Effects of Pulse-Modulated Radiofrequency Magnetic Field (RF-EMF) Exposure on Apoptosis, Autophagy, Oxidative Stress and Electron Chain Transport Function in Human Neuroblastoma and Murine Microglial Cells

Jana Zielinski, Angélique D. Ducray, Anja M. Moeller, Manuel Murbach, Niels Kuster, and Meike Mevissen, Toxicology in Vitro 2020, Volume 68, October 2020, 104963, online 08 August 2020; doi: 10.1016/j.tiv.2020.104963

The use of body-worn wireless devices with different communication protocols and rapidly changing exposure scenarios is still multiplying and the need to identify possible health effects of radiofrequency electromagnetic field (RF-EMF) exposure with extremely low-frequency (ELF) modulation envelops. In this study, effects of ELF-modulated 935 MHz RF-EMF on apoptosis, autophagy, oxidative stress and electron exchange in N9 microglial and SH-SY5Y neuroblastoma cells were investigated. Cells were exposed at 4 W/kg or sham-exposed for 2 and 24 h. RF-EMF exposure of both cell types did not alter apoptosis, the number of living cells nor the apoptosis-inducing factor (AIF), irrespective of the exposure duration. RF-EMF exposure for 24, but not for 2 h, increased protein levels of the autophagy marker ATG5, whereas LC3B-I and II and pERK were not altered in both cell types and exposure times investigated. A transient increase in glutathione (GSH), but not hydrogen peroxide and cytochrome c oxidase, was found only in SH-SY5Y cells, indicating that short-time RF-EMF, at specific absorption rate (SAR) levels accepted by today's safety guidelines, might cause autophagy and oxidative stress with the effect being dependent on cell type and exposure duration. Further studies should be performed to evaluate possible underlying mechanisms involved in pulse-modulated RF-EMF exposure.

The scientific and technical impact of the study can be summarized as:

  • This study investigated the effect of intermittent and ELF-modulated RF-EMF exposure for 2 and 24 h at 4 W/kg (SAR) on oxidative stress, apoptosis, and autophagy and electron transport chain function in SH-SY5Y and microglial cells
  • RF-EMF exposure (935 MHz, 4 W/kg) did not alter proportions of early and late apoptosis when compared to sham exposure in both microglial and neuroblastoma cells
  • A time-dependent increase in autophagy markers has been observed, dependent on the specific cell type and on the time of RF-EMF exposure, with neuroblastoma cells being more susceptible
  • A transient increase in oxidative stress was seen at SAR levels above the standards, however, these are found on earlier time points under the exposure regime and differences are no longer observed after an increased period of time