الفهرس 
TitleOnly 14 pages are availabe for public view
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Abstract
Microwaves are part of the electromagnetic spectrum and are considered to be that
radiation ranging in frequency from 300 million cycles per second (300 MHz) to 300
billion cycles per second (300 GHz), which correspond to a wavelength range of 1m down
to 1mm. This non-ionizing electromagnetic radiation is absorbed at molecular level and
manifests as changes in vibrational energy of the molecules or heat. The most important
sources of microwave radiation that humans may encounter are various industrial
microwave generators used for communications. During the last decade, the use of mobile
phones has increased substantially and has been paralleled by a growing concern about the
effects on health attributed to exposure to the electromagnetic fields produced by them and
their base stations. Mobile phones and base stations emit radio frequency or microwave
radiation. Exposure to such a radiation could affect health (120).
The biochemical action of microwave irradiation results from material-wave
interactions leading to thermal effects, which may be easily estimated by temperature
measurements and specific (non-thermal) effects. A combination of these two
contributions can be responsible for the observed effects.
It has been suggested that one of the interaction mechanisms of microwave radiation
(MWR) with biological matter is the biochemical mechanism that is based on the
responses caused by activating secondary chemical messengers such as ions, radicals or
molecules. Due to the overproduction of free radicals and deficiency in the amounts of
antioxidants, the balance between free radicals and antioxidants is disrupted in favor of the
free radicals resulting in oxidative damages which are known as oxidative stress (121).
It became clear that, especially under higher dosages, effects of microwaves
electromagnetic field (MW-EMF) may be observed. However, results are still not conclusive
and there is still some uncertainty about the low dosages, i.e., the non-thermal effects.
In the current study there has been a concern about investigating the effect that might
be occurred to the antioxidant defense system due to exposure to the microwave radiation
from the mobile phones, especially due to the non-thermal effect.
Three groups of (CD 1) mice have been used in this study (control group, on-call
group, standby group), to investigate the effect of the radiation from mobile phones both in
the standby case and while it is used in a conversation. Three biological markers have been
used (total antioxidant capacity, glutathione peroxidase activity, and concentration of MDA).
The study was divided into two stages: Stage 1 (exposure stage) in which we
investigated the effect of the microwave radiation emitted from mobile phones on the
values of the chosen biomarkers in the samples taken from mice directly after exposure.
This stage lasted for 3 months. Stage 2 (follow-up stage) in which we investigated the
changes occurred in the values of the same biomarkers after a period of time without
exposure to the radiation from mobile phones. This stage lasted for 1 month.
Summary and Conclusions
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Our study showed that at the end of stage 1 (exposure stage) there has been a very
slight difference but was not significant in the concentration of total antioxidant capacities
between the three groups (control, on-call, standby). Our results at the end of stage 2
(follow-up stage) and by comparing the results from stage 2 with those from stage 1
showed that, there has been a statistically significant difference in the concentration of total
antioxidant capacities between the two stages. There has been a reduction in the total
antioxidant capacity in samples from stage 2 than samples of stage 1. This indicates a
possible late effect due to exposure to the mobile phones radiation on the antioxidant in the
blood plasma.
Regarding to the activity of glutathione peroxidase (GSH-Px) enzyme in the brain
tissues of mice, our results showed that at the end of stage 1 (exposure stage) animals from
exposed groups (on-call, standby) had a lower level of glutathione peroxidase activity than
animals from (control group) but the difference was not significant. At the end of stage 2
(follow-up stage), the values of the activity of glutathione peroxidase from stage 2 groups
showed some improvement compared with values of stage 1 groups, yet the difference
noticed was not significant.
Concerning the levels of malondialdehyde (MDA) our results showed that, at the end
of stage 1 (exposure stage) animals from the exposed groups (on-call, standby) had a
slightly higher concentrations of MDA than (control group), yet the difference was not
statistically significant. At the end of stage 2 (follow-up stage) the concentration of MDA
in brain tissues samples from animals of stage 2 exposed groups (on-call, standby)
decreased in compare to those from stage 1, but the difference was not significant.