Recently, a very good research team from South Korea (Jisu Choi, Kyeongrae Min, Sangbong Jeon, Nam Kim, Jeong-Ki Pack & Kiwon Song) has published in a very good scientific journal (Scientific Reports, an open access spin-off from the Nature) an interesting study on the effects of 1.7 GHz 4G-LTE radiation exposures on proliferation, death and senescence of human cell lines.
However, as with nearly every published scientific study, some improvements could have been made and the peer-reviewers from the Science Reports have missed the opportunity to help to improve this interesting study. As for now, and this is just my opinion, the study is interesting but… nothing really new, except for the unnecessarily “flashy” conclusion speculation.
Let’s start with the science, which is good in this study…
The authors examined effects of 1.7 GHz continuous exposure, for up to 72 hours, on proliferation of several cell lines. Exposures were at 1 and 2 SAR and, because such exposures could generate heating, the authors used water cooling system to make sure that the temperature of the exposed cell will not rise. Thus, as they specified, they aimed to study the non-thermal effects.
This resembles the approach of my research team when we analyzed protein and gene expression in human cell lines exposed at SAR of 2 W/kg and we used water cooling to keep temperature of the cell cultures at 37oC.
In respect of our studies, the cooling was important as already 1h exposure without cooling system would led to increase in temperature of cell cultures. In South Korean study the exposures lasted for up to 72 hours and studying non-thermal effects at 1 and 2 SAR would be impossible without the cooling system.
The authors observed that the continuous exposure of cells to 1.7 GHz TE RF-EMF for 72 h at 1 and 2 SAR:
- decreased cell proliferation
- did not induce DNA damage
- did not induce apoptosis
- induce slight delay in transition from G1 phase to S phase of the cell cycle
- induce senescence in some cell lines
- increased generation of ROS
- ROS scavengers restored proliferation inhibitory effect of exposure
…and the authors concluded in their abstract that:
“These observations strongly suggest that 1.7 GHz LTE RF-EMF decrease proliferation and increase senescence by increasing intracellular ROS in human cells.”
Importantly, the authors seem to demonstrate that the high SAR exposures with well controlled temperature can cause non-thermal effects in cells grown in vitro.
Yet another indication that non-thermal effects exist, on the contrary to what ICNIRP thinks…
While the proliferation inhibition results seem to be well proven, there are some questions that were not answered… and could/should have been, in order to enhance the significance and physiological meaning of this interesting study.
The generation of ROS, inhibition of cell proliferation and restoration of normal proliferation levels with ROS scavengers are well presented.
However, the G1/S transition delay is not explained well. G1 arrest is most commonly caused by the need of a cell to repair DNA damage. The authors did not observe DNA damage.
The other reason for G1 arrest is a lack of growth factors. This possibility has not been examined. Also examining of the expression of several cyclins, proteins regulating cell cycle progression, was not performed. This would be helpful in determining the cause of G1/S arrest.
Furthermore, even if the cell cycle arrest occurs, for some yet to be determined reason, it is still unknown whether the G1/S arrest was irreversible or not. The authors did not examine what would happen to the cell cycle arrested cells when the radiation exposure would be terminated. The inhibition of proliferation was well seen already after 48 hours of continuous radiation exposure and it would be easily possible to terminate exposure at the 48 hour time-point and follow the fate of cells for the next 24 hours post-exposure.
Problem of finding out ‘what happens next’ is present in many EMF studies. Effects are observed but it is not being followed what will happen next, is the effect reversible or irreversible, to find out its physiological significance. For example:
- some studies indicate that RF exposures lead to increased levels of damaged DNA in exposed cells… but they do not examine what happens with the damaged DNA, is it repaired or does it remains unrepaired in cells that progress to S phase of the cell cycle? Without this knowledge it is not known if the RF effect is e.g. genotoxic.
- some studies indicate that long term avid use of cell phone increases risk of developing brain cancer… but what would happen if the user stops using cell phone after say 5 or 10 years, will the risk of developing brain cancer remain the same or change? Without this knowledge we don’t know the maximal period of cell phone use that doesn’t increase risk of brain cancer, and whether the risk is reversible.
The same problem of “what happens next” is in the South Korean study, proliferation of cells and the G1/S transition seem to be inhibited but… what happens next to the cells?
At the end of the article, the authors unnecessarily went to speculate what impact their observation might have:
“…It is not plausible to directly predict the physiological effects of 1.7 GHz LTE RF-EMF from our cell-based study. However, the anti-proliferative effect of 1.7 GHz LTE RF-EMF on various human cells in this study suggests that the exposure to 1.7 GHz LTE RF-EMF would be more harmful to children, whose adult stem cells should be very active for growth and may accelerate the aging of body cells…”
Thus, on one hand the authors state that the study can’t be used to directly predict impact on human physiology… but in the next sentence they speculate about stem cells and children.
This speculation, not supported by the in vitro evidence presented in the study, causes unfounded expectations among the activists. Just this particular conclusion speculation was disseminated on June 11th, 2020 in tweet from @MicrowaveNews
Why it is problematic to speculate about physiological impact of this study, besides the fact that it is solely in vitro study:
- nobody is exposed at 1 or 2 SAR for 72 hours periods continuously
- it is not known if inhibition of cell proliferation is permanent or reversible and what it means for the cell physiology = unknown physiological significance for humans
- it is not known what causes the inhibition (e.g. no DNA damage) of cell proliferation in form of G1/S cell cycle arrest = is this “slight” delay in G1/S transition real or artifact
Instead of speculation about stem cells in children, that feels really scary and is an easy attention catcher, it could have been speculated about possible impact on e.g. proliferation of the basal layer cells of skin epidermis. These cells are proliferating and dividing continuously. In fact, if the cell proliferation inhibitory effect, observed in the South Korean study, was happening in real life exposures, there should be detectable health problems with the skin and skin regeneration of the cell phone users. I am not aware of such study but, it is also possible that the issue was not studied yet.
Summa summarum, and interesting study, yet again proving existence of non-thermal effects at very high exposures but of yet unknown physiological significance, if any, for the users of wireless communication technology.