100 years of observation on British radiologists: mortality from cancer and other causes 1897-1997

Radiologists and radiotherapists were one of the earliest occupational grou ps to be exposed to ionizing radiation. Their patterns of mortality provide information on the long-term effects of fractionated external radiation ex posure. British radiologists who registered with a radiological society bet ween 1897 and 1979 have now been followed-up until 1 January 1997, and the mortality experience examined among those who registered with a society aft er 1920, when the first radiological protection recommendations were publis hed. The observed number of cancer deaths in those who registered after 192 0 was similar to that expected from death rates for all medical practitione rs combined (SMR=1.04; 95% CI 0.89-1.21). However, there was evidence of an increasing trend in risk of cancer mortality with time since first registr ation with a radiological society (p=0.002), such that in those registered for more than 40 years there was a 41% excess risk of cancer mortality (SMR =1.41; 95% CI 1.03-1.90). This is probably a long-term effect of radiation exposure in those who first registered during 1921-1935 and 1936-1954. Ther e was no evidence of an increase in cancer mortality among radiologists who first registered after 1954, in whom radiation exposures are likely to hav e been lower. Non-cancer causes of death were also examined in more detail than has been reported previously. There was no evidence of an effect of ra diation on diseases other than cancer even in the earliest radiologists, de spite the fact that doses of the size received by them have been associated with more than a doubling in the death rate among the survivors of the Jap anese atomic bombings.