The rats were divided into seven groups (n=6 each): daily exposure to the electromagnetic field from 3 to 5 h (group 1), 7 to 9 h (group 2), 11 to 13 h (group 3), 15 to 17 h (group 4), 19 to 21 h (group 5) and 23 to 1 h GMT (Greenwich Mean Time) on the next day (group 6) and sham exposure over 24 h/day (group 7) for 32 days. Subsequently to the last exposure period, blood samples were collected from each rat at 5, 9, 13, 17, 21 h and 1 h GMT on the following day.
|Chamber||six animals per cage (466 Œ 315 Œ 210 mm)|
|Setup||antenna was placed under a table to produce a vertical electromagnetic field in a shielded room; cage was placed on table, roof was hitched with microwave absorbing materials to avoid reflection; all animal handlings during the dark cycle were carried out using a dim red light (0.1 lux)|
|Sham exposure||A sham exposure was conducted.|
Analysis of the circadian concentrations of the investigated parameters in the sham exposure revealed that there was an independent circadian rhythm in concentration for each parameter.
Significant decreases of the circadian concentration of the parameters were found in all groups compared to the sham exposure, with the most profound and consistent decreases in groups 1 and 6 for melatonin, and in group 1 for superoxide dismutase and glutathione peroxidase. Moreover, the daily mean concentration of all parameters was decreased, most distinctly in groups 1 and 6.
The authors conclude that exposure of rats to a 1.8 GHz electromagnetic field can decrease the circadian concentration as well as the daily mean concentration of melatonin, superoxide dismutase and glutathione peroxidase.