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

PAPER pubmed Radiation and environmental biophysics 1978 Animal study Effect: no_effect Evidence: Moderate

Read original paper → DOI: 10.1007/bf01323461 PMID: 756056 Evidence Lab

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.

AI evidence extraction

At a glance

Study type

Animal study

Effect direction

no_effect

Population

rats

Sample size

—

Exposure

microwave · 1200 MHz · 30 min

Evidence strength

Moderate

Confidence: 70% · Peer-reviewed: yes

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.

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": 0.6999999999999999555910790149937383830547332763671875,
    "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/metadata and may be incomplete or incorrect. This content is for informational purposes only and is not medical advice.

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