Immediate post-exposure effects of high-peak-power microwave pulses on operant behavior of Wistar rats.

Bioelectromagnetics · 1991 · Mixed · Low evidence

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MixedLow evidencePaper 6274

Study snapshot

PublicationBioelectromagnetics · 1991

Study typeanimal

Reported directionMixed

Evidence ratingLow

Abstract

Behavioral effects of high-peak-power microwave pulses on Wistar rats were studied by operant schedules. Each of twelve rats that had been trained to press a lever to receive food pellets was assigned randomly in groups of four to three different schedules of reinforcement: fixed-ratio (FR), variable-interval (VI), and differential-reinforcement-of-low-rates (DRL). After achieving a steady baseline performance, each animal was exposed for 10 min to 1.25-GHz microwave radiation at 1-MW peak-power (10-microseconds pulse width). Each pulse produced a peak whole-body SA and SAR of 2.1 J/kg and 0.21 MW/kg. Total doses (SAs) were set to 0.50, 1.5, 4.5, and 14 kJ/kg by adjusting the pulse-repetition rate. The corresponding time-averaged whole-body SARs were 0.84, 2.5, 7.6, and 23 W/kg. A microwave-transparent animal holder was used to keep the animal's body axis parallel to the E-field. Exposures at the highest dose caused an average colonic temperature rise of 2.5 degrees C and these animals failed to respond at all for about 13 minutes after the exposure. Their colonic temperatures had decreased to 1.1 degrees C, or less, above their pre-exposure (normal) temperature level when they began to respond. The FR and VI animals failed to reach their baseline levels of performance thereafter, while those on the DRL schedule displayed variable effects. No behavioral effects were found at the lower dose levels. It is concluded that the behavioral perturbations produced by pulsed microwave irradiation were thermal in nature.

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Study typeanimal

Effect directionmixed

PopulationWistar rats

Sample size12

Exposuremicrowave · 1250 MHz · 23 W/kg · 10 min

Evidence strengthLowConfidence: 78% · Peer reviewed: yes

Main findings

Rats exposed for 10 minutes to 1.25-GHz high-peak-power microwave pulses showed no behavioral effects at lower dose levels, but at the highest dose animals had an average colonic temperature rise of 2.5°C and failed to respond for about 13 minutes post-exposure. After responding resumed, FR and VI animals did not return to baseline performance, while DRL animals showed variable effects; authors concluded effects were thermal in nature.

Outcomes measured

Operant behavior performance under fixed-ratio (FR), variable-interval (VI), and differential-reinforcement-of-low-rates (DRL) schedules
Colonic temperature change

Limitations

Small sample size (n=12)
Only immediate post-exposure effects described
Thermal effects present at highest exposure (colonic temperature rise), complicating attribution to non-thermal mechanisms

View raw extracted JSON

{
  "study_type": "animal",
  "exposure": {
    "band": "microwave",
    "source": null,
    "frequency_mhz": 1250,
    "sar_wkg": 23,
    "duration": "10 min"
  },
  "population": "Wistar rats",
  "sample_size": 12,
  "outcomes": [
    "Operant behavior performance under fixed-ratio (FR), variable-interval (VI), and differential-reinforcement-of-low-rates (DRL) schedules",
    "Colonic temperature change"
  ],
  "main_findings": "Rats exposed for 10 minutes to 1.25-GHz high-peak-power microwave pulses showed no behavioral effects at lower dose levels, but at the highest dose animals had an average colonic temperature rise of 2.5°C and failed to respond for about 13 minutes post-exposure. After responding resumed, FR and VI animals did not return to baseline performance, while DRL animals showed variable effects; authors concluded effects were thermal in nature.",
  "effect_direction": "mixed",
  "limitations": [
    "Small sample size (n=12)",
    "Only immediate post-exposure effects described",
    "Thermal effects present at highest exposure (colonic temperature rise), complicating attribution to non-thermal mechanisms"
  ],
  "evidence_strength": "low",
  "confidence": 0.78,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "microwave pulses",
    "high-peak-power",
    "1.25 GHz",
    "Wistar rats",
    "operant behavior",
    "fixed-ratio",
    "variable-interval",
    "DRL",
    "SAR",
    "specific absorption",
    "thermal effects",
    "colonic temperature"
  ],
  "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: 10.1002/bem.2250120306
PubMed: 1854355

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