Upper bound for broadband radiofrequency field disruption of magnetic compass orientation in night-

Abstract

Upper bound for broadband radiofrequency field disruption of magnetic compass orientation in night- migratory songbirds Leberecht B, Wong SY, Satish B, Döge S, Hindman J, Venkatraman L, Apte S, Haase K, Musielak I, Dautaj G, Solov'yov IA, Winklhofer M, Mouritsen H, Hore PJ. Upper bound for broadband radiofrequency field disruption of magnetic compass orientation in night-migratory songbirds. Proc Natl Acad Sci U S A. 2023 Jul 11;120(28):e2301153120. doi: 10.1073/pnas.2301153120. Epub 2023 Jul 3. PMID: 37399422; PMCID: PMC10334787. Abstract Night-migratory songbirds have a light-dependent magnetic compass sense, the mechanism of which is thought to depend on the photochemical formation of radical pairs in cryptochrome (Cry) proteins located in the retina. The finding that weak radiofrequency (RF) electromagnetic fields can prevent birds from orienting in the Earth's magnetic field has been regarded as a diagnostic test for this mechanism and as a potential source of information on the identities of the radicals. The maximum frequency that could cause such disorientation has been predicted to lie between 120 and 220 MHz for a flavin- tryptophan radical pair in Cry. Here we show that the magnetic orientation capabilities of Eurasian blackcaps (Sylvia atricapilla) are not affected by RF noise in the frequency bands 140 to 150 MHz and 235 to 245 MHz. From a consideration of its internal magnetic interactions, we argue that RF field effects on a flavin-containing radical-pair sensor should be approximately independent of frequency up to 116 MHz and that birds' sensitivity to RF disorientation should fall by about two orders of magnitude when the frequency exceeds 116 MHz. Taken together with our earlier finding that 75 to 85 MHz RF fields disrupt the magnetic orientation of blackcaps, these results provide compelling evidence that the magnetic compass of migratory birds operates by a radical pair mechanism. Open access paper: pnas.org

AI evidence extraction

Main findings

Magnetic orientation of Eurasian blackcaps was not affected by broadband RF noise in the 140–150 MHz and 235–245 MHz bands. The authors argue sensitivity to RF disorientation should decrease by about two orders of magnitude above 116 MHz, and interpret the findings (together with earlier disruption at 75–85 MHz) as evidence consistent with a radical-pair mechanism.

Outcomes measured

• Magnetic compass orientation / magnetic orientation capabilities
• Disruption (disorientation) of orientation in Earth's magnetic field under RF noise exposure

Limitations

• Sample size not stated in abstract
• Exposure intensity/field strength and dosimetry (e.g., SAR) not stated in abstract
• Exposure duration and experimental conditions not stated in abstract
• Findings include theoretical argumentation; empirical results limited to specific frequency bands tested

Suggested hubs

• rf-wildlife-navigation (0.9)
  Animal study on RF field effects on magnetic compass orientation in migratory birds.

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    "study_type": "animal",
    "exposure": {
        "band": "RF",
        "source": null,
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": null
    },
    "population": "Eurasian blackcaps (Sylvia atricapilla)",
    "sample_size": null,
    "outcomes": [
        "Magnetic compass orientation / magnetic orientation capabilities",
        "Disruption (disorientation) of orientation in Earth's magnetic field under RF noise exposure"
    ],
    "main_findings": "Magnetic orientation of Eurasian blackcaps was not affected by broadband RF noise in the 140–150 MHz and 235–245 MHz bands. The authors argue sensitivity to RF disorientation should decrease by about two orders of magnitude above 116 MHz, and interpret the findings (together with earlier disruption at 75–85 MHz) as evidence consistent with a radical-pair mechanism.",
    "effect_direction": "mixed",
    "limitations": [
        "Sample size not stated in abstract",
        "Exposure intensity/field strength and dosimetry (e.g., SAR) not stated in abstract",
        "Exposure duration and experimental conditions not stated in abstract",
        "Findings include theoretical argumentation; empirical results limited to specific frequency bands tested"
    ],
    "evidence_strength": "low",
    "confidence": 0.7399999999999999911182158029987476766109466552734375,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "radiofrequency",
        "RF noise",
        "magnetic compass",
        "orientation",
        "night-migratory songbirds",
        "Eurasian blackcap",
        "cryptochrome",
        "radical pair mechanism",
        "frequency dependence",
        "MHz"
    ],
    "suggested_hubs": [
        {
            "slug": "rf-wildlife-navigation",
            "weight": 0.90000000000000002220446049250313080847263336181640625,
            "reason": "Animal study on RF field effects on magnetic compass orientation in migratory birds."
        }
    ]
}

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