Analysis of three-dimensional SAR distributions emitted by mobile phones in an epidemiological perspective

Abstract

The three-dimensional distribution of the specific absorption rate of energy (SAR) in phantom models was analysed to detect clusters of mobile phones producing similar spatial deposition of energy in the head. The clusters' characteristics were described from the phones external features, frequency band and communication protocol. Compliance measurements with phones in cheek and tilt positions, and on the left and right side of a physical phantom were used. Phones used the Personal Digital Cellular (PDC), Code division multiple access One (CdmaOne), Global System for Mobile Communications (GSM) and Nordic Mobile Telephony (NMT) communication systems, in the 800, 900, 1500 and 1800 MHz bands. Each phone's measurements were summarised by the half-ellipsoid in which the SAR values were above half the maximum value. Cluster analysis used the Partitioning Around Medoids algorithm. The dissimilarity measure was based on the overlap of the ellipsoids, and the Manhattan distance was used for robustness analysis. Within the 800 MHz frequency band, and in part within the 900 MHz and the 1800 MHz frequency bands, weak clustering was obtained for the handset shape (bar phone, flip with top and flip with central antennas), but only in specific positions (tilt or cheek). On measurements of 120 phones, the three-dimensional distribution of SAR in phantom models did not appear to be related to particular external phone characteristics or measurement characteristics, which could be used for refining the assessment of exposure to radiofrequency energy within the brain in epidemiological studies such as the Interphone.

Numerical Implementation of Representative Mobile Phone Models for Epidemiological Studies

“…Some research [1,2] has been conducted to estimate the specific absorption rate (SAR) values in numerical human head models based on the measured SAR distribution in a specific anthropomorphic mannequin (SAM) phantom to provide the exposure gradient for the Interphone study [3][4][5], an epidemiological study about mobile phone use and the risk of brain cancer. In [1], a method was proposed to estimate the three-dimensional SAR distributions in a realistic head model using the data obtained from compliance testing measurements.…”

“…The basic concept is to project the SAR on the conformal plane of the SAM phantom to a numerical head model and then to extrapolate the SAR inside the model from the conformal plane assuming an exponential decay exposure gradient in specific locations of the brain. A large number of mobile phone models released in Europe and Japan were analyzed to identify those models with a similar volume and location of the area above -3 dB of the maximum SAR [2].…”

The Intracranial Distribution of Gliomas in Relation to Exposure From Mobile Phones: Analyses From the INTERPHONE Study

“…The main exposure measure in our model was distance between the tumor and the phone, but this is a simplification, because the intracranial distribution of SAR also depends on the frequency band and other characteristics (26,42). Further, the exposure source was modeled as a single point, though in reality the source is mainly the antenna of the phone, which is frequently embedded in the body of the phone.…”

A numerical assessment of the human body effect in the transmission of wireless microphones

“…Due to the proliferation of mobile communication technologies, body loss has been primarily characterized for cellular phones by conducting measurements of the power received from the cellular phone with and without the presence of a human user (or a human phantom) in an anechoic chamber setting . Numerous experimental studies also assessed electromagnetic (EM) radiation from the cellular phone into the human body using near‐field probe measurements and human‐head, hand, and/or thorax phantoms . In addition, many numerical studies characterized specific absorption rates (SAR) induced by the cellular phones .…”

“…1,2 Numerous experimental studies also assessed electromagnetic (EM) radiation from the cellular phone into the human body using near-field probe measurements and human-head, hand, and/or thorax phantoms. [3][4][5][6][7] In addition, many numerical studies characterized specific absorption rates (SAR) induced by the cellular phones. [8][9][10][11][12] All those studies were carried out for cellular phones and only at their specific operating frequency bands, for example, 800/900, 1800/1900 MHz, and, more recently, at higher 5G frequencies.…”