Microwave radiation absorption in the rat: frequency-dependent SAR distribution in body and tail.

Abstract

Experiments were conducted using twin-well calorimetry to determine the averaged whole-body specific absorption rate (SAR) for rat carcasses exposed to 360, 700, 915, and 2,450 MHz CW radiation in an anechoic chamber. All exposures were done with the long axis of the rat in an E-polarization. Additional experiments were conducted using a fiber optical temperature probe to determine local SAR in the brain, esophagus, colon, rectum, and tail during microwave exposure. The whole-body averaged SAR for the radiation frequencies examined follows a nonmonotonic function with 700 MHz as the resonant frequency. This result agrees with previous analytical estimates. Local SARs within the body and tail are nonuniform with significant frequency-specific hotspots in the colon, rectum, and tail.

AI evidence extraction

Main findings

Using twin-well calorimetry, whole-body averaged SAR in rat carcasses exposed to 360, 700, 915, and 2,450 MHz CW radiation showed a nonmonotonic frequency dependence with 700 MHz identified as a resonant frequency. Local SAR measured with a fiber optical temperature probe was nonuniform, with frequency-specific hotspots reported in the colon, rectum, and tail.

Outcomes measured

• Whole-body averaged specific absorption rate (SAR)
• Local SAR in brain, esophagus, colon, rectum, tail
• Frequency-dependent SAR distribution / hotspots

Limitations

• Study used rat carcasses rather than live animals
• Sample size not reported in the abstract
• Exposure duration and SAR levels (W/kg) not reported in the abstract

{
    "study_type": "exposure_assessment",
    "exposure": {
        "band": "RF",
        "source": null,
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": null
    },
    "population": "Rat carcasses",
    "sample_size": null,
    "outcomes": [
        "Whole-body averaged specific absorption rate (SAR)",
        "Local SAR in brain, esophagus, colon, rectum, tail",
        "Frequency-dependent SAR distribution / hotspots"
    ],
    "main_findings": "Using twin-well calorimetry, whole-body averaged SAR in rat carcasses exposed to 360, 700, 915, and 2,450 MHz CW radiation showed a nonmonotonic frequency dependence with 700 MHz identified as a resonant frequency. Local SAR measured with a fiber optical temperature probe was nonuniform, with frequency-specific hotspots reported in the colon, rectum, and tail.",
    "effect_direction": "unclear",
    "limitations": [
        "Study used rat carcasses rather than live animals",
        "Sample size not reported in the abstract",
        "Exposure duration and SAR levels (W/kg) not reported in the abstract"
    ],
    "evidence_strength": "insufficient",
    "confidence": 0.7399999999999999911182158029987476766109466552734375,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "microwave",
        "RF",
        "specific absorption rate",
        "SAR distribution",
        "rat",
        "calorimetry",
        "anechoic chamber",
        "continuous wave",
        "hotspots",
        "resonant frequency"
    ],
    "suggested_hubs": []
}

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