Brain cancer mortality at a manufacturer of aerospace electromechanical systems

Standardized proportional mortality ratios and mortality odds ratios were calculated for 583 deaths between 1950 and 1986 among employees who had worked for at least 10 years at a facility manufacturing missile and aircraft guidance systems. There was a statistically significant excess of brain cancer proportional mortality (PMR = 16/3.8 = 4.2, p = .0001). Among hourly employees, 12 brain cancer deaths occurred for 2.7 expected (PMR = 4.4, p = .00005). The PMR for brain cancer increased from 1.8 (p = .45) among hourly workers with less than 20 years to 8.7 (p = .000003) in those with more than 20 years employment. Work in "clean rooms," where gyroscopes were assembled, was associated with the brain cancer excess but did not fully account for it. Among 105 deceased hourly women, all three brain cancer deaths occurred among gyro assemblers working in clean rooms, and the risk increased with duration in clean rooms. Although the proportion of brain cancer deaths among hourly men with clean-room experience was similar to that for women, only three of the seven male brain cancer deaths occurred in this group. The suspect agents include gyro fluids and chlorofluorocarbon solvents.