A CASE COHORT STUDY OF SUICIDE IN RELATION TO EXPOSURE TO ELECTRIC AND MAGNETIC-FIELDS AMONG ELECTRICAL UTILITY WORKERS

Objectives-This case cohort study examines whether there is an associa tion between exposure to electric and magnetic fields and suicide in a population of 21 744 male electrical utility workers from the Canadia n Province of Quebec. Methods-49 deaths from suicide were identified b etween 1970 and 1988 and a subcohort was selected comprising a 1% rand om sample from this cohort as a basis for risk estimation. Cumulative and current exposures to electric fields, magnetic fields, and pulsed electromagnetic fields (as recorded by the POSITRON meter) were estima ted for the subcohort and cases through a job exposure matrix. Two ver sions of each of these six indices were calculated, one based on the a rithmetic mean (AM), and one on the geometric mean (GM) of field stren gths. Results-For cumulative exposure, rate ratios (RR) for all three fields showed mostly small non-significant increases in the medium and high exposure groups. The most increased risk was found in the medium exposure group for the GM of the electric field (RR = 2.76, 95% CI 1. 15-6.62). The results did not differ after adjustment for socioeconomi c state, alcohol use, marital state, and mental disorders. There was a little evidence for an association of risk with exposure immediately before the suicide. Conclusion-Some evidence for an association betwee n suicide and cumulative exposure to the GM of the electric fields was found. This specific index was not initally identified as the most re levant index, but rather emerged afterwards as showing the most positi ve association with suicide among the 10 indices studied. Thus the evi dence from this study for a causal association between exposure to ele ctric fields and suicide is weak. Small sample size (deaths fi om suic ide) and inability to control for all potential confounding factors we re the main limitations of this study.