Acute thermoregulatory responses of the immature rat to warming by low-level 2,450-MHz microwave radiation.

Abstract

Rats were tested at 6-7 days of age to determine thermoregulatory responses to microwave exposure (2,450-MHz; continuous wave). Each animal was partially restrained in a cylindrical holder and irradiated at a power density of either 5 or 20 mW/cm2 [specific absorption rate = 0.60 (W/kg)/(mW/cm2)] at a cold ambient temperature (Ta). Following a 1-hour thermal equilibration period, each rat was monitored at 1-min intervals during 1-hour microwave exposure and 1-hour recovery periods. Colonic temperature (Tco), determined with a Vitek probe, and metabolic heat production (M), derived from measures of oxygen consumption, were sampled and recorded during these periods. Tco increased significantly above initial level at both power densities and reached a plateau after 45 min of microwave exposure. Tco doubled with a four-fold increase in microwave intensity. Prior to exposure, M was elevated in response to cold Ta and remained unchanged during exposure at 5 mW/cm2, but decreased 7.2 W/kg during exposure at 20 mW/cm2. The results indicate that the hypothermic rat pup can be effectively warmed by low-level microwave irradiation and is capable of altering metabolism in response to such heating.

AI evidence extraction

Main findings

Colonic temperature increased significantly above initial level at both 5 and 20 mW/cm2 exposures and plateaued after 45 minutes; the increase was larger at higher intensity. Metabolic heat production remained unchanged during exposure at 5 mW/cm2 but decreased by 7.2 W/kg during exposure at 20 mW/cm2.

Outcomes measured

• Colonic temperature (Tco)
• Metabolic heat production (oxygen consumption-derived)

Limitations

• Sample size not reported in the abstract.
• Only acute exposure studied (1 hour) with short recovery (1 hour).
• Animal model (immature rat pups) limits direct generalization to humans.
• Exposure described by power density; SAR relationship given but SAR values for the specific conditions are not explicitly stated.

{
    "study_type": "animal",
    "exposure": {
        "band": "microwave",
        "source": null,
        "frequency_mhz": 2450,
        "sar_wkg": null,
        "duration": "1-hour microwave exposure (plus 1-hour recovery; after 1-hour equilibration)"
    },
    "population": "Rats (6–7 days old)",
    "sample_size": null,
    "outcomes": [
        "Colonic temperature (Tco)",
        "Metabolic heat production (oxygen consumption-derived)"
    ],
    "main_findings": "Colonic temperature increased significantly above initial level at both 5 and 20 mW/cm2 exposures and plateaued after 45 minutes; the increase was larger at higher intensity. Metabolic heat production remained unchanged during exposure at 5 mW/cm2 but decreased by 7.2 W/kg during exposure at 20 mW/cm2.",
    "effect_direction": "mixed",
    "limitations": [
        "Sample size not reported in the abstract.",
        "Only acute exposure studied (1 hour) with short recovery (1 hour).",
        "Animal model (immature rat pups) limits direct generalization to humans.",
        "Exposure described by power density; SAR relationship given but SAR values for the specific conditions are not explicitly stated."
    ],
    "evidence_strength": "low",
    "confidence": 0.7399999999999999911182158029987476766109466552734375,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "immature rat",
        "rat pup",
        "thermoregulation",
        "microwave radiation",
        "2450 MHz",
        "continuous wave",
        "power density",
        "specific absorption rate",
        "colonic temperature",
        "oxygen consumption",
        "metabolic heat production",
        "warming"
    ],
    "suggested_hubs": []
}

Comments

Log in to comment.

No comments yet.