Absence of acute ocular damage in humans after prolonged exposure to intense RF EMF.

Physics in medicine and biology · 2016 · No effect · Low evidence

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No effectLow evidencePaper 4720

Study snapshot

PublicationPhysics in medicine and biology · 2016

Study typeother

Reported directionNo effect

Evidence ratingLow

Abstract

The eye is considered to be a critical organ when determining safety standards for radio frequency (RF) radiation. Experimental data obtained using animals showed that RF heating of the eye, particularly over a specific threshold, can induce cataracts. During the treatment of cancer in the head and neck by hyperthermia, the eyes receive a considerable dose of RF radiation due to stray radiation from the prolonged (60 min) and intense exposure at 434 MHz of this region. In the current study, we verified the exposure guidelines for humans by determining the association between the electromagnetic and thermal dose in the eyes with the reported ocular effects. We performed a simulation study to retrospectively assess the specific absorption rate (SAR) and temperature increase in the eyes of 16 selected patients (encompassing a total of 74 treatment sessions) whose treatment involved high power delivery as well as a minimal distance between the tumor site and the eye. Our results show that the basic restrictions on the peak 10 g spatial-averaged SAR (10 W kg(-1)) and peak tissue temperature increase (1 °C) are exceeded by up to 10.4 and 4.6 times, on average, and by at least 6.2 and 1.8 times when considering the lower limit of the 95% confidence interval. Evaluation of the acute effects according to patients' feedback (all patients), the common toxicity criteria scores (all patients) and an ophthalmology investigation (one patient with the highest exposure) revealed no indication of any serious acute ocular effect, even though the eyes were exposed to high electromagnetic fields, leading to a high thermal dose. We also found that, although there is a strong correlation (R (2) = 0.88) between the predicted induced SAR and temperature in the eye, there are large uncertainties regarding the temperature-SAR relationship. Given this large uncertainty (129%) compared with the uncertainty of 3D temperature simulations (61%), we recommend using temperature simulations as a dosimetric measure in electromagnetic exposure risk assessments.

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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 typeother

Effect directionno_effect

Population16 selected head and neck cancer patients receiving hyperthermia treatment

Sample size16

ExposureRF · 434 MHz · prolonged (60 min) exposure; 74 treatment sessions across patients

Evidence strengthLowConfidence: 78% · Peer reviewed: yes

Main findings

Retrospective simulations in 16 patients (74 sessions) predicted that peak 10 g SAR and peak tissue temperature increase in the eyes exceeded guideline basic restrictions on average (up to 10.4× for SAR and 4.6× for temperature increase). Despite high predicted electromagnetic and thermal dose, evaluation of acute effects via patient feedback, toxicity criteria scores, and an ophthalmology investigation in the highest-exposure patient found no indication of serious acute ocular effects. Predicted SAR and temperature were strongly correlated (R^2=0.88), but the temperature–SAR relationship had large uncertainty (129%), leading the authors to recommend temperature simulations for dosimetry in risk assessment.

Outcomes measured

Acute ocular effects (patient feedback)
Acute ocular effects (common toxicity criteria scores)
Ophthalmology investigation (one patient)
Predicted eye SAR (peak 10 g spatial-averaged)
Predicted eye temperature increase
Correlation between predicted SAR and temperature (R^2)
Uncertainty in temperature-SAR relationship

Limitations

Retrospective simulation study (not direct measurement of SAR/temperature in the eye)
Small sample (16 patients) and selected high-exposure cases
Ophthalmology investigation reported for only one patient
Assessed acute effects; long-term/chronic ocular outcomes not described
Large uncertainty reported for the temperature–SAR relationship

View raw extracted JSON

{
  "study_type": "other",
  "exposure": {
    "band": "RF",
    "source": "medical hyperthermia (head and neck cancer treatment; stray RF exposure to eyes)",
    "frequency_mhz": 434,
    "sar_wkg": null,
    "duration": "prolonged (60 min) exposure; 74 treatment sessions across patients"
  },
  "population": "16 selected head and neck cancer patients receiving hyperthermia treatment",
  "sample_size": 16,
  "outcomes": [
    "Acute ocular effects (patient feedback)",
    "Acute ocular effects (common toxicity criteria scores)",
    "Ophthalmology investigation (one patient)",
    "Predicted eye SAR (peak 10 g spatial-averaged)",
    "Predicted eye temperature increase",
    "Correlation between predicted SAR and temperature (R^2)",
    "Uncertainty in temperature-SAR relationship"
  ],
  "main_findings": "Retrospective simulations in 16 patients (74 sessions) predicted that peak 10 g SAR and peak tissue temperature increase in the eyes exceeded guideline basic restrictions on average (up to 10.4× for SAR and 4.6× for temperature increase). Despite high predicted electromagnetic and thermal dose, evaluation of acute effects via patient feedback, toxicity criteria scores, and an ophthalmology investigation in the highest-exposure patient found no indication of serious acute ocular effects. Predicted SAR and temperature were strongly correlated (R^2=0.88), but the temperature–SAR relationship had large uncertainty (129%), leading the authors to recommend temperature simulations for dosimetry in risk assessment.",
  "effect_direction": "no_effect",
  "limitations": [
    "Retrospective simulation study (not direct measurement of SAR/temperature in the eye)",
    "Small sample (16 patients) and selected high-exposure cases",
    "Ophthalmology investigation reported for only one patient",
    "Assessed acute effects; long-term/chronic ocular outcomes not described",
    "Large uncertainty reported for the temperature–SAR relationship"
  ],
  "evidence_strength": "low",
  "confidence": 0.78,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "radiofrequency",
    "RF EMF",
    "eye",
    "ocular effects",
    "cataract",
    "hyperthermia",
    "head and neck cancer",
    "434 MHz",
    "specific absorption rate",
    "SAR",
    "temperature increase",
    "dosimetry",
    "exposure guidelines"
  ],
  "suggested_hubs": [
    {
      "slug": "who-icnirp",
      "weight": 0.6,
      "reason": "Study explicitly evaluates exceedance of basic restrictions/exposure guidelines using SAR and temperature criteria."
    },
    {
      "slug": "occupational-exposure",
      "weight": 0,
      "reason": null
    }
  ]
}

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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: 10.1088/0031-9155/61/2/488
PubMed: 26682777

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