## 1 Introduction
Current extensive research and growing evidence [23; 24; 25; 26; 27; 28; 29] from observed biological effects on various cell lines helps strengthen the reliability of the radical pairs mechanism affecting the ROS, despite the fact that detailed and exact physical description is still an object of investigation. However, the focus of this paper is on the mechanism of ELF MF action called ion parametric resonance (IPR), behind which are also a non-negligible body of contested studies [30; 31; 32; 33; 34; 35; 36; 37; 38; 39; 40; 41]. The model describes the mechanism of a parallelly combined time-varying (AC) and static (DC) magnetic field (MF) action on specific ions in biological structures (cell membrane proteins). The theory of IPR has been developing since the publication by [PERSON] in January 1991 [30]. The Russian physicist, based on the ion cyclotron resonance model [31], proposed the parametric resonance model where it is considered that ions bound to proteins (Ca\({}^{2+}\), K\({}^{+}\), and/or Mg\({}^{2+}\)) behave as isotropic coupled oscillators. These ions can serve as primary targets for AC MF [30; 31]. [PERSON]'s theory shows that the probability \(P\) of the AC MF biological effect is described by the square of the Bessel function of the first order--\(J_{1}\):  
\[P=J_{1}{}^{2}\bigg{(}\frac{B_{AC}}{B_{DC}}\bigg{)}, \tag{1}\]  
Accordingly, the resonance frequency formally corresponds to the cyclotron frequency [31]:  
\[f_{AC}=\frac{1}{n}\frac{q}{m}\frac{B_{DC}}{2\pi}, \tag{2}\]  
where \(f_{AC}\) is the frequency (in Hz) of the time-varying magnetic field, \(n=1,2,3\ldots\) represents the number of corresponding subharmonics, \(q\) is the electric charge (in C) of a specific ion,\(m\) is the mass of the ion (in kg), and \(B_{\text{DC}}\) is the induction value of the static magnetic field in (T). The maximal effects should be achieved when  
\[\mathbf{B}_{AC}=1.8\mathbf{\cdot}B_{DC}, \tag{3}\]  
For the case of weak \(B_{\text{AC}}\) (less than 10 \(\upmu\)T), it has been shown experimentally that [PERSON]'s model can describe the biological effects (amplitude and frequency dependences) of an AC MF tuned to the Larmor precession frequency for some nuclear spins as \({}^{1}\)H, \({}^{39}\)K, \({}^{55}\)Mn, \({}^{31}\)P, \({}^{35}\)Cl, \({}^{63}\)Cu, and \({}^{23}\)Na [40]. This model permits the calculation of the AC MF parameters necessary, on one hand, for achieving a maximal effect and, on the other hand, at known experimental AC MF parameters, for the identification of primary targets [32; 33; 34]. An experimental confirmation of this assumption in [PERSON]'s model is provided by the results presented in [37; 40], using two test systems: regenerating planarians and gravitropic reaction of plants. The results of [PERSON] et al. [40] presented in the Journal of Biophysics 5 suggest that for fields of industrial frequencies (50 and 60 Hz), the primary targets are the spins of nuclei of hydrogen atoms. The role of magnetic flux's density amplitude is detailed in an article from [PERSON] et al. [41], providing evidence to suggest that extremely weak alternating magnetic fields (EW AMF) with B\({}_{\text{AC}}\) values in the \(\upmu\)T, nT and even pT range can produce statistically significant effects in biological systems. It should be noted that most EW AMF experiments are performed in the presence of a static geomagnetic field (GMF) component. Available theoretical and experimental data confirm that an AC MF with a frequency of 50/60 Hz can induce biological effects at a magnetic flux density value of B\({}_{\text{AC}}\) > 10 \(\upmu\)T, while the possibility of biological effects of EW AMF with B\({}_{\text{AC}}\) < 10 \(\upmu\)T remains questionable. However, several results have also demonstrated the effect of B\({}_{\text{AC}}\) < 10 \(\upmu\)T on biological systems [42]. Despite the detailed mechanism descriptions, investigations and experimental evidence, there is no general scientific acceptance of any physical mechanism of ELF MF nonthermal action on biological samples.