Gene expression profiles in white blood cells of volunteers exposed to a 50 Hz electromagnetic field.

Radiation research · 2012 · No effect · Moderate evidence

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No effectModerate evidencePaper 4509

Study snapshot

PublicationRadiation research · 2012

Study typerandomized_trial

Reported directionNo effect

Evidence ratingModerate

Abstract

Consistent and independently replicated laboratory evidence to support a causative relationship between environmental exposure to extremely low-frequency electromagnetic fields (EMFs) at power line frequencies and the associated increase in risk of childhood leukemia has not been obtained. In particular, although gene expression responses have been reported in a wide variety of cells, none has emerged as robust, widely replicated effects. DNA microarrays facilitate comprehensive searches for changes in gene expression without a requirement to select candidate responsive genes. To determine if gene expression changes occur in white blood cells of volunteers exposed to an ELF-EMF, each of 17 pairs of male volunteers age 20-30 was subjected either to a 50 Hz EMF exposure of 62.0 ± 7.1 μT for 2 h or to a sham exposure (0.21 ± 0.05 μT) at the same time (11:00 a.m. to 13:00 p.m.). The alternative regime for each volunteer was repeated on the following day and the two-day sequence was repeated 6 days later, with the exception that a null exposure (0.085 ± 0.01 μT) replaced the sham exposure. Five blood samples (10 ml) were collected at 2 h intervals from 9:00 to 17:00 with five additional samples during the exposure and sham or null exposure periods on each study day. RNA samples were pooled for the same time on each study day for the group of 17 volunteers that were subjected to the ELF-EMF exposure/sham or null exposure sequence and were analyzed on Illumina microarrays. Time courses for 16 mammalian genes previously reported to be responsive to ELF-EMF exposure, including immediate early genes, stress response, cell proliferation and apoptotic genes were examined in detail. No genes or gene sets showed consistent response profiles to repeated ELF-EMF exposures. A stress response was detected as a transient increase in plasma cortisol at the onset of either exposure or sham exposure on the first study day. The cortisol response diminished progressively on subsequent exposures or sham exposures, and was attributable to mild stress associated with the experimental protocol.

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 typerandomized_trial

Effect directionno_effect

PopulationMale volunteers age 20–30

Sample size34

ExposureELF · 0.05 MHz · 2 h

Evidence strengthModerateConfidence: 78% · Peer reviewed: yes

Main findings

In pooled RNA from white blood cells analyzed on Illumina microarrays, no genes or gene sets showed consistent response profiles to repeated 50 Hz ELF-EMF exposures compared with sham/null conditions. A transient increase in plasma cortisol occurred at the onset of either exposure or sham exposure on the first study day and was attributed to mild protocol-related stress, diminishing on subsequent sessions.

Outcomes measured

Gene expression in white blood cells (Illumina microarrays)
Expression time courses of 16 previously reported ELF-EMF-responsive genes
Plasma cortisol (stress response)

Limitations

Small sample size (17 pairs of volunteers)
RNA samples were pooled for analysis (may mask individual-level responses)
Study population limited to males aged 20–30 (limited generalizability)
Exposure duration was short (2 h) and focused on acute responses

View raw extracted JSON

{
  "study_type": "randomized_trial",
  "exposure": {
    "band": "ELF",
    "source": null,
    "frequency_mhz": 0.05,
    "sar_wkg": null,
    "duration": "2 h"
  },
  "population": "Male volunteers age 20–30",
  "sample_size": 34,
  "outcomes": [
    "Gene expression in white blood cells (Illumina microarrays)",
    "Expression time courses of 16 previously reported ELF-EMF-responsive genes",
    "Plasma cortisol (stress response)"
  ],
  "main_findings": "In pooled RNA from white blood cells analyzed on Illumina microarrays, no genes or gene sets showed consistent response profiles to repeated 50 Hz ELF-EMF exposures compared with sham/null conditions. A transient increase in plasma cortisol occurred at the onset of either exposure or sham exposure on the first study day and was attributed to mild protocol-related stress, diminishing on subsequent sessions.",
  "effect_direction": "no_effect",
  "limitations": [
    "Small sample size (17 pairs of volunteers)",
    "RNA samples were pooled for analysis (may mask individual-level responses)",
    "Study population limited to males aged 20–30 (limited generalizability)",
    "Exposure duration was short (2 h) and focused on acute responses"
  ],
  "evidence_strength": "moderate",
  "confidence": 0.78,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "extremely low-frequency",
    "ELF-EMF",
    "50 Hz",
    "white blood cells",
    "gene expression",
    "microarray",
    "Illumina",
    "cortisol",
    "sham exposure",
    "null exposure"
  ],
  "suggested_hubs": [
    {
      "slug": "occupational-exposure",
      "weight": 0.25,
      "reason": "Controlled exposure to power-frequency (50 Hz) magnetic fields relevant to some workplace settings."
    }
  ]
}

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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: 10.1667/rr2859.1
PubMed: 22856684

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