The Bioeffects Resulting from Prokaryotic Cells and Yeast Being Exposed to an 18 GHz Electromagnetic Field.

PloS one · 2016 · Mixed · Low evidence

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MixedLow evidencePaper 4845

Study snapshot

PublicationPloS one · 2016

Study typein_vitro

Reported directionMixed

Evidence ratingLow

Abstract

The mechanisms by which various biological effects are triggered by exposure to an electromagnetic field are not fully understood and have been the subject of debate. Here, the effects of exposing typical representatives of the major microbial taxa to an 18 GHz microwave electromagnetic field (EMF)were studied. It appeared that the EMF exposure induced cell permeabilisation in all of the bacteria and yeast studied, while the cells remained viable (94% throughout the exposure), independent of the differences in cell membrane fatty acid and phospholipid composition. The resulting cell permeabilisation was confirmed by detection of the uptake of propidium iodine and 23 nm fluorescent silica nanospheres using transmission electron microscopy (TEM) and confocal laser scanning microscopy (CLSM). Upon EMF exposure, the bacterial cell membranes are believed to become permeable through quasi-endocytosis processes. The dosimetry analysis revealed that the EMF threshold level required to induce the uptake of the large (46 nm) nanopsheres was between three and six EMF doses, with a specific absorption rate (SAR) of 3 kW/kg and 5 kW/kg per exposure, respectively, depending on the bacterial taxa being studied. It is suggested that the taxonomic affiliation and lipid composition (e.g. the presence of phosphatidyl-glycerol and/or pentadecanoic fatty acid) may affect the extent of uptake of the large nanospheres (46 nm). Multiple 18 GHz EMF exposures over a one-hour period induced periodic anomalous increases in the cell growth behavior of two Staphylococcus aureus strains, namely ATCC 25923 and CIP 65.8T.

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AI evidence extraction

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Study typein_vitro

Effect directionmixed

PopulationProkaryotic cells (bacteria) and yeast; includes Staphylococcus aureus strains ATCC 25923 and CIP 65.8T

Sample sizeNot supplied

Exposuremicrowave · 18000 MHz · 3000 W/kg · multiple exposures over a one-hour period

Evidence strengthLowConfidence: 74% · Peer reviewed: yes

Main findings

Exposure to an 18 GHz microwave EMF induced cell permeabilisation in all bacteria and yeast studied while cells remained viable (reported 94% throughout exposure). Permeabilisation was supported by uptake of propidium iodine and 23 nm fluorescent silica nanospheres (TEM/CLSM). Dosimetry suggested a threshold for uptake of 46 nm nanospheres between three and six EMF doses, with SARs of 3 kW/kg and 5 kW/kg per exposure depending on taxa; repeated exposures over one hour induced periodic anomalous increases in growth in two S. aureus strains.

Outcomes measured

Cell permeabilisation
Cell viability
Uptake of propidium iodine
Uptake of fluorescent silica nanospheres (23 nm and 46 nm)
Cell growth behavior changes (periodic anomalous increases)

Limitations

Mechanisms are described as not fully understood; quasi-endocytosis is presented as a belief/suggestion rather than demonstrated mechanism
Sample size and detailed exposure protocol (e.g., exact number/length of exposures) not provided in abstract
Findings are from microbial/yeast in vitro models; generalizability to other organisms not addressed in abstract

View raw extracted JSON

{
  "study_type": "in_vitro",
  "exposure": {
    "band": "microwave",
    "source": null,
    "frequency_mhz": 18000,
    "sar_wkg": 3000,
    "duration": "multiple exposures over a one-hour period"
  },
  "population": "Prokaryotic cells (bacteria) and yeast; includes Staphylococcus aureus strains ATCC 25923 and CIP 65.8T",
  "sample_size": null,
  "outcomes": [
    "Cell permeabilisation",
    "Cell viability",
    "Uptake of propidium iodine",
    "Uptake of fluorescent silica nanospheres (23 nm and 46 nm)",
    "Cell growth behavior changes (periodic anomalous increases)"
  ],
  "main_findings": "Exposure to an 18 GHz microwave EMF induced cell permeabilisation in all bacteria and yeast studied while cells remained viable (reported 94% throughout exposure). Permeabilisation was supported by uptake of propidium iodine and 23 nm fluorescent silica nanospheres (TEM/CLSM). Dosimetry suggested a threshold for uptake of 46 nm nanospheres between three and six EMF doses, with SARs of 3 kW/kg and 5 kW/kg per exposure depending on taxa; repeated exposures over one hour induced periodic anomalous increases in growth in two S. aureus strains.",
  "effect_direction": "mixed",
  "limitations": [
    "Mechanisms are described as not fully understood; quasi-endocytosis is presented as a belief/suggestion rather than demonstrated mechanism",
    "Sample size and detailed exposure protocol (e.g., exact number/length of exposures) not provided in abstract",
    "Findings are from microbial/yeast in vitro models; generalizability to other organisms not addressed in abstract"
  ],
  "evidence_strength": "low",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "18 GHz",
    "microwave",
    "electromagnetic field",
    "EMF",
    "specific absorption rate",
    "SAR",
    "bacteria",
    "yeast",
    "Staphylococcus aureus",
    "cell permeabilisation",
    "propidium iodine",
    "silica nanospheres",
    "TEM",
    "CLSM",
    "growth behavior"
  ],
  "suggested_hubs": []
}

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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: 10.1371/journal.pone.0158135
PubMed: 27391488

Read the original paper →

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