Should SAR Guidelines Include Variability?

2021 · Unclear · Low evidence

← Research stream

UnclearLow evidencePaper 898

Study snapshot

Publicationmanual · 2021

Study typeengineering

Reported directionUnclear

Evidence ratingLow

Abstract

Should SAR Guidelines Include Variability? K. Masumnia-Bisheh, C. Furse. Should SAR Guidelines Include Variability? 2021 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting (APS/URSI), 2021, pp. 1945-1946, doi: 10.1109/APS/URSI47566.2021.9703740. Abstract Variations in 1-g and 10-g specific absorption rate (SAR) values due to variation in tissue dielectric properties are determined. To accomplish this goal, stochastic finite difference time domain (S-FDTD) and Monte Carlo methods are compared. A 3D head model with variable dielectric properties is exposed to a half wave dipole antenna at 835 and 1900 MHz. The results show that these variations can significantly affect the peak 1-g and 10-g SAR values and should be considered in SAR guidelines for cell phone assessment. Conclusions Variations in 1-g and 10-g SAR values caused by dielectric properties variation of the tissues are calculated in this paper. The results are obtained using S-FDTD and Monte Carlo methods for a head model adjacent to a half wave dipole antenna at 835 MHz and 1900 MHz frequencies. S-FDTD results were sufficiently close to the Monte Carlo results at 835 MHz, that we conclude that the more efficient S-FDTD approach can provide the assessment for this study. Table I Mean and standard deviation of 1-gram and 10-gram sar At both frequencies, the standard deviation of the peak 1-g SAR is within 50% of the mean SAR, and the standard deviation of the peak 10-g SAR is approximately 40% of the mean. A typical interpretation of the standard deviation for a normally distributed random variable, is that we can have a 95% confidence that the values will fall within two standard deviations of the mean. The significance of these results is that the effect of tissue property variation is too large to be ignored in SAR guidelines. The normal, expected variance in SAR should be considered in SAR guidelines. We recommend the next step in this research is to model realistic cell phones, at current (5G) frequencies, to determine the mean and standard deviation of the 1-g and 10-g SAR levels. If these follow the same trends we are seeing from a dipole antenna, it is then imperative that the SAR guidelines be revisited, and that an assessment of the effect of variation in tissue electrical properties be included in them. 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 directionunclear

PopulationNot supplied

Sample sizeNot supplied

ExposureRF

Evidence strengthLowConfidence: 74% · Peer reviewed: yes

Main findings

Using a 3D head model with variable dielectric properties exposed to a half-wave dipole antenna at 835 and 1900 MHz, the study found that variability in tissue properties can significantly affect peak 1-g and 10-g SAR values. Reported standard deviations were within ~50% of the mean for peak 1-g SAR and ~40% of the mean for peak 10-g SAR, leading the authors to argue this variability should be considered in SAR guidelines.

Outcomes measured

Variability in peak 1-g SAR due to tissue dielectric property variation
Variability in peak 10-g SAR due to tissue dielectric property variation
Comparison of stochastic FDTD vs Monte Carlo for SAR variability estimation

Limitations

Modeling study using a half-wave dipole antenna rather than a realistic cell phone (authors recommend modeling realistic phones as a next step).
Only two frequencies (835 and 1900 MHz) were evaluated; extension to current (5G) frequencies is suggested as future work.
No health outcomes assessed; focus is on SAR variability and guideline implications.

View raw extracted JSON

{
  "study_type": "engineering",
  "exposure": {
    "band": "RF",
    "source": "mobile phone",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": null
  },
  "population": null,
  "sample_size": null,
  "outcomes": [
    "Variability in peak 1-g SAR due to tissue dielectric property variation",
    "Variability in peak 10-g SAR due to tissue dielectric property variation",
    "Comparison of stochastic FDTD vs Monte Carlo for SAR variability estimation"
  ],
  "main_findings": "Using a 3D head model with variable dielectric properties exposed to a half-wave dipole antenna at 835 and 1900 MHz, the study found that variability in tissue properties can significantly affect peak 1-g and 10-g SAR values. Reported standard deviations were within ~50% of the mean for peak 1-g SAR and ~40% of the mean for peak 10-g SAR, leading the authors to argue this variability should be considered in SAR guidelines.",
  "effect_direction": "unclear",
  "limitations": [
    "Modeling study using a half-wave dipole antenna rather than a realistic cell phone (authors recommend modeling realistic phones as a next step).",
    "Only two frequencies (835 and 1900 MHz) were evaluated; extension to current (5G) frequencies is suggested as future work.",
    "No health outcomes assessed; focus is on SAR variability and guideline implications."
  ],
  "evidence_strength": "low",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "specific absorption rate",
    "SAR",
    "1-g SAR",
    "10-g SAR",
    "dielectric properties",
    "tissue variability",
    "stochastic FDTD",
    "Monte Carlo",
    "head model",
    "835 MHz",
    "1900 MHz",
    "SAR guidelines"
  ],
  "suggested_hubs": [
    {
      "slug": "who-icnirp",
      "weight": 0.62,
      "reason": "Discusses implications for SAR guidelines and recommends revisiting guideline treatment of variability."
    }
  ]
}

AI can be wrong. Always verify against the paper.

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/aps/ursi47566.2021.9703740
PubMed: Not supplied

Read the original paper →

Related papers

← Back to the Research Library