Auteurs

Ozgur E, Guler G, Seyhan, N. Mobile phone radiation-induced free radical damage in the liver is inhibited by the antioxidants n-acetyl cysteine and epigallocatechin-gallate. Int. J. Radiat. Biol. Ahead of print. Sep 1, 2010.

Background
Currently, there is no consensus about the non-thermal effects of radiofrequency radiation (RFR) exposure from devices, such as mobile phones, below present guidelines. One proposed mechanism for interaction between RFR and biological tissues is the formation of free radical molecules.

Objective
The objectives of the study were to investigate oxidative damage and antioxidant enzyme status in the liver of guinea pigs exposed to mobile phone-like RFR and the potential protective effects of N-acetyl cysteine (NAC) and epigallocatechin-gallate (EGCG) antioxidants.

Methods
A total of 96 adult male guinea pigs were divided into nine groups. All animals were injected with either saline, NAC, or EGCG. Three groups were sham groups in which half of the animals were subjected to 10 minutes of sham-exposure per day and the other half to 20 minutes of sham exposure per day for 7 days. The other six groups were treatment groups that were exposed to an 1800-MHz Global System for Mobile Communications (GSM)-modulated signal with an average whole-body Specific Absorption Rate (SAR) of 0.38 W/kg, for either 10 or 20 minutes per day for 7 days. Following the last exposure, liver tissues were dissected and malondialdehyde (MDA) and total nitric oxide (NOx) levels were measured as well as glutathione peroxidise (GSH-Px), superoxide dismutase (SOD), and myeloperoxidase (MPO) activity.

Results
Significant increases (P<0.05) in MDA and NOx levels were observed in treatment groups when compared to the control groups. When injected with saline, MDA and NOx levels in the 20-min exposure groups were significantly higher when compared with those of the 10-min exposure groups. EGCG treatment attenuated the effect on MDA levels in both the 10-min and 20-min exposure groups and a significantly larger increase in total NOx level was observed in the 20-min RFR-exposure group compared to the 10-min exposure group. EGCG treatment also attenuated the effect on NOx level in the 20-min RFR exposure group. Decreases in SOD, MPO, and GSH-Px activity were also observed after RFR exposure. Only NAC treatment induced increases in hepatic GSH-Px activities, whereas EGCG treatment alone attenuated MDA levels. The extent of oxidative damage was found to be proportional to duration of exposure (P<0.05).

Interpretation and Limitations
Lipid peroxidation and nitrosative stress increased, and antioxidant enzyme activities decreased, in the liver tissue of guinea pigs exposed to RF radiation and changes are more prominent with longer duration of exposure. Although there is no consensus among scientists about the validity of hypotheses for the interaction mechanism of RFR with living tissues, several studies have shown that treatment with antioxidants can affect free radicals. The authors suggest that treatment with antioxidants such as NAC and EGCG can provide protection against oxidative and nitrosative stress-induced liver injury and suggest that future studies should explore their effects in other tissues. The main limitations of this study are that it only focuses on liver tissue and that it is difficult to extrapolate the results to humans.

Conclusion
This study suggests that longer durations of exposure to mobile phone-like radiation increase free radical production and lipid peroxidation in guinea pig liver and decrease antioxidant enzyme activity.

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