Exposure to 5G Radiofrequency and Physiological Effects in Healthy Young Adults: Insights Into Heart Rate Variability and Salivary Stress Biomarkers

This study investigated the potential impact of fifth-generation (5 G) radiofrequency (RF) on the autonomic nervous system (ANS). Electrocardiograms (n = 43) and salivary samples (n = 33) were collected from healthy young volunteers before, during, and after exposure to a 3.5 GHz frequency (electrical field intensity ~1-2 V/m) emitted by an antenna while participants were seated at rest. Heart-rate (HR) and heart rate variability (HRV) indices, including time and frequency domain measures, were analyzed from short-term epochs during both "real" and "sham" exposure sessions, under eyes-open (EO) and eyes-closed (EC) conditions. Initial variations in RR intervals and HR were observed during 5 G exposure; however, these effects were not confirmed by post-hoc analyses after correction for multiple comparisons, suggesting the absence of consistent exposure-related modulation. The only statistically significant result was a time-by-exposure interaction for the RMSSD parameter during the final exposure period. This effect was small in magnitude, limited to a single time point, and not supported by other parasympathetic indices, and should therefore be interpreted cautiously as it may reflect normal physiological variability or a statistical artifact. No consistent exposure-related effects were detected in salivary stress biomarkers, including cortisol, alpha-amylase, and chromogranin A. Although minor variations were observed in some measures, all values remained within normal physiological ranges, and their clinical relevance remains uncertain. These findings are restricted to the specific experimental conditions examined, namely short-term far-field exposure (25.5 min) at low specific absorption rate (SAR) levels (0.008 mW/kg in the brain). Overall, the results provide preliminary baseline human data at 3.5 GHz rather than confirmatory evidence of biological effects. Further studies involving larger cohorts and longer exposure durations are required to determine whether subtle or cumulative autonomic effects of 5 G exposure can be reliably detected. Bioelectromagnetics. 00:00-00, 2026. © 2026 Bioelectromagnetics Society.