Study of low-intensity 2450-MHz microwave exposure enhancing the genotoxic effects of mitomycin C using micronucleus test and comet assay in vitro.

Abstract

OBJECTIVE: To determine the interaction between 2450-MHz microwaves (MW) radiation and mitomycin C (MMC). METHODS: The synergistic genotoxic effects of low-intensity 2450-MHz microwave and MMC on human lymphocytes were studied using single cell gel electrophoresis (SCGE) assay (comet assay) and cytokinesis-blocked micronucleus (CBMN) test in vitro. The whole blood cells from a male donor and a female donor were either only exposed to 2450-MHz microwaves (5.0 mW/cm2) for 2 h or only exposed to MMC (0.0125 microgram/mL, 0.025 microgram/mL and 0.1 microgram/mL) for 24 h; and the samples were exposed to MMC for 24 h after exposure to MW for 2 h. RESULTS: In the comet assay, the comet lengths (29.1 microns and 25.9 microns) of MW were not significantly longer than those (26.3 microns and 24.1 microns) of controls (P > 0.05). The comet lengths (57.4 microns, 68.9 microns, 91.4 microns, 150.6 microns, 71.7 microns, 100.1 microns, 145.1 microns) of 4 MMC groups were significantly longer than those of controls (P < 0.01). The comet lengths (59.1 microns, 92.3 microns, 124.5 microns, 182.7 microns and 57.4 microns, 85.5 microns, 137.5 microns, 178.3 microns) of 4 MW plus MMC groups were significantly longer than those of controls too (P < 0.01). The comet lengths of MW plus MMC groups were significantly longer than those of the corresponding MMC doses (P < 0.05 or P < 0.01) when the doses of MMC were > or = 0.025 microgram/mL. In the CBMN, the micronucleated cell (MNC) rates of MW were 5@1000 and 6@1000, which showed no difference compared with those (4@1000 and 4@1000) of controls (P > 0.05). The MNC rates of 4 MMC groups were 8@1000, 9@1000, 14@1000, 23@1000 and 8@1000, 8@1000, 16@1000, 30@1000 respectively. When the doses of MMC were > or = 0.05 microgram/mL, MNC rates of MMC were higher than those of controls (P < 0.05). MNC rates of 4 MW plus MMC groups were 12@1000, 13@1000, 20@1000, 32@1000 and 8@1000, 9@1000, 23@1000, 40@1000. When the doses of MMC were > or = 0.05 microgram/mL, MNC rates of MW plus MMC groups were much higher than those of controls (P < 0.01). MNC rates of 4 MW plus MMC groups were not significantly higher than those of the corresponding MMC doses. CONCLUSION: The low-intensity 2450-MHz microwave radiation can not induce DNA and chromosome damage, but can increase DNA damage effect induced by MMC in comet assay.

AI evidence extraction

Main findings

Microwave exposure alone (2450 MHz, 5.0 mW/cm2 for 2 h) did not significantly increase comet length or micronucleated cell rates versus controls. MMC increased DNA damage and (at higher doses) micronucleated cell rates. Microwave pre-exposure followed by MMC increased comet assay DNA damage compared with corresponding MMC doses at MMC doses ≥0.025 microgram/mL, while micronucleated cell rates in MW+MMC groups were not significantly higher than corresponding MMC-only groups.

Outcomes measured

• DNA damage (comet assay/SCGE; comet length)
• Chromosome damage (cytokinesis-blocked micronucleus test; micronucleated cell rate)
• Interaction/synergy with mitomycin C (MMC)

Limitations

• In vitro study; findings may not generalize to in vivo/humans
• Very small donor sample (one male and one female)
• SAR not reported; exposure characterized as power density (mW/cm2) only
• Micronucleus results did not show significant enhancement versus MMC alone despite comet assay enhancement

{
    "study_type": "in_vitro",
    "exposure": {
        "band": "microwave",
        "source": null,
        "frequency_mhz": 2450,
        "sar_wkg": null,
        "duration": "2 h"
    },
    "population": "Human lymphocytes (whole blood cells) from one male donor and one female donor",
    "sample_size": 2,
    "outcomes": [
        "DNA damage (comet assay/SCGE; comet length)",
        "Chromosome damage (cytokinesis-blocked micronucleus test; micronucleated cell rate)",
        "Interaction/synergy with mitomycin C (MMC)"
    ],
    "main_findings": "Microwave exposure alone (2450 MHz, 5.0 mW/cm2 for 2 h) did not significantly increase comet length or micronucleated cell rates versus controls. MMC increased DNA damage and (at higher doses) micronucleated cell rates. Microwave pre-exposure followed by MMC increased comet assay DNA damage compared with corresponding MMC doses at MMC doses ≥0.025 microgram/mL, while micronucleated cell rates in MW+MMC groups were not significantly higher than corresponding MMC-only groups.",
    "effect_direction": "mixed",
    "limitations": [
        "In vitro study; findings may not generalize to in vivo/humans",
        "Very small donor sample (one male and one female)",
        "SAR not reported; exposure characterized as power density (mW/cm2) only",
        "Micronucleus results did not show significant enhancement versus MMC alone despite comet assay enhancement"
    ],
    "evidence_strength": "low",
    "confidence": 0.7800000000000000266453525910037569701671600341796875,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "2450 MHz",
        "microwave radiation",
        "low-intensity",
        "genotoxicity",
        "comet assay",
        "single cell gel electrophoresis",
        "micronucleus test",
        "cytokinesis-blocked micronucleus",
        "human lymphocytes",
        "mitomycin C",
        "synergistic effect"
    ],
    "suggested_hubs": []
}

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