Environmental and auto-induced RF-EMF adult and children far-field exposure simulations between 450 MHz and 26 GHz

Abstract

Objective: Children's exposure to radio-frequency electromagnetic fields (RF-EMF) above 6 GHz lacks characterization. No study spans sub-GHz cellular bands to millimeter wave while including child phantoms. This study quantifies the specific absorption rate (SAR) and absorbed power density (APD) in two adult and two child anatomical phantoms across 15 frequencies from 450 MHz to 26 GHz. Approach: We performed 550 finite-difference time-domain (FDTD) simulations covering environmental (plane-wave) and auto-induced (beamforming) exposure. SAR and APD were computed following IEC/IEEE 62704-1 and IEC/IEEE 63195-4, respectively. The simulations included, for the first time, whole-body dosimetry at 26 GHz in child and adult phantoms, and child APD across 7-15 GHz. Results were normalized to the ICNIRP 2020 reference levels for general public exposure. Main results: Children show 1.5-1.9 times higher whole-body SAR than adults at all sub-6 GHz frequencies. A 6-year-old reaches 93% of the 80 mW/kg whole-body SAR limit at 2140 MHz, averaged over 12 plane-wave configurations, and 145% in the worst one. Whole-body SAR, not local SAR, determines compliance margins below 6 GHz. Brain SAR decreases by 96% from 450 MHz to 5.8 GHz as absorption shifts to the skin. Eye SAR drops 77-fold from 7 to 26 GHz as penetration depth falls below eyelid thickness. Under simplified MRT beamforming, psSAR10g at 3500 MHz exceeds the 2 W/kg head/torso limit for all four phantoms (131-158%). APD at 7 GHz exceeds 20 W/m^2 for a 6-year-old by 2.5%. Worst-case whole-body SAR agrees with the literature within 2%. Significance: The results identify frequency-phantom combinations where compliance margins narrow: 3500 MHz and 7 GHz under beamforming, and children near 2 GHz under environmental exposure. The organ-specific SAR data for brain, eyes, skin, and genitals support epidemiological exposure assessment and dose modeling across current and prospective wireless bands.

AI evidence extraction

Main findings

Across 450 MHz to 26 GHz simulations, children had 1.5–1.9 times higher whole-body SAR than adults at all sub-6 GHz frequencies. Some modeled configurations exceeded relevant limits, including worst-case environmental exposure for a 6-year-old at 2140 MHz, simplified MRT beamforming at 3500 MHz for all four phantoms, and APD at 7 GHz for a 6-year-old. Brain and eye SAR decreased substantially with increasing frequency as absorption became more superficial.

Outcomes measured

• Whole-body specific absorption rate (SAR)
• Peak spatial-average SAR over 10 g (psSAR10g)
• Absorbed power density (APD)
• Brain SAR
• Eye SAR
• Skin and genital SAR
• Compliance margins relative to ICNIRP 2020 reference levels

Limitations

• Computational FDTD simulations using anatomical phantoms rather than measurements in people
• Beamforming exposure was modeled using a simplified MRT approach
• Some reported results represent worst-case exposure configurations

Suggested hubs

• who-icnirp (0.9)
  Exposure results were normalized to ICNIRP 2020 general-public reference levels and evaluated against SAR and APD limits.

{
    "study_type": "engineering",
    "exposure": {
        "band": "RF, microwave, and mmWave",
        "source": "environmental plane-wave and auto-induced beamforming exposure",
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": null
    },
    "population": "Two adult and two child anatomical phantoms",
    "sample_size": 4,
    "outcomes": [
        "Whole-body specific absorption rate (SAR)",
        "Peak spatial-average SAR over 10 g (psSAR10g)",
        "Absorbed power density (APD)",
        "Brain SAR",
        "Eye SAR",
        "Skin and genital SAR",
        "Compliance margins relative to ICNIRP 2020 reference levels"
    ],
    "main_findings": "Across 450 MHz to 26 GHz simulations, children had 1.5–1.9 times higher whole-body SAR than adults at all sub-6 GHz frequencies. Some modeled configurations exceeded relevant limits, including worst-case environmental exposure for a 6-year-old at 2140 MHz, simplified MRT beamforming at 3500 MHz for all four phantoms, and APD at 7 GHz for a 6-year-old. Brain and eye SAR decreased substantially with increasing frequency as absorption became more superficial.",
    "effect_direction": "mixed",
    "limitations": [
        "Computational FDTD simulations using anatomical phantoms rather than measurements in people",
        "Beamforming exposure was modeled using a simplified MRT approach",
        "Some reported results represent worst-case exposure configurations"
    ],
    "evidence_strength": "moderate",
    "confidence": 0.979999999999999982236431605997495353221893310546875,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "RF-EMF",
        "dosimetry",
        "children",
        "adult phantoms",
        "FDTD simulation",
        "specific absorption rate",
        "absorbed power density",
        "beamforming",
        "millimeter wave",
        "450 MHz–26 GHz",
        "ICNIRP 2020",
        "whole-body SAR",
        "organ-specific SAR"
    ],
    "suggested_hubs": [
        {
            "slug": "who-icnirp",
            "weight": 0.90000000000000002220446049250313080847263336181640625,
            "reason": "Exposure results were normalized to ICNIRP 2020 general-public reference levels and evaluated against SAR and APD limits."
        }
    ]
}

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