MAGNETIC-FIELD EXPOSURE AMONG UTILITY WORKERS

The Electric and Magnetic Field Measurement Project for Utilities-the Electric Power Research Institute (EPRI) Electric and Magnetic Field D igital Exposure (EMDEX) Project (the EPRI EMDEX Project)- was a multif aceted project that entailed technology transfer, measurement protocol design, data management, and exposure assessment analyses. This paper addresses one specific objective of the project: the collection, anal ysis, and documentation of power-frequency magnetic field exposures fo r a diverse population of utility workers. Field exposure data measure d by an EMDEX system were collected by volunteer utility employees at 59 sites in four countries between September, 1988, and September, 198 9. Specially designed sampling procedures and data collection protocol s were used to ensure uniform implementation across sites. Volunteers within 13 job classifications recorded which of eight work or three no nwork environments they occupied while wearing an EMDEX meter. Approxi mately 50,000 hours of magnetic field exposure records taken at 10 s i ntervals were obtained, about 70% of which were from work environments . Exposures and time spent in environments were analyzed by primary wo rk environment, by occupied environment, and by job classification. Ge nerally, for utility-specific job classifications related to the gener ation, transmission, and distribution of electricity, the field and ex posure measurements in terms of workday mean field were higher than in more general occupations. The job classifications with the highest (m edian workday mean) exposure were substation operators (0.7 mu T) and electricians (0.5 mu T). Total variance also tended to be largest for utility-specific job classifications. For these workers, the contribut ions of between-worker and within-worker variances to total variance w ere about the same. Measurements in utility-specific environments were higher than in more general environments. Estimates of time-integrate d exposure indicated that utility-specific job classifications receive d about one-half or more of their total exposure on the job. The nonwo rk field and exposure distributions for workers in all job categories were comparable with median nonworkday means of about 0.09 mu T. (C) 1 995 Wiley-Liss, Inc.