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Transient Thermal Responses of Skin to Pulsed Millimeter Waves

2020 · Mixed · Low evidence

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MixedLow evidencePaper 1464

Using a one-dimensional skin thermal model (Pennes' bioheat equation), predicted temperature increases from 3-second pulses at 94 GHz agreed well with previous experimental results. The model suggests current FCC guidelines could, in extreme unrealistic cases…

Study snapshot

Publicationmanual · 2020
Study typeengineering
Reported directionMixed
Evidence ratingLow

Abstract

Transient Thermal Responses of Skin to Pulsed Millimeter Waves Kenneth R. Foster, Marvin C. Ziskin, Quirino Balzano, Akimasa Hirata. Transient Thermal Responses of Skin to Pulsed Millimeter Waves. IEEE Access. in press. Jul 9, 2020. doi: 10.1109/ACCESS.2020.3008322 Abstract This study examines thermal responses of skin to pulsed millimeter wave (mm-wave) radiofrequency (RF) radiation. We review limits for pulse fluence in the IEEE Std. C95.1-2019 and the 2020 guideline of the International Commission on Nonionizing Radiation Protection (ICNIRP), as well as the recently re-affirmed guidelines of the U.S. Federal Communications Commission (FCC). The study employs a simple one-dimensional thermal model for skin and Pennes' bioheat equation (BHTE). The predicted temperature increases produced by 3-sec pulses at 94 GHz agree well with previous experimental results with no adjustable parameters in the model, and the anticipated threshold of cutaneous thermal pain and burns are consistent with the scant available data for pulsed mm-waves, as well as a larger body of data on thermal hazards from pulsed infrared radiation. The model suggests that the implicit limits on pulse fluence in present FCC guidelines might allow, in extreme (and, in practice, unrealistic) cases, transient increases in skin temperature that can approach thresholds for thermal pain but well below those anticipated to cause thermal damage. Limits on pulse fluence in the current IEEE and ICNIRP exposure guidelines would preclude such effects. For realistic exposures from wireless and other technologies that transmit pulsed RF energy that comply with time-averaged exposure limits, the pulse fluence is far too low to produce hazardous thermal transients in skin. A thermal analysis of FCC's proposed "device-based time averaging" shows that the resulting limits on device emissions will result in thermal transients in skin that are roughly an order of magnitude below much slower increases in temperature due to time-averaged exposure. An appendix discusses the applicability of two approximations to the bioheat equation that can be used to estimate temperature increases in skin from exposure to mm-waves. This work was supported in part by the Microwave and Wireless Forum to three of the present authors (KRF, MCZ, and QB). Open access paper: ieeexplore.ieee.org

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 typeengineering
Effect directionmixed
PopulationNot supplied
Sample sizeNot supplied
ExposuremmWave · 94000 MHz · 3-sec pulses (modeled)
Evidence strengthLowConfidence: 74% · Peer reviewed: yes

Main findings

Using a one-dimensional skin thermal model (Pennes' bioheat equation), predicted temperature increases from 3-second pulses at 94 GHz agreed well with previous experimental results. The model suggests current FCC guidelines could, in extreme unrealistic cases, allow transient skin temperature increases approaching thermal pain thresholds but below levels anticipated to cause thermal damage, while IEEE and ICNIRP pulse fluence limits would preclude such effects; for realistic compliant exposures, pulse fluence is too low to produce hazardous thermal transients.

Outcomes measured

  • Skin temperature increase (thermal transients)
  • Thresholds for cutaneous thermal pain
  • Thermal burns/thermal damage risk
  • Implications of pulse fluence limits in IEEE C95.1-2019, ICNIRP 2020, and FCC guidelines
  • Effects of FCC proposed device-based time averaging on thermal transients

Limitations

  • Modeling study using a simple one-dimensional thermal model
  • Relies on comparison to limited ('scant') available data for pulsed mm-waves
  • Findings about FCC limits depend on extreme and described as unrealistic exposure scenarios
View raw extracted JSON
{
  "study_type": "engineering",
  "exposure": {
    "band": "mmWave",
    "source": "wireless and other technologies that transmit pulsed RF energy",
    "frequency_mhz": 94000,
    "sar_wkg": null,
    "duration": "3-sec pulses (modeled)"
  },
  "population": null,
  "sample_size": null,
  "outcomes": [
    "Skin temperature increase (thermal transients)",
    "Thresholds for cutaneous thermal pain",
    "Thermal burns/thermal damage risk",
    "Implications of pulse fluence limits in IEEE C95.1-2019, ICNIRP 2020, and FCC guidelines",
    "Effects of FCC proposed device-based time averaging on thermal transients"
  ],
  "main_findings": "Using a one-dimensional skin thermal model (Pennes' bioheat equation), predicted temperature increases from 3-second pulses at 94 GHz agreed well with previous experimental results. The model suggests current FCC guidelines could, in extreme unrealistic cases, allow transient skin temperature increases approaching thermal pain thresholds but below levels anticipated to cause thermal damage, while IEEE and ICNIRP pulse fluence limits would preclude such effects; for realistic compliant exposures, pulse fluence is too low to produce hazardous thermal transients.",
  "effect_direction": "mixed",
  "limitations": [
    "Modeling study using a simple one-dimensional thermal model",
    "Relies on comparison to limited ('scant') available data for pulsed mm-waves",
    "Findings about FCC limits depend on extreme and described as unrealistic exposure scenarios"
  ],
  "evidence_strength": "low",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "millimeter wave",
    "mm-wave",
    "pulsed RF",
    "94 GHz",
    "skin",
    "thermal model",
    "Pennes bioheat equation",
    "pulse fluence",
    "IEEE C95.1-2019",
    "ICNIRP 2020",
    "FCC guidelines",
    "device-based time averaging",
    "thermal pain",
    "burns"
  ],
  "suggested_hubs": [
    {
      "slug": "5g-policy",
      "weight": 0.62,
      "reason": "Discusses mm-wave exposures and compares IEEE/ICNIRP/FCC guideline limits relevant to mm-wave wireless technologies."
    },
    {
      "slug": "who-icnirp",
      "weight": 0.7,
      "reason": "Explicitly reviews and analyzes ICNIRP 2020 guideline pulse fluence limits (and IEEE/FCC limits)."
    }
  ]
}
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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.2020.3008322
PubMed: Not supplied

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