RF Safe

Absorption of 5G radiation in brain tissue as a function of frequency, power and time

2020 · Unclear · Low evidence

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UnclearLow evidencePaper 1490

RF exposure and absorption were examined in ex vivo bovine brain tissue and a brain simulating gel at 1.9 GHz, 4 GHz, and 39 GHz. The authors report experimentally derived relationships between temperature rise (ΔT), SAR, and incident power density (F), and r…

Study snapshot

Publicationmanual · 2020
Study typeexposure_assessment
Reported directionUnclear
Evidence ratingLow

Abstract

Absorption of 5G radiation in brain tissue as a function of frequency, power and time David H. Gultekin, Peter H. Siegel. Absorption of 5G radiation in brain tissue as a function of frequency, power and time. IEEE Access. Published online June 12, 2020. DOI: 10.1109/ACCESS.2020.3002183. Abstract The rapid release of 5G wireless communications networks has spurred renewed concerns regarding the interactions of higher radiofrequency (RF) radiation with living species. We examine RF exposure and absorption in ex vivo bovine brain tissue and a brain simulating gel at three frequencies: 1.9 GHz, 4 GHz and 39 GHz that are relevant to current (4G), and upcoming (5G) spectra. We introduce a highly sensitive thermal method for the assessment of radiation exposure, and derive experimentally, accurate relations between the temperature rise (ΔT), specific absorption rate (SAR) and the incident power density (F), and tabulate the coefficients, ΔT/ΔF and Δ(SAR)/ΔF, as a function of frequency, depth and time. This new method provides both ΔT and SAR applicable to the frequency range below and above 6 GHz as shown at 1.9, 4 and 39 GHz, and demonstrates the most sensitive experimental assessment of brain tissue exposure to millimeter-wave radiation to date, with a detection limit of 1 mW. We examine the beam penetration, absorption and thermal diffusion at representative 4G and 5G frequencies and show that the RF heating increases rapidly with frequency due to decreasing RF source wavelength and increasing power density with the same incident power and exposure time. We also show the temperature effects of continuous wave, rapid pulse sequences and single pulses with varying pulse duration, and we employ electromagnetic modeling to map the field distributions in the tissue. Finally, using this new methodology, we measure the thermal diffusivity of ex vivo bovine brain tissue experimentally. Open access paper: ieeexplore.ieee.org Also see: IEEE Committee on Man and Radiation (COMAR)

Machine Enhanced Logic

AI evidence extraction

Structured fields below were generated from the paper’s abstract and metadata to make the evidence easier to inspect. Automated extraction may be incomplete or incorrect; verify important details against the original paper.

Study typeexposure_assessment
Effect directionunclear
PopulationEx vivo bovine brain tissue; brain simulating gel
Sample sizeNot supplied
ExposureRF
Evidence strengthLowConfidence: 74% · Peer reviewed: yes

Main findings

RF exposure and absorption were examined in ex vivo bovine brain tissue and a brain simulating gel at 1.9 GHz, 4 GHz, and 39 GHz. The authors report experimentally derived relationships between temperature rise (ΔT), SAR, and incident power density (F), and report that RF heating increased rapidly with frequency under the conditions tested.

Outcomes measured

  • Temperature rise (ΔT)
  • Specific absorption rate (SAR)
  • Incident power density (F)
  • Beam penetration
  • Absorption
  • Thermal diffusion
  • Field distributions (electromagnetic modeling)
  • Thermal diffusivity (tissue)

Limitations

  • Ex vivo bovine brain tissue and gel model (not in vivo human exposure)
  • Frequencies tested limited to 1.9, 4, and 39 GHz
  • Sample size and detailed exposure conditions not provided in the abstract
View raw extracted JSON
{
  "study_type": "exposure_assessment",
  "exposure": {
    "band": "RF",
    "source": "5G/4G-relevant experimental exposure (ex vivo tissue)",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": null
  },
  "population": "Ex vivo bovine brain tissue; brain simulating gel",
  "sample_size": null,
  "outcomes": [
    "Temperature rise (ΔT)",
    "Specific absorption rate (SAR)",
    "Incident power density (F)",
    "Beam penetration",
    "Absorption",
    "Thermal diffusion",
    "Field distributions (electromagnetic modeling)",
    "Thermal diffusivity (tissue)"
  ],
  "main_findings": "RF exposure and absorption were examined in ex vivo bovine brain tissue and a brain simulating gel at 1.9 GHz, 4 GHz, and 39 GHz. The authors report experimentally derived relationships between temperature rise (ΔT), SAR, and incident power density (F), and report that RF heating increased rapidly with frequency under the conditions tested.",
  "effect_direction": "unclear",
  "limitations": [
    "Ex vivo bovine brain tissue and gel model (not in vivo human exposure)",
    "Frequencies tested limited to 1.9, 4, and 39 GHz",
    "Sample size and detailed exposure conditions not provided in the abstract"
  ],
  "evidence_strength": "low",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "5G",
    "4G",
    "radiofrequency",
    "millimeter wave",
    "brain tissue",
    "bovine",
    "ex vivo",
    "specific absorption rate",
    "SAR",
    "power density",
    "thermal method",
    "temperature rise",
    "thermal diffusion",
    "electromagnetic modeling",
    "39 GHz",
    "4 GHz",
    "1.9 GHz"
  ],
  "suggested_hubs": [
    {
      "slug": "5g-policy",
      "weight": 0.55,
      "reason": "Study explicitly examines exposure/absorption at a 5G-relevant frequency (39 GHz) and discusses 5G-related concerns."
    }
  ]
}
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AI-extracted fields are generated from the abstract and metadata and may be incomplete or incorrect. This material is for informational purposes and is not medical advice.

Identifiers and source

DOI: 10.1109/access.2020.3002183
PubMed: Not supplied

Read the original paper →

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