Occupational exposure to extremely low-frequency magnetic fields and the risk of ALS: A systematic review and meta-analysis

Bioelectromagnetics. · 2018 · Harm · Moderate evidence

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HarmModerate evidencePaper 2177

Study snapshot

PublicationBioelectromagnetics. · 2018

Study typemeta_analysis

Reported directionHarm

Evidence ratingModerate

Abstract

- Extremely Low Frequency Fields Occupational exposure to ELF magnetic fields and risk of ALS: systematic review and meta-analysis Huss A, Peters S, Vermeulen R. Occupational exposure to extremely low-frequency magnetic fields and the risk of ALS: A systematic review and meta-analysis. Bioelectromagnetics. doi:10.1002/bem.22104. Published online Jan 19, 2018. Abstract We performed a meta-analysis to examine associations of occupational exposure to extremely-low frequency magnetic fields (ELF-MF) with amyotrophic lateral sclerosis (ALS). Epidemiologic studies were identified in EMBASE and MEDLINE, in reference lists and a specialist database. We included studies that reported risk estimates of ALS in association with occupational ELF-MF exposure. Summary relative risks (RR) or odds ratios (OR) were obtained with random effect meta-analysis, and analyses were stratified by type of exposure assessment. This was done to evaluate whether observed heterogeneity between studies could be explained with differences in the way the exposure had been determined. We included 20 studies in our meta-analysis. Overall, studies reported a slightly increased risk of ALS in those exposed to higher levels of ELF-MF compared to lower levels with a summary RR (sRR) of 1.14 (95% Confidence Interval [CI] 1.00-1.30) and for workers in electrical occupations (sRR 1.41, CI 1.05-1.92), but with large heterogeneity between studies (I2 > 70%). Self- reported exposure or occupations determined from death certificates did not show increased risks. Highest- longest types of exposure translated into increased risks of ALS if the studies had evaluated the whole occupational history, in contrast to evaluating only few points in time (e.g., from census records); sRR were 1.89 (CI 1.31-2.73, I2 0%) and 1.06 (CI 0.75-1.57, I2 76%), respectively. In this meta-analysis, we observed an increased risk of ALS in workers occupationally exposed to ELF-MF. Results of studies depended on the quality of the exposure assessment. onlinelibrary.wiley.com

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AI evidence extraction

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Study typemeta_analysis

Effect directionharm

PopulationNot supplied

Sample size20

ExposureELF

Evidence strengthModerateConfidence: 70% · Peer reviewed: yes

Main findings

The meta-analysis of 20 studies found a slightly increased risk of ALS associated with higher occupational exposure to ELF magnetic fields, with a summary relative risk of 1.14 (95% CI 1.00-1.30). Electrical workers had a higher risk (sRR 1.41, CI 1.05-1.92). Studies with higher quality exposure assessment (whole occupational history) showed stronger associations (sRR 1.89, CI 1.31-2.73).

Outcomes measured

amyotrophic lateral sclerosis (ALS)

Limitations

Large heterogeneity between studies (I2 > 70%)
Risk estimates varied by exposure assessment method
Some exposure assessments based on self-report or death certificates showed no increased risk

View raw extracted JSON

{
  "study_type": "meta_analysis",
  "exposure": {
    "band": "ELF",
    "source": "occupational",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": null
  },
  "population": null,
  "sample_size": 20,
  "outcomes": [
    "amyotrophic lateral sclerosis (ALS)"
  ],
  "main_findings": "The meta-analysis of 20 studies found a slightly increased risk of ALS associated with higher occupational exposure to ELF magnetic fields, with a summary relative risk of 1.14 (95% CI 1.00-1.30). Electrical workers had a higher risk (sRR 1.41, CI 1.05-1.92). Studies with higher quality exposure assessment (whole occupational history) showed stronger associations (sRR 1.89, CI 1.31-2.73).",
  "effect_direction": "harm",
  "limitations": [
    "Large heterogeneity between studies (I2 > 70%)",
    "Risk estimates varied by exposure assessment method",
    "Some exposure assessments based on self-report or death certificates showed no increased risk"
  ],
  "evidence_strength": "moderate",
  "confidence": 0.7,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "ELF magnetic fields",
    "occupational exposure",
    "amyotrophic lateral sclerosis",
    "meta-analysis"
  ],
  "suggested_hubs": [
    {
      "slug": "occupational-exposure",
      "weight": 0.9,
      "reason": "Focus on occupational ELF magnetic field exposure and ALS risk"
    }
  ]
}

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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: 10.1002/bem.22104
PubMed: Not supplied

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