Characterising core body temperature response of free-moving C57BL/6 mice to 1.95 GHz whole-body

Abstract

Characterising core body temperature response of free-moving C57BL/6 mice to 1.95 GHz whole-body radiofrequency-electromagnetic fields Sylvester E, Deng C, McIntosh R, Iskra S, Frankland J, McKenzie R, Croft RJ. Characterising core body temperature response of free-moving C57BL/6 mice to 1.95 GHz whole-body radiofrequency- electromagnetic fields. Bioelectromagnetics. 2024 Oct 14. doi: 10.1002/bem.22527. Highlights • Exposure of 1.95 GHz electromagnetic fields at 5 W/kg whole-body average specific absorption rate increases core body temperature by 0.4°C. • The increased thermal energy at 3.75 W/kg is effectively managed by thermoregulation (max increase = 0.24°C). • An extended habituation period prior to RF-EMF exposure is necessary to account for the large effect of handling on mice core body temperature. Abstract The present study investigated the core body temperature (CBT) response of free-moving adult male and female C57BL/6 mice, during and following a 2-h exposure to 1.95 GHz RF-EMF within custom-built reverberation chambers, using temperature capsules implanted within the intraperitoneal cavity and data continuously logged and transmitted via radiotelemetry postexposure. Comparing RF-EMF exposures (WBA-SAR of 1.25, 2.5, 3.75, and 5 W/kg) to the sham-exposed condition, we identified a peak in CBT within the first 16 min of RF-EMF exposure (+0.15, +0.31, +0.24, +0.37°C at 1.25, 2.5, 3.75, and 5 W/kg respectively; statistically significant at WBA-SAR ≥ 2.5 W/kg only), which largely dissipated for the remainder of the exposure period. Immediately before the end of exposure, only the CBT of the 5 W/kg condition was statistically differentiable from sham. Based on our findings, it is apparent that mice are able to effectively compensate for the increased thermal load at RF-EMF strengths up to 5 W/kg. In addition, the elevated CBT at the end of the exposure period in the 5 W/kg condition was statistically significantly reduced compared to the sham condition immediately after RF-EMF exposure ceased. This would indicate that measures of CBT following the end of an RF-EMF exposure period may not reflect the actual change in the CBT of mice caused by RF-EMF exposure in mice. Open access paper: onlinelibrary.wiley.com

AI evidence extraction

Main findings

During a 2-h 1.95 GHz whole-body RF-EMF exposure, CBT peaked within the first 16 min relative to sham (+0.15, +0.31, +0.24, +0.37°C at 1.25, 2.5, 3.75, 5 W/kg, respectively), with statistical significance reported at WBA-SAR ≥ 2.5 W/kg. The elevation largely dissipated over the remainder of exposure; immediately before exposure end, only the 5 W/kg condition differed from sham, and CBT immediately after exposure cessation was reported as statistically significantly reduced compared with sham in the 5 W/kg condition.

Outcomes measured

• Core body temperature (CBT) during exposure
• CBT following exposure
• Thermoregulatory response to RF-EMF thermal load

Limitations

• Sample size not reported in provided abstract/metadata
• Exposure source/context (e.g., device type) not specified beyond reverberation chambers
• Findings limited to mice (C57BL/6) and a 2-hour exposure duration
• Handling/habituation effects on CBT noted as large and requiring extended habituation

Suggested hubs

• animal-studies (0.9)
  Experimental RF-EMF exposure study in mice measuring physiological (temperature) response.

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    "study_type": "animal",
    "exposure": {
        "band": "RF",
        "source": null,
        "frequency_mhz": 1950,
        "sar_wkg": 5,
        "duration": "2-h exposure"
    },
    "population": "Free-moving adult male and female C57BL/6 mice",
    "sample_size": null,
    "outcomes": [
        "Core body temperature (CBT) during exposure",
        "CBT following exposure",
        "Thermoregulatory response to RF-EMF thermal load"
    ],
    "main_findings": "During a 2-h 1.95 GHz whole-body RF-EMF exposure, CBT peaked within the first 16 min relative to sham (+0.15, +0.31, +0.24, +0.37°C at 1.25, 2.5, 3.75, 5 W/kg, respectively), with statistical significance reported at WBA-SAR ≥ 2.5 W/kg. The elevation largely dissipated over the remainder of exposure; immediately before exposure end, only the 5 W/kg condition differed from sham, and CBT immediately after exposure cessation was reported as statistically significantly reduced compared with sham in the 5 W/kg condition.",
    "effect_direction": "harm",
    "limitations": [
        "Sample size not reported in provided abstract/metadata",
        "Exposure source/context (e.g., device type) not specified beyond reverberation chambers",
        "Findings limited to mice (C57BL/6) and a 2-hour exposure duration",
        "Handling/habituation effects on CBT noted as large and requiring extended habituation"
    ],
    "evidence_strength": "low",
    "confidence": 0.7800000000000000266453525910037569701671600341796875,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "radiofrequency",
        "RF-EMF",
        "1.95 GHz",
        "whole-body average SAR",
        "WBA-SAR",
        "core body temperature",
        "thermoregulation",
        "reverberation chamber",
        "radiotelemetry",
        "C57BL/6 mice"
    ],
    "suggested_hubs": [
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            "slug": "animal-studies",
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