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Evaluation of genotoxicity of cell phone radiation in male and female rats and mice following subchronic exposure (NTP study)

2019 · Mixed · Moderate evidence

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MixedModerate evidencePaper 1661

After 19 weeks (rats) or 14 weeks (mice) of exposure to GSM or CDMA radiofrequency radiation, the comet assay showed significant increases in DNA damage in the frontal cortex of male mice (both modulations), leukocytes of female mice (CDMA only), and hippocam…

Study snapshot

Publicationmanual · 2019
Study typeanimal
Reported directionMixed
Evidence ratingModerate

Abstract

Evaluation of genotoxicity of cell phone radiation in male and female rats and mice following subchronic exposure (NTP study) Smith-Roe SL, Wyde ME, Stout MD, Winters JW, Hobbs CA, Shepard KG, Green AS, Kissling GE, Shockley KR, Tice RR, Bucher JR, Witt KL. Evaluation of the genotoxicity of cell phone radiofrequency radiation in male and female rats and mice following subchronic exposure. Environ Mol Mutagen. 2019 Oct 21. doi: 10.1002/em.22343. Abstract The National Toxicology Program tested two common radiofrequency radiation (RFR) modulations emitted by cellular telephones in a 2-year rodent cancer bioassay that included interim assessments of additional animals for genotoxicity endpoints. Male and female Hsd:Sprague Dawley SD rats and B6C3F1/N mice were exposed from gestation day 5 or postnatal day 35, respectively, to code division multiple access (CDMA) or global system for mobile (GSM) modulations over 18 h/day, at 10 min intervals, in reverberation chambers at specific absorption rates (SAR) of 1.5, 3, or 6 W/kg (rats, 900 MHz) or 2.5, 5, or 10 W/kg (mice, 1900 MHz).After 19 (rats) or 14 (mice) weeks of exposure, animals were examined for evidence of RFR-associated genotoxicity using two different measures. Using the alkaline (pH > 13) comet assay, DNA damage was assessed in cells from three brain regions, liver cells, and peripheral blood leukocytes; using the micronucleus assay, chromosomal damage was assessed in immature and mature peripheral blood erythrocytes. Results of the comet assay showed significant increases in DNA damage in the frontal cortex of male mice (both modulations), leukocytes of female mice (CDMA only), and hippocampus of male rats (CDMA only). Increases in DNA damage judged to be equivocal were observed in several other tissues of rats and mice. No significant increases in micronucleated red blood cells were observed in rats or mice. In conclusion, these results suggest that exposure to RFR is associated with an increase in DNA damage. ncbi.nlm.nih.gov Excerpts The NTP bioassay was designed to evaluate non-thermal effects of cell phone RFR exposure, which meant that body temperature could not change more than 1 C under our exposure conditions Therefore, we consider it unlikely that thermal effects were a confounding factor for our genetic toxicity tests, although more work in general is needed to clarify the thermal effects of RFR on different tissues, and the degree to which increases in body or tissue temperature affect genomic integrity. ... our results and the results of other experiments suggest that non-thermal exposure of cells or whole organisms to RFR may result in measurable genotoxic effects, despite varied and weak responses across studies overall (Brusick et al., 1998; Ruediger, 2009; Verschaeve et al., 2010). Induction of oxygen radicals or interference with DNA repair processes have been proposed as possible mechanisms by which RFR could cause DNA damage (Ruediger 2009; Yakymenko et al. 2015). ... NTP Technical Reports on the results of the 2-year cancer bioassay for exposure to RFR for rats (TR 595) and mice (TR 596) were finalized, peer reviewed, and made publicly available in 2018. The NTP concluded that results demonstrated clear evidence of carcinogenic activity of cell phone RFR (both modulations) based on incidences of malignant schwannomas of the heart in male rats. Malignant gliomas in the brain were also observed in male rats exposed to cell phone RFR and were considered to be related to exposure. Female rats exhibited malignant schwannomas of the heart and malignant gliomas, but incidences of these tumors were considered equivocal. The observation that cell phone RFR affects heart and brain tissue in Sprague Dawley rats after long-term exposure was replicated in a similar study (that used only the GSM modulation) by the Ramazzini Institute (Falcioni et al., 2018). The gliomas and schwannomas observed in rats are similar to the tumor types reported in some epidemiology studies to be associated with cell phone use. The NTP bioassay findings in mice, in which different organs were affected compared to rats, were considered equivocal.... The highest exposure of 6 W/kg in rats and 10 W/kg in mice, for a total of 9 h 10 min a day (achieved by cycling for 10 min on, 10 min off over 18 h 20 min), produced higher exposures than experienced by humans under normal cellular phone use conditions. Thus, whether the findings in the NTP animal studies (e.g. malignant gliomas in the brain and malignant schwannomas in the hearts of male rats; increased levels of DNA damage in hippocampal cells of male rats and the frontal cortex of male mice) indicate a potential for adverse health outcomes in humans remains a question. Because one of the most important questions prompted by our results concerns the mechanism(s) by which RFR might induce biological effects, follow-up studies by the NTP to investigate mechanisms of genetic damage associated with RFR exposure are underway.

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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 directionmixed
PopulationMale and female Hsd:Sprague Dawley SD rats and B6C3F1/N mice
Sample sizeNot supplied
ExposureRF · Subchronic exposure: 19 weeks (rats) or 14 weeks (mice); 18 h/day at 10 min intervals (10 min on/10 min off)
Evidence strengthModerateConfidence: 78% · Peer reviewed: yes

Main findings

After 19 weeks (rats) or 14 weeks (mice) of exposure to GSM or CDMA radiofrequency radiation, the comet assay showed significant increases in DNA damage in the frontal cortex of male mice (both modulations), leukocytes of female mice (CDMA only), and hippocampus of male rats (CDMA only), with additional equivocal increases in other tissues. No significant increases in micronucleated red blood cells were observed in rats or mice.

Outcomes measured

  • DNA damage (alkaline comet assay) in brain regions, liver, and peripheral blood leukocytes
  • Chromosomal damage (micronucleus assay) in immature and mature peripheral blood erythrocytes

Limitations

  • Sample size not reported in provided abstract/metadata
  • Some comet assay findings described as equivocal and responses varied by sex, species, tissue, and modulation
  • Micronucleus assay showed no significant increases despite comet assay DNA damage signals
View raw extracted JSON
{
  "study_type": "animal",
  "exposure": {
    "band": "RF",
    "source": "mobile phone",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": "Subchronic exposure: 19 weeks (rats) or 14 weeks (mice); 18 h/day at 10 min intervals (10 min on/10 min off)"
  },
  "population": "Male and female Hsd:Sprague Dawley SD rats and B6C3F1/N mice",
  "sample_size": null,
  "outcomes": [
    "DNA damage (alkaline comet assay) in brain regions, liver, and peripheral blood leukocytes",
    "Chromosomal damage (micronucleus assay) in immature and mature peripheral blood erythrocytes"
  ],
  "main_findings": "After 19 weeks (rats) or 14 weeks (mice) of exposure to GSM or CDMA radiofrequency radiation, the comet assay showed significant increases in DNA damage in the frontal cortex of male mice (both modulations), leukocytes of female mice (CDMA only), and hippocampus of male rats (CDMA only), with additional equivocal increases in other tissues. No significant increases in micronucleated red blood cells were observed in rats or mice.",
  "effect_direction": "mixed",
  "limitations": [
    "Sample size not reported in provided abstract/metadata",
    "Some comet assay findings described as equivocal and responses varied by sex, species, tissue, and modulation",
    "Micronucleus assay showed no significant increases despite comet assay DNA damage signals"
  ],
  "evidence_strength": "moderate",
  "confidence": 0.78,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "National Toxicology Program",
    "NTP",
    "radiofrequency radiation",
    "RFR",
    "cell phone",
    "GSM",
    "CDMA",
    "900 MHz",
    "1900 MHz",
    "specific absorption rate",
    "SAR",
    "rats",
    "mice",
    "comet assay",
    "micronucleus assay",
    "genotoxicity",
    "DNA damage"
  ],
  "suggested_hubs": [
    {
      "slug": "who-icnirp",
      "weight": 0.3,
      "reason": "NTP animal evidence on RF bioeffects/genotoxicity is relevant to major RF health risk assessments and 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: 10.1002/em.22343
PubMed: Not supplied

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