Associated
with the generation, transmission, and use of electrical
energy is the production of weak electric and magnetic fields
(EMF). In the United States, electricity is usually delivered
as alternating current that oscillates at 60 Hz putting fields
generated by this electrical energy in the extremely low
frequency (ELF) range. Prior to 1979 there was limited
awareness of any potential adverse effects from the use of
electricity aside from possible electrocution associated with
direct contact or fire from faulty wiring. Interest in this
area was catalyzed with the report of a possible association
between childhood cancer mortality and proximity of homes to
power distribution lines. Over the next dozen years, the U.S.
Department of Energy (DOE) and others conducted numerous
studies on the effects of of ELF-EMF on biological systems
that helped to clarify the risks and provide increased under-
standing. Despite much study in this area, considerable debate
remained over what, if any, health effects could be attributed
to ELF-EMF exposure. |
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The
scientific evidence suggesting that ELF-EMF exposures pose any
health risk is weak. The strongest evidence for health effects
comes from associations observed in human populations with
chronic lymphocytic leukemia in occupationally exposed adults.
While the support from individual studies is weak, the
epidemiological studies demonstrate, for some methods of
measuring exposure, a fairly consistent pattern of a small,
increased risk with increasing exposure that is somewhat
weaker for chronic lymphocytic leukemia than for childhood
leukemia. In contrast, the mechanistic pattern across studies
although sporadic findings of biological effects (including
increased cancers in animals) have been reported. No
indication of increased leukemias in experimental animals has
been observed. The lack of connection between the human data
and the experimental data (animal and mechanistic) severely
complicates the interpretation of these results.
NIEHS
Report on health effects from exposure to power-line frequency
electric and magnetic fields, NIH Publication No. 99-4493, May
4, 1999. |