Mortality experience of electrical engineers.

We have followed up the mortality experience of a group of 1254 electrical engineers during 1930-79, all of whom graduated from the Royal Institute of Technology in Stockholm. The study population consisted of all the men who graduated from this university from 1930 to 1959 with a master of science degree in electrical engineering. These men have been exposed to a variety of laboratory and technical practices in school as well as later, focusing on telecommunication and power engineering. The mortality experience was recorded from the time of graduation to the end of 1979, giving a study period of up to five decades. Of the 1254 men, 11 were lost in follow up, mainly due to emigration. The rest could be certified as either alive or dead at the end of the study period. For those 108 who were dead, death certificates were collected from the local parishes or the National Cause of Death Registry. The mortality in the study group was compared with the expected mortality calculated from age specific (five year groups) and calendar year specific mortality rates of the general Swedish male population for each diagnosis or group of diagnoses studied. The expected mortality for the earliest period (1930-50) was estimated from the rates for 1951-79, adjusted for trend. The standardised mortality ratios (SMR) were calculated for each diagnosis or class of diagnoses, together with a 95% confidence interval as described by Rothman and Boice.' The same was done for the group of 659 male architects who graduated from the same school during the same period to give a comparison with a group similar in background and social position. This group has been described in detail elsewhere.2 Risks for electrical engineers were also compared directly with those for architects and relative risk (RR) estimates were calculated for some diagnoses. When compared with the population at large the mortality of the engineers was found to be considerably lower than expected. As may be seen in the