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

Health physics · 1984 · Harm · Low evidence

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HarmLow evidencePaper 5922

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 st…

Study snapshot

PublicationHealth physics · 1984
Study typeanimal
Reported directionHarm
Evidence ratingLow

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.

Machine Enhanced Logic

AI evidence extraction

Structured fields below were generated from the paper’s abstract and metadata to make the evidence easier to inspect. Automated extraction may be incomplete or incorrect; verify important details against the original paper.

Study typeanimal
Effect directionharm
PopulationPregnant female Sprague-Dawley (CD) rats and their fetuses
Sample size47
Exposuremicrowave · 2450 MHz · 6 W/kg · 100 min daily on gestation days 6–15 (one-time exposure also described for temperature change)
Evidence strengthLowConfidence: 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
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": 0.86,
  "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 and metadata and may be incomplete or incorrect. This material is for informational purposes and is not medical advice.

Identifiers and source

DOI: 10.1097/00004032-198403000-00004
PubMed: 6698781

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