The aim of the study was to investigate whether non-thermal levels of radiofrequency (RF) fields, characteristic of some mobile phones, might be directly genotoxic when applied in vitro to unstimulated G0 or stimulated human lymphocytes. Also, the study aimed to investigate the possibility that RF fields might act epipigenetically when combined with x-rays, by modifying their effect when applied in vitro to G0 lymphocytes. In addition, the possibility of RF fields inducing apoptosis in murine neuroblastoma (N2a) cells was also examined. G0 lymphocytes from 4 donors were exposed for a total of 24 h to a continuous or an intermittent RF signal. The signals were 935 MHz GSM (Global System for Mobile Communication) Basic, 1800 MHz GSM Basic, 935 MHz continuous wave (CW) carrier frequency, and 935 MHz GSM Talk. Stimulated lymphocytes were exposed for a total of 48 h to intermittent 1800 MHz RF signals that were GSM Basic or the carrier frequency only. The RF fields used for the 24 h exposure of N2a cells were all at 935 MHz and consisted of GSM Basic, GSM Talk and a CW signal. The chosen Specific energy Absorption values of the signals were either 1 or 2 W/kg. These values are near the upper limit of actual energy absorbed in localised tissue by a person from some mobile phones. The field was applied to G0 human lymphocytes either alone or combined with an exposure to 1 Gy x-rays given immediately before or after the RF field. A dose of 4 Gy x-rays was used as a positive control for apoptosis induction in N2a cells and in the study with stimulated lymphocytes no x-rays were used. The lymphocytes were assayed by several standard methods to demonstrate genotoxicity. Unstable chromosome aberrations (stimulated lymphocytes and those exposed in G0), sister chromatid exchanges (SCE) and cytokinesis blocked micronuclei (MN) (lymphocytes exposed in G0). In addition the SCE and MN assays allowed nuclear division indices (NDI) to be calculated as NDI defines the cell cycle progression of lymphocytes after PHA stimulation and how this might be affected by RF exposure. N2a cells were assessed by fluorescence microscopy for levels of apoptosis at a number of time points post RF field or x-ray exposure, between 0 and 48 h. Three independent assays that detect different stages of the apoptotic pathway were used, the Annexin V binding, caspase activation and in situ end labelling. By comparison with appropriate sham exposed samples no effect of RF fields alone could be found in G0 or PHA stimulated lymphocytes exposed in vitro. Also, RF fields did not modify any measured effects of x-rays either given before or after RF exposure. No statistically significant difference in apoptosis levels were observed between RF exposed and sham exposed N2a cells in either a proliferating or differentiated state for any assay at any time point post exposure.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:511690 |
| Date | January 2009 |
| Creators | Moquet, Jayne Elizabeth |
| Publisher | Brunel University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://bura.brunel.ac.uk/handle/2438/4378 |
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