Human Electromagnetic Field Exposure in Wearable Communications: A Review <s> A. Justification of SAR as a Key Metric <s> Abstract Repeated Wi-Fi studies show that Wi-Fi causes oxidative stress, sperm/testicular damage, neuropsychiatric effects including EEG changes, apoptosis, cellular DNA damage, endocrine changes, and calcium overload. Each of these effects are also caused by exposures to other microwave frequency EMFs, with each such effect being documented in from 10 to 16 reviews. Therefore, each of these seven EMF effects are established effects of Wi-Fi and of other microwave frequency EMFs. Each of these seven is also produced by downstream effects of the main action of such EMFs, voltage-gated calcium channel (VGCC) activation. While VGCC activation via EMF interaction with the VGCC voltage sensor seems to be the predominant mechanism of action of EMFs, other mechanisms appear to have minor roles. Minor roles include activation of other voltage-gated ion channels, calcium cyclotron resonance and the geomagnetic magnetoreception mechanism. Five properties of non-thermal EMF effects are discussed. These are that pulsed EMFs are, in most cases, more active than are non-pulsed EMFs; artificial EMFs are polarized and such polarized EMFs are much more active than non-polarized EMFs; dose-response curves are non-linear and non-monotone; EMF effects are often cumulative; and EMFs may impact young people more than adults. These general findings and data presented earlier on Wi-Fi effects were used to assess the Foster and Moulder (F&M) review of Wi-Fi. The F&M study claimed that there were seven important studies of Wi-Fi that each showed no effect. However, none of these were Wi-Fi studies, with each differing from genuine Wi-Fi in three distinct ways. F&M could, at most conclude that there was no statistically significant evidence of an effect. The tiny numbers studied in each of these seven F&M-linked studies show that each of them lack power to make any substantive conclusions. In conclusion, there are seven repeatedly found Wi-Fi effects which have also been shown to be caused by other similar EMF exposures. Each of the seven should be considered, therefore, as established effects of Wi-Fi. <s> BIB001 </s> Human Electromagnetic Field Exposure in Wearable Communications: A Review <s> A. Justification of SAR as a Key Metric <s> Exposures to radiofrequency (RF) energy above 6 GHz are characterized by shallow energy penetration, typically limited to the skin, but the subsequent increase in skin temperature is largely determined by heat transport in subcutaneous layers. A detailed analysis of the energy reflection, absorption, and power density distribution requires a knowledge of the properties of the skin layers and their variations. We consider an anatomically detailed model consisting of 3 or 4 layers (stratum corneum, viable epidermis plus dermis, subcutaneous fat, and muscle). The distribution of absorbed power in the different tissue layers is estimated based on electrical properties of the tissue layers inferred from measurements of reflected millimeter wavelength energy from skin, and literature data for the electrical properties of fat and muscle. In addition, the thermal response of the model is obtained using Pennes bioheat equation as well as a modified version incorporating blood flow rate-dependent thermal conductivity that provides a good fit to experimentally-found temperature elevations. A greatly simplified 3-layer model (Dermis, Fat, and Muscle) that assumes surface heating in only the skin layer clarifies the contribution of different tissue layers to the increase in surface skin temperature. The model shows that the increase in surface temperature is, under many circumstances, determined by the thermal resistance of subcutaneous tissues even though the RF energy may be deposited almost entirely in the skin layer. The limits of validity of the models and their relevance to setting safety standards are briefly discussed. Bioelectromagnetics. 39:173-189, 2018. © 2018 Wiley Periodicals, Inc. <s> BIB002
Electromagnetic waves are able to penetrate human tissues and cause oscillating electric fields. Then human tissues absorb these waves, which can affect energy states at the molecular level and thus may lead to harmful effects BIB001 . Specifically, dielectric heating causes a temperature rise in the exposed part of a body BIB002 . This heating is what has been known to result in other potential impacts as a consequence BIB001 . PD and SAR are the two most widely accepted metrics to measure the intensity and effects of EMF exposure  . However, selection of an appropriate metric evaluating the EMF exposure still remains to be an open problem. The FCC suggests PD as a metric measuring the human exposure to EMF generated by devices operating at frequencies higher than 6 GHz  . Yet, later, a study suggested that a guideline defined in PD is not efficient to determine the impacts on health issues especially when devices are operating in a very close proximity to the human body such as in an uplink  . However, PD cannot evaluate the effect of certain transmission characteristics (e.g., reflection) adequately. Thus, temperature elevation and SAR at a direct contact area are proposed as the appropriate metric for EMF exposure above 6 GHz BIB002 . For this reason, this paper chooses SAR as a more adequate metric than the skin temperature, which is subject to be dispersed during propagation and be affected by the external atmosphere (i.e., air temperature).