Exposure time-dependent thermal effects of radiofrequency electromagnetic field exposure on the whole body of rats.

The Journal of toxicological sciences · 2016 · Mixed · Low evidence

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MixedLow evidencePaper 4821

Study snapshot

PublicationThe Journal of toxicological sciences · 2016

Study typeanimal

Reported directionMixed

Evidence ratingLow

Abstract

We investigated the thermal effects of radiofrequency electromagnetic fields (RF-EMFs) on the variation in core temperature and gene expression of some stress markers in rats. Sprague-Dawley rats were exposed to 2.14 GHz wideband code division multiple access (W-CDMA) RF signals at a whole-body averaged specific absorption rate (WBA-SAR) of 4 W/kg, which causes behavioral disruption in laboratory animals, and 0.4 W/kg, which is the limit for the occupational exposure set by the International Commission on Non-Ionizing Radiation Protection guideline. It is important to understand the possible in vivo effects derived from RF-EMF exposures at these intensities. Because of inadequate data on real-time core temperature analyses using free-moving animal and the association between stress and thermal effects of RF-EMF exposure, we analyzed the core body temperature under nonanesthetic condition during RF-EMF exposure. The results revealed that the core temperature increased by approximately 1.5°C compared with the baseline and reached a plateau till the end of RF-EMF exposure. Furthermore, we analyzed the gene expression of heat-shock proteins (Hsp) and heat-shock transcription factors (Hsf) family after RF-EMF exposure. At WBA-SAR of 4 W/kg, some Hsp and Hsf gene expression levels were significantly upregulated in the cerebral cortex and cerebellum following exposure for 6 hr/day but were not upregulated after exposure for 3 hr/day. On the other hand, there was no significant change in the core temperature and gene expression at WBA-SAR of 0.4 W/kg. Thus, 2.14-GHz RF-EMF exposure at WBA-SAR of 4 W/kg induced increases in the core temperature and upregulation of some stress markers, particularly in the cerebellum.

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Study typeanimal

Effect directionmixed

PopulationSprague-Dawley rats

Sample sizeNot supplied

ExposureRF · 2140 MHz · 4 W/kg · 3 hr/day or 6 hr/day (also reports 0.4 W/kg condition)

Evidence strengthLowConfidence: 78% · Peer reviewed: yes

Main findings

Rats exposed to 2.14 GHz W-CDMA RF at whole-body averaged SAR 4 W/kg showed an approximately 1.5°C increase in core temperature that reached a plateau during exposure. At 4 W/kg, some Hsp/Hsf genes were significantly upregulated in cerebral cortex and cerebellum after 6 hr/day exposure but not after 3 hr/day; at 0.4 W/kg there were no significant changes in core temperature or gene expression.

Outcomes measured

Core body temperature (real-time, nonanesthetized/free-moving)
Gene expression of heat-shock proteins (Hsp) and heat-shock transcription factors (Hsf) in cerebral cortex and cerebellum

Limitations

Sample size not reported in the abstract
Only two exposure levels reported (4 W/kg and 0.4 W/kg)
Gene expression outcomes limited to selected stress-marker families (Hsp/Hsf) and specific brain regions
Exposure duration comparison limited to 3 hr/day vs 6 hr/day (details of total study length not provided in abstract)

View raw extracted JSON

{
  "study_type": "animal",
  "exposure": {
    "band": "RF",
    "source": null,
    "frequency_mhz": 2140,
    "sar_wkg": 4,
    "duration": "3 hr/day or 6 hr/day (also reports 0.4 W/kg condition)"
  },
  "population": "Sprague-Dawley rats",
  "sample_size": null,
  "outcomes": [
    "Core body temperature (real-time, nonanesthetized/free-moving)",
    "Gene expression of heat-shock proteins (Hsp) and heat-shock transcription factors (Hsf) in cerebral cortex and cerebellum"
  ],
  "main_findings": "Rats exposed to 2.14 GHz W-CDMA RF at whole-body averaged SAR 4 W/kg showed an approximately 1.5°C increase in core temperature that reached a plateau during exposure. At 4 W/kg, some Hsp/Hsf genes were significantly upregulated in cerebral cortex and cerebellum after 6 hr/day exposure but not after 3 hr/day; at 0.4 W/kg there were no significant changes in core temperature or gene expression.",
  "effect_direction": "mixed",
  "limitations": [
    "Sample size not reported in the abstract",
    "Only two exposure levels reported (4 W/kg and 0.4 W/kg)",
    "Gene expression outcomes limited to selected stress-marker families (Hsp/Hsf) and specific brain regions",
    "Exposure duration comparison limited to 3 hr/day vs 6 hr/day (details of total study length not provided in abstract)"
  ],
  "evidence_strength": "low",
  "confidence": 0.78,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "radiofrequency electromagnetic fields",
    "RF-EMF",
    "2.14 GHz",
    "W-CDMA",
    "whole-body averaged SAR",
    "thermal effects",
    "core temperature",
    "heat-shock proteins",
    "Hsp",
    "heat-shock transcription factors",
    "Hsf",
    "cerebellum",
    "cerebral cortex",
    "rats"
  ],
  "suggested_hubs": [
    {
      "slug": "occupational-exposure",
      "weight": 0.55,
      "reason": "Includes an exposure level described as the ICNIRP occupational limit (0.4 W/kg WBA-SAR) and compares effects at that level."
    },
    {
      "slug": "who-icnirp",
      "weight": 0.45,
      "reason": "Explicitly references ICNIRP occupational exposure guideline limit."
    }
  ]
}

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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: 10.2131/jts.41.655
PubMed: 27665775

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