Aging and age-related health effects of ionizing radiation

There is increasing evidence showing a close relationship between human radiation sensitivity and age-related health effects including cancer. Individuals exposed to ionizing radiation (IR) are the most radiosensitive at early ages, and decrease in radiation sensitivity until maturity, but increase again at older ages, as measured with incidence of carcinogenic events. This article reviews the historical and current status of aging and age-related health effects induced by IR, with results obtained from epidemiological, animal and in vitro studies over the last 20 years. Mechanistic studies underlying these radiation-induced effects are summarized in terms of DNA damage and genomic instability, telomere(definition) erosion, oxidative stress and inflammation, as well as radiation-associated cellular senescence(definition) and epigenetic alterations. Since individual radiosensitivity changes with age and the life expectancy of population rises steadily, there is a pressing need for a better understanding of the aging-radiation exposure association so as to improve radiation protection in clinical practice.