Bary Wilson,
Larry Anderson and Richard Stevens. Pacific Northwest
National Laboratory, Richmond Washington, USA.
(Abstract of paper presented at the First World
Conference on Breast Cancer, held at Ontario, Canada,
in July 1997.)
The hypothesis that exposure to man-made
electromagnetic fields (EMF) and artificial light, or
light at night (LAN) may be etiologic factors in
breast cancer has been the subject of increasing
interest and scientific investigation since it was
first proposed in 1987. This hypothesis is based on
the demonstrated ability of such exposures to
decrease the production of the hormone melatonin, and
on the observation that melatonin, in turn, protects
against certain types of cancer. A number of
epidemiologic and laboratory studies have now
provided evidence to support this hypothesis. These
studies include both in vitro and in vivo laboratory
experiments wherein melatonin has been shown to have
oncostatic action against several types of cancers.
Particular attention has focused on breast cancer,
where the ability of EMF exposure to increase breast
cancer incidence in chemically treated animals and
block the oncostatic effects of melatonin in human
breast cancer cell lines has been demonstrated. This
paper describes several of these studies and
discusses what is known about the mechanisms by which
the hormone melatonin may influence cancer risk in
humans.
Potential implications of the work on effects of
EMF and LAN related to breast cancer risk and the
possibility that breast cancer risk may be reduced by
limiting these exposures, are also discussed.
