No observable non-thermal effect of microwave radiation on the growth of microtubules

Abstract

No observable non-thermal effect of microwave radiation on the growth of microtubules Hammarin G, Norder P, Harimoorthy R, Chen G, Berntsen P, Widlund PO, Stoij C, Rodilla H, Swenson J, Brändén G, Neutze R. No observable non-thermal effect of microwave radiation on the growth of microtubules. Sci Rep. 2024 Aug 7;14(1):18286. doi: 10.1038/s41598-024-68852-3. Abstract Despite widespread public interest in the health impact of exposure to microwave radiation, studies of the influence of microwave radiation on biological samples are often inconclusive or contradictory. Here we examine the influence of microwave radiation of frequencies 3.5 GHz, 20 GHz and 29 GHz on the growth of microtubules, which are biological nanotubes that perform diverse functions in eukaryotic cells. Since microtubules are highly polar and can extend several micrometres in length, they are predicted to be sensitive to non-ionizing radiation. Moreover, it has been speculated that tubulin dimers within microtubules might rapidly toggle between different conformations, potentially participating in computational or other cooperative processes. Our data show that exposure to microwave radiation yields a microtubule growth curve that is distorted relative to control studies utilizing a homogeneous temperature jump. However, this apparent effect of non-ionizing radiation is reproduced by control experiments using an infrared laser or hot air to heat the sample and thereby mimic the thermal history of samples exposed to microwaves. As such, no non-thermal effects of microwave radiation on microtubule growth can be assigned. Our results highlight the need for appropriate control experiments in biophysical studies that may impact on the sphere of public interest. Open access paper: nature.com

AI evidence extraction

Main findings

The study examined microwave exposures at 3.5, 20, and 29 GHz and observed a distorted microtubule growth curve relative to a homogeneous temperature-jump control. However, the same distortion was reproduced by thermal-mimic controls (infrared laser or hot air heating), leading the authors to conclude that no non-thermal effects of microwave radiation on microtubule growth can be assigned.

Outcomes measured

• Microtubule growth (growth curve)
• Non-thermal effects of microwave radiation on microtubule growth

Limitations

• Exposure metrics (e.g., SAR, power density) not reported in the abstract
• Exposure duration not reported in the abstract
• In vitro biophysical system; findings may not generalize to whole organisms or health outcomes

Suggested hubs

• 5g-policy (0.35)
  Includes 3.5 GHz and 29 GHz exposures, frequencies relevant to 5G discussions, though the study is in vitro and not policy-focused.

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    "study_type": "in_vitro",
    "exposure": {
        "band": "microwave",
        "source": null,
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": null
    },
    "population": null,
    "sample_size": null,
    "outcomes": [
        "Microtubule growth (growth curve)",
        "Non-thermal effects of microwave radiation on microtubule growth"
    ],
    "main_findings": "The study examined microwave exposures at 3.5, 20, and 29 GHz and observed a distorted microtubule growth curve relative to a homogeneous temperature-jump control. However, the same distortion was reproduced by thermal-mimic controls (infrared laser or hot air heating), leading the authors to conclude that no non-thermal effects of microwave radiation on microtubule growth can be assigned.",
    "effect_direction": "no_effect",
    "limitations": [
        "Exposure metrics (e.g., SAR, power density) not reported in the abstract",
        "Exposure duration not reported in the abstract",
        "In vitro biophysical system; findings may not generalize to whole organisms or health outcomes"
    ],
    "evidence_strength": "moderate",
    "confidence": 0.7800000000000000266453525910037569701671600341796875,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "microwave radiation",
        "non-ionizing radiation",
        "microtubules",
        "tubulin",
        "non-thermal effects",
        "temperature control",
        "3.5 GHz",
        "20 GHz",
        "29 GHz"
    ],
    "suggested_hubs": [
        {
            "slug": "5g-policy",
            "weight": 0.34999999999999997779553950749686919152736663818359375,
            "reason": "Includes 3.5 GHz and 29 GHz exposures, frequencies relevant to 5G discussions, though the study is in vitro and not policy-focused."
        }
    ]
}

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