Biological effects of prolonged exposure to ELF electromagnetic fields in rats: III. 50 Hz electromagnetic fields.

Bioelectromagnetics · 1998 · Mixed · Low evidence

← Research stream

MixedLow evidencePaper 5396

Study snapshot

PublicationBioelectromagnetics · 1998

Study typeanimal

Reported directionMixed

Evidence ratingLow

Abstract

Groups of adult male Sprague Dawley rats (64 rats each) were exposed for 8 months to electromagnetic fields (EMF) of two different field strength combinations: 5microT - 1kV/m and 100microT - 5kV/m. A third group was sham exposed. Field exposure was 8 hrs/day for 5 days/week. Blood samples were collected for hematology determinations before the onset of exposure and at 12 week intervals. At sacrifice, liver, heart, mesenteric lymph nodes, bone marrow, and testes were collected for morphology and histology assessments, while the pineal gland and brain were collected for biochemical determinations. At both field strength combinations, no pathological changes were observed in animal growth rate, in morphology and histology of the collected tissue specimens (liver, heart, mesenteric lymph nodes, testes, bone marrow), and in serum chemistry. An increase in norepinephrine levels occurred in the pineal gland of rats exposed to the higher field strength. The major changes in the brain involved the opioid system in frontal cortex, parietal cortex, and hippocampus. From the present findings it may be hypothesized that EMF may cause alteration of some brain functions.

Machine Enhanced Logic

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

PopulationAdult male Sprague Dawley rats

Sample size192

ExposureELF · 0.05 MHz · 8 months; 8 hrs/day, 5 days/week

Evidence strengthLowConfidence: 74% · Peer reviewed: yes

Main findings

Rats exposed for 8 months to 50 Hz EMF at 5 µT–1 kV/m or 100 µT–5 kV/m showed no pathological changes in growth rate, tissue morphology/histology (liver, heart, mesenteric lymph nodes, testes, bone marrow), or serum chemistry. Norepinephrine levels increased in the pineal gland at the higher field strength, and brain changes were reported involving the opioid system in several regions.

Outcomes measured

Animal growth rate
Hematology
Morphology and histology (liver, heart, mesenteric lymph nodes, testes, bone marrow)
Serum chemistry
Pineal gland norepinephrine levels
Brain biochemical measures (opioid system in frontal cortex, parietal cortex, hippocampus)

Limitations

Only adult male rats were studied.
The abstract does not report quantitative effect sizes or statistical details for biochemical findings.
Exposure source/setup details beyond field strengths and schedule are not provided in the abstract.

View raw extracted JSON

{
  "study_type": "animal",
  "exposure": {
    "band": "ELF",
    "source": null,
    "frequency_mhz": 0.05,
    "sar_wkg": null,
    "duration": "8 months; 8 hrs/day, 5 days/week"
  },
  "population": "Adult male Sprague Dawley rats",
  "sample_size": 192,
  "outcomes": [
    "Animal growth rate",
    "Hematology",
    "Morphology and histology (liver, heart, mesenteric lymph nodes, testes, bone marrow)",
    "Serum chemistry",
    "Pineal gland norepinephrine levels",
    "Brain biochemical measures (opioid system in frontal cortex, parietal cortex, hippocampus)"
  ],
  "main_findings": "Rats exposed for 8 months to 50 Hz EMF at 5 µT–1 kV/m or 100 µT–5 kV/m showed no pathological changes in growth rate, tissue morphology/histology (liver, heart, mesenteric lymph nodes, testes, bone marrow), or serum chemistry. Norepinephrine levels increased in the pineal gland at the higher field strength, and brain changes were reported involving the opioid system in several regions.",
  "effect_direction": "mixed",
  "limitations": [
    "Only adult male rats were studied.",
    "The abstract does not report quantitative effect sizes or statistical details for biochemical findings.",
    "Exposure source/setup details beyond field strengths and schedule are not provided in the abstract."
  ],
  "evidence_strength": "low",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "ELF",
    "50 Hz",
    "rats",
    "Sprague Dawley",
    "microtesla",
    "kilovolt per meter",
    "pineal gland",
    "norepinephrine",
    "brain",
    "opioid system",
    "histology",
    "serum chemistry"
  ],
  "suggested_hubs": [
    {
      "slug": "occupational-exposure",
      "weight": 0.25,
      "reason": "Prolonged ELF exposure with specified µT and kV/m levels may be relevant to occupational-style exposure scenarios, though the study is in animals."
    }
  ]
}

AI can be wrong. Always verify against the paper.

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/(sici)1521-186x(1998)19:1<57::aid-bem7>3.0.co;2-3
PubMed: 9453708

Read the original paper →

Related papers

← Back to the Research Library