Evaluation of Specific Absorption Rate in the Far-Field, Near-to-Far Field and Near-Field Regions for Integrative Radiofrequency Exposure Assessment

Ilaria Liorni, Myles Capstick, Luuk van Wel, Joe Wiart, Wout Joseph, Elisabeth Cardis, Mònica Guxens, Roel Vermeulen, and Arno Thielens, Radiation Protection Dosimetry 2020, ncaa127, online 28 September 2020; doi: 10.1093/rpd/ncaa127

The specific absorption rate (SAR) induced by wireless radiofrequency (RF) systems depends on many different parameters, such as frequency power output proximity to the body or location of point of closest proximity. Furthermore, the ways in which people use their wireless devices is continuously evolving beyond the condition of a single device, frequency, and technology, and for a limited number of localized RF sources under which SAR has mainly been assessed. The current and emerging mobile systems involve a wider range of usage scenarios and include numerous radio systems that are frequently used simultaneously, leading to combined exposures for which almost no exposure evaluation exists. The aim and novelty of this study is to close this gap of knowledge by developing new methods to rapidly evaluate the SAR induced by RF systems in such scenarios at frequencies from 50 MHz to 5.5 GHz. To this aim, analytical methods for SAR estimation in several usage scenarios were derived through a large-scale numerical study. These include subject-specific characteristics, properties of the RF systems and provide an estimation of the SAR in the whole body, tissues and organs, and different brain regions.

The scientific and technical impact of the study can be summarized as:

  • An easy-to-use approach has been proposed for fast estimation of RF-electromagnetic field exposure for use in epidemiological studies
  • System-specific analytical approximation formulas for quantification of the absorbed power of several RF systems over a wide range of human subjects and frequencies, accounting for variations in system location, posture, age, sex and morphology, have been developed
  • Estimates of the dose variations and uncertainties based on imprecise knowledge of the exact exposure configuration are also provided