Threshold of radiofrequency electromagnetic field effect on human brain (review)

International journal of radiation biology · 2021 · Mixed · Low evidence

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MixedLow evidencePaper 1050

Study snapshot

PublicationInternational journal of radiation biology · 2021

Study typereview

Reported directionMixed

Evidence ratingLow

Abstract

Threshold of radiofrequency electromagnetic field effect on human brain (review) Hiie Hinrikus, Jaanus Lass, Maie Bachmann. Threshold of radiofrequency electromagnetic field effect on human brain. Int J Radiat Biol. 2021 Aug 17;1-38. doi: 10.1080/09553002.2021.1969055. Abstract Purpose: This review aims to estimate the threshold of radiofrequency electromagnetic field (RF EMF) effects on human brain based on analyses of published research results. To clarify the threshold of the RF EMF effects, two approaches have been applied: 1) the analyses of restrictions in sensitivity for different steps of the physical model of low-level RF EMF mechanism and 2) the analyses of experimental data to clarify the dependence of the RF EMF effect on exposure level based on the results of published original neurophysiological and behavioral human studies for 15 years 2007-2021. Conclusions: The analyses of the physical model of non-thermal mechanisms of RF EMF effect leads to conclusion that no principal threshold of the effect can be determined. According to the review of experimental data, the rate of detected RF EMF effects is 76.7% in resting EEG studies, 41.7% in sleep EEG and 38.5% in behavioral studies. The changes in EEG probably appear earlier than alterations in behavior become evident. The lowest level of RF EMF at which the effect in EEG was detected is 2.45 V/m (SAR =0.003 W/kg). There is a preliminary indication that the dependence of the effect on the level of exposure follows rather field strength than SAR alterations. However, no sufficient data are available for clarifying linearity-nonlinearity of the dependence of effect on the level of RF EMF. The finding that only part of people are sensitive to RF EMF exposure can be related to immunity to radiation or hypersensitivity. The changes in EEG caused by RF EMF appeared similar in the majority of analyzed studies and similar to these in depression. The possible causal relationship between RF EMF effect and depression among young people is highly important problem. pubmed.ncbi.nlm.nih.gov Excerpt Does the RF EMF has a threshold, lower of which the RF EMF does not have biological effect? This is an important question and crucial to avoid possible consequences on health. Theoretical estimations for the sensitivity of living cells to electric field provided the threshold values about 10−6 - 10 −7 V/m Hz1/2 (Weaver and Astumian, 1990; Hinrikus et al., 1998). In the case of wide-band telecommunication technology, the threshold rises: at 1 MHz bandwidth, the sensitivity is 10−3 - 10 −4 V/m. However, these estimations used a simple single cell model. Realistic model involving combinations of different cells, molecules and partly nonlinear physiological processes is highly complex. To the best of our knowledge, the calculations using complex model have been not performed. Conclusions The analyses of the model of the non-thermal mechanism of RF EMF effect shows that the steps of the model contain no principal threshold for the effect. Therefore, the only way to estimate the possible threshold is analyses of experimental data. The review of experimental data of human RF EMF neurophysiological effects results in following main conclusions that indicated the directions of future research: 1) The lowest field strength that has caused the effect in EEG, according to the reviewed studies, is 2.45 V/m (SAR=0.003 W/kg), close to the radio and TV broadcasting RF EMF field strength about 0.1 V/m. The future large- scale human, animal and in vitro studies are required to clarify the level and to increase the reliability of the experimentally determined threshold of RF EMF effect. 2) There is a preliminary indication that the intensity of the effect follows rather the field strength than SAR alteration. However, no sufficient data are available for clarifying regularity and linearity-nonlinearity of the relationship. The studies with systematic variations in exposure level (electric and magnetic field strengths, power density) would help to advance the field. The research from cellular to humans is needed in this direction. 3) Very limited data are available about the repair and adaptive phenomena important in the interpretation of the RF EMF effects on health. Special studies are required to clarify the mechanisms and possibilities of the repair processes. 4) The finding that only part of people are sensitive to RF EMF exposure can be related to immunity to radiation or hypersensitivity. The variability of sensitivity between people and longterm stability of the status required large-scale long-term experimental studies. 5) The indication that the changes in EEG caused by RF EMF appeared similar to these in depression need a special attention. The fast increase of depression with the highest prevalence among young individuals and more intense use of mobile telecommunication technology with prevalence in young people during the same period needs attention. The possible causal relationship between RF EMF effect and depression among young people is the problem of high importance. The methodology and large-scale investigations in this direction are required.

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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 typereview

Effect directionmixed

PopulationHumans (neurophysiological and behavioral studies)

Sample sizeNot supplied

ExposureRF · 0.003 W/kg · 2007-2021 (reviewed studies timeframe)

Evidence strengthLowConfidence: 74% · Peer reviewed: yes

Main findings

The review concludes that, based on analysis of a non-thermal physical model, no principal threshold for RF EMF effects can be determined. In reviewed experimental human studies (2007–2021), detected effects were reported in 76.7% of resting EEG studies, 41.7% of sleep EEG studies, and 38.5% of behavioral studies; the lowest exposure level at which an EEG effect was detected was 2.45 V/m (reported SAR = 0.003 W/kg). The authors note insufficient data to determine linearity/nonlinearity of exposure–effect relationships and suggest effects may track field strength more than SAR.

Outcomes measured

Resting EEG changes
Sleep EEG changes
Behavioral outcomes
Threshold/level of RF EMF effect on brain
Sensitivity/hypersensitivity to RF EMF
Depression-related EEG similarity (hypothesized relevance)

Limitations

Review; methods for study selection/quality assessment not described in provided abstract
No sample sizes for included studies reported in provided abstract
Frequency and specific RF sources not specified in provided abstract
Insufficient data to clarify linearity/nonlinearity of exposure–effect relationship
Statements about depression are framed as possible/indicative and require further investigation

View raw extracted JSON

{
  "study_type": "review",
  "exposure": {
    "band": "RF",
    "source": null,
    "frequency_mhz": null,
    "sar_wkg": 0.003,
    "duration": "2007-2021 (reviewed studies timeframe)"
  },
  "population": "Humans (neurophysiological and behavioral studies)",
  "sample_size": null,
  "outcomes": [
    "Resting EEG changes",
    "Sleep EEG changes",
    "Behavioral outcomes",
    "Threshold/level of RF EMF effect on brain",
    "Sensitivity/hypersensitivity to RF EMF",
    "Depression-related EEG similarity (hypothesized relevance)"
  ],
  "main_findings": "The review concludes that, based on analysis of a non-thermal physical model, no principal threshold for RF EMF effects can be determined. In reviewed experimental human studies (2007–2021), detected effects were reported in 76.7% of resting EEG studies, 41.7% of sleep EEG studies, and 38.5% of behavioral studies; the lowest exposure level at which an EEG effect was detected was 2.45 V/m (reported SAR = 0.003 W/kg). The authors note insufficient data to determine linearity/nonlinearity of exposure–effect relationships and suggest effects may track field strength more than SAR.",
  "effect_direction": "mixed",
  "limitations": [
    "Review; methods for study selection/quality assessment not described in provided abstract",
    "No sample sizes for included studies reported in provided abstract",
    "Frequency and specific RF sources not specified in provided abstract",
    "Insufficient data to clarify linearity/nonlinearity of exposure–effect relationship",
    "Statements about depression are framed as possible/indicative and require further investigation"
  ],
  "evidence_strength": "low",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "radiofrequency",
    "RF EMF",
    "human brain",
    "EEG",
    "sleep EEG",
    "behavior",
    "threshold",
    "non-thermal mechanisms",
    "field strength",
    "SAR",
    "hypersensitivity",
    "depression"
  ],
  "suggested_hubs": [
    {
      "slug": "who-icnirp",
      "weight": 0.32,
      "reason": "Review discusses thresholds and exposure metrics (field strength vs SAR), relevant to guideline/assessment context but no specific organizations mentioned."
    }
  ]
}

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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: 10.1080/09553002.2021.1969055
PubMed: 34402382

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