With the widespreade use of mobile telephony public concern around the possible adverse effects of electromagnetic radiation has arisen. Special attention has been paid to the search of harm to the brain because the use of mobile phones typically results in higher exposures to the head. Research to date has found only subtle effects, in terms of increased alpha activity (from the electroencephalogram) (1,2,3). Previous research has been based on the assumption that any effect of mobile phones will be the same in all subjects (the nomothetic approach).We explore the possibility that the effect can be different between subjects, but consistent in the same subject in repeated exposures. To this end, we conducted a retest study using the same procedure and subjects as in a previous study.
MATERIALS AND METHODS
We obtained 15 middle-aged healthy participants (20-45 year olds) from a total of 42 subjects who participated in a previous mobile phone study with the same procedure employed in the present study (as described below). The exclusion criteria was self-reported depression, anxiety, history of epilepsy or brain damage, or illicit drug use. This study was approved by the human research ethics committee of Swinburne University. A double-blind counterbalanced (left vs right exposure) crossover (Sham vs 2G exposure) design was used, with two sessions 1 week apart. Performance and event-related potential measures for oddball and n-back tasks were collected in addition to the resting alpha. The exposure was a 2G GSM mobile phone (Nokia 6110) set to transmit with a mean power output of 250 mW, peak power of 2 W (DTX and adaptative power control disabled). The 895 MHz carrier was modulated at 217 Hz with a duty cycle of 12.5% (pulse width = 576 ms). SAR measurements were done with a specific anthropomorphic mannequin and a RF dosimetric robot (DASY4). The maximum SAR value (10g average) in the temporal lobe just below the antenna was 0.110 W/kg without the EEG cap and leads. EEG was recorded with a Neuroscan Synmap2 system and 4.2 sofware using a 58 scalp electrodes cap referenced to both mastoids and EOG was recorded with four electrodes. The electrode’s contact impedances were below 5 K at the beginning of the recording. The data was sampled at 500 Hz and bandpass filtered (0.05-250 Hz). To explore the hypothesis that the effect can be different between subjects but consistent in the same subject in repeated exposures, we will group the subjects according to whether or not they increased alpha activity (8-12 Hz) in the first study, and then perform a directional between subjects t-test to determine whether the participants responded consistently.
RESULTS AND CONCLUSIONS.
The data is being analysed and will be presented.
The authors acknowledge Telstra Research Laboratories for providing equipment and technical assistance and Nikolas Perentos for the assessment of phone emissions.
Croft RJ, Hamblin DL, Spong J, Wood AW, McKenzie RJ, Stough C. The effect of mobile phone electromagnetic fields on the alpha rhythm of human electroencephalogram. Bioelectromagnetics. 29(1):1-10, 2008.
 Röschke J, Mann K. No short-term effects of digital mobile radio telephone on the awake human electroencephalogram. Bioelectromagnetics,18(2):172-6, 1997
Hietanen M, Kovala T, Hämäläinen AM. Human brain activity during exposure to radiofrequency fields emitted by cellular phones. Scand J Work Environ Health, 26(2):87-92, 2000.