Markkanen A, Penttinen P, Naarala J, Pelkonen J, et al. (2004):
The aim of this study was to investigate whether RFR exposure affects cell death processes of yeast cells.
Programmed cell death (apoptosis) is a response to DNA damage, and involves several alterations in cell structure. One of these is the exposure of phosphatidylserine (PS) residues at the outer plasma membrane leaflet. This can be detected using a special staining procedure.
Yeast cell cultures (both a wild-type strain and a mutant strain) were exposed to 900 or 872 MHz RF fields, with or without exposure to ultraviolet radiation, and incubated simultaneously with elevated temperature (+37°C) to induce apoptosis. A pulse modulated signal resembling that of the GSM mobile phone system was used. The 900 MHz frequency exposure had a SAR of about 0.4 W/kg, and the 872 MHz exposure had a SAR of 3.0 W/kg. In both experiments identical exposures were performed also using continuous wave signals. The RF exposure was for 1 hour. A sham exposure was used for control cells.
None of the RF field exposures alone had significant effects on programmed cell death. The GSM modulated fields, at both SAR levels used, increased UV induced apoptosis in the mutant strain, compared to the cells exposed to UV only. There was no enhancement of UN induced apoptosis in the cells exposed to continuous wave (unmodulated) RF fields.
The authors consider that the procedures used to lower the temperature of the water under the Petri dishes containing the yeast cells was enough to ensure that the effects seen were non-thermal in nature. They argue that this conclusion is strengthened by the lack of effect with continuous wave RF exposure.