. For these low exposures, radiation-induced double-strand breaks (DSB) and locally multiply damaged sites (LMDS) are considered very deleterious for cells, leading to lethality, mutations, genetic instability and cancer. However, recent results suggest that LMDS are much less frequent than generally thought. DNA lesions are recognised by sensor proteins which activate cellular IR responses such as cell cycle arrest, DNA repair or cell death. These processes clearly differ with dose and dose-rate, challenging the linear non-threshold hypothesis for radiation risk assessments.