Electrification in developed countries has progressively increased the
mean level of extremely low-frequency electromagnetic fields (ELF-EMF
s) to which populations are exposed; these humanmade fields are substa
ntially above the naturally occurring ambient electric and magnetic fi
elds of similar to 10(-4) Vm(-1) and similar to 10(-13) T, respectivel
y, Several epidemiological studies have concluded that ELF-EMFs may be
linked to an increased risk of cancer, particularly childhood leukemi
a, These observations have been reinforced by cellular studies reporti
ng EMF-induced effects on biological systems, most notably on the acti
vity of components of the pathways that regulate cell proliferation, H
owever, time limited number of attempts to directly replicate these ex
perimental findings have been almost uniformly unsuccessful, and no EM
F-induced biological response has yet been replicated in independent l
aboratories, Many of the most well-defined effects have come from gene
expression studies; several attempts have been made recently to repea
t these key findings, This review analyses these studies and summarize
s other reports of major cellular responses to EMFs and the published
attempts at replication, The opening sections discuss quantitative asp
ects of exposure to EMFs and the incidence of cancers that have been c
orrelated with such fields, The concluding section considers the probl
ems that confront research in this area and suggests feasible strategi
es.