Occupational Exposure to Extremely Low-Frequency Magnetic Fields and Risk of Amyotrophic Lateral Sclerosis: Results of a Feasibility Study for a Pooled Analysis of Original Data

2021 · Unclear · Insufficient evidence

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UnclearInsufficient evidencePaper 1204

Study snapshot

Publicationmanual · 2021

Study typereview

Reported directionUnclear

Evidence ratingInsufficient

Abstract

Occupational Exposure to Extremely Low-Frequency Magnetic Fields and Risk of Amyotrophic Lateral Sclerosis: Results of a Feasibility Study for a Pooled Analysis of Original Data Dan Baaken, Dagmar Dechent, Maria Blettner, Sarah Drießen, Hiltrud Merzenich. Occupational Exposure to Extremely Low-Frequency Magnetic Fields and Risk of Amyotrophic Lateral Sclerosis: Results of a Feasibility Study for a Pooled Analysis of Original Data. Bioelectromagnetics. 2021 Mar 25. doi: 10.1002/bem.22335. Abstract Previous meta-analyses have suggested an increased risk of amyotrophic lateral sclerosis (ALS) associated with occupational exposure to extremely low-frequency magnetic fields (ELF-MF). However, results should be interpreted with caution since studies were methodologically heterogeneous. Here, we assessed the feasibility of a pooling study to harmonize and re-analyze available original data. A systematic literature search was conducted. Published epidemiological studies were identified in PubMed and EMF-Portal from literature databases' inception dates until January 2019. The characteristics of all studies were described, including exposure metrics, exposure categories, and confounders. A survey among the principal investigators (PI) was carried out to assess their willingness to provide their original data. The statistical power of a pooling study was evaluated. We identified 15 articles published between 1997 and 2019. Studies differed in terms of outcome, study population, exposure assessment, and exposure metrics. Most studies assessed ELF-MF as average magnetic flux density per working day; however, exposure categories varied widely. The pattern of adjustment for confounders was heterogeneous between studies, with age, sex, and socioeconomic status being most frequent. Eight PI expressed their willingness to provide original data. A relative risk of ≥1.14 for ALS and occupational exposure to ELF-MF can be detected with a power of more than 80% in a pooled study. The pooling of original data is recommended and could contribute to a better understanding of ELF-MF in the etiology of ALS based on a large database and reduced heterogeneity due to a standardized analysis protocol with harmonized exposure metrics and exposure categories. Open access paper: onlinelibrary.wiley.com

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 typereview

Effect directionunclear

PopulationNot supplied

Sample sizeNot supplied

ExposureELF

Evidence strengthInsufficientConfidence: 74% · Peer reviewed: yes

Main findings

This feasibility study identified 15 epidemiological articles (1997–2019) on occupational ELF-MF and ALS with substantial heterogeneity in outcomes, populations, exposure assessment/metrics, exposure categories, and confounder adjustment. Eight principal investigators indicated willingness to share original data, and the authors estimated that a pooled analysis could detect a relative risk of ≥1.14 with >80% power; pooling and harmonized re-analysis were recommended.

Outcomes measured

amyotrophic lateral sclerosis (ALS) risk

Limitations

Feasibility-focused review; no pooled risk estimate reported.
Identified studies were methodologically heterogeneous (outcome definitions, populations, exposure assessment/metrics, exposure categories, confounder adjustment).
Only a subset of investigators (8) expressed willingness to provide original data, potentially limiting pooling coverage.

View raw extracted JSON

{
  "study_type": "review",
  "exposure": {
    "band": "ELF",
    "source": "occupational",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": null
  },
  "population": null,
  "sample_size": null,
  "outcomes": [
    "amyotrophic lateral sclerosis (ALS) risk"
  ],
  "main_findings": "This feasibility study identified 15 epidemiological articles (1997–2019) on occupational ELF-MF and ALS with substantial heterogeneity in outcomes, populations, exposure assessment/metrics, exposure categories, and confounder adjustment. Eight principal investigators indicated willingness to share original data, and the authors estimated that a pooled analysis could detect a relative risk of ≥1.14 with >80% power; pooling and harmonized re-analysis were recommended.",
  "effect_direction": "unclear",
  "limitations": [
    "Feasibility-focused review; no pooled risk estimate reported.",
    "Identified studies were methodologically heterogeneous (outcome definitions, populations, exposure assessment/metrics, exposure categories, confounder adjustment).",
    "Only a subset of investigators (8) expressed willingness to provide original data, potentially limiting pooling coverage."
  ],
  "evidence_strength": "insufficient",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "extremely low-frequency magnetic fields",
    "ELF-MF",
    "occupational exposure",
    "magnetic flux density",
    "amyotrophic lateral sclerosis",
    "ALS",
    "systematic literature search",
    "pooled analysis",
    "data harmonization",
    "confounding"
  ],
  "suggested_hubs": [
    {
      "slug": "occupational-exposure",
      "weight": 0.95,
      "reason": "Focuses on occupational exposure to ELF magnetic fields."
    }
  ]
}

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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.22335
PubMed: Not supplied

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