Effects of microwave exposure and temperature on survival of mice infected with Streptococcus pneumoniae.

Abstract

Female CD-1 mice were injected with an LD50 dose of Streptococcus pneumoniae and then exposed to 2.45 GHz (CW) microwave radiation at an incident power density of 10 mW/cm2 (SAR = 6.8 W/kg), 4 h/d for 5 d at ambient temperatures of 19 degrees C, 22 degrees C, 25 degrees C, 28 degrees C, 31 degrees C, 34 degrees C, 37 degrees C and 40 degrees C. Four groups of 25 animals were exposed at each temperature with an equal number of animals concurrently sham-exposed. Survival was observed for a 10-d period after infection. Survival of the sham-exposed animals increased as ambient temperature increased from 19 degrees C-34 degrees C. At ambient temperatures at or above 37 degrees C the heat induced in the body exceeded the thermoregulatory capacity of the animals and deaths from hyperthermia occurred. Survival of the microwave-exposed animals was significantly greater than the shams (approximately 20%) at each ambient temperature below 34 degrees C. Based on an analysis of the data it appears that the hyperthermia induced by microwave exposure may be more effective in increasing survival in infected mice than hyperthermia produced by conventional methods (ie, high ambient temperature). Microwave radiation may be beneficial to infected animals at low and moderate ambient temperatures, but it is detrimental when combined with high ambient temperatures.

AI evidence extraction

Main findings

Across ambient temperatures below 34°C, microwave-exposed mice had significantly greater survival than concurrently sham-exposed mice (approximately 20% higher). At ambient temperatures at or above 37°C, deaths from hyperthermia occurred, and the abstract states microwave exposure may be detrimental when combined with high ambient temperatures.

Outcomes measured

• Survival over 10 days after infection
• Hyperthermia-related deaths at high ambient temperatures

Limitations

• Mechanism is inferred as hyperthermia; non-thermal effects are not established in the abstract
• Results depend on ambient temperature conditions; high-temperature conditions caused hyperthermia-related mortality
• No additional details provided on randomization/blinding or statistical methods in the abstract

{
    "study_type": "animal",
    "exposure": {
        "band": "microwave",
        "source": null,
        "frequency_mhz": 2450,
        "sar_wkg": 6.79999999999999982236431605997495353221893310546875,
        "duration": "4 h/d for 5 d"
    },
    "population": "Female CD-1 mice infected with an LD50 dose of Streptococcus pneumoniae",
    "sample_size": 400,
    "outcomes": [
        "Survival over 10 days after infection",
        "Hyperthermia-related deaths at high ambient temperatures"
    ],
    "main_findings": "Across ambient temperatures below 34°C, microwave-exposed mice had significantly greater survival than concurrently sham-exposed mice (approximately 20% higher). At ambient temperatures at or above 37°C, deaths from hyperthermia occurred, and the abstract states microwave exposure may be detrimental when combined with high ambient temperatures.",
    "effect_direction": "mixed",
    "limitations": [
        "Mechanism is inferred as hyperthermia; non-thermal effects are not established in the abstract",
        "Results depend on ambient temperature conditions; high-temperature conditions caused hyperthermia-related mortality",
        "No additional details provided on randomization/blinding or statistical methods in the abstract"
    ],
    "evidence_strength": "low",
    "confidence": 0.7800000000000000266453525910037569701671600341796875,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "2.45 GHz",
        "microwave radiation",
        "SAR 6.8 W/kg",
        "power density 10 mW/cm2",
        "hyperthermia",
        "ambient temperature",
        "mouse",
        "Streptococcus pneumoniae",
        "survival"
    ],
    "suggested_hubs": []
}

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