Decreased body weight in fetal rats after irradiation with 2450-MHz (CW) microwaves.

PAPER pubmed Health physics 1984 Animal study Effect: harm Evidence: Low

Read original paper → DOI: 10.1097/00004032-198403000-00004 PMID: 6698781 Evidence Lab

Abstract

Female Sprague-Dawley (CD) rats were exposed to 2450-MHz (CW) microwave radiation at incident power densities of 0 or 40 mW/cm2 (SAR = 6.0 W/kg) for 100 min daily on the sixth through 15th day of gestation. One-time exposure to the same conditions increased average colonic temperatures 2 degrees C at the end of irradiation in pregnant rats of similar size. There were 23 sham-irradiated and 24 microwave-irradiated females. When these groups were compared on the 21st day of gestation, no significant differences were found in pregnancy rates; in the numbers of live, dead or total fetuses; nor in the incidences of external, visceral or skeletal anomalies or variations. However, mean fetal body weight was significantly (p = 0.0008) lower after microwave irradiation and was 9% less than that of sham-irradiated litters. Sternal ossification was also significantly delayed in the microwave-irradiated fetuses (p = 0.007). It is concluded that even though a change in the malformation rate is not effected in rats, a fetotoxic effect does occur due to microwave-exposure conditions which raise maternal rectal temperatures to approx. 40 degrees C and produce a specific absorption rate (SAR) greater than or equal to 6 W/kg in the dam.

AI evidence extraction

At a glance

Study type

Animal study

Effect direction

harm

Population

Pregnant female Sprague-Dawley (CD) rats and their fetuses

Sample size

Exposure

microwave · 2450 MHz · 6 W/kg · 100 min daily on gestation days 6–15 (one-time exposure also described for temperature change)

Evidence strength

Low

Confidence: 86% · Peer-reviewed: yes

Main findings

Compared with sham irradiation (0 mW/cm2), exposure to 2450-MHz continuous-wave microwaves at 40 mW/cm2 (SAR 6.0 W/kg) for 100 min/day on gestation days 6–15 produced significantly lower mean fetal body weight (9% lower; p=0.0008) and significantly delayed sternal ossification (p=0.007) on gestation day 21. No significant differences were reported for pregnancy rates, numbers of live/dead/total fetuses, or incidences of external, visceral, or skeletal anomalies/variations.

Outcomes measured

pregnancy rate
number of live fetuses
number of dead fetuses
total fetuses
external anomalies/variations
visceral anomalies/variations
skeletal anomalies/variations
fetal body weight
sternal ossification delay
maternal colonic/rectal temperature change

Limitations

Mechanistic attribution to heating is suggested but not experimentally separated from non-thermal effects in the abstract
Only one exposure level (40 mW/cm2; SAR 6 W/kg) is described
Details on randomization/blinding and litter-level statistical handling are not provided in the abstract

Suggested hubs

who-icnirp (0.25)
Animal study reports effects at SAR 6 W/kg with maternal temperature elevation, relevant to exposure guideline discussions.

View raw extracted JSON

{
    "study_type": "animal",
    "exposure": {
        "band": "microwave",
        "source": null,
        "frequency_mhz": 2450,
        "sar_wkg": 6,
        "duration": "100 min daily on gestation days 6–15 (one-time exposure also described for temperature change)"
    },
    "population": "Pregnant female Sprague-Dawley (CD) rats and their fetuses",
    "sample_size": 47,
    "outcomes": [
        "pregnancy rate",
        "number of live fetuses",
        "number of dead fetuses",
        "total fetuses",
        "external anomalies/variations",
        "visceral anomalies/variations",
        "skeletal anomalies/variations",
        "fetal body weight",
        "sternal ossification delay",
        "maternal colonic/rectal temperature change"
    ],
    "main_findings": "Compared with sham irradiation (0 mW/cm2), exposure to 2450-MHz continuous-wave microwaves at 40 mW/cm2 (SAR 6.0 W/kg) for 100 min/day on gestation days 6–15 produced significantly lower mean fetal body weight (9% lower; p=0.0008) and significantly delayed sternal ossification (p=0.007) on gestation day 21. No significant differences were reported for pregnancy rates, numbers of live/dead/total fetuses, or incidences of external, visceral, or skeletal anomalies/variations.",
    "effect_direction": "harm",
    "limitations": [
        "Mechanistic attribution to heating is suggested but not experimentally separated from non-thermal effects in the abstract",
        "Only one exposure level (40 mW/cm2; SAR 6 W/kg) is described",
        "Details on randomization/blinding and litter-level statistical handling are not provided in the abstract"
    ],
    "evidence_strength": "low",
    "confidence": 0.85999999999999998667732370449812151491641998291015625,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "2450 MHz",
        "microwave",
        "continuous wave",
        "CW",
        "pregnancy",
        "gestation",
        "rat",
        "fetal weight",
        "ossification",
        "SAR",
        "hyperthermia",
        "teratology"
    ],
    "suggested_hubs": [
        {
            "slug": "who-icnirp",
            "weight": 0.25,
            "reason": "Animal study reports effects at SAR 6 W/kg with maternal temperature elevation, relevant to exposure guideline discussions."
        }
    ]
}

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AI-extracted fields are generated from the abstract/metadata and may be incomplete or incorrect. This content is for informational purposes only and is not medical advice.

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