Establishment of International Norms, 1922–40

Before and during World War I, Europe’s medical radiologists had met regularly but managed without recourse to collective international decisions. The War interrupted professional international meetings, which revived slowly due to strong nationalist sentiments and an Allied boycott of German science and medicine, which ended in 1925. By then, therapeutic progress in Germany had made international cooperation a necessity for comparing and validating clinical results. Faced with public pressure to deny or reproduce German results, physicists and physician-specialists, led by the British, French, and Germans, formed in 1925 the International Commission for Radiological Units to generate norms for measuring radiation and in 1928 the International Commission for X-ray and Radium Protection, to set norms for radiation protection. These norms were well-established within medical radiology, if not always followed, nationally and internationally, by the beginning of World War II. The basis of the recommendations was the idea of a “tolerance dose,” which assumed a threshold for the effects of ionizing radiation on human beings. But even before World War II it was known that there was no threshold for genetic effects, which were debated but, in the absence of pressure from inside and outside medical radiology, rejected as a factor in setting radiation protection norms, except in Germany.