Exploring the Safety Margin in Current Guidelines for Electromagnetic Exposure

Exposure to radio-frequency (RF) electromagnetic fields (EMF) is unavoidable in today's modern life. This exposure is growing mainly because of rapid growth in telecommunication systems. Awareness of the possible risks of exposure to EMF has raised public concern. To avoid any potential adverse health effect, international organizations of ICNIRP and IEEE have developed basic restrictions (BRs) on specific absorption rate (SAR) for human exposure to RF EMF. These restrictions were derived based on limited data, i.e. experimental assessments (almost entirely) in animals or dose assessment using generic phantoms (approximated human anatomy). In order to account for uncertainties in the data and to provide a sufficient level of safety, the limits are lowered by large safety factors which were selected based on expert opinion rather than a rigorous quantitative process. The safety factors are not quantified for various exposure scenarios. In view of the lack of knowledge on the incorporated safety factor, and in the light of unique opportunity that medical applications can provide to establish dose-response relationship for humans, the aim of this thesis is to explore the relevance of the current BRs for functional tissue changes and to tailor SAR limits for localized exposure above which tissue damage takes place. This thesis, by means of advanced simulation tools, shows that the current restrictions on local exposure to RF EMF are conservative and should be more refined based on accurate dosimetry and useful data on experimental assessments in humans

SAR thresholds for electromagnetic exposure using functional thermal dose limits

Background and purpose: To protect against any potential adverse effects to human health from localised exposure to radio frequency (100 kHz–3 GHz) electromagnetic fields (RF EMF), international health organisations have defined basic restrictions on specific absorption rate (SAR) in tissues. These exposure restrictions incorporate safety factors which are generally conservative so that exposures that exceed the basic restrictions are not necessarily harmful. The magnitude of safety margin for various exposure scenarios is unknown. This shortcoming becomes more critical for medical applications where the safety guidelines are required to be relaxed. The purpose of this study was to quantify the magnitude of the safety factor included in the current basic restrictions for various exposure scenarios under localised exposure to RF EMF. Materials and methods: For each exposure scenario, we used the lowest thermal dose (TD) required to induce acute local tissue damage reported in literature, calculated the corresponding TD-functional SAR limits (SARTDFL) and related these limits to the existing basic restrictions, thereby estimating the respective safety factor. Results: The margin of safety factor in the current basic restrictions on 10 g peak spatial average SAR (psSAR10g) for muscle is large and can reach up to 31.2. Conclusions: Our analysis provides clear instructions for calculation of SARTDFL and consequently quantification of the incorporated safety factor in the current basic restrictions. This research can form the basis for further discussion on establishing the guidelines dedicated to a specific exposure scenario, i.e. exposure-specific SAR limits, rather than the current generic guidelines

Systematic review of pre-clinical and clinical devices for magnetic resonance-guided radiofrequency hyperthermia

Clinical trials have demonstrated the therapeutic benefits of adding radiofrequency (RF) hyperthermia (HT) as an adjuvant to radio- and chemotherapy. However, maximum utilization of these benefits is hampered by the current inability to maintain the temperature within the desired range. RF HT treatment quality is usually monitored by invasive temperature sensors, which provide limited data sampling and are prone to infection risks. Magnetic resonance (MR) temperature imaging has been developed to overcome these hurdles by allowing noninvasive 3D temperature monitoring in the target and normal tissues. To exploit this feature, several approaches for inserting the RF heating devices into the MR scanner have been proposed over the years. In this review, we summarize the status quo in MR-guided RF HT devices and analyze trends in these hybrid hardware configurations. In addition, we discuss the various approaches, extract best practices and identify gaps regarding the experimental validation procedures for MR - RF HT, aimed at converging to a common standard in this process

A Meta-Analysis of Online Shopping Studies: Review and Synthesis Online sShopping Studies Results

Shopping is an intrinsic part of people's daily lives. Due to the rapid growth of Internet technology, customer buying behavior has changed; And the Internet has created a public space where people interact with others, do their banking activities And shopping that have affecting multiple factors people's shopping intentions. The main purpose of this study is to identify the factors affecting online shopping intentions and to review and synthesis the results of research conducted in this area with a meta-analysis approach. The statistical population of the study is online shopping studies published in international journals between 2000 and 2018. To conduct this research, after reviewing and screening more than 635 articles related to online shopping, 89 articles were selected for meta-analysis. After reviewing the selected articles, a total of 24 variables with a frequency greater than 5 were identified that were selected as influencing variables on online shopping intentions. The results related to the effect size of the variables showed that the satisfaction variable with the effect size of 0.614 had the most impact and then perceived value and shopping experience had the most impact on online shopping

SAR thresholds for electromagnetic exposure using functional thermal dose limits

\u3cp\u3eBACKGROUND AND PURPOSE: To protect against any potential adverse effects to human health from localised exposure to radio frequency (100 kHz-3 GHz) electromagnetic fields (RF EMF), international health organisations have defined basic restrictions on specific absorption rate (SAR) in tissues. These exposure restrictions incorporate safety factors which are generally conservative so that exposures that exceed the basic restrictions are not necessarily harmful. The magnitude of safety margin for various exposure scenarios is unknown. This shortcoming becomes more critical for medical applications where the safety guidelines are required to be relaxed. The purpose of this study was to quantify the magnitude of the safety factor included in the current basic restrictions for various exposure scenarios under localised exposure to RF EMF.\u3c/p\u3e\u3cp\u3eMATERIALS AND METHODS: For each exposure scenario, we used the lowest thermal dose (TD) required to induce acute local tissue damage reported in literature, calculated the corresponding TD-functional SAR limits (SARTDFL) and related these limits to the existing basic restrictions, thereby estimating the respective safety factor.\u3c/p\u3e\u3cp\u3eRESULTS: The margin of safety factor in the current basic restrictions on 10 g peak spatial average SAR (psSAR10g) for muscle is large and can reach up to 31.2.\u3c/p\u3e\u3cp\u3eCONCLUSIONS: Our analysis provides clear instructions for calculation of SARTDFL and consequently quantification of the incorporated safety factor in the current basic restrictions. This research can form the basis for further discussion on establishing the guidelines dedicated to a specific exposure scenario, i.e. exposure-specific SAR limits, rather than the current generic guidelines.\u3c/p\u3

Investigating Factors Affecting the Adoption of Information Technology by Hotels: A Case Study on Shiraz Hotels

In recent decades, information technology (IT) has become a key element in all aspects of people’s lives, especially in their working and professional lives. Application of IT in various sectors, businesses and organizations and its increasing growth, has provided a special importance for investigating the effective factors of IT acceptance, especially in hospitality-related businesses. Despite of the essence advantages of IT, accepting and using of it, has encountered with the staff resistance. Therefore, the purpose of this study is to investigate the factors affecting hotel staff acceptance of information technology. Descriptive survey has been determined as the research methodology. The hotels’ staff in Shiraz city have been selected as the statistical population. SPSS20 software and Smart PLS have been used to analyze the collected data. The results showed that such factors as attitudes, common beliefs toward IT and subjective norms have a significant and positive impact on accepting and applying IT

Impact of Head Morphology on Local Brain Specific Absorption Rate From Exposure to Mobile Phone Radiation

Among various possible health effects of mobile phone radiation, the risk of inducing cancer has the strongest interest of laymen and health organizations. Recently, the Interphone epidemiological study investigated the association between the estimated Radio Frequency (RF) dose from mobile phones and the risk of developing a brain tumor. Their dosimetric analysis included over 100 phone models but only two homogeneous head phantoms. So, the potential impact of individual morphological features on global and local RF absorption in the brain was not investigated. In this study, we performed detailed dosimetric simulations for 20 head models and quantified the variation of RF dose in different brain regions as a function of head morphology. Head models were exposed to RF fields from generic mobile phones at 835 and 1900MHz in the tilted and cheek positions. To evaluate the local RF dose variation, we used and compared two different post-processing methods, that is, averaging specific absorption rate (SAR) over Talairach regions and over sixteen predefined 1cm(3) cube-shaped field-sensors. The results show that the variation in the averaged SAR among the heads can reach up to 16.4dB at a 1cm(3) cube inside the brain (field-sensor method) and alternatively up to 15.8dB in the medulla region (Talairach method). In conclusion, we show head morphology as an important uncertainty source for dosimetric studies of mobile phones. Therefore, any dosimetric analysis dealing with RF dose at a specific region in the brain (e.g., tumor risk analysis) should be based upon real morphology. Bioelectromagnetics. 35:66-76, 2015. (c) 2014 Wiley Periodicals, Inc

Impact of head morphology on local brain specific absorption rate from exposure to mobile phone radiation

\u3cp\u3eAmong various possible health effects of mobile phone radiation, the risk of inducing cancer has the strongest interest of laymen and health organizations. Recently, the Interphone epidemiological study investigated the association between the estimated Radio Frequency (RF) dose from mobile phones and the risk of developing a brain tumor. Their dosimetric analysis included over 100 phone models but only two homogeneous head phantoms. So, the potential impact of individual morphological features on global and local RF absorption in the brain was not investigated. In this study, we performed detailed dosimetric simulations for 20 head models and quantified the variation of RF dose in different brain regions as a function of head morphology. Head models were exposed to RF fields from generic mobile phones at 835 and 1900 MHz in the tilted and cheek positions. To evaluate the local RF dose variation, we used and compared two different post-processing methods, that is, averaging specific absorption rate (SAR) over Talairach regions and over sixteen predefined 1 cm(3) cube-shaped field-sensors. The results show that the variation in the averaged SAR among the heads can reach up to 16.4 dB at a 1 cm(3) cube inside the brain (field-sensor method) and alternatively up to 15.8 dB in the medulla region (Talairach method). In conclusion, we show head morphology as an important uncertainty source for dosimetric studies of mobile phones. Therefore, any dosimetric analysis dealing with RF dose at a specific region in the brain (e.g., tumor risk analysis) should be based upon real morphology.\u3c/p\u3

Systematic review of pre-clinical and clinical devices for magnetic resonance-guided radiofrequency hyperthermia

\u3cp\u3eClinical trials have demonstrated the therapeutic benefits of adding radiofrequency (RF) hyperthermia (HT) as an adjuvant to radio- and chemotherapy. However, maximum utilization of these benefits is hampered by the current inability to maintain the temperature within the desired range. RF HT treatment quality is usually monitored by invasive temperature sensors, which provide limited data sampling and are prone to infection risks. Magnetic resonance (MR) temperature imaging has been developed to overcome these hurdles by allowing noninvasive 3D temperature monitoring in the target and normal tissues. To exploit this feature, several approaches for inserting the RF heating devices into the MR scanner have been proposed over the years. In this review, we summarize the status quo in MR-guided RF HT devices and analyze trends in these hybrid hardware configurations. In addition, we discuss the various approaches, extract best practices and identify gaps regarding the experimental validation procedures for MR - RF HT, aimed at converging to a common standard in this process.\u3c/p\u3

Absence of acute ocular damage in humans after prolonged exposure to intense RF EMF

\u3cp\u3eThe eye is considered to be a critical organ when determining safety standards for radio frequency (RF) radiation. Experimental data obtained using animals showed that RF heating of the eye, particularly over a specific threshold, can induce cataracts. During the treatment of cancer in the head and neck by hyperthermia, the eyes receive a considerable dose of RF radiation due to stray radiation from the prolonged (60 min) and intense exposure at 434 MHz of this region. In the current study, we verified the exposure guidelines for humans by determining the association between the electromagnetic and thermal dose in the eyes with the reported ocular effects. We performed a simulation study to retrospectively assess the specific absorption rate (SAR) and temperature increase in the eyes of 16 selected patients (encompassing a total of 74 treatment sessions) whose treatment involved high power delivery as well as a minimal distance between the tumor site and the eye. Our results show that the basic restrictions on the peak 10 g spatial-averaged SAR (10 W kg(-1)) and peak tissue temperature increase (1 °C) are exceeded by up to 10.4 and 4.6 times, on average, and by at least 6.2 and 1.8 times when considering the lower limit of the 95% confidence interval. Evaluation of the acute effects according to patients' feedback (all patients), the common toxicity criteria scores (all patients) and an ophthalmology investigation (one patient with the highest exposure) revealed no indication of any serious acute ocular effect, even though the eyes were exposed to high electromagnetic fields, leading to a high thermal dose. We also found that, although there is a strong correlation (R (2) =  0.88) between the predicted induced SAR and temperature in the eye, there are large uncertainties regarding the temperature-SAR relationship. Given this large uncertainty (129%) compared with the uncertainty of 3D temperature simulations (61%), we recommend using temperature simulations as a dosimetric measure in electromagnetic exposure risk assessments.\u3c/p\u3