Influence of RF electromagnetic fields of mobile communication on human fibroblasts (genotoxicity)
Technische Universitšt Darmstadt
Aim of the study was to clarify, whether the effects reported by the REFLEX program in human fibroblasts (DNA strand breaks and induction of micronuclei) can be reproduced independently. Furthermore possible molecular mechanisms of genotoxic effects should be investigated. The investigations were carried out with fibroblasts of various donors of two age groups, in order to assess inter-individual variability.
Statistical analysis showed no significant evidences for genotoxic or dose-dependent effects induced by high frequency EMF-exposure (GSM 1800 MHz, intermittent, 5 min on, 10 min off, SAR 0, 0.2, 2 and 10 W/kg). No dose-dependent effects could be observed and no evidence for a special sensitivity of one of the two age groups was found.
10 juvenile (19-20 years) and 13 adult (50-60 years) donors were recruited on the basis of a questionnaire, including questions about health status and lifestyle etc to assess inter-individual variability.
Primary dermal fibroblasts from these donors (10 juvenile and 10 adult) were exposed to 1800 MHz frequency EMF-fields (exposure system sXc1800 XL) with SAR-values of 0 (sham control), 0.2, 2 and 10 W/kg, 5 min on, 10 min off (intermittent exposure). Corresponding positive controls with assay-based chemical toxins were performed in parallel.
The alkaline COMET-Assay was analyzed for DNA strand break induction after 4, 16 and 24 hrs of exposure.
The COMET-Assay with Fpg-endonuclease incubation was used for the detection of ROS-induced DNA damage.
The induction of micronuclei and the distinction between clastogenic and aneugenic effects was analyzed with the CREST-based Micronuclei test (MNT) after 15 and 72 hrs of EMF-exposure. This endpoint was also analyzed by the numeric chromosomal aberration assay.
Flow-cytometric analysis of the cell cycle and the TUNEL-assay for apoptotic events were performed as well.
Exposure and analyses were carried out under blinded conditions. The real exposure situation was known only by the technical partner ITIS Foundation, Zurich.
Biopsies and flow-cytometric analysis of the cell cycle were done at the Dermatology Centre, Elbekliniken Buxtehude. The COMET-Assays were performed at the University of Applied Sciences Darmstadt. MNT-Assays, nCA-Tests and the TUNEL-Assays were carried out at the Technical University Darmstadt. The statistical analyses were done at the Institute of Medical Biostatistics, Epidemiology and Informatics (IMBEI), University Mainz. All analyses were performed a) for the whole group and b) for both age groups separately.
In the discussion about possible biological effects of high frequency electromagnetic fields it is often postulated, that effects of RF-EMF are cell type specific and that fibroblasts are an appropriate in vitro model for testing genotoxic effects of RF-EMF. However, no evidence for EMF-induced genotoxic or chromosome damaging effects was found in primary human dermal fibroblasts. Likewise negative was a multicenter study with PHA stimulated human lymphocytes. Overall, no evidence for genotoxic effects of a pulsed 1.8 GHz GSM mobile phone signal at intermittent exposure (5 min on, 10 min off) with specific absorption rates of 0.2, 2 and 10 W/kg could be observed in human fibroblasts. The results showed no evidence for induced oxidative DNA damage or for a specific vulnerability of one of the different age groups. Results of the REFLEX programme (published e.g. in Diem et al. 2005, Mutation Research 583, 178-183; Schwarz et al. 2008 Int Arch Occup Environ Health 81, 755-767) could not be confirmed. The results of this study are in accordance with the results published by Speit et al. 2007, Mutation Research 626, 42-47 and with the results from the SEAWIND Project (final report: http://seawind-fp7.eu/uploads/SEAWIND_FINAL.pdf).
The final report is available as pdf-file (12 MB) in German, summary in English.