diciembre 2001

Mobile phone effects on EEG in narcolepsy

There have been a number of reports of EEG studies in subjects exposed to RF radiation (see "Research - Clinical" for details). A recent study reports experiments on subjects with narcolepsy, who fall asleep suddenly in certain situations, mainly during monotonous activities.

Twenty-two patients were exposed for 45 minutes to 900 MHz, SAR 0.06 W/kg, close to their right ear. No changes were seen on the EEG after this exposure. The authors had postulated that the RF field would produce a hypnotic effect in these patients, but this was not seen.

A subgroup was studied while performing a visual task. Some EEG changes were seen in response to certain visual stimuli. These were mainly seen in the right hemisphere. The reaction time was also shortened by 20 ms in response to target stimuli. The authors suggest that the RF radiation might enhance performance in subjects with narcolepsy.

Reference: Jech R, Sonka K, Ruzicka E, Nebuzelsky, et al. Electromagnetic field of mobile phone affects visual event related potential in patients with narcolepsy. Bioelectromagnetics 2001;22:519-528.

Two more negative genotoxicity studies

In "What's New" of March of this year we reported a study by Vijayalaxmi and colleagues that failed to find evidence of genotoxicity in blood cells exposed to 835.62 MHz continuous wave radiation (FDMA). SThese same authors have now reported similar negative results when lymphocytes were exposed for 24 hours to continuous -wave 847.74 MHz RF radiation (CDMA) at a SAR of 4.9 or 5.5 W/kg.

In another study this group report a study in which rats were exposed to 2450 MHz continuous wave radiation for 24 hours. The average whole-body SAR was 12W/kg. There was no difference in the incidence of micronuclei (a sign of chromosome damage) in red blood or bone marrow cells in the exposed rats, compared to controls.

More details of genotoxic studies can be found in "Toxicological Experiments - cancer studies".

References: Vijayalaxmi, Bisht KS, Pickard WF, Meltz ML, Roti Roti JL, et al.(2001): Chromosome damage and micronucleus formation in human blood lymphocytes exposed in vitro to radiofrequency radiation at a cellular telephone frequency (847.74 MHz, CDMA). Radiation Research 156:430-433.

Vijayalaxmi, Pickard WF, Bisht KS, Prihoda TJ, et al. (2001): Micronuclei in the peripheral blood and bone marrow cells of rats exposed to 2450 MHz radiofrequency radiation. International Journal of Radiation Biology 77:1109-1115.

Effects of low intensity RF fields in rat brain tissue

This study explored the effect of 700 MHz continuous wave RF fields at low intensity on the electrical activity in slices of rat brain from the hippocampus area. The maximum field intensity was calculated to produce a SAR between 0.0016 and 0.0044 W/kg. Changes were noted in the electrical activity of the rat brain slices. These results were seen in the absence of detectable temperature change. The authors state that the hippocampus is important in spatial learning and memory processes, and that the changes in electrical excitability may be consistent with reported behavioural effects of RF fields.

Reference: Tattersall JEH, Scott IR, Wood SJ, Nettell JJ, et al. (2001): Effects of low intensity radiofrequency electromagnetic fields on electrical activity in rat hippocampal slices. Brain Research 904:43-53.