Reproductive integrity of mammalian cells exposed to power frequency electromagnetic fields.

Abstract

Human lymphocytes and Chinese hamster ovary (CHO) fibroblasts were analyzed for cytogenetic and cytotoxic endpoints to determine whether exposure to power frequency (60 Hz) electromagnetic fields (EMF) interferes with normal cell growth and reproduction. An exposure chamber was built to apply variable electric current densities of 3, 30, 300, and 3,000 microA/cm2, simultaneously with a fixed magnetic field of 2.2 G to proliferating cells. The current densities were chosen to bracket those that may be induced in the human body by fields measured beneath high voltage (765 kV) power transmission lines. The electric current was applied through the media of a cell culture chamber positioned between two stainless steel electrodes but separated from direct contact with the culture media by a salt bridge composed of a 1% agarose gel. The magnetic field was generated using two pairs of Helmholtz coils driven 73 degrees out of phase producing an elliptically polarized magnetic field 36 degrees out of phase with the electric field. The EMFs were measured and mapped inside the cell culture chamber to insure their uniformity. CHO cells were exposed continuously for 24-96 hr (depending on experiment) and human lymphocytes were exposed continuously for 72 hr. The EMFs were monitored throughout the entire treatment period using a multichannel chart recorder to verify continuous application of the desired fields. Sister-chromatid exchange and micronuclei were monitored to evaluate the potential for genotoxicity. In addition, standard growth curves, clonogenicity, and cell cycle kinetics were analyzed to evaluate possible cytotoxic effects. The experimental data consistently showed that the growth rate and reproductive integrity of both cell types was unaffected by exposure to the electromagnetic fields.

AI evidence extraction

Main findings

Across tested electric current densities (3, 30, 300, 3,000 microA/cm2) with a fixed 2.2 G magnetic field at 60 Hz, growth rate and reproductive integrity of CHO cells and human lymphocytes were consistently reported as unaffected. No effects were reported on genotoxicity endpoints (sister-chromatid exchange, micronuclei) or cytotoxicity-related measures (growth curves, clonogenicity, cell cycle kinetics).

Outcomes measured

• Sister-chromatid exchange
• Micronuclei
• Growth rate (growth curves)
• Clonogenicity
• Cell cycle kinetics

Limitations

• Sample size not reported in abstract.
• In vitro study; findings may not generalize to in vivo human health outcomes.
• Exposure metrics reported as current density and magnetic field; no SAR reported.

Suggested hubs

• occupational-exposure (0.35)
  Exposure levels were selected to bracket currents that may be induced beneath high-voltage power transmission lines.

{
    "study_type": "in_vitro",
    "exposure": {
        "band": "ELF",
        "source": "power transmission lines",
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": "CHO cells: continuous 24–96 hr; human lymphocytes: continuous 72 hr"
    },
    "population": "Human lymphocytes and Chinese hamster ovary (CHO) fibroblasts (cell cultures)",
    "sample_size": null,
    "outcomes": [
        "Sister-chromatid exchange",
        "Micronuclei",
        "Growth rate (growth curves)",
        "Clonogenicity",
        "Cell cycle kinetics"
    ],
    "main_findings": "Across tested electric current densities (3, 30, 300, 3,000 microA/cm2) with a fixed 2.2 G magnetic field at 60 Hz, growth rate and reproductive integrity of CHO cells and human lymphocytes were consistently reported as unaffected. No effects were reported on genotoxicity endpoints (sister-chromatid exchange, micronuclei) or cytotoxicity-related measures (growth curves, clonogenicity, cell cycle kinetics).",
    "effect_direction": "no_effect",
    "limitations": [
        "Sample size not reported in abstract.",
        "In vitro study; findings may not generalize to in vivo human health outcomes.",
        "Exposure metrics reported as current density and magnetic field; no SAR reported."
    ],
    "evidence_strength": "low",
    "confidence": 0.7800000000000000266453525910037569701671600341796875,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "ELF EMF",
        "60 Hz",
        "power frequency",
        "in vitro",
        "human lymphocytes",
        "CHO cells",
        "sister-chromatid exchange",
        "micronuclei",
        "genotoxicity",
        "cytotoxicity",
        "power transmission lines"
    ],
    "suggested_hubs": [
        {
            "slug": "occupational-exposure",
            "weight": 0.34999999999999997779553950749686919152736663818359375,
            "reason": "Exposure levels were selected to bracket currents that may be induced beneath high-voltage power transmission lines."
        }
    ]
}

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