Development of an in Vitro Assay to Evaluate the Biological Impact of 5G Technology on Human Skin—Shield Effect of a Tannin-Rich Plant Extract

Background: The new 5G telecommunication technology has stirred concerns about potential negative effects on human health by radiofrequency electromagnetic fields. As to whether skin biology can be affected by 5G waves has remained an unsolved challenge despite recent studies dealing with this issue. In particular, a strategy for rational design of an assay allowing to 1) reproducibly evaluate and decipher the 5G effects on skin as well as 2) test the potential protective effects of cosmetic active ingredients, has yet to be found. Here we describe an in vitro model of human normal keratinocytes irradiated by 5G waves and show their impact on two biomarkers of inflammatory stress, i.e. interleukin-1β (IL-1β) and reactive oxygen species (ROS) production. In addition, the capacity of a tannin-rich plant extract to protect against 5G impact is evaluated. Materials and Methods: In the first series of experiments, monolayers of human normal keratinocytes were irradiated or not (control) by 5G waves (3.5 GHz) in an anechoic chamber and were incubated at 37˚C for 24 hours. At the end of the incubation period, extracellular IL-1β and intracellular ROS were quantified using specific ELISA and colorimetric assays, respectively. In the second series of experiments, the effect of an overnight pre-incubation with increasing concentrations of a tannin-rich plant extract was evaluated. Additionally, we studied in a prospective way the expression of a set of 88 genes selected for their relevance to keratinocyte homeostasis, in relation to the 5G challenge as well as the protective effect of a tannin-rich plant extract. Results: 5G waves significantly increased IL-1β production by 48.4% (p < 0.001) and ROS generation by 16.7% (p < 0.001). Furthermore, the tannin-rich plant extract dose-dependently protected the keratinocytes against the deleterious effects of 5G as measured by IL-1β and ROS production. Finally, the expression of 47 genes was modified by 5G waves and/or by the tannin-rich plant extract. Conclusion: This is to our knowledge the first evaluation of the impact of 5G technology on inflammatory biomarkers of human normal skin cells. Here we provide an innovative and pertinent tool to screen for natural compounds with protective effects against 5G waves to develop cosmetic products shielding