Teratology, survival, and reversal learning after fetal irradiation of mice by 2450-MHz microwave energy.

Abstract

In the first of two factorially designed studies, 80 primigravid mice of the C3H-HeJ strain were subjected to 2450-MHz sinusoidally modulated microwave radiation or to sham radiation (with or without an accompanying injection of 5 mg of cortisone as a teratological marker) on the 11th, 12th, 13th or 14th day of gestation. The radiation treatment consisted of a single intense dosing of microwave energy (38 mW/g for 600 sec.= 22.8 J/g) in a multi-mode cavity. On the 19th day of gestation fetuses were taken via Caesarean section and were observed for gross structural abnormalities. While radiation of dams failed reliably to increase the incidence of fetal mortality or morbidity above that of controls, the dams treated with cortisone gave birth to reliably greater numbers of stillborn and deformed fetuses. In the second experiment and during their 14th day of gestation 60 primigravid mice received the radiation of sham-radiation treatment, half with, half without, the accompanying injection of cortisone. A virtually complete failure to survive to weaning characterized the pups born of the sham-radiated cortisone-treated group of dams, but the incidence of cortisone-induced mortality was reliably reduced in pups whose dams were also radiated by microwave energy. Pups sampled from all but the depleted group were observed later as young adults for competency in mastering a series of reversal habits in a water maze. No differences in maze performances were observed in the mice as a function of their placement in the control or the radiation condition, but offspring of cortisone-treated, radiated dams made reliably more errors. Careful measurement of elevations of colonic temperatures of radiated dams shortly after treatment with cortisone revealed an averaged deltaT that is close to that observed in a comparably radiated volume of water of equivalent mass. If the finding has generality beyond the gravid mouse-it, that is, cortisone effectively and reversibly renders the mammal ectothermic-an important advance in biological dosimetry of non-ionizing radiation may be at hand.

AI evidence extraction

Main findings

Experiment 1: A single intense 2450-MHz exposure (38 mW/g for 600 sec) did not reliably increase fetal mortality or morbidity versus controls, while cortisone increased stillborn and deformed fetuses. Experiment 2: Cortisone-treated sham-radiated dams had near-complete failure of pups to survive to weaning, and this cortisone-induced mortality was reliably reduced when dams were also exposed to microwave energy. Maze performance did not differ by radiation vs control overall, but offspring of cortisone-treated, radiated dams made reliably more errors.

Outcomes measured

• Fetal gross structural abnormalities (teratology)
• Fetal mortality/stillbirth
• Survival to weaning
• Reversal learning performance in a water maze (errors/maze performance)
• Maternal colonic temperature elevation (deltaT) after treatment

Limitations

• Outcomes and effects are reported in the context of co-exposure to cortisone; radiation-only effects may be difficult to isolate for some endpoints.
• Abstract does not report randomization/blinding procedures or detailed statistical estimates.
• Exposure described as a single intense dose; generalizability to other exposure levels/patterns is unclear from abstract.

Suggested hubs

• who-icnirp (0.2)
  Animal study of microwave exposure with thermal dosimetry relevance; potentially relevant to guideline discussions, though no policy content is provided.

{
    "study_type": "animal",
    "exposure": {
        "band": "microwave",
        "source": null,
        "frequency_mhz": 2450,
        "sar_wkg": 38,
        "duration": "Single exposure of 600 sec (on gestation day 11, 12, 13, or 14 in experiment 1; day 14 in experiment 2)"
    },
    "population": "Primigravid C3H-HeJ mice and their fetuses/pups",
    "sample_size": 140,
    "outcomes": [
        "Fetal gross structural abnormalities (teratology)",
        "Fetal mortality/stillbirth",
        "Survival to weaning",
        "Reversal learning performance in a water maze (errors/maze performance)",
        "Maternal colonic temperature elevation (deltaT) after treatment"
    ],
    "main_findings": "Experiment 1: A single intense 2450-MHz exposure (38 mW/g for 600 sec) did not reliably increase fetal mortality or morbidity versus controls, while cortisone increased stillborn and deformed fetuses. Experiment 2: Cortisone-treated sham-radiated dams had near-complete failure of pups to survive to weaning, and this cortisone-induced mortality was reliably reduced when dams were also exposed to microwave energy. Maze performance did not differ by radiation vs control overall, but offspring of cortisone-treated, radiated dams made reliably more errors.",
    "effect_direction": "mixed",
    "limitations": [
        "Outcomes and effects are reported in the context of co-exposure to cortisone; radiation-only effects may be difficult to isolate for some endpoints.",
        "Abstract does not report randomization/blinding procedures or detailed statistical estimates.",
        "Exposure described as a single intense dose; generalizability to other exposure levels/patterns is unclear from abstract."
    ],
    "evidence_strength": "low",
    "confidence": 0.7399999999999999911182158029987476766109466552734375,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "mouse",
        "pregnancy",
        "fetal irradiation",
        "microwave radiation",
        "2450 MHz",
        "SAR",
        "teratology",
        "fetal mortality",
        "cortisone",
        "survival to weaning",
        "reversal learning",
        "water maze",
        "thermal effects",
        "colonic temperature"
    ],
    "suggested_hubs": [
        {
            "slug": "who-icnirp",
            "weight": 0.200000000000000011102230246251565404236316680908203125,
            "reason": "Animal study of microwave exposure with thermal dosimetry relevance; potentially relevant to guideline discussions, though no policy content is provided."
        }
    ]
}

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