RF Safe

Mapping of static magnetic fields near the surface of mobile phones

2021 · Unclear · Moderate evidence

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UnclearModerate evidencePaper 1031

Using a tri-axis magnetometer, the authors mapped static magnetic fields at several distances from the screens of 5 mobile phones, fit a mathematical model, extrapolated to the screen, and estimated SMF on the skin of a 3D head model in the µT to mT range. An…

Study snapshot

Publicationmanual · 2021
Study typeexposure_assessment
Reported directionUnclear
Evidence ratingModerate

Abstract

Mapping of static magnetic fields near the surface of mobile phones L. Zastko, L. Makinistian, A. Tvarožná, F. L. Ferreyra & I. Belyaev. Mapping of static magnetic fields near the surface of mobile phones. Scientific Reports. 11:19002. 2021. doi: 10.1038/s41598-021-98083-9. Abstract Whether the use of mobile phones (MP) represents a health hazard is still under debate. As part of the attempts to resolve this uncertainty, there has been an extensive characterization of the electromagnetic fields MP emit and receive. While the radiofrequencies (RF) have been studied exhaustively, the static magnetic fields (SMF) have received much less attention, regardless of the fact there is a wealth of evidence demonstrating their biological effects. We performed 2D maps of the SMF at several distances from the screen of 5 MP (models between 2013 and 2018) using a tri-axis magnetometer. We built a mathematical model to fit our measurements, extrapolated them down to the phones’ screen, and calculated the SMF on the skin of a 3D head model, showing that exposure is in the µT to mT range. Our literature survey prompts the need of further research not only on the biological effects of SMF and their gradients, but also on their combination with extremely low frequency (ELF) and RF fields. The study of combined fields (SMF, ELF, and RF) as similar as possible to the ones that occur in reality should provide a more sensible assessment of potential risks. Excerpts The maximum SMF estimated in this work (6.6 mT) and others’ (20 mT) 14 are far below the 400 mT exposure limit for the general public recommended by the International Commission on Non-Ionizing Radiation Protection (ICNIRP)26. This might lead to the temptation of completely disregarding SMF as a variable of interest when assessing MP fields. In fact, a recent fact sheet from the Swiss Federal Office of Public Health 13 completely omitted any reference to SMF. Nevertheless, the sole capacity of these fields of inducing potentially harmful biological effects such as promotion of the production of reactive oxygen species (ROS) 21 should be enough to consider them seriously. As for the possible underlying mechanisms of interaction, the one based on magnetite nanoparticles 27 is of particular interest because these nanoparticles have been found in the human brain 28,29. Besides the brain, the ear is of an obvious interest for its proximity to the upper HS of MP. Interestingly, magnetic material was reported on the lagenal otoliths of fish and birds 30 (although this structure is not conserved in mammals). To the best of our knowledge, there have not been studies reporting the search of magnetic materials as constituents of the human inner ear. In this regard, it is to be mentioned that some epidemiological studies found an association between MP use and tinnitus (the perception of a sound in the absence of an external source), while a meta-analysis found no association 31... Our measurements and calculations, along with the preceding discussion of the literature, prompt the need of further studies of the biological effects of the SMF and RF EMF generated by MP. We suggest special emphasis should be put into (1) inhomogeneous SMF (with a detailed characterization of both, intensities and gradients), and (2) combination of SMF (homogeneous and inhomogeneous) with RF EMF, with a fine sweeping of the parameters within the range of typical exposures (in opposition to testing single combinations). In even more complicated experiments, ELF EMF should also be considered 12 since their relationship with SMF have been long known 53. Lastly it is worth mentioning that substantial reduction of the SMF from MP could be accomplished by replacing the standard electrodynamic loudspeakers and microphones (which include a permanent magnet) by their capacitive counterparts (which do not). Open access paper: nature.com

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 size5
Exposurestatic
Evidence strengthModerateConfidence: 74% · Peer reviewed: yes

Main findings

Using a tri-axis magnetometer, the authors mapped static magnetic fields at several distances from the screens of 5 mobile phones, fit a mathematical model, extrapolated to the screen, and estimated SMF on the skin of a 3D head model in the µT to mT range. An excerpt notes a maximum SMF estimated in this work of 6.6 mT, described as far below the ICNIRP general public exposure limit of 400 mT.

Outcomes measured

  • Static magnetic field (SMF) intensity near mobile phone surface
  • Estimated SMF exposure on skin using a 3D head model

Limitations

  • Only 5 mobile phone models (2013–2018) were measured
  • Focuses on exposure characterization/modeling rather than direct health outcomes
  • Extrapolation/model-based estimation to the phone screen and to a 3D head model (not direct in vivo measurement)
View raw extracted JSON
{
  "study_type": "exposure_assessment",
  "exposure": {
    "band": "static",
    "source": "mobile phone",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": null
  },
  "population": null,
  "sample_size": 5,
  "outcomes": [
    "Static magnetic field (SMF) intensity near mobile phone surface",
    "Estimated SMF exposure on skin using a 3D head model"
  ],
  "main_findings": "Using a tri-axis magnetometer, the authors mapped static magnetic fields at several distances from the screens of 5 mobile phones, fit a mathematical model, extrapolated to the screen, and estimated SMF on the skin of a 3D head model in the µT to mT range. An excerpt notes a maximum SMF estimated in this work of 6.6 mT, described as far below the ICNIRP general public exposure limit of 400 mT.",
  "effect_direction": "unclear",
  "limitations": [
    "Only 5 mobile phone models (2013–2018) were measured",
    "Focuses on exposure characterization/modeling rather than direct health outcomes",
    "Extrapolation/model-based estimation to the phone screen and to a 3D head model (not direct in vivo measurement)"
  ],
  "evidence_strength": "moderate",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "static magnetic fields",
    "SMF",
    "mobile phones",
    "exposure mapping",
    "tri-axis magnetometer",
    "3D head model",
    "ICNIRP"
  ],
  "suggested_hubs": [
    {
      "slug": "who-icnirp",
      "weight": 0.6,
      "reason": "Mentions ICNIRP general public exposure limit for static magnetic fields and discusses relevance for assessing mobile phone fields."
    }
  ]
}
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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: 10.1038/s41598-021-98083-9
PubMed: Not supplied

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