Studies on blood-brain barrier permeability after microwave-radiation.

Radiation and environmental biophysics · 1978 · No effect · Moderate evidence

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No effectModerate evidencePaper 6084

No increase in blood-brain barrier permeability was observed in rats after exposure to 1.2-1.3 GHz microwave radiation at various power densities unless the rats were made hyperthermic by a warm-air environment. Microwave radiation alone did not alter permeab…

Study snapshot

PublicationRadiation and environmental biophysics · 1978

Study typeanimal

Reported directionNo effect

Evidence ratingModerate

Abstract

Since the reported alterations of permeability of the blood-brain barrier by microwave radiation have implications for safety considerations in man, studies were conducted to replicate some of the initial investigations. No transfer of parenterally-administered fluorescein across the blood-brain barrier of rats after 30 min of 1.2-GHz radiation at power densities from 2--75 mW/cm2 was noted. Increased fluorescein uptake was seen only when the rats were made hyperthermic in a warm-air environment. Similarly, no increase of brain uptake of 14C-mannitol using the Oldendorf dual isotope technique was seen as a result of exposure to pulsed 1.3-GHz radiation at peak power densities up to 20 mW/cm2, or in the continuous wave mode from 0.1--50 mW/cm2. An attempt to alter the permeability of the blood-brain barrier for serotonin with microwave radiation was unsuccessful. From these studies it would appear that the brain must be made hyperthermic for changes in permeability of the barrier induced by microwave radiation to occur.

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 typeanimal

Effect directionno_effect

Populationrats

Sample sizeNot supplied

Exposuremicrowave · 1200 MHz · 30 min

Evidence strengthModerateConfidence: 70% · Peer reviewed: yes

Main findings

Outcomes measured

blood-brain barrier permeability
fluorescein transfer
14C-mannitol brain uptake
serotonin permeability

Limitations

sample size not specified
only rat models studied
hyperthermia confounding factor

View raw extracted JSON

{
  "study_type": "animal",
  "exposure": {
    "band": "microwave",
    "source": null,
    "frequency_mhz": 1200,
    "sar_wkg": null,
    "duration": "30 min"
  },
  "population": "rats",
  "sample_size": null,
  "outcomes": [
    "blood-brain barrier permeability",
    "fluorescein transfer",
    "14C-mannitol brain uptake",
    "serotonin permeability"
  ],
  "main_findings": "No increase in blood-brain barrier permeability was observed in rats after exposure to 1.2-1.3 GHz microwave radiation at various power densities unless the rats were made hyperthermic by a warm-air environment. Microwave radiation alone did not alter permeability for fluorescein, 14C-mannitol, or serotonin.",
  "effect_direction": "no_effect",
  "limitations": [
    "sample size not specified",
    "only rat models studied",
    "hyperthermia confounding factor"
  ],
  "evidence_strength": "moderate",
  "confidence": 0.7,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "blood-brain barrier",
    "microwave radiation",
    "permeability",
    "hyperthermia",
    "rats"
  ],
  "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: 10.1007/bf01323461
PubMed: 756056

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