Authors: Palone, F.; Novelli, F.; Pasquali, E.; Leonardi, S.; De Stefano, I.; Fratini, E.; Tanori, M.; Piscitelli, M.; Merla, C.; Pinto, R.; Ardoino, L.; Zambotti, A.; Camera, F.; Pazzaglia, S.; Capstick, M.; Samaras, T.; Mancuso, M.
Reproductive Toxicology, 2026, 109370, ISSN 0890-6238, doi: https://doi.org/10.1016/j.reprotox.2026.109370
Abstract
Background
The biological impact of prolonged exposure to 5G millimeter-wave frequencies (FR2) on male reproductive health remains insufficiently characterized despite the global deployment of this technology in the near future. Here, we investigated the effects of chronic 27.5 GHz FR2 exposure on testicular function and sperm quality in three mouse strains with distinct genetic backgrounds (Car-S, CD1, and C57BL/6 J).
Methods
Adult males (8-weeks old at the onset of the study) were exposed for 100 days to low (6.67 W/m²) or high (20 W/m²) power density, or were SHAM-exposed. Reproductive parameters were assessed through testicular histopathology, serum testosterone measurement, and quantitative and qualitative sperm analyses.
Results
Continuous temperature monitoring and dosimetry confirmed that exposure remained strictly non-thermal throughout the experiments. The average ambient temperature recorded during the study was 22.8°C, while the mean whole-body specific absorption rate (SAR) was 0.26 W/kg and 0.77 W/kg under the LPD and HPD exposure conditions, respectively. Car-S mice showed significant reductions in sperm concentration and motility, increased tail abnormalities, and alterations in testicular architecture and testosterone levels, irrespective of prior carcinogen treatment administered for the evaluation of skin carcinogenesis. CD1 mice were largely resistant, displaying preserved sperm parameters with only minor morphological defects, whereas C57BL/6 J mice exhibited intermediate sensitivity, with reduced sperm viability and motility but normal concentration, morphology, and histology.
Conclusions
These findings demonstrate that genetic background strongly influences susceptibility to long-term 27.5 GHz FR2 exposure, highlighting the importance of integrating functional sperm endpoints and population heterogeneity in human health risk assessment.