Em Fields On Brain Tumor Incidence
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..."In a series of studies, Hardell and colleagues have examined the
relationship between the side of the head habitually used in operation
of cellular and cordless phones and a possible relationship to the
site of brain tumors ([Hardell et al., 2003]). The risk for
ipsilateral (same side) use significantly increased the risk for
astrocytoma for all types of phones, but use of the phone on the
opposite side of the head was not associated with significantly
increased risk. Overall, use of FM (analog) phones gave an increased
risk, whereas digital and cordless phones did not increase risks
significantly."...
This excellent piece of work by Dr Adey (so typical of this towering
figure in EM and Cell research) should put to rest the debate on the
dangers of Cell phones (obviously this applies to all the wireless
stuff that is so much the rage these days as well) . While the danger
cannot be avoided at least it can be minimized, to some extent, as per
above. Those who insist on using them can further reduce their
exposure by shortening transmissions (cutting out the 'gift of the
gab') and listening more (pun intended)...which besides lessening the
exposure should improve their listen skills (a much maligned attribute
of our modern society)..
This paper is a must read for those interested in non thermal effects
EMF (Electromagnetic Fields) particularly the collective cell/neuron
response/behavior/properties to stimuli. It is an eye opener and very
useful when dealing with vested interests who continually ignore non
thermal effects to promote their wares with self serving rhetoric.
Chris Gupta
5. Influence of EM fields on brain tumor incidence in man and in
animal models (10)
5.1. Epidemiological studies
Environmental EM fields may act jointly with exposure to environmental
chemicals with known cancer-promoting actions in enhancing
occupational brain tumor risks. Experimental evidence supports cell
membranes as a site for joint actions of many chemical cancer
promoters with EM fields ([Adey, 1992b]). The latter include
pesticides, weedicides and electrical solvents. A case control study
by the U.S. National Cancer Institute of brain tumor incidence in RF/
microwave occupational exposures ([Thomas et al., 1987]) in the states
of New Jersey, Pennsylvania and Louisiana concluded that all excess
risk for primary brain tumors in white males aged over 30 years
derived from jobs involving design, manufacture, installation and
repair of electronic equipment (Risk Ratio=2.3, 95% CI=1.3,4.2). Cases
were divided into cohorts with 5, 10, 15 and 20+ years of exposure.
Risks of astrocytomas increased to ten-fold for those employed 20
years or more, when concurrent exposure to electrical and electronic
solvents was involved. RRs were not increased in men exposed to RF/
microwave fields, but who never worked in electrical or electronics
jobs; leading the authors to emphasize concurrent exposures to
soldering fumes, solvents and a variety of chemicals as possible co-
factors with RF/microwave fields in tumor promotion.
In a case-control study of risk factors for gliomas and meningiomas in
males in Los Angeles County, involving 272 men aged 25-69 with primary
brain tumors and 272 matched neighbor controls ([Preston-Martin et
al., 1989]), glioma (but not meningioma) risk related to prior
employment in jobs likely to involve high exposure to electric and
magnetic fields (P<0.05). The risk was greatest for astrocytoma (OR
for employment in such jobs for >5 years=4.3; CI=1.2-15.6). As in the
study of microwave workers cited above, there was evidence of
concurrent action of chemical factors. More glioma cases had worked in
the rubber industry (discordant pairs 6/1), and more worked in hot
processes using plastics (9/1).
[Savitz and Loomis (1995)] have linked work site magnetic field
measurements to individual work histories in a cohort mortality study
(138,905 men) at 5 large American electric power companies over a
period of 36 years. Brain cancer risk increased by a factor of 1.94
per microtesla-year of magnetic field exposure in the previous 2-10
years, with a mortality rate ratio of 2.6 in the highest exposure
category.
In a series of studies, Hardell and colleagues have examined the
relationship between the side of the head habitually used in operation
of cellular and cordless phones and a possible relationship to the
site of brain tumors ([Hardell et al., 2003]). The risk for
ipsilateral use significantly increased the risk for astrocytoma for
all types of phones, but use of the phone on the opposite side of the
head was not associated with significantly increased risk. Overall,
use of FM (analog) phones gave an increased risk, whereas digital and
cordless phones did not increase risks significantly.
5.2. Animal models of brain tumor promotion
There are few accepted animal models of spontaneous malignant central
nervous system (CNS) tumors, although there has been increasing use of
the Fischer 344 rat, with a reported incidence of spontaneous
malignant tumors as high as 11%. Two life term studies using this rat
model have compared exposures to the North American Digital Standard
(NADC) digital phone field using 11
Time Division Multiple Access (TDMA) modulation pulsed at 50 "packets"/
sec, with comparable exposures to the older type of FM (analog) phone
fields ([Adey et al., 1999]; [Adey et al., 2000]). Rats were exposed
in utero to a single dose of the short-lived neurocarcinogen
ethylnitrosourea (ENU), and thereafter, exposed intermittently to
either TDMA or FM fields for 23 months.
In the TDMA study, when compared with rats receiving ENU but
unexposed, rats that died from a primary CNS tumor before termination
of the study showed a significant reduction in tumor incidence
(P<0.015). A similar but non-significant reduction in spontaneous
tumor incidence occurred in rats field-exposed but not receiving ENU
(P<0.08). In the balanced design of this experiment, consistent non-
significant differences in survival rates were noted between the four
rat groups, with higher death rates in a progression:
sham/field:sham/sham:ENU/field:ENU/sham. By contrast in the FM study,
no field-related effects were observed in number, incidence or types
of either spontaneous or ENU-induced CNS tumors.
These observations of an apparent protective effect against ENU-
induced and spontaneous CNS tumors are not isolated. Low dosage of X-
rays in fetal rats at the time of ENU dosage sharply reduce subsequent
incidence of induced tumors ([Warkany et al., 1976]), through
activation of AT (alkylguanine-DNA-alkyltransferase) enzymes that
participate in DNA repair ([Stammberger et al., 1990]). Other studies
with nonionizing (microwave) fields also suggest their actions in
mechanisms of DNA repair. Modulation of levels of single-strand breaks
in brain cell DNA has been reported following low-level, long-term
microwave exposure in mice ([Sarkar et al., 1994]) and in acute
experiments in rats ([Lai and Singh, 1995]).
6. Summary: intrinsic and induced electric fields as threshold
determinants in central nervous tissue; the potential role of cell
ensembles
The intact nervous system might be expected to be more sensitive to
induced electric fields and currents than in vitro preparations, due
to a higher level of spontaneous activity and a greater number of
interacting neurons. However, these fields induced in the body are
almost always much lower than those capable of stimulating peripheral
nerve tissue ([Saunders and Jefferys, 2002]). Weak electric field
effects, below action potential thresholds, have been demonstrated in
in vitro brain slice preparations ([Faber and Korn; 1989]; [Jefferys,
1995]}.Behavioral sensitivities in sharks and rays may be as low as
0.5 nV/mm for tissue components of electrical fields in the
surrounding ocean ([Kalmijn, 1971]), or 100 times below measurable
thresholds of individual electroreceptor organs ([Valberg et al.,
1997]).
Research in sensory physiology supports the concept that some
threshold properties in excitable tissues may reside in highly
cooperative properties of a population elements, rather than in a
single detector ([Adey,1998, 2003a, 2003b]). Seminal observations in
the human auditory system point to a receptor vibrational displacement
of 10-11m, or approximately the diameter of a single hydrogen atom
([Bialek, 1983]; [Bialek and Wit, 1984]). It is notable that
suppression of intrinsic thermal noise allows the ear to function as
though close to 0 degree K, suggesting system properties inherent in
the detection sequence. Human olfactory thresholds for musk occur at
10-11 M, with odorant molecules distributed over 240 mm2 ([Adey,
1959]). Human detection of single photons of bluegreen light occurs at
energies of 2.5 eV ([Hagins, 1979]). In another context, pathogenic
bacteria, long thought to function independently, exhibit ensemble
properties by a system recognizing (12) colony numbers as an essential
step preceding release of toxins. These quorum sensing systems may
control expression of virulence factors in the lungs of patients with
cystic fibrosis ([Erickson et al., 2002]).
Although far from a consensus on mechanisms mediating these low-level
EMF sensitivities, appropriate models are based in nonequilibrium
thermodynamics, with nonlinear electrodynamics as an integral feature.
Heating models, based in equilibrium thermodynamics, fail to explain a
wide spectrum of observed nonthermal EMF bioeffects in central nervous
tissue. The findings suggest a biological organization based in
physical processes at the atomic level, beyond the realm of chemical
reactions between biomolecules. Much of this signaling within and
between cells may be mediated by free radicals of the oxygen and
nitrogen species. Emergent concepts of tissue thresholds to EMF
sensitivities address ensemble or domain functions of populations of
cells, cooperatively "whispering together " in intercellular
communication, and organized hierarchically at atomic and molecular
levels.
7. See Also Search Neuroscion Bibliographic References
Extracted from:
Electromagnetic fields, the modulation of brain tissue functions
-- A possible paradigm shift in biology
W. Ross Adey
Informant: Tim Campbell
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