A study of the effects of mobile-phone type signals on calcium ion levels with a human leukaemic T cell line

Abstract

The work presented here outlines experiments done using a novel RF exposure chamber. This device allows biological cells to be exposed to microwave radiation similar to those emitted by mobile telephones, whilst imaging them using a laserscanning confocal microscope. Jurkat E6.1 T lymphocytes in the exposure chamber were kept within ±0.5°C of 37°C, allowing for the investigation of possible athermal effects of microwave energies. These cells were loaded with the fluorescent probe Fluo-3 AM, which is specific for calcium ions, and were monitored over two 10minute periods. The first period being a control period, the second being a period where the cells were either exposed to RF energy or sham exposed. Another 5min imaging period was for the positive control,where maximal fluorescence can be achieved by the addition of the ionophore A23187. 5 different conditions for cell exposure were investigated. Both continuous wave 900MHz and continuous wave 900MHz pulse modulated at 217Hz exposures were carried out on cells that were either unactivated, or those that were activated by the mitogen phytohaemaglutinin (PHA). For these 4 conditions the average Specific Absorption Rate (SAR) was calculated to be 1.5W/kg. A group of unactivated cells were also exposed to continuous wave 900MHz energy with an average SAR calculation of 7.5W/kg. Results showed that no significant changes in calcium ion levels occurred when averaged fluorescence slopes were compared between RF exposed cells and the control period. The mean change in slopes exposed/sham period - control period)between cells that were exposed and those sham exposed also showed no significant difference. Following an inference made in the work of Galvanovskis et al. (1999)1 who showed there is a change in the calcium ion oscillation spectrum as a result of 50Hz magnetic fields, a measure of the mean frequencies of all cells was determined using a Fast Fourier Transform (FFT) analysis. The change in the average mean frequencies in cells was then measured for all conditions. Of statistical significance was the change in average mean frequency between the control period and the sham/exposed period between cells that were exposed and those sham exposed, when cells were activated by PHA. The results also showed that there was an overall drop in average mean frequency as a result of RF exposure. Assuming there is a biological significance to the findings of this thesis, careful analysis of the calcium dynamics of tissue samples and cell types associated with RF exposure from mobile phones would need to be carried out to determine what they are. This was unfortunately beyond the scope of the present study