Mobile phones have revolutionized communications
throughout the world and become incontestably a
mainstream utility, essential nowadays for certain
professions. Industry estimates suggest that over
one billion mobile phones are in use worldwide.
Numerous studies have raised concerns about
possible health consequences resulting from the
interaction of radiofrequency (RF) fields involved
in mobile phone use and the human body tissues,
especially the brain. Other studies have concluded to no effect or no demonstrable effects in the short term
but the debate continues within the scientific community. Due to the close proximity of the mobile
phone device to the head, most of the radiation absorption occurs in the head and neck with
calculated peak 1-g specific absorption rates of the order of 1.13 mW/g for adults to 1.56 mW/g for
children at 835 MHz with time and space averaging to lower values (Gandhi et al. 1996).
Many studies have been conducted to monitor various biological effects of the exposure to mobile
phone type microwave radiation in animals and humans. In animals, effects have been reported on
neuronal structures (Salford et al. 2003), blood brain barrier permeability to various agents (Salford et al.
1994) and memory function (Lai et al. 1994). DNA mutations were reported in cell studies (Sarkar et al.
1994, Diem et al. 2005). However, other studies measured no effect on neuronal structure (Tsurita
et al. 2000), blood brain barrier permeability (Tsurita et al. 2000), memory function (Cosquer
et al. 2005) and cell DNA structure (Zeni et al.2005), for example. In humans, changes in visual
cerebral potentials (Freude et al. 1998) were reported, but contradictory results have been published
on the effects of microwaves on cognitive performances (Koivisto et al. 2000, Haarala et al.
2003, Krause et al. 2004), EEG (Huber et al. 2002,D’Costa et al. 2003, Krause et al. 2004), melatonin
levels (Burch et al. 1999, de Seze et al. 1999, Juutilainen et al. 2000) and blood flow (Huber et al.
2002, Tahvanainen et al. 2004). However, the major concern and the most investigated effect is the
possible induction of brain tumors by microwaves used in cellular phones. Although most studies have
concluded that no relation exists between cellular
phone use and the incidence of brain tumors
(Repacholi 1997, Moulder et al. 1999, Elwood
2003, Hansson et al. 2003, Christensen et al.
2005), a recent review article of epidemiological
studies concluded that all studies that approached
reasonable latencies (Hardell et al. 1999, Hardell
et al. 2001, Stang et al. 2001, Hardell et al. 2002)
found an increased risk associated with mobile phone
use (Kundi 2004). Although an association between
mobile phone use and cancer remains unproven and
controversial, reported increased cancer rates for
lengthy microwave exposure justify additional research
efforts in this field.
Magnetic resonance spectroscopy (MRS) allows
one to non-invasively examine the brain by measuring
the levels of several metabolites reflecting
neuronal condition, glial condition, membrane
metabolism and energy status. Compared to magnetic
resonance imaging (MRI) and other imaging
techniques, the effects of diseased conditions can be
observed earlier by MRS because changes in the
chemical state of tissues occur before macroscopic
morphological changes become detectable. This
study was designed to take advantage of the
possibility of observing early effects of the use of
mobile phones on the brain of long term extensive
phone users by MRS. Spectra of the most
exposed brain regions were compared between users
and nonusers and between the exposed and
contralateral brain regions to monitor metabolite
changes.
Figure 2 displays examples of 1H magnetic resonance
spectra obtained in the exposed pontobulbar area
(Figure 2A) and in the right temporal region (Figure
2B) of a mobile phone user. Average values of the
NAA/Cr, Cho/Cr and mI/Cr metabolite ratios for
the mobile phone users and for the control subjects
are presented in Table I. All metabolite ratios were
practically identical between mobile phone users and
nonusers and no statistically significant changes
could be calculated in the right temporal and
pontobulbar areas. In addition, the comparison
between the exposed right temporal area and the
contralateral left temporal area for the 21 mobile
phone users did not show any statistically significant
difference for any metabolite ratio.
To our knowledge, the effect of mobile phone use
has not been previously investigated by MRS. Our
results suggest that even for extensive users, no
change in the concentrations of MRS-detectable
metabolites can be detected. This is in agreement
with multiple studies which failed to show any effect
of mobile phone use on various brain functions and
diseases (Krause et al. 2004, Haarala et al. 2003,
Juutilainen et al. 2000, de Seze et al. 1999,
Tahvanainen et al. 2004, Repacholi 1997, Moulder
et al. 1999, Elwood, 2003, Hansson et al. 2003,
Christensen et al. 2005) but in disagreement with
other studies demonstrating some effects (Salford
et al. 2003, Freude et al. 1998, Koivisto et al. 2000,
D’Costa et al. 2003, Huber et al. 2002, Burch et al.
1999, Hardell et al. 1999, Hardell et al. 2002,
Hardell et al. 2001, Stang et al. 2001). In his review
article, Kundi (2004) proposed that an association
between mobile phone use and cancer could be
found in epidemiological studies when reasonable
latency periods (5 – 10 years) were used (other
epidemiological studies did not reach that conclusion).
In this study, participants had been using a
mobile phone for 5.5+2.2 years at a rate of
2.4+1.1 hours per day. These periods are comparable
to those of studies where effects have been
reported. However, epidemiological studies are
based on thousands of mobile phone users out of
whom effects on a low number of users can be
measured. It is thus possible that such effects will not
be detected in a group of 21 mobile phone users as