Brain Accumulation of Airborne Magnetite Nanoparticles under Earphone/Smartphone-Embedded Magnetic Fields Triggers Neurotoxicity

Abstract

Magnetism is an important property of nanomaterials. Natural, incidental, and engineered magnetic nanoparticles are ubiquitous in nature and human activities. As an air pollutant, magnetite nanoparticles (MNPs) can enter the human body and even the brain, posing serious health concerns. However, unlike other physicochemical properties such as size, shape, or surface chemistry, the influence of magnetism on nanoparticle biodistribution and toxicity remains unclear. The manifestation of nanoparticle magnetism requires exposure to magnetic fields, which are ubiquitous in daily life, such as those from mobile phones and earphones. Here, we used six-to eight-week-old C57BL/6J mice coexposed to airborne MNPs and earphone/smartphone-embedded magnetism (EEM) to investigate the impact of nanomaterial magnetism on the in vivo fate and neurotoxicity of inhaled nanoparticles. Co-exposure significantly impaired cognitive performance, as evidenced by reduced target quadrant entries and increased escape latency in the Morris water maze (p < 0.01). EEM increased brain accumulation of inhaled MNPs by approximately 5-fold compared to non-EEM controls. Transcriptomics, immunohistochemistry, metallomics, and reactome profiling, revealed neurodegeneration-related molecular alterations enriched in the Mitogen-Activated Protein Kinase (MAPK) and guanosine triphosphatase-associated signaling pathways. Compared to exposure to non-EEM, or nonmagnetic engineered iron oxide nanoparticles or magnetism-reduced fine particulate matter (PM2.5), the magnetism-mediated toxicity mechanism induced more severe behavioral damage in mice. Our findings reveal the link between nanomaterial magnetism and toxicity, discovering that exogenous nanoparticles can act as a direct medium in vivo for the health impacts of magnetic field exposure, and provide novel insights into the health impacts of magnetic field exposure and air pollution.

AI evidence extraction

Main findings

In mice coexposed to airborne magnetite nanoparticles and earphone/smartphone-embedded magnetism, cognitive performance was significantly impaired and brain accumulation of inhaled magnetite nanoparticles increased by about 5-fold versus non-EEM controls. Multi-omics and histological analyses indicated neurodegeneration-related molecular alterations, with enriched MAPK and GTPase-associated signaling pathways, and co-exposure produced more severe behavioral damage than comparison exposures involving non-EEM or less magnetic particles.

Outcomes measured

• Cognitive performance in Morris water maze
• Brain accumulation of inhaled magnetite nanoparticles
• Neurodegeneration-related molecular alterations
• MAPK signaling pathway changes
• GTPase-associated signaling pathway changes
• Behavioral damage/neurotoxicity

Limitations

• Animal study
• Frequency and magnetic field exposure parameters were not stated in the abstract
• Sample size was not stated in the abstract
• Findings are based on co-exposure to airborne magnetite nanoparticles and embedded magnetism rather than magnetic field exposure alone

{
    "study_type": "animal",
    "exposure": {
        "band": null,
        "source": "mobile phone, earphones",
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": null
    },
    "population": "Six- to eight-week-old C57BL/6J mice",
    "sample_size": null,
    "outcomes": [
        "Cognitive performance in Morris water maze",
        "Brain accumulation of inhaled magnetite nanoparticles",
        "Neurodegeneration-related molecular alterations",
        "MAPK signaling pathway changes",
        "GTPase-associated signaling pathway changes",
        "Behavioral damage/neurotoxicity"
    ],
    "main_findings": "In mice coexposed to airborne magnetite nanoparticles and earphone/smartphone-embedded magnetism, cognitive performance was significantly impaired and brain accumulation of inhaled magnetite nanoparticles increased by about 5-fold versus non-EEM controls. Multi-omics and histological analyses indicated neurodegeneration-related molecular alterations, with enriched MAPK and GTPase-associated signaling pathways, and co-exposure produced more severe behavioral damage than comparison exposures involving non-EEM or less magnetic particles.",
    "effect_direction": "harm",
    "limitations": [
        "Animal study",
        "Frequency and magnetic field exposure parameters were not stated in the abstract",
        "Sample size was not stated in the abstract",
        "Findings are based on co-exposure to airborne magnetite nanoparticles and embedded magnetism rather than magnetic field exposure alone"
    ],
    "evidence_strength": "low",
    "confidence": 0.89000000000000001332267629550187848508358001708984375,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "magnetite nanoparticles",
        "magnetic nanoparticles",
        "air pollution",
        "mobile phones",
        "earphones",
        "magnetic fields",
        "brain accumulation",
        "neurotoxicity",
        "mice",
        "MAPK signaling"
    ],
    "suggested_hubs": []
}

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