octobre 20

Review of cell phones and effects on brain   

Valentini and colleagues have produced a detailed review of studies that examined the effects of electromagnetic fields (EMFs) emitted from cell phones on human brain activity. They used clearly defined criteria for inclusion of studies. Four groups of studies are reviewed - those on waking EEG, on sleep EEG, on evoked and/or induced cerebral activity, and on measures of brain metabolism and excitability. The authors state in their summary:

            "It is concluded that MP-EMFs may influence normal physiology through changes in cortical excitability and that in future research particular care should be dedicated to both methodological and statistical control".

For more, see "Research - Clinical - EEG, Cognitive function, and Others - Hearing".

Reference: Valentini E, Corcio G, Moroni F, Ferrara M, et al. Neurophysiological effects of mobile phone electromagnetic fields on humans: A comprehensive review. Bioelectromagnetics 2007;28:415-432.

Delay in sleep onset after RFR exposure from a cell phone

Hung and colleagues found that sleep onset was significantly delayed after "talk" mode exposure, compared to "listen" and "sham" modes, when subjects were exposed to different modes of cell phone use. This could be related to a higher SAR level or to different ELF components in the "talk" mode.

For more, see "Research - Clinical - EEG".

Reference: Hung CS, Anderson C, Horne JA, McEvoy P (2007): Mobile phone "talk-mode" signal delays EEG-determined sleep onset. Neurosci Lett 421:82-6.
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Review of thermal mechanisms of RF effects

Foster and Glaser have reviewed thermal mechanisms of interaction between RF fields and biological systems. They focus on theoretical frameworks that are of potential use in setting guidelines for human exposure to RF energy. Some molecular and physiological reactions might be induced by temperature increases below 0.1 degrees. The authors suggest that some reported "nonthermal" effects of RF energy may be thermal in nature. They propose that future revisions of exposure guidelines make explicit use of thermal models and empirical data on thermal effects in quantifying potential hazards of RF fields.

For more, see "Wireless phones".

Reference: Foster KR, Glaser R (2007): Thermal mechanisms of interaction of radiofrequency energy with biological systems with relevance to exposure guidelines. Health Phys 92:609-620.

Short-term RFR exposure induces injury to rat brain cells

The aim of this study was reproduce the observation made by Mausset-Bonnefont and colleagues in 2004 that an acute exposure of rats to RFR at 900 MHz and SAR 0f 6 W/kg could induce astroglial activation 72 h later. The rats were exposed to the RFR for 15 minutes. The brains were examined at 2,3, 6, and 10 days after exposure, and compared with sham controls control by an immunohistochemical method to assess the amount of Glial Fibrillary Acidic Protein (GFAP), which appears rapidly after astrocyte injury. A statistically significant increase in GFAP surface area was seen in several areas of the brain within 2-3 days. These effects were not seen after 6 or 10 days. These results are in broad agreement with the results of Mausset-Bonnefont et al.

For more, see "Research - Laboratory studies - brain function".

Reference: Brillaud E, Piotrowski A, de Seze R (2007): Effect of an acute 900 MHz GSM exposure on glia in the rat brain: A time-dependent study. Toxicology 238:23-33.
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French INTERPHONE study

The results of the French part of the INTERPHONE study have been published online. The Odds Ratio (OR) for regular use of a cell phone was 1.15 ((%% CI 0.65-2.05) for glioma, 0.74 (0.43-1.28) for meningioma, and 0.92 (0.53-1.59) for acoustic neuroma. The risk for use of a cell phone on the same side as a glioma was 0.87 (0.59-1.26). There was a slight tendency for increasing risk trends with increasing duration of use and with increased use, but these were not statistically significant. As with other segments of the INTERPHONE study, there was a relatively low participation rate.

Reference: Hours M, Bernard M, Montestrucq L, Arslan M, et al. (2007): Téléphone mobile, risque de tumeurs cérébrales et du nerf vestibulaacoustique: l'étude cas-témojns INTERPHONE en France. (Cell phones and risk of brain and acoustic nerve tumours: the French INTERPHONE case-control study). Revue d'Épidémiologie et de Santé Publique 2007, doi: 10.10.16/j.respe.2007.06.002

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