Behavioral teratologic studies using microwave radiation: is there an increased risk from exposure to cellular phones and microwave ovens?

Abstract

The objective of the investigations presented in this review was to determine if there are adverse effects due to chronic prenatal microwave exposure in rats at term and/or alterations in neonatal and adult offspring psychophysiologic development and growth. Following the establishment of a nonhyperthermal power density level of microwave radiation, pregnant rats were exposed throughout pregnancy to continuous wave 915 MHz, 2450 MHz, or 6000 MHz radiation at power density levels of 10, 20, or 35 mW/cm2, respectively. Teratologic evaluation included the following parameters: maternal weight and weight gain; mean litter size; maternal organ weight and organ weight/body weight ratios; body weight ratios of brain, liver, kidneys, and ovaries; maternal peripheral blood parameters including hematocrit, hemoglobin, and white cell counts; number of resorptions and resorption rate; number of abnormalities and abnormality rate; mean term fetal weight. Mothers were rebred, and the second, nonexposed litters were evaluated for teratogenic effects. Exposed offspring were evaluated using the following perinatal and adult tests: eye opening, surface righting, negative geotaxis, auditory startle, air righting, open field, activity wheel, swimming, and forelimb hanging. Offspring were also monitored for weekly weight and weight gain. Animals exposed to 915 MHz did not exhibit any consistent significant alterations in any of the above parameters. Exposure to 2450 MHz resulted only in a significantly increased adult offspring activity level compared to nonexposed offspring. Offspring exposed to 6000 MHz radiation exhibited an initial slight, but significant, retardation in term weight, while mothers had a significantly reduced monocyte count. No changes in any of the other term parameters were observed. A few postnatal parameters were affected in offspring exposed to 6000 MHz. Weekly weights were lower in the exposed offspring, but they recovered by the fifth week. Eye opening was delayed, and there were changes in the water T-maze and open field performance levels. Several organ/body weight ratios differed from those of the control offspring. These results indicate that exposure to 6000 MHz radiation at this power density level may result in subtle long-term neurophysiologic alterations. However, in the absence of a hyperthermic state, the microwave frequencies tested, which included frequencies used in cellular phones and microwave ovens, do not induce a consistent, significant increase in reproductive risk as assessed by classical morphologic and postnatal psychophysiologic parameters.

AI evidence extraction

Main findings

In rat prenatal exposure studies at nonhyperthermal power density levels, 915 MHz exposure showed no consistent significant alterations across assessed teratologic or behavioral parameters. 2450 MHz exposure was associated with significantly increased adult offspring activity level. 6000 MHz exposure was associated with slight but significant term weight retardation, reduced maternal monocyte count, transiently lower weekly offspring weights (recovered by week 5), delayed eye opening, and changes in some behavioral tests and organ/body weight ratios; authors describe these as potentially subtle long-term neurophysiologic alterations. Overall, the review concludes no consistent, significant increase in reproductive risk under nonhyperthermic conditions for the tested microwave frequencies (including those used in cellular phones and microwave ovens).

Outcomes measured

• Teratologic outcomes (maternal weight/weight gain, litter size, organ weights/ratios, blood parameters incl. hematocrit/hemoglobin/WBC/monocytes, resorptions, abnormalities, term fetal weight)
• Neonatal/adult offspring psychophysiologic development (eye opening, surface righting, negative geotaxis, auditory startle, air righting, open field, activity wheel, swimming, forelimb hanging)
• Offspring growth (weekly weight and weight gain)

Limitations

• Sample size not reported in abstract
• Review scope and study selection methods not described in abstract
• Exposure metric reported as power density; SAR not provided
• Findings vary by frequency and endpoint; some effects described as subtle

Suggested hubs

• animal-studies (0.9)
  Prenatal microwave exposure experiments in rats and offspring outcomes.

{
    "study_type": "review",
    "exposure": {
        "band": "microwave",
        "source": "mobile phone, microwave oven",
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": "throughout pregnancy (prenatal, chronic)"
    },
    "population": "Pregnant rats and their offspring",
    "sample_size": null,
    "outcomes": [
        "Teratologic outcomes (maternal weight/weight gain, litter size, organ weights/ratios, blood parameters incl. hematocrit/hemoglobin/WBC/monocytes, resorptions, abnormalities, term fetal weight)",
        "Neonatal/adult offspring psychophysiologic development (eye opening, surface righting, negative geotaxis, auditory startle, air righting, open field, activity wheel, swimming, forelimb hanging)",
        "Offspring growth (weekly weight and weight gain)"
    ],
    "main_findings": "In rat prenatal exposure studies at nonhyperthermal power density levels, 915 MHz exposure showed no consistent significant alterations across assessed teratologic or behavioral parameters. 2450 MHz exposure was associated with significantly increased adult offspring activity level. 6000 MHz exposure was associated with slight but significant term weight retardation, reduced maternal monocyte count, transiently lower weekly offspring weights (recovered by week 5), delayed eye opening, and changes in some behavioral tests and organ/body weight ratios; authors describe these as potentially subtle long-term neurophysiologic alterations. Overall, the review concludes no consistent, significant increase in reproductive risk under nonhyperthermic conditions for the tested microwave frequencies (including those used in cellular phones and microwave ovens).",
    "effect_direction": "mixed",
    "limitations": [
        "Sample size not reported in abstract",
        "Review scope and study selection methods not described in abstract",
        "Exposure metric reported as power density; SAR not provided",
        "Findings vary by frequency and endpoint; some effects described as subtle"
    ],
    "evidence_strength": "low",
    "confidence": 0.7399999999999999911182158029987476766109466552734375,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "microwave radiation",
        "prenatal exposure",
        "rats",
        "teratology",
        "neurobehavioral development",
        "915 MHz",
        "2450 MHz",
        "6000 MHz",
        "nonhyperthermal",
        "power density"
    ],
    "suggested_hubs": [
        {
            "slug": "animal-studies",
            "weight": 0.90000000000000002220446049250313080847263336181640625,
            "reason": "Prenatal microwave exposure experiments in rats and offspring outcomes."
        }
    ]
}

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