Je. Deadman et al., EXPOSURE TO 60-HZ MAGNETIC AND ELECTRIC-FIELDS AT A CANADIAN ELECTRICUTILITY, Scandinavian journal of work, environment & health, 22(6), 1996, pp. 415-424
Objectives The purpose of this study was to estimate exposure to extre
mely low frequency (ELF) magnetic and electric fields in the Quebec el
ectrical utility Hydro-Quebec. Methods Personal exposures to ELF magne
tic and electric fields were measured for workers randomly selected fr
om 32 job categories at Hydro-Quebec. Weekly arithmetic and geometric
means, and other indices of exposure were estimated from 465 worker-we
eks of data. Results By job category, the arithmetic means of the ELF
magnetic field exposures ranged from 0.09 to 2.36 mu T. Those of the E
LF electric field exposures ranged from 2.5 to 400 V . m(-1). Within e
ach field, correlations of either the arithmetic or geometric means wi
th alternative indices, including an index of the time rate of change,
were generally high (r greater than or equal to 0.8). Exceptions were
the 20th percentile of the electric means and the proportion of time
above 12.4 and 100 mu T. The day-to-day variation of exposure was grea
ter than the variation between workers. The median between-day and bet
ween-worker components of variance (as geometric standard deviations)
by job category were 2.13 and 1.71 for magnetic fields (2.24 and 1.81
for electric fields). Conclusions Substation workers, hydroelectric ge
nerating station operators, and cable splicers showed the highest arit
hmetic means for 60-Hz magnetic fields above 1 mu T. For 60-Hz electri
c fields, forestry workers, equipment electricians in 735 kV substatio
ns, and distribution linemen (contact method) had arithmetic mean expo
sures greater than 100 W . m(-1). Of the total variance in the logarit
hms of the weekly magnetic and electric field means, job category expl
ained 49.6% and 59.5%, respectively.