Humanity faces a new era of telecommunication technology. The “Internet of Things” (IoT) refers to a global connectivity platform of devices and sensors, which are meant to make our everyday lives easier. To make this happen, a new standard for wireless communication networks has to be created because ever-increasing amounts of data have to be transmitted. In the near future, this change will be facilitated by the deployment of the 5G standard. The currently existing frequency ranges used for wireless connectivity are not suitable for the envisioned data expansion. Therefore, the 5G standard also includes frequencies at 28 GHz and could reach into the sub-THz range later. The price for the exorbitant bandwidth (up to 10,000 mbit/s) needed for this level of connectivity is the increasing exposure to electromagnetic fields. The cell phone industry denies any health risks of 5G. Over the last years, however, numerous studies have been published that even question the safety of the currently deployed 4G technology (LTE).
The authors of this paper propose a thesis as to why 5G might be not as safe for humans as has been previously assumed. The helical structure of the sweat ducts in our skin form the basis of their thesis. Human skin consists essentially of three components (from the outer to the inner layer): epidermis (upper skin), dermis (corium) and subcutis (lower skin). The epidermis is less transparent to electric fields than the dermis. Due to this difference in electromagnetic properties of the dermis and epidermis as well as the helical structure of the sweat ducts, the scientists conceived the idea that sweat ducts could act as small, imperfect helical antennas. The scientists predicted that sweat ducts may receive signals in the sub-THz range. Previously, they could show an association between the activities of sweat glands (induced by physical activity or mental stress) and a change in the reflection pattern of electromagnetic waves in the W band (75–110 GHz).
The polarization of the reflected electromagnetic fields was another indicator that sweat ducts are involved. Similar to lactic acid, the helical (coiled) structure of the ducts has chirality, which means that the incident radiation is reflected back either in a clockwise (right-handed) or counterclockwise (lefthanded) direction. Indeed, the large majority of sweat ducts in our skin are right-handed and thus also cause a right-handed circular polarization in the radiation.
The study authors created a simulation model of the human skin to calculate SAR values. In their model, they considered the various skin layers, the specified water content in each segment and the helical structure of sweat ducts. They ran a thin skin simulation and a thick skin simulation with electrical conductivities of 2000, 5000 and 10,000 S/m. For the simulation, a perpendicular plane wave was chosen as the radiation source.
The thin skin model, with an electrical conductivity of 10,000 S/m, suggests that, at a frequency of 440 GHz, the energy is mainly absorbed in the sweat ducts. The same was also found in the thick skin model at 450 GHz. The thin skin model shows that the maximum absorption of electromagnetic waves in the sub-THz range in our skin occurs at 440 and 580 GHz. In the thick skin model, the maximum absorption occurs at 410 and 500 GHz. Furthermore, the simulation model shows that even at a low electrical conductivity of the skin at 2000 S/m, a much higher SAR value is reached when the helical structure of sweat ducts are considered.
With their simulation model, the authors of this study show that the helical sweat ducts of our sweat glands represent an important mechanism for the absorption of electromagnetic fields in the sub-THz range. The high band of 5G technology starts at 28 GHz, but could also reach into the sub-THz range. The methods currently used by the industry to evaluate SAR values do not consider the antenna character of sweat ducts at sub-THz frequencies. As a result, lower SAR values are calculated than they could occur in reality. Lastly, the authors call for a deeper investigation into possible health effects caused by the use of 5G technology. According to their opinion, there is sufficient evidence for nonthermal effects. (RH)