No direct genotoxic potential of different radiofrequency electromagnetic fields in MRC-5 cells and B6C3F1 mice
Public exposure to electromagnetic fields in the radiofrequency spectrum (RFEMF) has increased dramatically, attracting notice to health risk evaluation. RFEMF was classified as possibly carcinogenic to humans (Group 2B) by the IARC in 2011. But clear risk assessment is still limited by data gaps and contradictory data, not only for mobile phones but also for wireless network devices. As there are some indications for disturbance of DNA-integrity by RF-EMF exposure, we evaluated the in vitro and in vivo genotoxic potential of different RF-EMF signals by using well established and standardized genotoxicity. In vitro, normal human MRC-5 lung fibroblasts were exposed intermittently (5 min ON, 10 min OFF) in a 1950 MHz exposure system for 1, 4, and 24 h to various RF-EMF signals (continous wave (CW), UMTS, WiFi, GSM-basic, RFID) at specific absorption rates (SAR) up to 4.92 W/kg. DNA-strand break (SB) induction and oxidative DNA-damage were subsequently evaluated in an enzyme (hOGG1)-modified comet assay. In vivo, male B6C3F1 mice were whole-body exposed to CW, UMTS, WiFi, or RFID signals at SAR of 1.6, 4.0 and 10 W/kg for 14 d, 20 h/d (5 min ON, 10 min OFF) using a reverberation chamber. Micronucleus (MN) frequency was determined in peripheral blood, immature bone marrow erythrocytes and keratinocytes. Irrespective of signal type, SAR-value, and exposure duration RF-EMF did not mediate significant cytotoxicity, induction of DNA-strand breaks, or oxidative DNAdamage in MRC-5 cells, compared to concurrently sham-exposed cells. In addition, no increase in MN formation was observed in B6C3F1 mice. In conclusion, none of the tested signal modulations revealed evidence for a direct DNA-damaging or cytotoxic potential of RF-EMF. This study was part of the SEAWIND project, funded by the European Union's Seventh Framework Programme ([FP7/2007-2013)] under grant agreement No. 244149.