# Estimation of SAR Average in Rats during 5G NR Chronic Exposure
## 5 Conclusions  
Despite the rough approximations of rat phantoms used in simulations, the numerical calculation of SAR is qualitatively comparable to the theoretical estimate. A more accurate estimate requires the use of high-resolution model phantoms and a more detailed statistical analysis of EMF distribution and animal position. The differences between the approximate theoretical estimate and numerical simulations were 7% and 10% for the distributed and non-distributed absorptions, respectively. The whole-body average SARs in the approximate in vivo theoretical estimates were 0.0431, 0.0076, and 0.0059 W/kg for the first, second, and third groups, respectively. In fact, ambient illumination in combination with multiple reflections make accurate dosimetry more challenging. Adjustments to the actual amount of absorbed power are made by the fact that a living thing cannot stand still in a long-term experiment. The waveguide method can be considered the most accurate measurement of the whole body average SAR. It is possible to measure the power transmitted and reflected from the subject, which can accurately determine the specific absorption rate. However, such conditions are not suitable for long-term experiments to study the physiological reactions of animals. In [2], a threshold value of 4 W/kg under various exposure conditions was believed to cause some animal species, including non-human primates, to alter their complex behavioral patterns. Behavioral disturbance is often (but not always) accompanied by a 1.0 degC rise in body temperature. Even at exposure levels well above current standards, human body temperature is effectively regulated by mobilizing appropriate heat loss mechanisms such as sweating and skin blood flow. All first-group study animals (SAR = 0.043 W/kg) were recorded to have their body temperature rise by an average of 1 degC. In addition, the maximum possible absorption exceeded the allowable norms by 0.18/0.08 = 2.25 times. Despite the fact that the average SAR value was below the acceptable level, prolonged EMF exposure caused a rise in temperature. Changing temperatures were not registered during the exposure of rats. The study of physiological reactions of animals in the first group was stopped because the temperature increase was not acceptable. The other groups were within normal temperature limits, and the results of physiologic studies are described in [22]. Expression (3) requires modifications related to the statistical distribution of the positions of rats in the cage. The posture positions of rats obviously depend on their number in the cage, the shape of the cage, the location of the feeder, the behavioral properties of the animals, etc. The developments in this domain are being planned for the near future. Conceptualization, N.K. and S.S.; methodology, R.M., N.K., and S.S.; software, I.T. and R.M. ; validation, R.M., I.T., and S.S.; formal analysis, R.M. and S.S.; investigation, R.M. ; resources, N.K. and S.S.; data curation, N.K. and S.S.; writing--original draft preparation, R.M. ; writing--review and editing, S.S., I.T., and N.K. ; visualization, R.M. and I.T. ; supervision, S.S.; project administration, N.K. ; funding acquisition, N.K. All authors have read and agreed to the published version of the manuscript. This research was funded by Tomsk State University Development Programme (Priority-2030) grant number NU 2.4.9.22 ONG--\"The Study of Physiological Reactions in the Brain and Skin of Higher Mammals Exposed to Chronic RF 5G Radiation\". All animals were treated in accordance with the EU Council Directive of 24 November 1986 (86/609/EEC) and were approved by the Animal Research Ethics Committee of Tomsk State University. Not applicable. The data used to support the findings of this study are included within the article. The authors declare no conflicts of interest. The following abbreviations are used in this manuscript: