Low-dose ionizing radiation exposure: understanding the risk for cellular transformation

Radiation is energy transfer. When radiation has sufficient energy to remove an orbital electron from its atom, an ionized atom is formed, and radiation with the capacity to do this is called ionizing radiation. The primary effect of radiation is the induction of free radicals and Reactive Oxygen Species (ROS). All the molecules in every cell of the body are potential targets, but the final effect of radiation will be mainly of concern if the molecule impaired is a molecule critical for life. ROS are also generated as a result of the aerobic respiration (metabolic ROS) in much larger quantity than from the natural radiation background. During evolution, life has developed powerful control and repair mechanisms that greatly contribute to minimize the risks associated with the generation of free radicals and ROS. At low irradiation doses the probability of the risk is therefore proportional to the dose, and the ALARA (As Low As Reasonable Achievable) principle seems to be a valuable goal in radioprotection policies.