Quantitative Assessment of Thermal Effects on the Auricle Region Caused by Mobile Phones

Abstract

Quantitative Assessment of Thermal Effects on the Auricle Region Caused by Mobile Phones Operating in Different Modes Rok T, Kacprzyk A, Rokita E, Kantor D, and Taton G. Quantitative Assessment of Thermal Effects on the Auricle Region Caused by Mobile Phones Operating in Different Modes. AIMS Biophys 11, no. 4 (2024): 427–44. doi.org. Abstract To analyze thermal effects caused by mobile phones on the human auricle region, we performed an experiment with controlled exposure to mobile phones operating in different modes for a group of 40 men. Temperature changes were measured with the use of infrared thermography. Thermograms were taken before and after a standardized 15-minute phone call when the mobile phone was placed lightly against the skin surface in the auricle region. The measurements were performed in three modes: OFF, ON, and FLIGHT. Statistically significant differences (p = 0.03) were observed between the experimental temperature increase of the auricle region in OFF mode (average temperature rise = 1.1 °C ± 0.2 °C) and in ON mode (average temperature rise = 1.9 °C ± 0.3 °C), while between FLIGHT (average temperature rise = 1.4 °C ± 0.2 °C) and ON modes, no statistical differences were observed (p = 0.20). Based on thermographic measurements and the model of heat transfer between the ear and the phone, it was shown that the human ear is the largest heat source in the system and that the increase in skin temperature is mainly caused by the handheld mobile phone restricting heat dissipation from the skin surface. Excerpt for the assessment of near-field exposure, Received Signal Strength Indicator (RSSI) and Specific Absorption Rate (SAR) were used. During exposure sessions RSSI values were continuously measured and retrospectively controlled. All the participants received exposure at an arbitrary mean value of RSSI between −90 and −80 dBm. The SAR quantifies the absorption of RF-EMF in tissues, and for the human body, it depends on the dielectric properties of tissues due to the complexity of the human head anatomy its estimation is a subject of great challenge [21],[22] and for the phone used (Huawei P20 Lite), it was reported as 0.75 W/kg in the manual. For the far-field exposure a personal exposure meter (ExpoM-RF, Zurich, Switzerland) performing a spectral analysis of RF-EMF within 16 different frequency bands from 87.5 MHz up to 5.875 GHz was used. Based on electric field strength, the power density was calculated as 45 μW. The uplink and downlink radiation remained on a comparable level throughout a simulated phone call. In OFF mode, the smartphone was switched off, while in FLIGHT mode, there was no connection with the GSM network, so music was constantly playing. In ON mode, the mobile phone was fully connected to the GSM network and the smartphone was operating at a frequency of 1800 MHz. Open access paper: aimspress.com

AI evidence extraction

Main findings

In a controlled experiment, auricle-region temperature increased after a 15-minute session in all modes, with a statistically significant difference between OFF mode (mean +1.1 °C ± 0.2 °C) and ON mode (mean +1.9 °C ± 0.3 °C; p=0.03). No statistically significant difference was observed between FLIGHT mode (mean +1.4 °C ± 0.2 °C) and ON mode (p=0.20). A heat-transfer model and thermography suggested the temperature increase was mainly due to the phone restricting heat dissipation from the skin surface, with the ear as the largest heat source in the system.

Outcomes measured

• Auricle/ear-region skin temperature change measured by infrared thermography
• Near-field exposure metrics (RSSI, SAR)
• Far-field RF-EMF (electric field strength/power density via personal exposure meter)

Limitations

• Only men were included (n=40).
• Exposure details are limited to the described phone model/modes and a single standardized 15-minute session.
• SAR value appears to be taken from the phone manual rather than measured in-study.
• Far-field exposure is summarized (e.g., power density 45 μW) without additional context in the abstract/excerpt.

Suggested hubs

• who-icnirp (0.2)
  Study concerns RF exposure metrics (SAR) and thermal effects relevant to RF safety guideline discussions.

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    "study_type": "other",
    "exposure": {
        "band": "RF",
        "source": "mobile phone",
        "frequency_mhz": 1800,
        "sar_wkg": 0.75,
        "duration": "15-minute phone call (standardized)"
    },
    "population": "40 men",
    "sample_size": 40,
    "outcomes": [
        "Auricle/ear-region skin temperature change measured by infrared thermography",
        "Near-field exposure metrics (RSSI, SAR)",
        "Far-field RF-EMF (electric field strength/power density via personal exposure meter)"
    ],
    "main_findings": "In a controlled experiment, auricle-region temperature increased after a 15-minute session in all modes, with a statistically significant difference between OFF mode (mean +1.1 °C ± 0.2 °C) and ON mode (mean +1.9 °C ± 0.3 °C; p=0.03). No statistically significant difference was observed between FLIGHT mode (mean +1.4 °C ± 0.2 °C) and ON mode (p=0.20). A heat-transfer model and thermography suggested the temperature increase was mainly due to the phone restricting heat dissipation from the skin surface, with the ear as the largest heat source in the system.",
    "effect_direction": "mixed",
    "limitations": [
        "Only men were included (n=40).",
        "Exposure details are limited to the described phone model/modes and a single standardized 15-minute session.",
        "SAR value appears to be taken from the phone manual rather than measured in-study.",
        "Far-field exposure is summarized (e.g., power density 45 μW) without additional context in the abstract/excerpt."
    ],
    "evidence_strength": "low",
    "confidence": 0.7399999999999999911182158029987476766109466552734375,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "mobile phone",
        "auricle",
        "ear",
        "thermal effects",
        "infrared thermography",
        "RSSI",
        "SAR",
        "GSM",
        "1800 MHz",
        "flight mode",
        "heat dissipation",
        "RF-EMF",
        "personal exposure meter"
    ],
    "suggested_hubs": [
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        }
    ]
}

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