Functional and network analyses of human exposure to long-term evolution signal (4G study)

Environmental science and pollution research international · 2020 · Mixed · Low evidence

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MixedLow evidencePaper 2027

Study snapshot

PublicationEnvironmental science and pollution research international · 2020

Study typeother

Reported directionMixed

Evidence ratingLow

Abstract

Functional and network analyses of human exposure to long-term evolution signal (4G study) Lei Yang, Chen Zhang, Zhiye Chen, Congsheng Li, Tongning Wu. Functional and network analyses of human exposure to long-term evolution signal. Environ Sci Pollut Res Int. 2020 Sep 25. doi: 10.1007/s11356-020-10728- w. Abstract Human exposure to the electromagnetic field emitted by wireless communication systems has raised public concerns. There were claims of the potential association of some neurophysiological disorders with the exposure, but the mechanism is yet to be established. The wireless networks, recently, experience a transition from the 4th generation (4G) to 5th generation (5G), while 4G long-term evolution (LTE) is still the frequently used signal in wireless communication. In the study, exposure experiments were conducted using the LTE signal. The subjects were divided into sham and real exposure groups. Before and after the exposure experiments, they underwent functional magnetic resonance imaging. Within-session and between-session comparisons have been executed for functional connectivity and network properties. Individual specific absorption rate (SAR) was also calculated. The results indicated that acute LTE exposure beneath the safety limits modulated both the functional connection and graph-based properties. To characterize the effect of functional activity, SAR averaged over a certain tissue mass was not an appropriate metric. The potential neurophysiological effect of 5G exposure has also been discussed in the study. pubmed.ncbi.nlm.nih.gov Excerpts Since 2019, the fifth-generation (5G) wireless network has been implemented. Two different frequency ranges available for 5G wireless technology include- frequency range 1 (FR1) and frequency range 2 (FR2). At present, the popular commercial frequency at FR1 was around 2.4 and 3.5 GHz, close to the current 3G and 4G frequencies. The emission power of 5G mobile phones is comparable to that of 3G and 4G terminals. Most of the existed literature, as well as our studies, narrated similar activated sites (frontal and temporal lobules) for different frequencies/modulations. It is, therefore, reasonable to expect that the exposure to new generation wireless signals would result in a similar effect. Conclusion Human brain modulation following LTE exposure was firstly evaluated by functional and network metrics. The topological changes have been reported, and their consistency with the previous analysis was highlighted. Integrating the results from the regional BOLD variation, intraregional similarity, and hypothesis-driven FC analysis, a comprehensive view for the brain activity by the exposure of LTE signal and the signal of next- generation can be obtained. Another novelty was that no correlation was found between the peak SAR values and the altered topological parameters. It demonstrated peak SAR averaged over a certain mass, which was used for assessing the thermal effect of human exposure, was incongruous to quantify the neurophysiological effect of EMF exposure. It may clarify the inconsistency in current human exposure studies

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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 typeother

Effect directionmixed

PopulationHuman subjects

Sample sizeNot supplied

ExposureRF · acute

Evidence strengthLowConfidence: 66% · Peer reviewed: yes

Main findings

In sham vs real exposure comparisons using an LTE signal, acute exposure beneath safety limits was reported to modulate functional connectivity and graph-based network properties measured by fMRI. No correlation was found between peak SAR averaged over a certain tissue mass and altered topological parameters, and the authors state that SAR averaged over a certain tissue mass was not an appropriate metric for characterizing functional activity effects.

Outcomes measured

Functional connectivity (fMRI)
Graph-based brain network properties
BOLD-related functional activity metrics
Correlation between SAR metrics and network/topological changes

Limitations

Sample size not reported in provided abstract/metadata
LTE frequency and exposure duration not specified in provided abstract/metadata
Specific SAR values and exposure setup details not provided in provided abstract/metadata
Outcomes are neuroimaging/network metrics; clinical relevance not established in provided abstract/metadata

View raw extracted JSON

{
  "study_type": "other",
  "exposure": {
    "band": "RF",
    "source": "mobile phone",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": "acute"
  },
  "population": "Human subjects",
  "sample_size": null,
  "outcomes": [
    "Functional connectivity (fMRI)",
    "Graph-based brain network properties",
    "BOLD-related functional activity metrics",
    "Correlation between SAR metrics and network/topological changes"
  ],
  "main_findings": "In sham vs real exposure comparisons using an LTE signal, acute exposure beneath safety limits was reported to modulate functional connectivity and graph-based network properties measured by fMRI. No correlation was found between peak SAR averaged over a certain tissue mass and altered topological parameters, and the authors state that SAR averaged over a certain tissue mass was not an appropriate metric for characterizing functional activity effects.",
  "effect_direction": "mixed",
  "limitations": [
    "Sample size not reported in provided abstract/metadata",
    "LTE frequency and exposure duration not specified in provided abstract/metadata",
    "Specific SAR values and exposure setup details not provided in provided abstract/metadata",
    "Outcomes are neuroimaging/network metrics; clinical relevance not established in provided abstract/metadata"
  ],
  "evidence_strength": "low",
  "confidence": 0.66,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "LTE",
    "4G",
    "RF-EMF",
    "human exposure",
    "fMRI",
    "functional connectivity",
    "brain network",
    "graph theory",
    "SAR"
  ],
  "suggested_hubs": [
    {
      "slug": "who-icnirp",
      "weight": 0.3,
      "reason": "Mentions exposure beneath safety limits and discusses SAR as an assessment metric."
    }
  ]
}

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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: 10.1007/s11356-020-10728
PubMed: 32974829

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