The skin is the largest and most visible organ in the human body. Its primary function is to form a protective barrier against external stimuli. In addition to radiofrequency electromagnetic fields (HF-EMFs), environmental factors such as ultraviolet radiation (UVR) affect the skin as well. Small amounts of UV radiation have been shown to have positive health benefits and play an essential role in vitamin D synthesis. However, excessive UV exposure is clearly associated with negative effects, such as DNA mutations. The same French research group that conducted the Hurtier 2025 study [1] conducted this study (see the review in this issue of ElektrosmogReport). The researchers investigated the effects of a 24-hour, 5G-modulated 3.5 GHz signal on skin cells at three different specific absorption rate (SAR) values. To accomplish this, they used human fibroblasts and keratinocytes, some of which had previously been exposed to UVB radiation and some of which had not.
The UVB radiation at 312 nm was generated artificially. First, the researchers measured the UVB dose that triggered approximately 50% of the maximum effect. This dose was then used for all experiments. This approach allowed the researchers to determine whether 5G exposure could influence the effect of UVB radiation on skin cells, that is, whether it could enhance or reduce the effect. This study used a true 5G-modulated frequency of 3.5 GHz. The 5G EMF exposure setup consisted of a modified cell culture incubator similar to the one used in the aforementioned study [1]. Cells irradiated with UVB were exposed to 5G immediately after UVB irradiation for 24 hours at SARs of 0.25, 1, or 4 W/kg.
A MitoSOX Red probe was used to measure mitochondrial stress in human fibroblasts and keratinocytes. Changes in mitochondrial membrane potential and apoptosis were monitored using the MitoStatus TMRE dye. Positive controls were used in each experimental series to validate the results. All measurements were performed under blinded conditions.
This study revealed a statistically significant decrease (15%) in mitochondrial ROS levels in fibroblasts exposed to 5G at 1 W/kg. However, RF-EMF exposure at 0.25 or 4 W/kg did not alter ROS production.
No difference was observed between sham and RF-EMF exposure in keratinocytes, regardless of the SAR value.
Exposure to RF-EMF increased UVB-induced ROS production by 28%, 20%, or 16% at 0.25, 1, and 4 W/kg, respectively, in keratinocytes previously irradiated with UVB radiation and in keratinocytes subjected to sham RF-EMF exposure. The lowest dose (0.25 W/kg) produced the strongest effect. The authors view this as evidence of a hormetic (U-shaped) dose–response relationship, which appears plausible [3].
This study demonstrates the interaction between UVB radiation and RF-EMF exposure on ROS production in human keratinocytes. However, RF-EMF exposure alone was not found to increase mitochondrial ROS production. Consistent with studies demonstrating the pro-oxidative effects of RF-EMF exposure, ROS production is considered a rapid and transient response that decreases over time due to the activation of antioxidant metabolic pathways. Furthermore, no association was observed with changes in UVB-induced mitochondrial membrane potential or apoptosis. Taken together, these results suggest that the increase in UVB-induced ROS production caused by RF-EMF exposure is insufficient to adversely affect mitochondrial membrane potential, apoptosis, or necrosis. The authors summarize their findings and provide an overview of related studies. They conclude that only a few heterogeneous studies have investigated the effects of RF-EMF on skin models in vitro or in vivo. This heterogeneity is evident in the experimental conditions (e.g. cell type, RF-EMF frequency, presence or absence of RF-EMF signal modulation, and exposure duration) and biological outcomes in terms of ROS production. These differences currently prevent a clear conclusion. Further studies using 3D or in vivo skin models are needed to reach a definitive conclusion.
Editor’s note:
This is an interesting and well-conducted study, even if the results are puzzling and as yet unexplained. Since humans are regularly exposed to UVB radiation from the sun, it makes sense to consider the combined effects of this radiation and that from wireless communication technologies. The researchers state that they intend to examine more realistic models than isolated cells in the future, such as multilayer or 3D skin models. This is important because in vivo studies generally reveal more severe adverse effects than cell culture studies [2, 3]. (AT)
1. Hurtier A, Patrignoni L, Canovi A, Orlacchio R, Tjiou H, Gannes FP et al. (2025). Effects of simultaneous in-vitro exposure to 5G-modulated 3.5 GHz and GSM-modulated 1.8 GHz radio-frequency electromagnetic fields on neuronal network electrical activity and cellular stress in skin fibroblast cells. Bioelectromagnetics, 46(7), e70026. https://doi.org/10.1002/bem.70026
2. Souchelnytskyi S (2025). Human cells response to electromagnetic waves of radio and microwave frequencies. The Ukrainian Biochemical Journal, 97(6), 5–22. https://doi.org/10.15407/ubj97.06.005
3. Weller SG, McCredden JE, Leach V, Chu C, Lam AK (2025). A scoping review and evidence map of radiofrequency field exposure and genotoxicity: Assessing in vivo, in vitro, and epidemiological data. Frontiers in Public Health, 13, 1613353. https://doi.org/10.3389/fpubh.2025.1613353