Exposure to magnetic fields from power lines & childhood asthma in Danish National Birth Cohort

2017 · No effect · Moderate evidence

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No effectModerate evidencePaper 2235

Study snapshot

Publicationmanual · 2017

Study typecohort

Reported directionNo effect

Evidence ratingModerate

Abstract

Exposure to magnetic fields from power lines & childhood asthma in Danish National Birth Cohort Sudan M, Arah OA, Becker T, Levy Y, Sigsgaard T, Olsen J, Vergara X, Kheifets L. Re-examining the association between residential exposure to magnetic fields from power lines and childhood asthma in the Danish National Birth Cohort. PLoS One. 2017 May 17;12(5):e0177651. doi: 10.1371/journal.pone.0177651. Abstract BACKGROUND: A study reported an increased risk of asthma in children whose mothers were exposed to magnetic field (MF) levels above 0.2 μT during pregnancy. We re-examined this association using data from mothers and children in the Danish National Birth Cohort (DNBC). METHODS: This study included 92,676 singleton-born children and their mothers from the DNBC. MF exposure from power lines was estimated for all residences where the mothers lived during pregnancy and for all children from birth until the end of follow up. Exposure was categorized into 0 μT, 0.1 μT, and ≥ 0.2 μT for analysis. Definitive and possible asthma cases were identified using data from three independent data sources: 1) mothers' reports, 2) a national hospitalization register, 3) a national prescription drug register. We calculated hazard ratios (HR) and 95% confidence intervals (CI) for the association between the highest level of exposure during pregnancy and asthma in children, adjusting for several potential confounding factors. We also examined the sensitivity of the risk estimates to changes in exposure and outcome definitions. RESULTS: No differences or trends in the risk of asthma development were detected between children with different levels of MF exposure regardless of the asthma case definition or outcome data source. For definitive cases, the HR (95% CI) for those with any exposure was 0.72 (0.27-1.92), and it was 0.41 (0.06-2.92) for those exposed to ≥ 0.2 μT. Adjustments for confounding and variations in the exposure definition did not appreciably alter the results. CONCLUSION: We did not find evidence that residential exposure to MF during pregnancy or early childhood increased the risk of childhood asthma. This interpretation is in line with the lack of an established biological mechanism directly linking MF exposure to asthma, but high exposure was very rare in this cohort. ncbi.nlm.nih.gov

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 typecohort

Effect directionno_effect

PopulationMothers and singleton-born children in the Danish National Birth Cohort (DNBC)

Sample size92676

ExposureELF · During pregnancy (maternal residential exposure) and from birth until end of follow-up (child residential exposure)

Evidence strengthModerateConfidence: 78% · Peer reviewed: yes

Main findings

In 92,676 mother–child pairs, no differences or trends in childhood asthma risk were detected across categories of residential magnetic-field exposure from power lines. For definitive asthma cases, hazard ratios were 0.72 (95% CI 0.27–1.92) for any exposure and 0.41 (95% CI 0.06–2.92) for exposure ≥0.2 μT; results were similar across outcome definitions and sensitivity analyses.

Outcomes measured

Childhood asthma (definitive and possible cases; identified via mothers' reports, national hospitalization register, and national prescription drug register)

Limitations

High exposure (≥0.2 μT) was very rare in this cohort
Exposure was estimated (not directly measured) for residences

View raw extracted JSON

{
  "study_type": "cohort",
  "exposure": {
    "band": "ELF",
    "source": "power lines (residential)",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": "During pregnancy (maternal residential exposure) and from birth until end of follow-up (child residential exposure)"
  },
  "population": "Mothers and singleton-born children in the Danish National Birth Cohort (DNBC)",
  "sample_size": 92676,
  "outcomes": [
    "Childhood asthma (definitive and possible cases; identified via mothers' reports, national hospitalization register, and national prescription drug register)"
  ],
  "main_findings": "In 92,676 mother–child pairs, no differences or trends in childhood asthma risk were detected across categories of residential magnetic-field exposure from power lines. For definitive asthma cases, hazard ratios were 0.72 (95% CI 0.27–1.92) for any exposure and 0.41 (95% CI 0.06–2.92) for exposure ≥0.2 μT; results were similar across outcome definitions and sensitivity analyses.",
  "effect_direction": "no_effect",
  "limitations": [
    "High exposure (≥0.2 μT) was very rare in this cohort",
    "Exposure was estimated (not directly measured) for residences"
  ],
  "evidence_strength": "moderate",
  "confidence": 0.78,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "extremely low frequency",
    "ELF",
    "magnetic fields",
    "power lines",
    "residential exposure",
    "pregnancy",
    "early childhood",
    "asthma",
    "Danish National Birth Cohort",
    "hazard ratio"
  ],
  "suggested_hubs": [
    {
      "slug": "power-lines-elf",
      "weight": 0.95,
      "reason": "Residential magnetic-field exposure estimated from power lines (ELF MF) and health outcome in children."
    }
  ]
}

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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: 10.1371/journal.pone.0177651
PubMed: Not supplied

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