Salama N, Kishimoto T, Kanayama HO. Effects of exposure to a mobile phone on testicular function and structure in adult rabbit. Int J Androl. Dec 2 2008 Ahead of print.
Because men usually keep mobile phones (MPs) in the standby position in their pockets (close to testes), assessment of the effects of electromagnetic radiation from mobile phones on male reproductive function is of great importance. Studies in humans have shown negative impacts of mobile phones on semen quality, but the natural history of these impacts has not been extensively studied. Animal studies addressing the effects of mobile phones on male reproductive function are numerous compared to human studies and provide conflicting results.
The objective of the study was to describe the accumulating effects on testicular function and structure of exposure to emissions from a mobile phone kept in the standby position, through longitudinal evaluation in rabbits.
Twenty-four adult male White New Zealand rabbits were randomly divided into three groups. Eight rabbits were exposed for 12 weeks (8 hours daily) in specifically designed cages to radiofrequency (800 MHz) radiation from GSM mobile phone handsets which were turned to the standby position (MP group). Two control groups were used. The animals in the first control group (sham or stress control, n=8) were placed in the cages of the same design for 8 hours a day during the study period to evaluate any effect of cage-induced anxiety. The phone was switched off for this group. The animals in the second control group (ordinary control, n=8) were kept in the conventional cages throughout the time of the study. Rectal temperature assessment was carried out twice a week. Semen analysis (sperm concentration and motility) and sperm function tests (eosin-nigrosin viability test, hypo-osmotic swelling test to assess functional integrity of cell membranes, and acridine orange test to assess DNA status) were conducted weekly. Histological testicular sections and serum total testosterone were also evaluated.
Mean rectal temperature did not alter following exposure. A drop in the sperm concentration started to appear in the MP group at week 6 and became statistically significant at week 8 compared with the two control groups (133, 339 and 356´106/mL respectively) and compared with the initial sperm count in the MP group (341´106/mL). Motile sperm population was similar in the three groups (between about 70% and 75%) until week 10 when it declined significantly in the MP and stress control groups, with more significant decline in the MP animals (50%, 61% and 72.4% in the MP, stress and ordinary control groups, respectively). Histological examination showed a significant decrease in the diameter of seminiferous tubules in the MP group compared with the stress and ordinary controls (191 mm vs. 206 and 226 mm, respectively). No group differences in any other study indices were detected.
Experimental research suggests that stress can lead to decrease in sperm count, motility and morphology. The current study has demonstrated that stress could play a role in the observed decrease in the motile sperm population. However, since the decrease was more profound in the MP animals than in the stress control group, the authors believe that it was induced not only by stress, but also by mobile phone exposure itself. The observed changes can be explained by non-thermal effects of electromagnetic mobile phone exposure through mechanisms discussed in the literature. Even though there was no change in rectal temperature, a thermal effect of mobile phone exposure cannot be excluded. A combination of thermal and non-thermal mechanisms could play a role in the pathogenesis of the mobile phone effects. Literature data on genotoxic effects of radiofrequency radiation are not conclusive. Using the acridine orange test, no DNA alterations have been detected in the current study. This test, however, is not very sensitive and provides reliable results only when there is a high degree of DNA fragmentation.
The current study shows that the low intensity pulsed RF radiation emitted by a conventional GSM mobile phone kept in the standby position could affect the testicular function and structure in adult rabbits. More studies are needed to identify the mechanisms for these health effects.