Mobile phone radiation results may ring the changes

It is true that some research labs have found no link between mobile phone radiation and the increased occurrence of animal cancers, but other groups have found that the radiation does induce changes in the genes and proteins in cell cultures. And there are still the long-term risks to consider. It may take many years for any health effects to emerge in significant numbers, by which time a great number of users might be affected. The concerns centre on the type of radiation that the phones generate: radio-frequency electromagnetic fields (RF EMF). The RF fields from phones penetrate human tissue to depths of about one centimetre and are absorbed by the body, generating heat that is dispersed by the body's normal thermoregulatory processes. The WHO states that all currently recognised health effects of RF exposure are related to heating. The debate on the health implications of mobile phone irradiation has not been helped by two recent studies which give contradictory results, although one team gives a clue as to why research to date has been so inconclusive. The results were reported in the same issue of the journal Proteomics, in a special issue devoted to the application of proteomics and transcriptions to EMF research. In the first report, Zhengping Xu and colleagues from the Bioelectromagnetics Laboratory and the Research Centre for Environmental Genomics at the Zhejiang University School of Medicine studied the effects of RF EMF on the human breast cancer cell line MCF-7. They exposed or sham-exposed cells with an intermittent 1800 MHz signal (most phones operate at 800-1800 MHz), over 24 h, switching on for 5 min and off for 10 min, to simulate real usage. For genomics studies, the average specific absorption rates (SAR) were 2.0 and 3.5 W/kg, the former value being the safety limit set by the International Commission on Non-Ionizing Radiation Protection. After exposure, RNA was isolated and subjected to GeneChip analysis to generate gene expression profiles. For proteomics studies, the SAR was 3.5 W/kg for 1-24 h and extracted proteins were subjected to 2D gel electrophoresis (2-DE) and image analysis to determine the protein expression patterns. At 2.0 W/kg, no changes in gene expression were observed, whereas at 3.5 W/kg, 5 genes were up-regulated, but only by less than 2-fold. However, these changes were not verified by quantitative real-time PCR, so the team concluded that the genes were not actually responding to RF EMF exposure but to some other factor, possibly related to the experimental conditions. Similar results were obtained in the proteomics analysis, in which the expression levels of only a few proteins appeared to be affected by RF EMF. The number varied with the exposure duration but there was no direct relationship between exposure time and differentially expressed proteins. Once again, it appeared that RF EMF had no effect on protein levels, with Xu concluding "the observed effects might have occurred by chance." The second research report emanated from the Radiation Biology Laboratory, STUK in Finland from Dariusz Leszczynski and Reetta Nylund. They studied the response of two closely related human endothelial cell lines to a 900 MHz signal at an average SAR of 2.8 W/kg for 1 h. They also studied the genomic and proteomic changes by cDNA expression analysis and 2-DE, respectively, and observed notable changes in gene and protein expression. In direct contrast to the observations of Xu's team, the two cell lines showed 1 and 13 genes, respectively, with statistically significant changes in expression, and 38 and 45 protein spots with altered expression levels. However, the two cell lines responded differently to exposure even though they were closely related and the research duo were unable to specify those genes that were responsible for the diversity. So, the cell response to mobile phone radiation may be genome- and proteome-dependent. If that were the case, Leszczynski argues, it could explain why different laboratories have failed to replicate each other's results. Indeed, different types of cells, or cells from different species, may respond differently to RF EMF depending on the active genes and proteins at the time of exposure. The same cell line grown for extended periods in different labs might somehow acquire new properties that modify their responses. Although more data is required to back up these conclusions, it is an intriguing proposition that would go a long way to explain the well-documented discrepancies between published data on the cellular effects of mobile phone radiation. "Source":[ http://www.spectroscopynow.com/coi/cda/detail.cda?id=14478&type=Feature&chId=10&page=1]

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