Studies of the induction of dominant lethals and translocations in male mice after chronic exposure to microwave radiation.

Abstract

Male C3H mice were exposed to 100 W m-2 of 2.45 GHz continuous-wave microwave radiation for 6 h per day for a total of 120 h over an 8-week period. The exposure level was chosen so that the specific energy absorption rate (SAR) would be approximately equal to the level of 4 W kg-1 which is considered by a number of organizations to be a threshold for adverse biological effects. At the end of the treatment period the mice were mated with a different group of (C3H x 101) F1 hybrid females each week for the following 8 weeks. There was no significant reduction in pregnancy rate, preimplantation survival or postimplantation survival in the exposed group compared to sham-exposed controls. At the end of the mating period a cytogenetic analysis was carried out of meiotic chromosome preparations of testicular tissue, thus sampling cells that were stem cell spermatogonia during the treatment regime. The results showed no difference in the frequency of reciprocal translocations between the sham and treated groups, or in the frequency of cells with autosome or sex chromosome univalents. Low levels of fragments and exchanges were found in both groups. It is concluded that there is no evidence in this experiment to show that chronic exposure of male mice to 2.45 GHz microwave radiation induces a mutagenic response in male germ cells. This conclusion is in agreement with the observations of Berman et al. (1980), who reported a lack of male germ cell mutagenesis after repetitive or chronic exposure of rats to 2.45 GHz.

AI evidence extraction

Main findings

Male mice chronically exposed to 2.45 GHz continuous-wave microwaves (100 W m-2; SAR ~4 W/kg) showed no significant differences versus sham controls in pregnancy rate, preimplantation survival, or postimplantation survival. Cytogenetic analysis found no differences in reciprocal translocations or univalents; low levels of fragments/exchanges occurred in both groups, and the authors concluded no evidence of male germ-cell mutagenesis under these conditions.

Outcomes measured

• Pregnancy rate
• Preimplantation survival
• Postimplantation survival
• Reciprocal translocations (meiotic chromosomes, testicular tissue)
• Autosome or sex chromosome univalents
• Chromosome fragments and exchanges
• Dominant lethals (via mating outcomes)

Limitations

• Sample size not reported in the abstract
• Details of randomization/blinding and exposure dosimetry beyond stated SAR approximation are not provided in the abstract

Suggested hubs

• who-icnirp (0.3)
  Abstract references SAR ~4 W/kg as a threshold cited by organizations, relating to exposure guideline concepts.

{
    "study_type": "animal",
    "exposure": {
        "band": "microwave",
        "source": null,
        "frequency_mhz": 2450,
        "sar_wkg": 4,
        "duration": "6 h/day; total 120 h over 8 weeks"
    },
    "population": "Male C3H mice (mated with (C3H x 101) F1 hybrid females)",
    "sample_size": null,
    "outcomes": [
        "Pregnancy rate",
        "Preimplantation survival",
        "Postimplantation survival",
        "Reciprocal translocations (meiotic chromosomes, testicular tissue)",
        "Autosome or sex chromosome univalents",
        "Chromosome fragments and exchanges",
        "Dominant lethals (via mating outcomes)"
    ],
    "main_findings": "Male mice chronically exposed to 2.45 GHz continuous-wave microwaves (100 W m-2; SAR ~4 W/kg) showed no significant differences versus sham controls in pregnancy rate, preimplantation survival, or postimplantation survival. Cytogenetic analysis found no differences in reciprocal translocations or univalents; low levels of fragments/exchanges occurred in both groups, and the authors concluded no evidence of male germ-cell mutagenesis under these conditions.",
    "effect_direction": "no_effect",
    "limitations": [
        "Sample size not reported in the abstract",
        "Details of randomization/blinding and exposure dosimetry beyond stated SAR approximation are not provided in the abstract"
    ],
    "evidence_strength": "low",
    "confidence": 0.7800000000000000266453525910037569701671600341796875,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "2.45 GHz",
        "microwave radiation",
        "continuous-wave",
        "chronic exposure",
        "SAR 4 W/kg",
        "male mice",
        "germ cells",
        "mutagenesis",
        "dominant lethals",
        "reciprocal translocations",
        "cytogenetics",
        "testis"
    ],
    "suggested_hubs": [
        {
            "slug": "who-icnirp",
            "weight": 0.299999999999999988897769753748434595763683319091796875,
            "reason": "Abstract references SAR ~4 W/kg as a threshold cited by organizations, relating to exposure guideline concepts."
        }
    ]
}

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