# Comprehensive Survey on VLC in E-Healthcare: Channel Coding Schemes and Modulation Techniques
## 2 Effects of Electromagnetic Fields (EMFs) on Health  
The terrestrial electromagnetic environment has been significantly altered by technological advancements, with electromagnetic waves posing potential risks due to excessive radiation exposure. EMR is categorized by frequency into extremely-low-frequency-EMF and radiofrequency radiation. Studies have explored the health effects of EMFs, focusing on humans and rats. For example, exposure to pulsed microwaves at 3 GHz, 5.5 GHz, and 9.4 GHz in the workplace has been linked to genetic and cellular alterations, with oxidative stress identified as a key mechanism for DNA and cell damage [15; 16]. Study [17] investigated the formation of reactive oxygen species (ROS) in L929 cells after exposure to 900 MHz RF radiation, with and without a carcinogen (MX), concluding that 900 MHz RF does not induce oxidative stress. Similarly, ref. [18] found no significant oxidative stress in mouse macrophage cells exposed to RF radiation modulated by FMCW and CDMA, suggesting no carcinogenic link. Research on mobile RF use [19] also found no increased cancer risk, even for long-term users. Additionally, experiments have shown that 2450 MHz microwave radiation does not cause significant DNA damage or crosslinks in cultured cells [20]. Other studies have focused on oxidative damage in rat brains from 900 MHz microwaves [21] and on cardiovascular mortality related to extremely low-frequency magnetic fields in Swiss railway workers [22], with no significant health risks found. While RF radiation can affect patients' health, most studies, including those on gamma and X-ray radiation in healthcare, indicate limited evidence of significant risk [23]. The use of RF wireless technology in healthcare raises concerns about electromagnetic interference (EMI), which can affect medical devices, such as pacemakers, and can compromise patient safety [24; 25]. Health Canada has called for stricter EMC standards to mitigate these risks. RF waves are also used in medical imaging and therapy, including CT scans, X-rays, and cancer treatments [26]. This study explores the interactions between EMR and living beings and EMR's potential clinical applications. The authors in [27] provided a detailed analysis of the benefits and risks of EMR, along with safety recommendations for healthcare professionals and communications professionals, to address potential hazards. EMF shows promise in treating disorders such as cancer, kidney stones, and brain conditions, although its use presents challenges, including adverse effects, such as hair loss [28; 29]. Non-ionizing EMR has been used in cancer treatments to eliminate micro-organisms [30]. A review comparing electromagnetic field therapy (EMFT) and ultrasound (US) for wound healing highlights the need for more quantitative studies to validate these methods [31]. Table 1 summarizes various healthcare applications of EMF. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**SI. No** & **EMF Applications** & **Healthcare Systems** & **Health Effects** & **Ref. ** \\ \hline \multirow{4}{*}{1} & 7 mT, 50 Hz MF for 3 h, ferrous chloride (FeCl\({}_{2}\), 10 ug/mL), melatonin (0.5 or 1.0 mM). & Rat peripheral blood lymphocytes in alkaline comet assay. & Melatonin ameliorates the effect of simultaneous exposure to FeCl\({}_{2}\) and MF, resulting in significant DNA damage. & [32] \\ \cline{1-1} \cline{2-4}  & & & When microwave (mW) radiation was combined with toluene it resulted in significant cytogenetic effects. However, neither MW radiation alone nor toluene alone caused these effects. & \\ \cline{1-1} \cline{2-4}  &  
Finally, in the context of healthcare applications, it has been discovered that melatonin administration reduces DNA damage from simultaneous exposure to FeCl2 and magnetic fields (MF) at 7 mT for 3 h [32]. EMF exposure at various frequencies, including 980, 950, and 2100 MHz, has been linked to oxidative stress and DNA damage in some cases, though the results are inconsistent [33; 35].