Julio 2007

Use of EMF sources not associated with increased symptoms

The authors carried out a cross-sectional study on students at 2 Iranian universities, asking about use of EMF sources, as well as basic demographic data and self-reported symptoms. No significantly higher prevalence of symptoms was found in individuals who used cell phones, video display terminals or cordless phones more frequently than others.

Reference: Mortazavi SMJ, Ahmadi J, Shariati M (2007): Prevalence of subjective poor health symptoms associated with exposure to electromagnetic fields among university students. Biolectromagnetics 28:326-330.
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RFR exposure has no effect on apoptosis or heat shock response in skin cells.

Sanchez and colleagues exposed cultured skin cells to a 48-h GSM-1800 exposure at 2 W/kg. In parallel experiments skin cells were exposed to ultraviolet radiation (600 mJ/cm² single dose) or to heat shock (45°C, 20 min), as positive controls for apoptosis and HSP expression, respectively. There was no effect of the RFR exposure on either keratinocytes or fibroblasts, in contrast to UVB-radiation or heat-shock treatments, which injured cells.

Reference: Sanchez S, Haro E, Ruffie G, Veyret B et al. (2007): In vitro study of the stress response of human skin cells to GSM-1800 mobile phone signals compared to UVB radiation and heat shock. Radiation Research. 167:572-580.
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For more, see "Research - Laboratory studies - others - Heat shock response, and Cell death".


RFR exposure and the hearing system of rats

Parazzini and colleagues have previously reported studies on the effect of RFR on the auditory system of animals. In this study they compared the effect of RFR exposure at 900 MHz for 4 weeks with that of gentamicin. There was no effect of the RFR exposure on the inner auditory system of the animals, either in normal ears or in those damaged by gentamicin.

Reference: Parazzini M, Galloni P, Piscitelli M, Pinto R et al. (2007): Possible combined effects of 900 MHz continuous-wave electromagnetic fields and gentamicin on the auditory system of rats. Radiation Research 167:600-605.
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For more, see "Research - Laboratory studies - others -Ear".

Three papers discuss exposure assessment in cell phone studies

Three recent papers address the important issue of exposure assessment in studies of cell phone use.

Bürgi and colleagues (2007) have developed a geospatial model that allowed the estimation of ambient HF-EMF strengths with spatial resolution. They included cell phone base stations and broadcast transmitters in their model, which considers the location and transmission patterns of the transmitters, the three-dimensional topography, and shielding effects of buildings. In an evaluation of their method in the region of Basel in Switzerland, they found good correlation between modeling and measurements.

Inyang et al. (2007) reviewed the different methods of exposure assessment in epidemiological studies of cell phones. They conclude that hardware-modified phones offer considerable advantages. They automatically log the call duration and number of calls, and thus avoid the potential for faulty recall by the study participant. These phones also capture the various tilts and rotations that occur in everyday use, and record power fluctuations of each call.

Morrisey (2006) used software-modified phones (SMPs) that record both talk time and dynamically changing transmit power levels. He enlisted the help of Motorola employees in different sites around the world. These volunteers used the SMPs for 2 weeks, and the data were later analyzed. Each volunteer was sent a questionnaire within 2 weeks that included questions on their phone use. He found considerable variability in transmit power within a single call, in separate calls, between individuals in the same study region, and between averaged values from different study groups. Morrisey also found that there was significant inaccuracy (45-60%) in recalling "time of use". He suggests that recent epidemiological studies need to be interpreted carefully in light of his findings.
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References:
Bürgi A, Theis G, Siegenthaler A, Röösli M (2007): Exposure modeling of high-frequency electromagnetic fields. J Expo Anal Environ Epidemiol 4 April 2007;doi:10.1038/sj.jes.7500575.

Inyang I, Benke G, McKenzie R, Abramson M (2007): Comparison of measuring instruments for radiofrequency radiation from mobile telephones in epidemiological studies: Implications for exposure assessment. J Expo Anal Environ Epidemiol 28 February 2007;doi:10.1038/sj.jes.7500555.

Morrisey J. Radio frequency exposure in mobile phone users: Implications for exposure assessment in epidemiological studies. Rad Prot Dosim Online 9 January 2007; doi:10.1093/rpd/ncl547.

For more on this subject, see "Research - Exposure assessment".



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