Multimarker Approach to Evaluate the Exposure to Electromagnetic Fields at 27 GHz on Danio rerio Larvae

5G technology aims to satisfy several service requirements, leading to high data-rate connections and lower latency times than current ones. 5G systems use different frequency bands of the radio wave spectrum, taking advantage of higher frequencies than previous mobile radio generations. To guarantee capillary radio coverage, it will be necessary to install a huge number of repeaters since electromagnetic waves at higher frequencies, and especially microwaves at higher bands, exhibit lower capacity to propagate in free space. Since the introduction of this new technology, there has been growing concern about possible harmful effects on human health. The aim of this study was to investigate the possible short-term effects induced by 5G-millimeter waves on the embryonic development of zebrafish (Danio rerio). Fertilized eggs were exposed to 27 GHz using a non-commercial high-gain pyramidal horn antenna, and several endpoints were monitored every 24 h. As a result, exposure to electromagnetic fields at 27 GHz caused no significant impacts on mortality or on morphology since the exposed larvae showed normal detachment of the tail, the presence of a heartbeat, and well-organized somites. Exposure to 27 GHz caused an increase in the heart rate in exposed embryos compared to that in the control group at 48 h. However, this increase was not observed at 72 and 96 h. Finally, very weak positivity regarding exposed larvae was highlighted by immunohistochemical analysis.