Do GSM 900MHz signals affect cerebral blood circulation? A near-infrared spectrophotometry study.

Optics express · 2006 · Mixed · Low evidence

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MixedLow evidencePaper 5123

Study snapshot

PublicationOptics express · 2006

Study typerandomized_trial

Reported directionMixed

Evidence ratingLow

Abstract

Effects of GSM 900MHz signals (EMF) typical for a handheld mobile phone on the cerebral blood circulation were investigated using near-infrared spectrophotometry (NIRS) in a three armed (12W/kg, 1.2W/kg, sham), double blind, randomized crossover trial in 16 healthy volunteers. During exposure we observed borderline significant short term responses of oxyhemoglobin and deoxyhemoglobin concentration, which correspond to a decrease of cerebral blood flow and volume and were smaller than regular physiological changes. Due to the relatively high number of statistical tests, these responses may be spurious and require further studies. There was no detectable dose-response relation or long term response within 20min. The detection limit was a fraction of the regular physiological changes elicited by functional activation. Compared to previous studies using PET, NIRS provides a much higher time resolution, which allowed investigating the short term effects efficiently, noninvasively, without the use of radioactive tracers and with high sensitivity.

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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 typerandomized_trial

Effect directionmixed

Population16 healthy volunteers

Sample size16

ExposureRF · 900 MHz · 12 W/kg · 20 min

Evidence strengthLowConfidence: 78% · Peer reviewed: yes

Main findings

In a double-blind randomized crossover trial with GSM 900 MHz exposure (12 W/kg, 1.2 W/kg, sham), borderline-significant short-term changes in oxyhemoglobin and deoxyhemoglobin were observed during exposure, corresponding to decreased cerebral blood flow and volume and smaller than regular physiological changes. The authors note these responses may be spurious due to multiple statistical tests; no detectable dose-response relationship or long-term response within 20 minutes was found.

Outcomes measured

Cerebral blood circulation (cerebral blood flow and volume inferred from oxyhemoglobin/deoxyhemoglobin via NIRS)
Oxyhemoglobin concentration
Deoxyhemoglobin concentration

Limitations

Small sample size (n=16)
Borderline significant findings with a relatively high number of statistical tests; authors state responses may be spurious
No detectable dose-response relation
No long-term response detected within 20 minutes (limited follow-up duration)

View raw extracted JSON

{
  "study_type": "randomized_trial",
  "exposure": {
    "band": "RF",
    "source": "mobile phone",
    "frequency_mhz": 900,
    "sar_wkg": 12,
    "duration": "20 min"
  },
  "population": "16 healthy volunteers",
  "sample_size": 16,
  "outcomes": [
    "Cerebral blood circulation (cerebral blood flow and volume inferred from oxyhemoglobin/deoxyhemoglobin via NIRS)",
    "Oxyhemoglobin concentration",
    "Deoxyhemoglobin concentration"
  ],
  "main_findings": "In a double-blind randomized crossover trial with GSM 900 MHz exposure (12 W/kg, 1.2 W/kg, sham), borderline-significant short-term changes in oxyhemoglobin and deoxyhemoglobin were observed during exposure, corresponding to decreased cerebral blood flow and volume and smaller than regular physiological changes. The authors note these responses may be spurious due to multiple statistical tests; no detectable dose-response relationship or long-term response within 20 minutes was found.",
  "effect_direction": "mixed",
  "limitations": [
    "Small sample size (n=16)",
    "Borderline significant findings with a relatively high number of statistical tests; authors state responses may be spurious",
    "No detectable dose-response relation",
    "No long-term response detected within 20 minutes (limited follow-up duration)"
  ],
  "evidence_strength": "low",
  "confidence": 0.78,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "GSM",
    "900 MHz",
    "RF-EMF",
    "mobile phone",
    "near-infrared spectrophotometry",
    "NIRS",
    "cerebral blood flow",
    "oxyhemoglobin",
    "deoxyhemoglobin",
    "double blind",
    "randomized crossover",
    "sham"
  ],
  "suggested_hubs": [
    {
      "slug": "mobile-phones-rf",
      "weight": 0.9,
      "reason": "GSM 900 MHz signals typical for a handheld mobile phone; sham-controlled crossover exposure."
    }
  ]
}

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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: 10.1364/oe.14.006128
PubMed: 19516785

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