No measurable impact of acute 26 GHz 5G exposure on salivary stress markers in healthy adults.

The rapid deployment of fifth generation (5G) wireless networks has raised concerns about potential health effects associated with exposure to novel radiofrequency electromagnetic field (RF) frequencies, particularly the 26 GHz band which represents a new exposure scenario for the general population with limited prior use in telecommunications. However, evidence regarding the acute biological impact of these exposures remains limited and inconclusive. This study aimed to assess whether short-term exposure (26.5 min) of healthy adults to 5G RF at 26 GHz, at levels representative of real-world environmental conditions, affects salivary cortisol and alpha-amylase, two established biomarkers of stress and autonomic nervous system activity. Thirty-one participants completed a triple-blind, randomized protocol with electroencephalography recordings. A subset of sixteen participants from this group also participated in an exploratory protocol with cognitive testing and higher temporal sampling resolution (5 min intervals). Saliva samples were collected before, during, and after exposure in both protocols. RF exposure was delivered via a horn antenna at 2 V/m (head) and 1 V/m (torso), in line with upper-range environmental measurements. Statistical analyses revealed no significant differences in salivary cortisol or alpha-amylase concentrations between real and sham exposures. Descriptive examination of the exploratory cognitive protocol, with higher temporal sampling resolution, showed consistent temporal stability of both biomarkers in both conditions. These findings suggest that acute 5G RF exposure at 26 GHz, under controlled and realistic conditions, does not elicit measurable changes in stress biomarkers. Further research is warranted to evaluate the effects of repeated or long-term exposures and to investigate potential impacts in vulnerable populations.