Human Electromagnetic Field Exposure in Wearable Communications: A Review <s> C. EMF Exposure in Commercial Wearable Products <s> BACKGROUND ::: In previous studies we found measurable effects on variability of heart rate and on blood-pressure parameters of workers exposed to radiofrequency electromagnetic fields (EMF)compared with a control population, but none of the effects could be assigned clinical significance. In general, the obtained results strongly suggested that dysregulation of the autonomic control of the circulatory system was occurring. Therefore, it seemed logical that analysis of diurnal rhythms of blood pressure and heart rate, on the basis of data from 24 h recordings, might further support the above hypothesis. ::: ::: ::: OBJECTIVE ::: The aim of this study was to determine the course of diurnal rhythms of blood pressure and heart rate in a group of workers exposed to various intensities of radiofrequency electromagnetic fields. ::: ::: ::: METHODS ::: In the study we used 61 healthy workers (aged 30-50 years) who had been exposed to radiofrequency EMF of 0.738-1.503 Mhz and 42 healthy workers at radio-line stations (aged 28-49 years), who had not been exposed to EMF occupationally. The work patterns of these two groups were identical (12 h day working shift, 24 h interval, 12 h night shift and then 48 h rest). During the second day of the rest period 24 h ambulatory blood pressure (ABP) was recorded. For analysis of diurnal rhythms the group of exposed workers was divided into two subgroups: group A of 38 subjects exposed to low intensities of radiofrequency EMF (20-180 V/m) and group B of 23 subjects exposed to high intensities of radiofrequency EMF (200-550 V/m). Parameters of diurnal rhythms of blood pressure and heart rate (acrophase, amplitude and mean) were calculated by performing a least-square fit of a 24 h cosinor (single cosinor analysis) at P < 0.05. ::: ::: ::: RESULTS ::: Healthy men aged 28-49 years, working on a pattern of 12-24-12-48 h, exhibited typical, well-preserved diurnal rhythms of blood pressure and heart rate with two maxima (at about 1400 and 1700-1800 h) and one minimum (at about 0200-0400 h). For workers exposed to radiofrequency EMF we noted a significant lowering of the amplitudes of rhythms of blood pressure and heart rate (P < 0.01) and a shift of the acrophase to an earlier time (1100-1200 h; P < 0.05). These changes were more pronounced among workers exposed to high intensities of radiofrequency EMF. ::: ::: ::: CONCLUSIONS ::: Occupational exposure to radiofrequency EMF can result in changes of the diurnal rhythms of blood pressure and heart rate with lowering of their amplitudes and a shift of the acrophase. The clinical relevance of the present finding needs to be investigated in further studies. <s> BIB001 </s> Human Electromagnetic Field Exposure in Wearable Communications: A Review <s> C. EMF Exposure in Commercial Wearable Products <s> Energy dissipation by millimeter-wavelength electromagnetic-radiation (MMW; f~3-300 GHz) exposure to mammalian skin occurs within the outer surface. The penetration depth is less than 1 mm for frequencies above 25 GHz. A transport-lattice system model is used, which incorporates two spatial scales to estimate heat and chemical transport in rat skin in vivo: 1) a layered skin model involving the outer several millimeters of the body coupled to 2) a whole body model. The whole body model accounts for core-body heating, which provides a time-dependent reference temperature for blood perfusion in the skin model as well as the chemical concentration in the bloodstream and renal elimination. The model's thermal response to MMW exposure is consistent with the subcutaneous and colonic temperature measurements reported for 75 mWmiddotcm-2 and 40-min exposures at 94 GHz in anesthetized rats. The simultaneous involvement of two biophysical mechanisms that create different chemical changes in response to the field exposure is also considered. First, a traditional nonspecific thermal-injury indicator is used to estimate denaturing molecular change due directly to heating as a function of depth in the skin. Rat skin exposed in vivo to 75 mWmiddotcm-2 for long times (40 min) has a significant direct injury, while a 10-s exposure to 1 Wmiddotcm -2 results in a much less direct injury. Second, the biophysical mechanism of biochemical release through cell membranes within the tissue regions that reach supraphysiologic temperatures is also considered. The released molecules are delivered to other skin regions by diffusion and into the bloodstream by perfusion, where according to our hypothesis, the molecules interact with susceptible cells. This raises the possibility of additional indirect injury at nearby deeper skin regions that experience insignificant heating. Biochemical release may also lead to injury at distant sites within the body by perfusion clearance that transfers molecules into the systemic circulation to reach other susceptible cells. The hypothesis of simultaneous direct- and indirect-injury mechanisms is also illustrated by creating and solving didactic, coupled thermal, and chemical transport-lattice models <s> BIB002 </s> Human Electromagnetic Field Exposure in Wearable Communications: A Review <s> C. EMF Exposure in Commercial Wearable Products <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> BIB003 </s> Human Electromagnetic Field Exposure in Wearable Communications: A Review <s> C. EMF Exposure in Commercial Wearable Products <s> The objective of this paper is to determine a maximum averaging area for power density (PD) that limits the maximum temperature increase to a given threshold for frequencies above 6 GHz. This maximum area should be conservative for any transmitter at any distance >2 mm from the primary transmitting antennas or secondary field-generating sources. To derive a generically valid maximum averaging area, an analytical approximation for the peak temperature increase caused by localized exposure was derived. The results for a threshold value of 1 K temperature rise were validated against simulations of a series of sources composed of electrical and magnetic elements (dipoles, slots, patches, and arrays) that represented the spectrum of relevant transmitters. The validation was successful for frequencies in which the power deposition occurred superficially (i.e., >10 GHz). In conclusion, the averaging area for a PD limit of 10 W/m2 that conservatively limits the temperature increase in the skin to less than 1 K at any distance >2 mm from the transmitters is frequency dependent, increases with distance, and ranges from 3 cm2 at <10 GHz to 1.9 cm2 at 100 GHz. In the far-field, the area depends additionally on distance and the antenna array aperture. The correlation was found to be worse at lower frequencies (<10 GHz) and very close to the source, the systematic evaluation of which is part of another study to investigate the effect of different coupling mechanisms in the reactive near-field on the ratio of temperature increase to incident power density. The presented model can be directly applied to any other PD and temperature thresholds. Bioelectromagnetics. 39:617-630, 2018. © 2018 Wiley Periodicals, Inc. <s> BIB004 </s> Human Electromagnetic Field Exposure in Wearable Communications: A Review <s> C. EMF Exposure in Commercial Wearable Products <s> Extreme broadband wireless devices operating above 10 GHz may transmit data in bursts of a few milliseconds to seconds. Even though the time- and area-averaged power density values remain within the acceptable safety limits for continuous exposure, these bursts may lead to short temperature spikes in the skin of exposed people. In this paper, a novel analytical approach to pulsed heating is developed and applied to assess the peak-to-average temperature ratio as a function of the pulse fraction α (relative to the averaging time [INCREMENT]T; it corresponds to the inverse of the peak-to-average ratio). This has been analyzed for two different perfusion-related thermal time constants (τ1 = 100 s and 500 s) corresponding to plane-wave and localized exposures. To allow for peak temperatures that considerably exceed the 1 K increase, the CEM43 tissue damage model, with an experimental-data-based damage threshold for human skin of 600 min, is used to allow large temperature oscillations that remain below the level at which tissue damage occurs. To stay consistent with the current safety guidelines, safety factors of 10 for occupational exposure and 50 for the general public were applied. The model assumptions and limitations (e.g., employed thermal and tissue damage models, homogeneous skin, consideration of localized exposure by a modified time constant) are discussed in detail. The results demonstrate that the maximum averaging time, based on the assumption of a thermal time constant of 100 s, is 240 s if the maximum local temperature increase for continuous-wave exposure is limited to 1 K and α ≥ 0.1. For a very low peak-to-average ratio of 100 (α ≥ 0.01), it decreases to only 30 s. The results also show that the peak-to-average ratio of 1,000 tolerated by the International Council on Non-Ionizing Radiation Protection guidelines may lead to permanent tissue damage after even short exposures, highlighting the importance of revisiting existing exposure guidelines. <s> BIB005
Hitherto, there has been no comprehensive survey investigating the EMF exposure in currently sold commercial wearable devices. According to a recent article  , many of fitness wear devices that are currently out in the market have been found to be untested, unscientific, and anxiety causing. Of course there are other opinions stating that the concerns are exaggerated and the EMF from earbuds is far too weak to have any noticeable impact on the human body  . However, we believe that such a controversy only fortifies justification of further investigation and conservative deployment of highenergy-emitting wearable devices. 1) Fitbit: In fact, Fitbit, a company well-known for its Wi-Fi-based watch-type health monitoring device series, recalled its activity tracker product in 2014 due to continued reports of dizziness, erratic pulse, nausea, pain, and headaches  . A closer investigation on each model has been reported  . Some users particularly reported that wearing a Fitbit causes pain in their arm  . Relevantly, a recent study suggested that wearing a sleep tracker may worsen an insomnia  . 2) AirPod: Unlike Fitbit, a head-worn device such as a wireless headset represents another dimension of potential risk. An example is AirPod, a wireless earbud product series by Apple. The product has been found to generate quite high SARs for a Bluetooth device  . Moreover, considering the close proximity to the brain, the health concern around an AirPod becomes more grave than other wearble devices. 3) Apple Watch: The key concern about Apple Watch is the exposure time. The smartwatch product performs a wider variety of applications than just health monitoring or music streaming and hence is expected to be worn for a longer time  . It has been acknowledged that a longer exposure to EMF radiation can elevate the hazardous impacts over time BIB002 . A further problem is that a device still needs to generate radio emission even when not used to interact with a nearby signal source (i.e., access point)  . As such, the time duration of exposure can become longer, which can exacerbate the human EMF exposure problem than one expects. D. Health Effect 1) Heating: Temperature elevation of skin is one representative impact on a human body caused by an EMF exposure. The temperature for a skin outer surface normally ranges from 30 to 35 • C. The pain detection threshold temperature for human skin is approximately 43 • C  and any temperature exceeding it can cause a long-term injury. Heating is considered as a significant impact since it can cause subsequent effects such as cell damage and protein induction BIB003 . It is also known that high-frequency EMF affects the sweat glands (which may serve as helical antennas), peripheral nerves, the eyes and the testes, and may have indirect effects on many organs in the body  . Recent publications in the field of biology studied health impacts of EMF in frequencies above 6 GHz. In a latest study  , EMF power transmitted to the body was analyzed as a function of angle of incidence and polarization, and its relevance to the current guidelines was discussed. Another study BIB004 determined a maximum averaging area for power density (PD) that limits the maximum temperature increase to a given threshold. Also, considering 'bursty' traffic patterns in modern wireless data communications, an analytical approach to 'pulsed' heating was developed and applied to assess the peak-to-average temperature ratio as a function of the pulse fraction BIB005 . 2) Neuron: Also, a recent study reported that exposure of fetal mice to EMF radiation from 800-1900 MHz-rated cellular telephones (24 h/day throughout gestation) affected neuron development and subsequent behavior. Exposed subjects showed memory impairments, as determined by the novel object recognition task  . Furthermore, there is research that proves that these exposure levels can open the blood-brain barrier, leading to neurodegenerative disease and even cancer. Even though FCC states that low levels of radiation emitted by devices like Bluetooth headphones are safe, users are recommended to turn off the Bluetooth function when not in use  . Research has shown that the softer brains of children make them much more susceptible to radiation which means they will absorb more radiation than adults  . For this reason, exposure to EMF generated by wearable devices can be particularly dangerous for children. Other factors can affect the specific absorption rate of a device. The more wireless connections, the higher the absorption rate will be. For instance, if one has Bluetooth and Wi-Fi on, the overall SAR will increase. 3) Heartbeat: Disturbance in heartbeats due to EMF exposure has been studied BIB001 . Diurnal rhythms of blood pressure and heart rate of healthy men aged 28-49 years were measured on the basis of data from 24 hours of recordings. The study concluded that exposure to EMF for occupation can result in changes of the diurnal rhythms of blood pressure and heart rate with lowering of their amplitudes and a shift of the acrophase.