Where does our information come from?
Information on the mechanisms underlying the induction of health effects by radiation have been obtained from in vivo and in vitro studies on animals, and from human epidemiology. These studies have largely been conducted over the last 70 years, i.e. since the time of the Manhattan Project, but significant information was available from about 1900 onward, due to the early use of x-rays and radium in medicine, and the application of radium in other contexts, e.g. in luminous paint.