ASSESSMENT AND GROUPING OF OCCUPATIONAL MAGNETIC-FIELD EXPOSURE IN 5 ELECTRIC UTILITY COMPANIES

Objectives Occupational exposure to 60-Hz magnetic fields was surveyed among randomly selected workers in five electric power companies. Met hods The study facilitated the examination of exposure variability and provided the base for a job-exposure matrix linking health outcomes a nd occupational magnetic field exposures. Results Average exposures ra nged from 0.11 to 1.50 mu T. The differences among the five companies were small, the more urban companies showing somewhat higher averages. The day-to-day component of variance exceeded the within- and between -group components of variance. The final job-exposure matrix consisted of five groups with average exposure levels of 0.12, 0.21, 0.39, 0.62 , and 1.27 mu T. Given the variance in exposure, even this optimal gro uping considerably overlapped. Conclusions The job-exposure matrix use d in this study efficiently incorporated the differences in exposure w ithin occupational categories between companies and provided an object ive and statistically based method for estimating cumulative magnetic field exposure.