Exposure to 60-Hz magnetic and electric fields at a Canadian electric utility.

Scandinavian journal of work, environment & health · 1996 · Unclear · Moderate evidence

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UnclearModerate evidencePaper 4202

Study snapshot

PublicationScandinavian journal of work, environment & health · 1996

Study typeexposure_assessment

Reported directionUnclear

Evidence ratingModerate

Abstract

OBJECTIVES: The purpose of this study was to estimate exposure to extremely low frequency (ELF) magnetic and electric fields in the Québec electrical utility Hydro-Quebec. METHODS: Personal exposures to ELF magnetic and electric fields were measured for workers randomly selected from 32 job categories at Hydro-Québec. Weekly arithmetic and geometric means, and other indices of exposure were estimated from 465 worker-weeks of data. RESULTS: By job category, the arithmetic means of the ELF magnetic field ranged from 0.09 to 2.36 microT. Those of the ELF electric field exposures ranged from 2.5 to 400 V.m-1. Within each field, correlations of either the arithmetic or geometric means with alternative indices, including an index of the time rate of change, were generally high (r > or = 0.8). Exceptions were the 20th percentile of the electric means and the proportion of time above 12.4 and 100 microT. The day-to-day variation of exposure was greater than the variation between workers. The median between-day and between-worker components of variance (as geometric standard deviations) by job category were 2.13 and 1.71 for magnetic fields (2.24 and 1.81 for electric fields). CONCLUSIONS: Substation workers, hydroelectric generating station operators, and cable splicers showed the highest arithmetic means for 60-Hz magnetic fields above 1 microT. For 60-Hz electric fields, forestry workers, equipment electricians in 735 kV substations, and distribution linemen (contact method) had arithmetic mean exposures greater than 100 W.m-1. Of the total variance in the logarithms of the weekly magnetic and electric field means, job category explained 49.6% and 59.5%, respectively.

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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 typeexposure_assessment

Effect directionunclear

PopulationWorkers at Hydro-Québec (Québec electrical utility) across 32 job categories

Sample sizeNot supplied

ExposureELF · 0.06 MHz · weekly personal measurements (465 worker-weeks)

Evidence strengthModerateConfidence: 78% · Peer reviewed: yes

Main findings

Personal weekly arithmetic mean ELF magnetic-field exposures by job category ranged from 0.09 to 2.36 microT, and electric-field exposures ranged from 2.5 to 400 V/m. Correlations between arithmetic/geometric means and alternative indices were generally high (r ≥ 0.8), with exceptions for the 20th percentile of electric means and the proportion of time above 12.4 and 100 microT. Day-to-day exposure variation exceeded variation between workers; job category explained 49.6% of variance in weekly magnetic-field means and 59.5% for electric-field means.

Outcomes measured

Personal exposure levels to 60-Hz magnetic fields (microT)
Personal exposure levels to 60-Hz electric fields (V/m)
Exposure variability (between-day and between-worker components of variance)
Correlation of mean exposure metrics with alternative indices (including time rate of change)
Proportion of variance in weekly means explained by job category

Limitations

Sample size (number of workers) not stated in abstract
Measurements summarized as worker-weeks; individual-level participation details not provided
Exposure metrics and thresholds referenced (eg, 12.4 and 100 microT) not fully defined in abstract

View raw extracted JSON

{
  "study_type": "exposure_assessment",
  "exposure": {
    "band": "ELF",
    "source": "occupational",
    "frequency_mhz": 0.06,
    "sar_wkg": null,
    "duration": "weekly personal measurements (465 worker-weeks)"
  },
  "population": "Workers at Hydro-Québec (Québec electrical utility) across 32 job categories",
  "sample_size": null,
  "outcomes": [
    "Personal exposure levels to 60-Hz magnetic fields (microT)",
    "Personal exposure levels to 60-Hz electric fields (V/m)",
    "Exposure variability (between-day and between-worker components of variance)",
    "Correlation of mean exposure metrics with alternative indices (including time rate of change)",
    "Proportion of variance in weekly means explained by job category"
  ],
  "main_findings": "Personal weekly arithmetic mean ELF magnetic-field exposures by job category ranged from 0.09 to 2.36 microT, and electric-field exposures ranged from 2.5 to 400 V/m. Correlations between arithmetic/geometric means and alternative indices were generally high (r ≥ 0.8), with exceptions for the 20th percentile of electric means and the proportion of time above 12.4 and 100 microT. Day-to-day exposure variation exceeded variation between workers; job category explained 49.6% of variance in weekly magnetic-field means and 59.5% for electric-field means.",
  "effect_direction": "unclear",
  "limitations": [
    "Sample size (number of workers) not stated in abstract",
    "Measurements summarized as worker-weeks; individual-level participation details not provided",
    "Exposure metrics and thresholds referenced (eg, 12.4 and 100 microT) not fully defined in abstract"
  ],
  "evidence_strength": "moderate",
  "confidence": 0.78,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "extremely low frequency",
    "ELF",
    "60-Hz",
    "magnetic field",
    "electric field",
    "occupational exposure",
    "personal monitoring",
    "utility workers",
    "Hydro-Québec",
    "job category",
    "exposure variability"
  ],
  "suggested_hubs": [
    {
      "slug": "occupational-exposure",
      "weight": 0.95,
      "reason": "Personal ELF magnetic and electric field exposure assessment in utility workers across job categories."
    }
  ]
}

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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: 10.5271/sjweh.162
PubMed: 9000308

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