# Zebrafish Larval Melanophores Respond to Electromagnetic Fields Exposure
## 4 Discussion
### Radio-Frequency Electromagnetic Fields  
Zebrafish embryos/early larvae exposed to both very-high- (100 MHz, 240 nT) and ultra-high- (900 MHz, 240 nT) frequency magnetic fields did not show increased mortality, but a slight delay in development with respect to control. Both radio frequencies caused abnormal swimming behavior because of hypo-neurovascular activity, slow swimming speed and failure to maintain posture, even in the absence of spinal curvatures. Limited pericardial oedema could also be present in the developing larvae. In this case, alterations in development pigmentation were found only in the zebrafish head. These findings largely match with results from other groups. For example, [PERSON] et al. [19] showed that at 100 MHz, an electromagnetic field affects various aspects of zebrafish embryonic development from 24 to 72 hpf. At the 48 hpf stage, reduced growth, increased transcription of oxidative stress genes, the onset of apoptotic/autophagic processes, and modification in cholesterol metabolism have been detected. In addition, zebrafish embryos face stress induced by radiation by triggering detoxification mechanisms. Our results are worthy, but require more follow-ups and data collection, such as histopathological examinations of the neuromuscular tissue to appreciate the lesions, to fully address the question of the effects of a magnetic field in the zebrafish model. In this context, the fact that the zebrafish, as well as other fish, do sense the geomagnetic field (which is known as'magnetoreception'), as well as other natural magnetic fields [2; 20; 21; 22], is not to be underestimated. In this way, our results can contribute to the advancement of research on the effects of magnetic fields on biological matter. Moreover, our findings can be beneficial for fully assessing the role of magnetic radiations on humans and, thus, be useful for their implications in medicine (as e.g., for MRI). In a perspective, the rapid deployment of the 5G transmission mode of the telecommunications industry will have to be considered. Since exposures to radio-frequency radiations, >2.4 GHz, are still uncommon, concerns about their potential health impacts are ongoing. The embryonic zebrafish has already been used to assess the impacts of a 3.5 GHz radio-frequency radiation on biological matter [23]. Exposing developing zebrafish from 6 to 48 hpf and measuring a battery of morphological and behavioral endpoints at 120 hpf revealed no significant impacts on mortality, morphology, or photomotor response and a modest inhibition of startle response. This suggests that cell-phone radiations at low-GHz-level frequencies are likely benign on the zebrafish model, with subtle sensorimotor effects. The following supporting information can be downloaded at [[https://www.mdpi.com/article/10.3390/app13084721/s1](https://www.mdpi.com/article/10.3390/app13084721/s1)]([https://www.mdpi.com/article/10.3390/app13084721/s1](https://www.mdpi.com/article/10.3390/app13084721/s1)): Supplementary Figure S1: Sketch of the B0 static magnetic field apparatus. ; Supplementary Figure S2: ELF magnetic field setup, Supplementary Figure S3: LF magnetic field setup. Coil (L), capacitor (C = 100 nF) and electronic circuit. Supplementary Figure S4: Output signal from probe VL and trigger signal. Vertical scale 2 V/div; horizontal scale 2 us/div. Supplementary Figure S5: Flat transmission line adapted for very-high-frequency (VHF) irradiation. Supplementary Figure S6: Short flat transmission line for ultra-high-frequency (UHF) irradiation. **Author Contributions:** Conceptualization, L.V., P.A., T.V. and V.N. ; methodology, A.M., G.D.V., L.V. and T.V. ; validation, A.M. and G.D.V. ; formal analysis, A.M. and G.D.V. ; investigation, A.M., G.D.V., L.V. and A.C.; resources, T.V. ; writing--original draft preparation, A.M., G.D.V. and L.V. ; writing--review and editing, L.V., P.A., A.C., T.V. and V.N. ; supervision, T.V. and V.N. ; funding acquisition, G.D.V. and T.V. All authors have read and agreed to the published version of the manuscript.