Radiofrequency (microwave) radiation exposure of mammalian cells during UV-induced DNA repair synthesis.

Abstract

The effect of continuous-wave (CW) and pulsed-wave (PW) radiofrequency radiation (RFR) in the microwave range on UV-induced DNA repair has been investigated in MRC-5 normal human diploid fibroblasts. RFR exposure at power densities of 1 (or 5) and 10 mW/cm2 gave a maximum specific absorption rate (SAR) (at 10 mW/cm2) of 0.39 +/- 0.15 W/kg for 350 MHz RFR, 4.5 +/- 3.0 W/kg for 850 MHz RFR, and 2.7 +/- 1.6 W/kg for 1.2 GHz RFR. RFR exposures for 1 to 3 h at 37 degrees C, in either continuous-wave or pulsed-wave modes, had no effect on the rate of repair replication label incorporated into preexisting UV-damaged DNA. RFR exposures (PW), with a constant medium temperature of 39 degrees C at 350 and 850 MHz during the repair period after UV damage, also had no effect. Assay for induction of repair synthesis by RFR exposure alone in non-UV irradiated cells was negative for the 350-, 850-, and 1200-MHz CW and PW RFR at 37 degrees C and the 350- and 850-MHz PW RFR at 39 degrees C. RFR does not induce DNA repair under these exposure conditions. In preliminary experiments--with the tissue culture medium maintained at 39 degrees C and RFR exposures (PW) at the frequencies of 350, 850, and 1200 MHz--no effect on incorporation of [3H]thymidine into DNA undergoing semiconservative synthesis was observed.

AI evidence extraction

Main findings

In MRC-5 human fibroblasts, continuous-wave and pulsed-wave microwave-range RFR exposures (350, 850, and 1200 MHz) for 1–3 h at 37°C showed no effect on the rate of UV-induced DNA repair synthesis. Pulsed-wave exposures at 350 and 850 MHz with medium held at 39°C during the post-UV repair period also showed no effect. RFR exposure alone did not induce repair synthesis under the tested conditions, and preliminary experiments found no effect on semiconservative DNA synthesis ([3H]thymidine incorporation) at 39°C.

Outcomes measured

• UV-induced DNA repair synthesis (repair replication label incorporation into UV-damaged DNA)
• Induction of repair synthesis by RFR alone (non-UV irradiated cells)
• [3H]thymidine incorporation into DNA undergoing semiconservative synthesis (preliminary experiments)

Limitations

• Sample size not reported in abstract
• Exposure source/setup not described beyond frequency, power density, SAR, and temperature
• Some results described as preliminary (semiconservative DNA synthesis)

{
    "study_type": "in_vitro",
    "exposure": {
        "band": "RF",
        "source": null,
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": "1 to 3 h"
    },
    "population": "MRC-5 normal human diploid fibroblasts (cell culture)",
    "sample_size": null,
    "outcomes": [
        "UV-induced DNA repair synthesis (repair replication label incorporation into UV-damaged DNA)",
        "Induction of repair synthesis by RFR alone (non-UV irradiated cells)",
        "[3H]thymidine incorporation into DNA undergoing semiconservative synthesis (preliminary experiments)"
    ],
    "main_findings": "In MRC-5 human fibroblasts, continuous-wave and pulsed-wave microwave-range RFR exposures (350, 850, and 1200 MHz) for 1–3 h at 37°C showed no effect on the rate of UV-induced DNA repair synthesis. Pulsed-wave exposures at 350 and 850 MHz with medium held at 39°C during the post-UV repair period also showed no effect. RFR exposure alone did not induce repair synthesis under the tested conditions, and preliminary experiments found no effect on semiconservative DNA synthesis ([3H]thymidine incorporation) at 39°C.",
    "effect_direction": "no_effect",
    "limitations": [
        "Sample size not reported in abstract",
        "Exposure source/setup not described beyond frequency, power density, SAR, and temperature",
        "Some results described as preliminary (semiconservative DNA synthesis)"
    ],
    "evidence_strength": "low",
    "confidence": 0.7800000000000000266453525910037569701671600341796875,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "radiofrequency radiation",
        "microwave",
        "continuous-wave",
        "pulsed-wave",
        "MRC-5",
        "human fibroblasts",
        "UV-induced DNA repair",
        "repair synthesis",
        "specific absorption rate",
        "power density",
        "350 MHz",
        "850 MHz",
        "1200 MHz"
    ],
    "suggested_hubs": []
}

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