Numerical dosimetry of specific absorption rate of insects exposed to far-field radiofrequency

Abstract

Numerical dosimetry of specific absorption rate of insects exposed to far-field radiofrequency electromagnetic fields Jeladze V, Nozadze T, Partsvania B, Thielens A, Shoshiashvili L, Gogoladze T (2025). Numerical dosimetry of specific absorption rate of insects exposed to far-field radiofrequency electromagnetic fields. International Journal of Radiation Biology, 1–14. doi: 10.1080/09553002.2024.2442693. Abstract Purpose This paper reports a study of electromagnetic field (EMF) exposure of several adult insects: a ladybug, a honey bee worker, a wasp, and a mantis at frequencies ranging from 2.5 to 100 GHz. The purpose was to estimate the specific absorption rate (SAR) in insect tissues, including the brain, in order to predict the possible biological effects caused by EMF energy absorption. Method Numerical dosimetry was executed using the finite-difference time-domain (FDTD) method. Insects were modeled as 3-tissue heterogeneous dielectric objects, including the cuticle, the inner tissue, and the brain tissue. The EMF source was modeled as sinusoidal plane waves at a single frequency (far-field exposure). Results The whole-body averaged, tissue averaged, and 1 milligram SAR values were determined in insects for all considered frequencies for 10 different incident plane waves. SAR values were normalized to the incident power density of 1 mW/cm2. Maximal EMF absorption in the inner and brain tissues was observed at 6, 12, and 25 GHz for the considered insects, except the brain tissue of a ladybug (max at 60 GHz). Conclusion The paper presented the first estimation of the SAR for multiple insects over a wide range of RF frequencies using 3-tissue heterogenous insect 3D models created for this specific research. The selection of tissues’ dielectric properties was validated. The obtained results showed that EMF energy absorption in insects highly depends on frequency, polarization, and insect morphology. Conclusion The paper presented a study of RF-EMF dosimetry of honeybee worker, wasp, mantis, and ladybug from 2.5 to 100 GHz, including frequencies that will be utilized in future 5 G technologies. Discrete, 3-tissue heterogenous insect 3D models were created and used for FDTD modeling. The whole-body averaged SAR values and tissue-averaged SAR values were estimated in insects’ tissues for 9 considered frequencies and 10 polarizations of incident plane wave. For the first time, 1 mg SAR values were determined in insect tissues. The obtained results showed SAR values in honeybee, wasp, ladybug, and mantis body tissues, which depend on the direction of the incident plane wave and polarization, frequency, and the insects’ body sizes and peculiarities. The highest values of the peak 1 mg SAR for the honeybee and wasp − 39.2 W/kg and 169.2 W/kg for an incident field strength of 1 mW/cm2 , were observed when E-field polarization was directed along the insect’s length (pol. E3, E5, E9). The obtained results showed maximal tissue-specific SAR values in the brain at 25 GHz for the honeybee (3.6 W/kg), 12 GHz for the wasp (5.4 W/kg), 25 GHz for the mantis (5.2 W/kg), and 60 GHz for the ladybug (10 W/kg), all for an incident power density of 1 mW/cm2 . Maximal EMF absorption in the inner tissue was observed at 12 GHz, 4.3 W/kg, 5.9 W/kg, 4.8 W/kg for the honey bee, wasp, and ladybug, respectively, and for the mantis 3.3 W/kg at 6 GHz for an incident power density of 1 mW/cm2 . The absorption in insects’ cuticles increased proportionally with frequency. For example, for the ladybug, the tissue-specific SAR in the cuticle was 0.1 W/kg at 2.5 Ghz and 11.9 W/kg at 100 GHz for the same incident power density of 1 mW/cm2 . Future studies will consider introducing insect models that will be obtained using micro-CT scanning, examining the effects of high-frequency electromagnetic fields on other insects of different forms and sizes, conducting thermal simulations along with EM simulations, and evaluating temperature rise in insect tissues. Based on the present results, we expect this research to have an impact on (environmental) policymaking and standardization and regulation regarding RF-EMF emissions. We expect to contribute to the harmonization of 5G EMF safety and compliance doses and to the development of future recommendations about safe frequencies and doses of 5G-EMF on the organisms studied in the present research. tandfonline.com

AI evidence extraction

Main findings

Using FDTD numerical dosimetry with far-field plane-wave exposure normalized to 1 mW/cm2 incident power density, SAR in insect tissues depended strongly on frequency, polarization, and morphology. Maximal absorption in inner/brain tissues occurred at 6, 12, and 25 GHz for the considered insects, except ladybug brain tissue which peaked at 60 GHz; example maxima reported include brain SAR of 3.6 W/kg (honeybee, 25 GHz), 5.4 W/kg (wasp, 12 GHz), 5.2 W/kg (mantis, 25 GHz), and 10 W/kg (ladybug, 60 GHz), and peak 1 mg SAR up to 39.2 W/kg (honeybee) and 169.2 W/kg (wasp) for certain polarizations.

Outcomes measured

• Whole-body averaged SAR
• Tissue-averaged SAR (cuticle, inner tissue, brain)
• Peak 1 mg SAR
• Frequency dependence of SAR
• Polarization/direction dependence of SAR

Limitations

• Numerical modeling study (dosimetry) without direct biological/health outcome measurements
• Exposure modeled as idealized far-field sinusoidal plane waves at single frequencies
• Insects represented as 3-tissue heterogeneous models; future work noted to use micro-CT-derived models and add thermal simulations/temperature rise evaluation

Suggested hubs

• 5g-policy (0.6)
  Includes 2.5–100 GHz and explicitly mentions frequencies utilized in future 5G technologies and potential policy/standardization impact.

{
    "study_type": "exposure_assessment",
    "exposure": {
        "band": "RF/mmWave",
        "source": "far-field plane-wave (sinusoidal) exposure",
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": null
    },
    "population": "Adult insects (ladybug, honey bee worker, wasp, mantis) modeled as 3-tissue heterogeneous dielectric objects (cuticle, inner tissue, brain)",
    "sample_size": null,
    "outcomes": [
        "Whole-body averaged SAR",
        "Tissue-averaged SAR (cuticle, inner tissue, brain)",
        "Peak 1 mg SAR",
        "Frequency dependence of SAR",
        "Polarization/direction dependence of SAR"
    ],
    "main_findings": "Using FDTD numerical dosimetry with far-field plane-wave exposure normalized to 1 mW/cm2 incident power density, SAR in insect tissues depended strongly on frequency, polarization, and morphology. Maximal absorption in inner/brain tissues occurred at 6, 12, and 25 GHz for the considered insects, except ladybug brain tissue which peaked at 60 GHz; example maxima reported include brain SAR of 3.6 W/kg (honeybee, 25 GHz), 5.4 W/kg (wasp, 12 GHz), 5.2 W/kg (mantis, 25 GHz), and 10 W/kg (ladybug, 60 GHz), and peak 1 mg SAR up to 39.2 W/kg (honeybee) and 169.2 W/kg (wasp) for certain polarizations.",
    "effect_direction": "unclear",
    "limitations": [
        "Numerical modeling study (dosimetry) without direct biological/health outcome measurements",
        "Exposure modeled as idealized far-field sinusoidal plane waves at single frequencies",
        "Insects represented as 3-tissue heterogeneous models; future work noted to use micro-CT-derived models and add thermal simulations/temperature rise evaluation"
    ],
    "evidence_strength": "insufficient",
    "confidence": 0.7800000000000000266453525910037569701671600341796875,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "numerical dosimetry",
        "FDTD",
        "specific absorption rate",
        "SAR",
        "insects",
        "honeybee",
        "wasp",
        "ladybug",
        "mantis",
        "far-field",
        "plane wave",
        "radiofrequency",
        "mmWave",
        "2.5–100 GHz",
        "5G"
    ],
    "suggested_hubs": [
        {
            "slug": "5g-policy",
            "weight": 0.59999999999999997779553950749686919152736663818359375,
            "reason": "Includes 2.5–100 GHz and explicitly mentions frequencies utilized in future 5G technologies and potential policy/standardization impact."
        }
    ]
}

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