Mobile phone technology, one of the fastest growing technologies worldwide, has become an indispensable part of our everyday life. It is used at home, in public places, at work and in schools. The potential harmful effects of this technology are therefore an important area of research. Mobile phones emit nonionizing radio-frequency radiation. Various researchers report that radiation emitted by mobile phones can have harmful effects at the cellular and molecular level. These effects include DNA damage, various cancers, oxidative stress, lipid peroxidation and chromosomal abnormalities. Long-term exposure to radio-frequency radiation could lead to the accumulation of negative effects. Possible cumulative effects depend on the intensity and duration of the exposure. The biological mode of action of electromagnetic fields (EMF) is already recorded at intensities far below thermal effects. Therefore, classical thermodynamic theories cannot explain this phenomenon. Since mobile phones are usually kept close to the head during calls, radio-frequency radiation is able to penetrate 4–6 cm into the head and thus the brain. Our brain is particularly susceptible to reactive oxygen species (ROS) as it contains large amounts of lipids and unsaturated fatty acids. Furthermore, it has a weak antioxidant protection system. Single- or double-strand DNA breaks that are not properly repaired can lead to cancer or chromosomal anomalies. Chromosomal anomalies, however, can cause cell death and mutations. In the scientific literature, no uniform opinion exists as to whether radio- frequency radiation is capable of causing genetic damage. For this reason, the scientists of the present study tried to determine whether DNA damage occurs in the brain as a result of exposure to radio-frequency radiation emitted by mobile phones. In addition, the extent and effects of oxidative stress were investigated.
A total of 28 adult male Sprague Dawley rats were studied. They were divided into four groups. Group 1: sham group; group 2: 900 MHz exposure; group 3: 1800 MHz exposure; group 4: 2100 MHz exposure. The RF radiation exposure was carried out over 6 months for 2 hours per day. The generator antenna was placed in the center of a Plexiglass carousel. The heads of the rats were pointing toward the antenna during exposure. The antennas were equivalent to those of mobile phones. The calculated whole-body SAR values were 0.638, 0.166 and 0.174 W/kg, respectively, for 900, 1800 and 2100 MHz. After sample collection, the scientists examined DNA single-strand breaks in the brain. In addition, different markers for oxidative stress were analyzed: TAS (total antioxidant status); TOS (total oxidant status); OSI (oxidative stress index); MDA (Malondialdehyde); 8-OHdG (8-Hydroxydeoxyguanosine); total serum nitrite level. The TAS value determines the antioxidant capacity of a sample. This is specified as the equivalent of the vitamin E derivate Trolox. Similarly, the oxidative capacity of a sample, determined by the TOS value, is specified as H2O2 equivalent. The OSI represents the quotient of TOS and TAS. MDA is formed during lipid peroxidation. 8-OHdG also is a biological marker for oxidative stress and cancer and is induced by DNA oxidation. The serum nitrite level indicates nitrosative stress (reactive nitrogen species).
The scientists found a statistically significant increase in DNA single-strand breaks only in the 2100 MHz group compared to all other groups. This indicates that higher frequency radiation can cause DNA damage. The TOS value was statistically significantly higher in all exposed groups compared to the sham group. That correlated to a lower TAS value in the exposed groups compared to the sham group. Furthermore, the scientists observed a statistically significant increase in OSI, MDA and 8-OHdG parameters in the exposed groups compared to the sham group. Remarkably, the exposed groups also differed significantly among each other. Thus, a frequency dependence of the oxidative stress in brain cells can be assumed. In addition, elevated nitrite levels were detected in the 1800 MHz and 2100 MHz groups.
The authors of the present study addressed the question of whether long-term exposure to radio-frequency radiation emitted by mobile phones at three different frequencies (900, 1800 and 2100 MHz) is able to cause DNA damage and oxidative stress. The mobile phone radiation appears to be capable of causing oxidative stress, lipid peroxidation and DNA damage in the frontal lobe of the brain. A higher frequency correlates with more severe damage. According to the authors, this is consistent with many recent studies and supports the hypothesis that mobile phone radiation can be responsible for damaging biological tissue.