Int J Environ Res Public Health. 2019 Jun; 16(12): 2085.
Published online 2019 Jun 13. doi: 10.3390/ijerph16122085
The human concern about the effect of electromagnetic fields (EMFs) has changed over time from the effects produced by EMFs of extremely low frequencies (ELFs) to the effects produced by exposure to a radio frequency (RF), with concerns shifting toward EMFs due to the development of new technologies and forms of communication. Previous studies have analysed the effects produced at different frequencies without considering in detail the effect of the time of exposure. Therefore, in the present study, we analysed in vitro the effect produced by a 100 µT EMF at different ELFs and exposure times in glioblastomas, as well as the effect produced in a fibroblast by an RF-EMF of 2.54 GHz. Our results indicate a significant time dependence in cell viability of fibroblasts exposed to an RF-EMF of 2.54 GHz and a non-time-dependent effect in cell viability of glioblastomas exposed to an ELF-EMF, highlighting the possible relation between frequency and time of exposure.
The main hypothesis of the study is that is that cell variability is correlated with frequency and time of exposure
In most of the in vitro studies that have been done with EMFs, the time of exposure has not been considered in detail, even though cellular responses, such as cell proliferation, viability and death, clearly vary between chronic and acute exposure.
Our results demonstrate a time dependence of NIH/3T3 cell viability when exposed to an RF-EMF of 2.54 GHz, which decreases with time to obtain a 71.12% decline in viability after 21 h of exposure.
On the other hand, our results for an ELF-EMF of 100 µT have demonstrated non-time-dependent effects. Frequency dependence effects were observed, obtaining a primary increase in cell viability at 50 Hz and a reduction in cell viability at 30 Hz, showing that even the recommended exposure level affects cell viability.
Therefore, the relationship between the frequency and time of exposure could determine the cellular response, demonstrating a need for further research.
Comments by EMFSA as noted from the study:
-The effect produced by an EMF depends on the cell line.
-There is a sex and species dependence in tumour development as per the NTP study.
-Clear evidence that RF-EMF produces changes in vitro and in vivo.
-There is no doubt that a significant cellular decrease occurs after 6 hours of exposure in NIH/3T3 cells but the authors point out that it is not clear whether the decrease in cell viability is related to an increase in mortality or to the antiproliferative properties of the EHF-EMF.
– The authors’ finding with NIH/3T3 cells cannot be completely compared with previous RF-EMF exposure results:
- Few studies have been performed using a certified testing chamber
- No recent studies have been done in vitro with fibroblasts at a frequency of 2.54 GHz.
— According to the authors it is not enough to investigate the cellular response of other cancerous and non-cancerous cell lines at different power densities and frequency – but also according to their results the exposition time is fundamental.