Review of the heat shock response to RFR
As we mentioned in the March '05 edition of "What's New", the effect of radiofrequency radiation (RFR) on the heat shock response is unclear. In a recent article, Cotgreave reviews the evidence and concludes that many of the studies "are flawed by inconsistencies in exposure models, cell types used and the independent reproducibility of the findings".
Cotgreave IA (2005): Biological stress responses to radio frequency
electromagnetic radiation: are mobile phones really so (heat) shocking?
Arch Biochem Biophys 435:227-40.
and associates have published another paper based on the case-control
study they carried out in Sweden from 1997 to 2000. On this occasion
they have re-analyzed their data to examine whether rural users of cell
phones have a higher risk of brain tumour than urban users. The output
power level from cell phones may be higher in rural areas because of
the greater distance between base stations. The authors report that
for digital phone users with more than 5 years latency time between
first use of the phone and diagnosis of a tumour, the odds
ratio was 3.2. The authors state, however, that their results should
be interpreted with caution, because of the low numbers of cases in
some of their calculations.
Reference: Hardell L, Carlberg M, Mild KH (2005): Use of cellular telephones and brain tumour risk in urban and rural areas. Occup Environ Med 62:390-394.
Several recent publications have addressed the question of whether exposure to electromagnetic fields (EMFs) from mobile phones affect the functioning of the human ear.
Uloziene and colleagues from Lithuania found that short-term exposure (10 minutes) had no effect on the hearing of 30 young adult volunteers. Oysu et al. from Istanbul reported no adverse effect on auditory brainstem responses from 15 minutes exposure. A German team found no effect on either hearing or vestibular (balance) functions.
For more, see "Research - Clinical Experiments - Others - Hearing".
References: Uloziene I, Uloza V, Gradauskiene E, Saferis V. Assessment of potential effects of the electromagnetic fields of mobile phones on hearing. BMC Public Health 2005;5:39
Oysu C, Topak M, Celik O, Yilmaz HB, et al. Effects of the acute exposure to the electromagnetic field of mobile phones on human auditory brainstem responses. Eur Arch Otorhinolaryngol 2005 Feb 25 (Epub ahead of print).
Pau HW, Sievert U, Eggert S, Wild W. Can electromagnetic fields emitted by mobile phones stimulate the vestibular organ? Otolaryngol Head Neck Surg 2005;132:43-9.
U, Eggert S, Pau HW. Can mobile phone emissions affect auditory functions
of cochlea or brain stem? Otolaryngol Head Neck Surg 2005;132:451-5.
In the October '04 issue of "What's New" we mentioned the study of Lonn and colleagues that reported an association between long-term use of cell phones and acoustic neuroma. In the May publication of the journal "Epidemiology" there are five letters discussing various aspects of the study. Some of the authors previously published articles on this subject.
Mobile phone use and acoustic neuromas. Epidemiology, May 2005:414-418.
Ayata and colleagues reported that exposure to 900 MHz RFR for 30 minutes a day for 10 days led to increased fibrosis in exposed rats' skins, and that this effect was likely due to oxidative stress. Melatonin administered for 10 days orally prior to the radiation reduced the fibrosis. There are no details, however, of the temperatures induced by the radiation.
For more, see "Research - Toxicological experiments - others - free oxygen radicals".
Ayata A, Mollaoglu H, Yilmaz HR, Akturk O, et al. Oxidative stress-mediated
skin damage in an experimental mobile phone model can be prevented by
The authors studied the effects of RFR on the biochemistry and microscopic anatomy of the rat's brain. They used a heads-only exposure system for 15 minutes, and the RFR was emitted at 900 MHz frequency with pulse modulation. The SAR was 6 W/kg. They found significant changes in chemicals involved in various neurotransmission systems, and observed a strong glial reaction (suggesting damage to nerve cells) on microscopy.
The authors do not believe that the results noted are due to thermal effects, but base this on experiments on a gel phantom and not on direct measurement. They state that their experiments should be repeated at lower power e.g. 2W/kg.
Reference: Mausset-Bonnefont AL, Hirbec H, Bonnefont X, Privat A, et al. Acute exposure to GSM-900 MHz electromagnetic fields induces glial reactivity and biochemical modifications in the rat brain. Neurobiol Dis 2004;17:445-454.