Mobile phone types and SAR characteristics of the human brain

2017 · Unclear · Insufficient evidence

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UnclearInsufficient evidencePaper 1310

Study snapshot

Publicationmanual · 2017

Study typeexposure_assessment

Reported directionUnclear

Evidence ratingInsufficient

Abstract

Mobile phone types and SAR characteristics of the human brain Lee AK, Hong SE, Kwon JH, Choi HD, Cardis E. Mobile phone types and SAR characteristics of the human brain.Phys Med Biol. 2017 Mar 7;62(7):2741-2761. doi: 10.1088/1361-6560/aa5c2d. Abstract Mobile phones differ in terms of their operating frequency, outer shape, and form and location of the antennae, all of which affect the spatial distributions of their electromagnetic field and the level of electromagnetic absorption in the human head or brain. For this paper, the specific absorption rate (SAR) was calculated for four anatomical head models at different ages using 11 numerical phone models of different shapes and antenna configurations. The 11 models represent phone types accounting for around 86% of the approximately 1400 commercial phone models released into the Korean market since 2002. Seven of the phone models selected have an internal dual-band antenna, and the remaining four possess an external antenna. Each model was intended to generate an average absorption level equivalent to that of the same type of commercial phone model operating at the maximum available output power. The 1 g peak spatial SAR and ipsilateral and contralateral brain-averaged SARs were reported for all 11 phone models. The effects of the phone type, phone position, operating frequency, and age of head models on the brain SAR were comprehensively determined. ncbi.nlm.nih.gov Excerpts Both the psSAR in the brain and the brain hemisphere-averaged SAR were analyzed for the four anatomical head models and 11 representative phone models. The head models used are Eartha and Billie (8 and 11 year-old females), and Louis and Duke (14 and 34 year-old males) from IT'IS. The 11 phone models include bar, slider, and flip types operating at 835 and 1850 MHz (1765 MHz for some of the flip-type models) .... • Phone positions and SAR. The gap in the psSAR between the cheek and tilt positions is small in the brain compared to that in the SAM phantom. Flip-type phone models with an external antenna (M8h, M8w, M9h, and M9w) generated higher SAR levels at the left position than at the right position for both frequencies. • Frequency and SAR. Both the psSAR and the brain hemisphere-averaged SAR are higher at low frequency (835 MHz) than at high frequency (1850 or 1765 MHz). This seems to be because the electromagnetic energy penetrates deeper and is deposited in a larger 'hot spot' area at lower frequency. • Phone types and SAR The closer the antenna is located to the receiver of the phone, the higher the SAR that seems to appear in the brain. The variability in the psSAR in the brain is much higher between the different phone types than between the different head models. It suggests that it is crucial for study subjects to report exact information on the phone models used for proper exposure assessments in epidemiological studies. • Laterality of brain hemisphere-averaged SAR. The contralateral brain-averaged SAR level of some models such as M7 and M8 at low frequency is comparable to their ipsilateral brain-averaged SAR at high frequency. • Age-related changes in SAR. Both the psSAR (tables 2 and 3) and the brain hemisphere-averaged SAR (figures 11 and 12) seem to be strongly influenced by the distance between the head (or auricle) surface and the surface of the temporal lobe of the brain; the temporal lobe of Eartha is the farthest away from the phone body out of all of head models, and Eartha showed the lowest 1 g psSAR and lowest ipsilateral brain-averaged SAR for most of the cases considered. Overall, the variability in the brain SAR of the four head models in this study did not form a consistent pattern with age. It is impossible to obtain the proper amount of global information regarding the outer shape, antenna location, operating frequency, and detailed SAR values because the SAR-compliance process for mobile phones varies by country. The phone models used in this paper cover the phone types of around 86% of all commercial models released onto the Korean market since 2002. The closer the antenna is located to the receiver of the phone, the higher the SAR is generally produced in the human brain. The maximum difference in psSAR in the brain between the numerical phone models amounted to around 12 dB. The results suggest that it is very important for all subjects to report exact information on the phone models they use if accurate exposure levels are to be obtained in epidemiological studies .... The issue of whether children are more sensitive to EMF emitted from mobile phones has been a hot topic among many researchers over the past two decades. In this study, a maximum psSAR variability of 5.6 dB was shown between the four head models, but was not dependent on age. To generate representative head models, the anatomical morphology of the human head at different ages and for both genders is being statistically investigated using MR images of hundreds of Koreans from early childhood to adult. The resultant statistical figures will become the foundation for detecting age-related influences on the SAR.

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

PopulationNot supplied

Sample sizeNot supplied

ExposureRF

Evidence strengthInsufficientConfidence: 78% · Peer reviewed: yes

Main findings

SAR was numerically calculated for four anatomical head models (ages 8, 11, 14, and 34) using 11 representative phone models (bar/slider/flip; internal dual-band vs external antenna) operating at 835 and 1850 MHz (1765 MHz for some flip models). Both 1 g peak spatial SAR and brain hemisphere-averaged SAR were higher at 835 MHz than at 1850/1765 MHz, and phone type/antenna location strongly influenced brain SAR; flip-type models with external antennas generated higher SAR at the left position than at the right position for both frequencies. Variability in brain SAR across the four head models did not show a consistent pattern with age.

Outcomes measured

1 g peak spatial SAR (psSAR) in the brain
Ipsilateral brain-averaged SAR
Contralateral brain-averaged SAR
Effects of phone type/shape and antenna configuration on brain SAR
Effects of phone position (cheek/tilt; left/right) on brain SAR
Effects of operating frequency on brain SAR
Effects of head model/age on brain SAR

Limitations

Numerical modeling study using 11 phone models intended to represent ~86% of ~1400 commercial phone models released in the Korean market since 2002; generalizability beyond these models/market not established in the abstract.
Only four anatomical head models were used; age-related conclusions are limited and described as not forming a consistent pattern.
Paper notes difficulty obtaining global information on phone shape/antenna/frequency/SAR due to country-specific SAR-compliance processes.

View raw extracted JSON

{
  "study_type": "exposure_assessment",
  "exposure": {
    "band": "RF",
    "source": "mobile phone",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": null
  },
  "population": null,
  "sample_size": null,
  "outcomes": [
    "1 g peak spatial SAR (psSAR) in the brain",
    "Ipsilateral brain-averaged SAR",
    "Contralateral brain-averaged SAR",
    "Effects of phone type/shape and antenna configuration on brain SAR",
    "Effects of phone position (cheek/tilt; left/right) on brain SAR",
    "Effects of operating frequency on brain SAR",
    "Effects of head model/age on brain SAR"
  ],
  "main_findings": "SAR was numerically calculated for four anatomical head models (ages 8, 11, 14, and 34) using 11 representative phone models (bar/slider/flip; internal dual-band vs external antenna) operating at 835 and 1850 MHz (1765 MHz for some flip models). Both 1 g peak spatial SAR and brain hemisphere-averaged SAR were higher at 835 MHz than at 1850/1765 MHz, and phone type/antenna location strongly influenced brain SAR; flip-type models with external antennas generated higher SAR at the left position than at the right position for both frequencies. Variability in brain SAR across the four head models did not show a consistent pattern with age.",
  "effect_direction": "unclear",
  "limitations": [
    "Numerical modeling study using 11 phone models intended to represent ~86% of ~1400 commercial phone models released in the Korean market since 2002; generalizability beyond these models/market not established in the abstract.",
    "Only four anatomical head models were used; age-related conclusions are limited and described as not forming a consistent pattern.",
    "Paper notes difficulty obtaining global information on phone shape/antenna/frequency/SAR due to country-specific SAR-compliance processes."
  ],
  "evidence_strength": "insufficient",
  "confidence": 0.78,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "specific absorption rate",
    "SAR",
    "mobile phone",
    "brain",
    "head models",
    "antenna configuration",
    "phone position",
    "frequency",
    "835 MHz",
    "1850 MHz",
    "1765 MHz",
    "laterality",
    "children"
  ],
  "suggested_hubs": [
    {
      "slug": "mobile-phones-sar",
      "weight": 0.9,
      "reason": "Study computes brain SAR metrics across multiple mobile phone types, antenna configurations, positions, and frequencies."
    }
  ]
}

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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: 10.1088/1361-6560/aa5c2d
PubMed: Not supplied

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