A MORTALITY STUDY OF ELECTRICAL UTILITY WORKERS IN QUEBEC

Objectives-The objective of this study was to investigate the mortalit y of electrical utility workers exposed to electric and magnetic field s. Methods-A historical cohort mortality study was carried out on 21 7 44 workers who were employed in an electrical company in the province of Quebec between 1970 and 1988. The last job held by each study subje ct was coded. A job exposure matrix (JEM) was used to estimate the exp osure to 60 Hz electric and magnetic fields, and pulsed electromagneti c fields (as recorded by the PEMF (POSITRON) meter) in this job. Stand ardised mortality ratios (SMRs) were calculated relative to Quebec men . Because the exposure was exclusively among blue collar workers, the remainder of the analyses by exposure were restricted to them. Rate ra tios (RRs) in the exposed groups relative to the background groups wer e Poisson regression. deaths by the end of follow up. Results-SMRs wer e almost all below one and never substantially increased, although the re were a few increased rate ratios (RRs). There was a significant RR of 2.00 (95% confidence interval (95% CI) 1.37-2.93) for deaths caused by accidents and violence in workers exposed to magnetic fields, RR o f 1.82 (95% CI 1.25-2.65) for electric fields, and RR of 1.62 (95% CT 1.13-2.32) for pulsed electromagnetic fields. Occupational accidents r elated to power lines explain some of the excess of deaths from accide nts and violence. Some association was found between magnetic fields a nd leukaemia, brain cancer, and suicide, between electric fields and b rain cancer and suicide, and between pulsed electromagnetic fields and lung cancer, but these were not significant. Conclusion-These results are broadly reassuring that major causes of death are not strongly as sociated with exposure to electric and magnetic fields, but small numb ers and approximate exposure assessments preclude the denial of any ri sk, in particular if it were to affect a rare cause of death.