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Proximity to overhead power lines and childhood leukaemia: an international pooled analysis

2018 · Mixed · Moderate evidence

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MixedModerate evidencePaper 2088

Pooled individual-level data from 11 record-based studies found no material association between childhood leukaemia and distance to the nearest overhead power line of any voltage. For residences <50 m from 200+ kV lines, the adjusted odds ratio was 1.33 (95% …

Study snapshot

Publicationmanual · 2018
Study typemeta_analysis
Reported directionMixed
Evidence ratingModerate

Abstract

Proximity to overhead power lines and childhood leukaemia: an international pooled analysis Amoon AT, Crespi CM, Ahlbom A, Bhatnagar M, Bray I, Bunch KJ, Clavel J, Feychting M, Hémon D, Johansen C, Kreis C, Malagoli C, Marquant F, Pedersen C, Raaschou-Nielsen O, Röösli M, Spycher BD, Sudan M, Swanson J, Tittarelli A, Tuck DM, Tynes T, Vergara X, Vinceti M, Wünsch-Filho V, Kheifets L. Proximity to overhead power lines and childhood leukaemia: an international pooled analysis. Br J Cancer. 2018 May 29. doi: 10.1038/s41416- 018-0097-7. Abstract BACKGROUND: Although studies have consistently found an association between childhood leukaemia risk and magnetic fields, the associations between childhood leukaemia and distance to overhead power lines have been inconsistent. We pooled data from multiple studies to assess the association with distance and evaluate whether it is due to magnetic fields or other factors associated with distance from lines. METHODS: We present a pooled analysis combining individual-level data (29,049 cases and 68,231 controls) from 11 record-based studies. RESULTS: There was no material association between childhood leukaemia and distance to nearest overhead power line of any voltage. Among children living < 50 m from 200 + kV power lines, the adjusted odds ratio for childhood leukaemia was 1.33 (95% CI: 0.92-1.93). The odds ratio was higher among children diagnosed before age 5 years. There was no association with calculated magnetic fields. Odds ratios remained unchanged with adjustment for potential confounders. CONCLUSIONS: In this first comprehensive pooled analysis of childhood leukaemia and distance to power lines, we found a small and imprecise risk for residences < 50 m of 200 + kV lines that was not explained by high magnetic fields. Reasons for the increased risk, found in this and many other studies, remains to be elucidated. ncbi.nlm.nih.gov In conclusion, we found a small, imprecise association between childhood leukaemia and residence located within 50 m of 200 + kV lines, which was stronger for younger children, in our individual-data pooled analysis of 11 studies. This association was not explained by exposure to high MF levels or by other measured confounders. We found no evidence for bias as a potential explanation and in particular, we only included record-based studies, making selection bias unlikely. Although exposure misclassification is likely to be present, the risk of bias due to distance misclassification is quite small. The previous UK findings of risk estimates for distances beyond 200 m are not supported by the pooled data from other countries. The decrease in effect over time are not clearly supported by the pooled data from other countries, although numbers of exposed cases and controls for the earlier time period are small for both the United Kingdom and for other countries combined. Although pooled analysis is a powerful approach to integrating data, it is only as good as the underlying data. Reasons for the small yet fairly consistent increase in the risk of childhood leukaemia in relation to proximity to power lines found in many studies remain to be elucidated.

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 typemeta_analysis
Effect directionmixed
PopulationChildren (childhood leukaemia cases and controls)
Sample size97280
ExposureELF
Evidence strengthModerateConfidence: 78% · Peer reviewed: yes

Main findings

Pooled individual-level data from 11 record-based studies found no material association between childhood leukaemia and distance to the nearest overhead power line of any voltage. For residences <50 m from 200+ kV lines, the adjusted odds ratio was 1.33 (95% CI: 0.92–1.93), with higher odds ratios among children diagnosed before age 5 years. There was no association with calculated magnetic fields, and adjustment for potential confounders did not materially change results.

Outcomes measured

  • childhood leukaemia

Limitations

  • Association for <50 m from 200+ kV lines was small and imprecise (wide CI including 1.0).
  • Exposure misclassification is likely (noted by authors), though distance misclassification considered small.
  • Pooled analysis depends on quality/consistency of underlying studies; exposed numbers in earlier time periods were small in some strata.
View raw extracted JSON
{
  "study_type": "meta_analysis",
  "exposure": {
    "band": "ELF",
    "source": "overhead power lines",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": null
  },
  "population": "Children (childhood leukaemia cases and controls)",
  "sample_size": 97280,
  "outcomes": [
    "childhood leukaemia"
  ],
  "main_findings": "Pooled individual-level data from 11 record-based studies found no material association between childhood leukaemia and distance to the nearest overhead power line of any voltage. For residences <50 m from 200+ kV lines, the adjusted odds ratio was 1.33 (95% CI: 0.92–1.93), with higher odds ratios among children diagnosed before age 5 years. There was no association with calculated magnetic fields, and adjustment for potential confounders did not materially change results.",
  "effect_direction": "mixed",
  "limitations": [
    "Association for <50 m from 200+ kV lines was small and imprecise (wide CI including 1.0).",
    "Exposure misclassification is likely (noted by authors), though distance misclassification considered small.",
    "Pooled analysis depends on quality/consistency of underlying studies; exposed numbers in earlier time periods were small in some strata."
  ],
  "evidence_strength": "moderate",
  "confidence": 0.78,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "childhood leukaemia",
    "overhead power lines",
    "distance",
    "proximity",
    "magnetic fields",
    "pooled analysis",
    "case-control",
    "ELF"
  ],
  "suggested_hubs": [
    {
      "slug": "occupational-exposure",
      "weight": 0.05,
      "reason": "Study concerns power lines but is residential/childhood rather than occupational; hub match is weak."
    }
  ]
}
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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: 10.1038/s41416
PubMed: Not supplied

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