Commercial outdoor plant nurseries as a confounder for electromagnetic fields and childhood leukemia risk

2022 · Mixed · Moderate evidence

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MixedModerate evidencePaper 819

Study snapshot

Publicationmanual · 2022

Study typecase_control

Reported directionMixed

Evidence ratingModerate

Abstract

Commercial outdoor plant nurseries as a confounder for electromagnetic fields and childhood leukemia risk A Nguyen, C M Crespi, X Vergara, L Kheifets. Commercial outdoor plant nurseries as a confounder for electromagnetic fields and childhood leukemia risk. Environ Res. 2022 May 10;212(Pt C):113446. doi: 10.1016/j.envres.2022.113446. Highlights • Close proximity to plant nurseries is a potential childhood leukemia risk factor. • Proximity to nurseries did not explain distance to power lines and CL associations. • Proximity to nurseries did not explain magnetic field and CL associations. • First detailed study of pesticides as a confounder for magnetic fields and CL. Abstract Background: Close residential proximity to powerlines and high magnetic fields exposure may be associated with elevated childhood leukemia risks as reported by prior studies and pooled analyses. Magnetic fields exposure from high-voltage powerlines is associated with proximity to these powerlines and consequently with any factor varying with distance. Areas underneath powerlines in California may be sites for commercial plant nurseries that can use pesticides, a potential childhood leukemia risk factor. Objectives: Assess if potential pesticide exposure from commercial plant nurseries is a confounder or interacts with proximity or magnetic fields exposure from high-voltage powerlines to increase childhood leukemia risk. Methods: A comprehensive childhood leukemia record-based case-control study with 5788 cases and 5788 controls (born and diagnosed in California, 1986-2008) was conducted. Pesticide, powerline, and magnetic field exposure assessment utilized models that incorporated geographical information systems, aerial satellite images, site visits and other historical information. Results: The relationship for calculated fields with childhood leukemia (odds ratio (OR) 1.51, 95% confidence interval (CI) 0.70-3.23) slightly attenuated when controlling for nursery proximity (OR 1.43, 95% CI 0.65-3.16) or restricting analysis to subjects living far (>300 m) from nurseries (OR 1.43, 95% CI 0.79-2.60). A similar association pattern was observed between distance to high-voltage powerlines and childhood leukemia. The association between nursery proximity and childhood leukemia was unchanged or only slightly attenuated when controlling for calculated fields or powerline distance; ORs remained above 2 when excluding subjects with high calculated fields or close powerline proximity (OR 2.16, 95% CI 0.82-5.67 and OR 2.15, 95% CI 0.82-5.64, respectively). The observed relationships were robust to different time periods, reference categories, and cut points. Discussion: Close residential proximity to nurseries is suggested as an independent childhood leukemia risk factor. Our results do not support plant nurseries as an explanation for observed childhood leukemia risks for powerline proximity and magnetic fields exposure, although small numbers of subjects concurrently exposed to high magnetic fields, close powerline proximity and plant nurseries limited our ability to fully assess potential confounding. Open access paper: sciencedirect.com

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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 typecase_control

Effect directionmixed

PopulationChildren born and diagnosed in California (1986–2008)

Sample size11576

ExposureELF

Evidence strengthModerateConfidence: 78% · Peer reviewed: yes

Main findings

In this California record-based case-control study (5788 cases, 5788 controls), the association between calculated magnetic fields and childhood leukemia (OR 1.51, 95% CI 0.70–3.23) was slightly attenuated after controlling for nursery proximity (OR 1.43, 95% CI 0.65–3.16) or restricting to those living >300 m from nurseries (OR 1.43, 95% CI 0.79–2.60). Similar patterns were reported for distance to high-voltage powerlines. Nursery proximity showed ORs remaining above 2 in some analyses even after excluding subjects with high calculated fields or close powerline proximity, and results were described as robust to alternative specifications; authors conclude nursery proximity may be an independent risk factor and does not explain powerline/magnetic-field associations, though small numbers limited assessment of joint exposure/confounding.

Outcomes measured

childhood leukemia risk
association between calculated magnetic fields and childhood leukemia
association between distance to high-voltage powerlines and childhood leukemia
potential confounding/interaction by proximity to commercial plant nurseries (pesticide exposure proxy)

Limitations

Small numbers of subjects concurrently exposed to high magnetic fields, close powerline proximity, and plant nurseries limited ability to fully assess potential confounding/interaction
Exposure assessment based on models incorporating GIS, aerial images, site visits, and historical information (potential for exposure misclassification)

View raw extracted JSON

{
  "study_type": "case_control",
  "exposure": {
    "band": "ELF",
    "source": "high-voltage powerlines",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": null
  },
  "population": "Children born and diagnosed in California (1986–2008)",
  "sample_size": 11576,
  "outcomes": [
    "childhood leukemia risk",
    "association between calculated magnetic fields and childhood leukemia",
    "association between distance to high-voltage powerlines and childhood leukemia",
    "potential confounding/interaction by proximity to commercial plant nurseries (pesticide exposure proxy)"
  ],
  "main_findings": "In this California record-based case-control study (5788 cases, 5788 controls), the association between calculated magnetic fields and childhood leukemia (OR 1.51, 95% CI 0.70–3.23) was slightly attenuated after controlling for nursery proximity (OR 1.43, 95% CI 0.65–3.16) or restricting to those living >300 m from nurseries (OR 1.43, 95% CI 0.79–2.60). Similar patterns were reported for distance to high-voltage powerlines. Nursery proximity showed ORs remaining above 2 in some analyses even after excluding subjects with high calculated fields or close powerline proximity, and results were described as robust to alternative specifications; authors conclude nursery proximity may be an independent risk factor and does not explain powerline/magnetic-field associations, though small numbers limited assessment of joint exposure/confounding.",
  "effect_direction": "mixed",
  "limitations": [
    "Small numbers of subjects concurrently exposed to high magnetic fields, close powerline proximity, and plant nurseries limited ability to fully assess potential confounding/interaction",
    "Exposure assessment based on models incorporating GIS, aerial images, site visits, and historical information (potential for exposure misclassification)"
  ],
  "evidence_strength": "moderate",
  "confidence": 0.78,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "childhood leukemia",
    "magnetic fields",
    "ELF",
    "high-voltage powerlines",
    "distance to powerlines",
    "case-control",
    "confounding",
    "plant nurseries",
    "pesticides",
    "GIS exposure assessment",
    "California"
  ],
  "suggested_hubs": [
    {
      "slug": "occupational-exposure",
      "weight": 0.1,
      "reason": "Mentions commercial plant nurseries and pesticide use, but study population is residential childhood exposure rather than occupational."
    }
  ]
}

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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: 10.1016/j.envres.2022.113446
PubMed: Not supplied

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