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

Abstract

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, Arno Thielens. Evaluation of Specific Absorption Rate in the Far-Field, Near-to-Far Field and Near- Field Regions for Integrative Radiofrequency Exposure Assessment. Radiat Prot Dosimetry. 2020 Sep 28;ncaa127. doi: 10.1093/rpd/ncaa127. Abstract The specific absorption rate (SAR) induced by wireless radiofrequency (RF) systems depends on different parameters. Previously, SAR was mainly assessed under conditions of a single frequency and technology and for a limited number of localized RF sources. The current and emerging mobile systems involve a wider range of usage scenarios and 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. pubmed.ncbi.nlm.nih.gov Conclusions In this study, an easy-to-use approach for fast estimation of RF-EMF exposure in terms of SAR within the human body resulting from simultaneously operated RF systems in different exposure scenarios is proposed. 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 were developed. To this aim, numerical simulations of advanced human anatomical phantoms exposed to several RF systems to simulate far-field, near-to-far field, and near-field exposure conditions were executed and analyzed. The approximation formulas permit to have an estimation of the absorbed power in the whole body, tissues and organs and different brain regions. Since the general population is normally exposed to numerous sources of RF exposure during the day, these approximation formulas represent a useful tool for epidemiology studies to predict the cumulative exposure for assessment of health impact. Indeed, the SAR levels can be combined with personal information about the conditions and duration of use of each RF source and scaled with respect to the actual output power of each device to obtain typical and personal integrated and cumulative RF doses

AI evidence extraction

Main findings

The study developed system-specific analytical approximation formulas, derived from large-scale numerical simulations of anatomical human phantoms, to rapidly estimate SAR from simultaneously operated RF systems across 50 MHz to 5.5 GHz in far-field, near-to-far field, and near-field scenarios. The approach accounts for variations in system location, posture, age, sex, and morphology and provides estimates for whole-body, tissue/organ, and brain-region absorbed power/SAR.

Outcomes measured

• Specific absorption rate (SAR) estimation/quantification in whole body, tissues/organs, and brain regions across far-field, near-to-far field, and near-field exposure conditions

Suggested hubs

• occupational-exposure (0.15)
  Mentions multiple RF exposure scenarios and integrative assessment methods, but does not clearly focus on occupational settings.

{
    "study_type": "engineering",
    "exposure": {
        "band": "RF",
        "source": "wireless radiofrequency (RF) systems (multiple simultaneously operated RF systems)",
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": null
    },
    "population": null,
    "sample_size": null,
    "outcomes": [
        "Specific absorption rate (SAR) estimation/quantification in whole body, tissues/organs, and brain regions across far-field, near-to-far field, and near-field exposure conditions"
    ],
    "main_findings": "The study developed system-specific analytical approximation formulas, derived from large-scale numerical simulations of anatomical human phantoms, to rapidly estimate SAR from simultaneously operated RF systems across 50 MHz to 5.5 GHz in far-field, near-to-far field, and near-field scenarios. The approach accounts for variations in system location, posture, age, sex, and morphology and provides estimates for whole-body, tissue/organ, and brain-region absorbed power/SAR.",
    "effect_direction": "unclear",
    "limitations": [],
    "evidence_strength": "insufficient",
    "confidence": 0.7399999999999999911182158029987476766109466552734375,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "specific absorption rate",
        "SAR",
        "RF-EMF",
        "radiofrequency exposure assessment",
        "analytical approximation formulas",
        "numerical simulations",
        "anatomical phantoms",
        "far-field",
        "near-field",
        "near-to-far field",
        "cumulative exposure",
        "integrative exposure assessment",
        "50 MHz to 5.5 GHz"
    ],
    "suggested_hubs": [
        {
            "slug": "occupational-exposure",
            "weight": 0.1499999999999999944488848768742172978818416595458984375,
            "reason": "Mentions multiple RF exposure scenarios and integrative assessment methods, but does not clearly focus on occupational settings."
        }
    ]
}

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