## 1 Introduction  
In addition to natural electromagnetic fields (EMFs), so-called artificial electromagnetic fields exist in the biosphere, the intensities of which exceed the natural background by several orders of magnitude. The main sources of artificial EMFs include power grids, mobile communications, electrical installations and devices, industrial inductive devices, radio/TV transmitters, and wireless Wi-Fi routers. Collectively, these fields are some of the largest energy pollutants on Earth [1]. Among the areas using electromagnetic fields, wireless communication technology deserves special attention because of its dynamic development. According to the International Telecommunication Union's 2023 report, 78 percent of the worldwide population (aged 10 and over) owns a mobile phone [2].  
Interest in the impact of EMFs on living organisms, among other things, is due to their association with the generation of bioelectric phenomena; therefore, they may interfere with the functioning of biological structures. Electromagnetic fields generated in the bodies of mammals, including humans, are irregular (with different amplitudes) and non-stationary (that is, the mean, variance, and autocorrelation function are variable over time). EMF values measured at the tissue level range from 1 to 200 V/m, and the densities of generated currents do not exceed 100 \(\mu\)A/cm\({}^{2}\)[3]. On a cellular scale, electrical fields with much higher intensities can be observed in the body. In each cell of the body, ion diffusion transport through the cell membrane and the action of the Na+/K+ pump form a cell membrane resting potential of 70 mV; combined with the thickness of the cell membrane (10 nm), this generates an electric field with an intensity of 7 \(\times\) 10\({}^{7}\) V/m [4]. Studies on the effects of EMFs on living organisms have a very wide scope, from the electrical properties of organs and the absorption and processing of electromagnetic field energy in tissues to the mechanisms of their effects on biological structures. The interaction between electromagnetic radiation and a living organism depends on several parameters, including the length of exposure, the value of energy transferred, and the type of tissue acted upon. Studies on the impact of EMFs are very difficult to conduct, as changing even one field parameter can lead to a completely different effect on matter. Therefore, despite the numerous papers on EMFs published every year, questions concerning a full understanding of the mechanisms and identification of the effects of this factor on living organisms have not yet been answered [5; 6; 7; 8; 9].  
Although still under investigation, quantum phenomena such as electron and proton tunneling have been proposed as possible mechanisms of EMF interactions with biological systems [10; 11; 12; 13; 14; 15; 16; 17]. While beyond the scope of our study, these phenomena remain important in the broader landscape of biophysical research.  
Experiments on the impact of EMFs on animals may reveal their health risks to humans and help biologists identify what biological processes and mechanisms are affected by them. Therefore, it is important to conduct complex experiments examining the impact of various environmental factors on living organisms to understand the overall effect of EMFs on the body; thus, the use of animal models is still necessary [18]. Rats are an example of model animals used in biological experiments. Their common use in laboratory studies is associated with the fact that about 90% of rat DNA is similar to that of humans. Furthermore, most human genes--the damage of which ends in disease--have equivalents in the DNA of this rodent [19].  
This study aimed to determine the impact of electromagnetic fields at a frequency of 1800 MHz on the concentration of selected hormones, sperm motility, viability, morphology, and behavior in laboratory rats (_Rattus norvegicus_).