have a more favourable survival experience than males in the general population, at least in the United States. Also, the numerical adequacy of the British data might be questionable, since with groups of the order of 1000 persons a lifeshortening effect of as much as 10 years could go undetected, even if present. Other differences of substance may have regarded the more careful and earlier adoption of safety measures in Britain than in the United States; the fact that in Britain most radiological practice was carried out in hospitals and therefore much of the exposure might have been taken by radiology technicians and not by the specialists themselves; the wider use of fluoroscopy than of radiography and also the greater number of films used per radiological examination in the United It should be pointed out, however, that both the States than in Britain [V7]. British and the United States series agree in showing that since adoption of radiation protection limitations any hazard attributable to radiation can no longer be documented. 349, Two papers from Japan on a small group of radiology technicians were also reported. In the first one [K17] estimates of radiation injuries such as leu- kaemia, cancer of the skin and tumours of the inner organs were carried out but no mention was made of life-span-shortening associated with the exposure of this group of people. The second paper [K18] reported that during the period 1933-1963 there were 52 radiology technicians dead in three Japanese prefectures. The corrected death rate corresponding to this number was significantly higher than that in the population at large employed in similar professions and aged over 15 years in 1955. There was some tendency of the death rate to in- crease with increasing occupational exposure, but no correlation with the age at which exposure first began. Except for skin cancer which was significantly higher, other causes of death were similar in this group as in the general population. Life expectancy in each age class was shorter than in male persons of comparable social and working conditions which were over 15 years of age in 1951 and 1952. A life-span-shortening amounting to 6.6 years in the x-ray technicians was found, corresponding to an estimated loss of 0.92 days/R. 350. New data on the effects of ionizing radiation or radiologists were repor- ted in 1966 by Warren and Lombard [Wi]. The study comprised 5.982 certified ra- diologists which were compared with all United States physicians in 1949-1951, with the United States male population aged over 25 years in 1950 and with a group of 3.176 Massachussets dentists. Although the number of certified radio- logists increased more than three-fold from 1940 to 1960, their mean age did not