Exposure of rats to 425-MHz (cW) radiofrequency radiation: effects on lymphocytes.

Abstract

Four experiments were performed in which six pregnant rats were exposed from day 12 of pregnancy to parturition, for 4 hours a day in a temperature-controlled environment, to 425-MHz (CW) radiation, using a multimode rectangular strip transmission line. Four male pups born to each dam were subsequently irradiated under the same RF exposure condition for 20-21 days of age (2 pups) and 40-41 days of age (2 pups). Specific absorption rates (SARs) for rats of different ages were determined by twin-well calorimetry as well as from calculations of power measurements of incident, reflected, and transmitted energy. Values of SARs between 3.1 and 6.7 mW/g were obtained for rats so exposed at 425 MHz. At selected times, rats were weighed to determine if the irradiation affected growth. Two rats from each litter (4 pups) were euthanized at 20-21 and two at 40-41 days of age and blood was obtained for complete blood counts. The in vitro blastogenic response of blood and lymph-node lymphocytes was measured by 3H-thymidine incorporation into DNA following stimulation of cells with T- or B-lymphocyte mitogens. No difference was observed in the weights of irradiated compared with sham-irradiated rats. No consistent change in the peripheral blood picture was observed between irradiated and sham-irradiated rats. Significant increases in the response of lymph-node but not of blood lymphocytes from irradiated rats following stimulation with mitogens was observed in two of four experiments. These changes were observed for both T- and B-lymphocytes. In another experiment at the same frequency, six pregnant rats were irradiated for 16 hours daily from day 6 through day 19 of pregnancy. The pups born to these dams were not subsequently irradiated. These rats, born to irradiated dams, showed a similar increased response of node but not of blood lymphocytes to T-cell mitogens at 42 days of age. These results indicate that exposure to 425-MHz microwave radiation, under the conditions described, may lead to increased responsiveness of node lymphocytes to in vitro stimulation by mitogen.

AI evidence extraction

Main findings

SAR values between 3.1 and 6.7 mW/g were reported for 425 MHz exposure. No differences in weight were observed between irradiated and sham-irradiated rats, and no consistent changes were seen in peripheral blood counts. Significant increases in mitogen-stimulated lymph-node (but not blood) lymphocyte responses were observed in two of four experiments; a separate prenatal-only exposure experiment also reported increased lymph-node response to T-cell mitogens at 42 days of age.

Outcomes measured

• Growth/weight
• Complete blood counts (peripheral blood picture)
• In vitro lymphocyte blastogenic response (3H-thymidine incorporation) of blood lymphocytes
• In vitro lymphocyte blastogenic response (3H-thymidine incorporation) of lymph-node lymphocytes
• T- and B-lymphocyte mitogen responses

Limitations

• Sample size not fully reported in abstract (number of dams given, but total pups analyzed per group and sham group sizes not specified).
• Effects on lymph-node lymphocytes were not consistent across all experiments (reported in 2 of 4 experiments).
• Exposure duration for pups described by age windows, but exact exposure schedule/number of days not fully specified in abstract.

Suggested hubs

• animal-studies (0.9)
  Controlled RF exposure experiments in pregnant rats and offspring with immune outcomes.
• rf-immunology (0.75)
  Assessed lymphocyte mitogen responses in blood and lymph-node cells after RF exposure.

{
    "study_type": "animal",
    "exposure": {
        "band": "RF",
        "source": null,
        "frequency_mhz": 425,
        "sar_wkg": null,
        "duration": "Pregnant rats: 4 h/day from gestation day 12 to parturition (temperature-controlled); pups: irradiated under same conditions at ages 20–21 days (2 pups/dam) and 40–41 days (2 pups/dam) for unspecified number of days. Separate experiment: pregnant rats 16 h/day from gestation day 6 to day 19; pups not subsequently irradiated."
    },
    "population": "Pregnant rats and male rat pups (offspring)",
    "sample_size": null,
    "outcomes": [
        "Growth/weight",
        "Complete blood counts (peripheral blood picture)",
        "In vitro lymphocyte blastogenic response (3H-thymidine incorporation) of blood lymphocytes",
        "In vitro lymphocyte blastogenic response (3H-thymidine incorporation) of lymph-node lymphocytes",
        "T- and B-lymphocyte mitogen responses"
    ],
    "main_findings": "SAR values between 3.1 and 6.7 mW/g were reported for 425 MHz exposure. No differences in weight were observed between irradiated and sham-irradiated rats, and no consistent changes were seen in peripheral blood counts. Significant increases in mitogen-stimulated lymph-node (but not blood) lymphocyte responses were observed in two of four experiments; a separate prenatal-only exposure experiment also reported increased lymph-node response to T-cell mitogens at 42 days of age.",
    "effect_direction": "mixed",
    "limitations": [
        "Sample size not fully reported in abstract (number of dams given, but total pups analyzed per group and sham group sizes not specified).",
        "Effects on lymph-node lymphocytes were not consistent across all experiments (reported in 2 of 4 experiments).",
        "Exposure duration for pups described by age windows, but exact exposure schedule/number of days not fully specified in abstract."
    ],
    "evidence_strength": "low",
    "confidence": 0.7800000000000000266453525910037569701671600341796875,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "425 MHz",
        "continuous wave (CW)",
        "radiofrequency radiation",
        "microwave",
        "SAR",
        "pregnancy exposure",
        "rat pups",
        "lymphocytes",
        "lymph node",
        "blastogenic response",
        "mitogens",
        "T cells",
        "B cells",
        "3H-thymidine incorporation"
    ],
    "suggested_hubs": [
        {
            "slug": "animal-studies",
            "weight": 0.90000000000000002220446049250313080847263336181640625,
            "reason": "Controlled RF exposure experiments in pregnant rats and offspring with immune outcomes."
        },
        {
            "slug": "rf-immunology",
            "weight": 0.75,
            "reason": "Assessed lymphocyte mitogen responses in blood and lymph-node cells after RF exposure."
        }
    ]
}

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