Lack of promoting effects of chronic exposure to 1.95-GHz W-CDMA signals for IMT-2000 cellular system on development of N-ethylnitrosourea-induced central nervous system tumors in F344 rats.

Bioelectromagnetics · 2007 · No effect · Moderate evidence

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No effectModerate evidencePaper 5064

Study snapshot

PublicationBioelectromagnetics · 2007

Study typeanimal

Reported directionNo effect

Evidence ratingModerate

Abstract

The present study was performed to evaluate effects of a 2-year exposure to an electromagnetic near-field (EMF) equivalent to that generated by cellular phones on tumor development in the central nervous system (CNS) of rats. For this purpose, pregnant F344 rats were given a single administration of N-ethylnitrosourea (ENU) on gestational day 18. A total of 500 pups were divided into five groups, each composed of 50 males and 50 females: Group 1, untreated controls; Group 2, ENU alone; Groups 3 to 5, ENU + EMF (sham exposure and two exposure levels). A 1.95-GHz wide-band code division multiple access (W-CDMA) signal, which is a feature of the International Mobile Telecommunication 2000 (IMT-2000) cellular system was employed for exposure of the rat head starting from 5 weeks of age, 90 min a day, 5 days a week, for 104 weeks. Brain average specific absorption rates (SARs) were designed to be .67 and 2.0 W/kg for low and high exposures, respectively. The incidence and numbers of brain tumors in female rats exposed to 1.95-GHz W-CDMA signals showed tendencies to increase but without statistical significance. Overall, no significant increase in incidences or numbers, either in the males or females, was detected in the EMF-exposed groups. In addition, no clear changes in tumor types in the brain were evident. Thus, under the present experimental conditions, exposure of heads of rats to 1.95-GHz W-CDMA signals for IMT-2000 for a 2-year period was not demonstrated to accelerate or otherwise affect ENU-initiated brain tumorigenesis.

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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 directionno_effect

PopulationPregnant F344 rats (offspring/pups followed)

Sample size500

ExposureRF · 1950 MHz · 2 W/kg · 90 min/day, 5 days/week, for 104 weeks (starting at 5 weeks of age)

Evidence strengthModerateConfidence: 78% · Peer reviewed: yes

Main findings

Across 2 years of head exposure to 1.95-GHz W-CDMA signals (brain-average SARs 0.67 or 2.0 W/kg), no statistically significant increase in incidences or numbers of ENU-initiated brain tumors was detected in male or female rats compared with controls. Female rats showed non-significant tendencies toward increased incidence and numbers, and no clear changes in tumor types were observed.

Outcomes measured

Incidence of central nervous system (brain) tumors
Number of brain tumors
Brain tumor types

Limitations

Female rats showed non-significant tendencies toward increased tumor incidence/numbers (unclear biological significance).
Tumors were chemically initiated with N-ethylnitrosourea (ENU), so findings address promotion/acceleration of initiated tumorigenesis rather than de novo tumor induction.

View raw extracted JSON

{
  "study_type": "animal",
  "exposure": {
    "band": "RF",
    "source": "mobile phone (near-field, head exposure)",
    "frequency_mhz": 1950,
    "sar_wkg": 2,
    "duration": "90 min/day, 5 days/week, for 104 weeks (starting at 5 weeks of age)"
  },
  "population": "Pregnant F344 rats (offspring/pups followed)",
  "sample_size": 500,
  "outcomes": [
    "Incidence of central nervous system (brain) tumors",
    "Number of brain tumors",
    "Brain tumor types"
  ],
  "main_findings": "Across 2 years of head exposure to 1.95-GHz W-CDMA signals (brain-average SARs 0.67 or 2.0 W/kg), no statistically significant increase in incidences or numbers of ENU-initiated brain tumors was detected in male or female rats compared with controls. Female rats showed non-significant tendencies toward increased incidence and numbers, and no clear changes in tumor types were observed.",
  "effect_direction": "no_effect",
  "limitations": [
    "Female rats showed non-significant tendencies toward increased tumor incidence/numbers (unclear biological significance).",
    "Tumors were chemically initiated with N-ethylnitrosourea (ENU), so findings address promotion/acceleration of initiated tumorigenesis rather than de novo tumor induction."
  ],
  "evidence_strength": "moderate",
  "confidence": 0.78,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "1.95 GHz",
    "W-CDMA",
    "IMT-2000",
    "cellular phone",
    "near-field exposure",
    "specific absorption rate",
    "SAR",
    "F344 rats",
    "N-ethylnitrosourea",
    "ENU",
    "central nervous system tumors",
    "brain tumors",
    "chronic exposure"
  ],
  "suggested_hubs": [
    {
      "slug": "mobile-phones-rf",
      "weight": 0.9,
      "reason": "Near-field head exposure equivalent to cellular phone signals (1.95-GHz W-CDMA) with SAR reporting."
    },
    {
      "slug": "animal-carcinogenicity",
      "weight": 0.85,
      "reason": "Two-year rat study assessing effects on brain tumor development."
    }
  ]
}

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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/bem.20324
PubMed: 17516507

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