Parental occupational exposure to low-frequency magnetic fields and risk of leukemia in offspring: Findings from Childhood Leukemia International Consortium

2019 · No effect · Moderate evidence

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No effectModerate evidencePaper 1727

Study snapshot

Publicationmanual · 2019

Study typemeta_analysis

Reported directionNo effect

Evidence ratingModerate

Abstract

Parental occupational exposure to low-frequency magnetic fields and risk of leukemia in offspring: Findings from Childhood Leukemia International Consortium Talibov M, Olsson A, Bailey H, Erdmann F, Metayer C, Magnani C, Petridou E, Auvinen A, Spector L, Clavel J, Roman E, Dockerty J, Nikkilä A, Lohi O, Kang A, Psaltopoulou T, Miligi L, Vila J, Cardis E, Schüz J. Parental occupational exposure to low-frequency magnetic fields and risk of leukaemia in the offspring: findings from the Childhood Leukaemia International Consortium (CLIC). Occup Environ Med. 2019 Jul 29. pii: oemed-2019- 105706. doi: 10.1136/oemed-2019-105706. Abstract OBJECTIVES: Previously published studies on parental occupational exposure to extremely low-frequency magnetic fields (ELF-MF) and risk of acute lymphoblastic leukaemia (ALL) and acute myeloid leukaemia (AML) in their offspring were inconsistent. We therefore evaluated this question within the Childhood Leukemia International Consortium. METHODS: We pooled 11 case-control studies including 9723 childhood leukaemia cases and 17 099 controls. Parental occupational ELF-MF exposure was estimated by linking jobs to an ELF-MF job-exposure matrix (JEM). Logistic regression models were used to estimate ORs and 95% CIs in pooled analyses and meta-analyses. RESULTS: ORs from pooled analyses for paternal ELF-MF exposure >0.2 microtesla (µT) at conception were 1.04 (95% CI 0.95 to 1.13) for ALL and 1.06 (95% CI 0.87 to 1.29) for AML, compared with ≤0.2 µT. Corresponding ORs for maternal ELF-MF exposure during pregnancy were 1.00 (95% CI 0.89 to 1.12) for ALL and 0.85 (95% CI 0.61 to 1.16) for AML. No trends of increasing ORs with increasing exposure level were evident. Furthermore, no associations were observed in the meta-analyses. CONCLUSIONS: In this large international dataset applying a comprehensive quantitative JEM, we did not find any associations between parental occupational ELF-MF exposure and childhood leukaemia. "The major limitation of this study was potential exposure misclassification, which can arise in any study with retrospec - tive exposure assessment. Exposure misclassification could occur because the ELF-MF JEM, like most JEMs, assigns the mean exposure level to all persons in the same occupation, while expo - sure heterogeneity within the occupation may be substantial. It does not specify jobs by industrial groups, and exposure intensity might vary in the same occupation by industrial group Exposure misclassification was likely to be non- differential in our study because the JEM was applied in the same way to all parents and independently of case- control status of the child. Bias from non-differential exposure misclassification is generally towards the null for dichotomous exposures.30 For polytomous exposures, non-differential misclassification can bias ORs away from the null only for intermediate exposure categories, but ORs for the highest category will be towards the null.31 Therefore, ORs for dichotomous ELF-MF exposures and for high categories of polytomous exposures would be underestimated if non-differential exposure misclassification was present in this study. Selection bias may also be a concern in this study " Open access paper: oem.bmj.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 typemeta_analysis

Effect directionno_effect

PopulationParents (occupationally exposed) and their offspring (childhood leukemia cases/controls) from 11 case-control studies in the Childhood Leukemia International Consortium (CLIC)

Sample size26822

ExposureELF · paternal exposure at conception; maternal exposure during pregnancy

Evidence strengthModerateConfidence: 86% · Peer reviewed: yes

Main findings

In pooled analyses, paternal occupational ELF-MF exposure >0.2 µT at conception was not associated with ALL (OR 1.04, 95% CI 0.95 to 1.13) or AML (OR 1.06, 95% CI 0.87 to 1.29) versus ≤0.2 µT. Maternal occupational ELF-MF exposure during pregnancy was not associated with ALL (OR 1.00, 95% CI 0.89 to 1.12) or AML (OR 0.85, 95% CI 0.61 to 1.16), with no exposure–response trends and no associations in meta-analyses.

Outcomes measured

Childhood acute lymphoblastic leukaemia (ALL)
Childhood acute myeloid leukaemia (AML)

Limitations

Potential exposure misclassification due to retrospective exposure assessment using a job-exposure matrix (JEM) that assigns mean exposure within occupations despite substantial within-occupation heterogeneity
JEM does not specify jobs by industrial groups; exposure intensity may vary within the same occupation by industrial group
Possible selection bias (not further detailed in abstract)
Non-differential exposure misclassification could bias estimates toward the null, potentially underestimating associations for dichotomous/high exposure categories

View raw extracted JSON

{
  "study_type": "meta_analysis",
  "exposure": {
    "band": "ELF",
    "source": "occupational",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": "paternal exposure at conception; maternal exposure during pregnancy"
  },
  "population": "Parents (occupationally exposed) and their offspring (childhood leukemia cases/controls) from 11 case-control studies in the Childhood Leukemia International Consortium (CLIC)",
  "sample_size": 26822,
  "outcomes": [
    "Childhood acute lymphoblastic leukaemia (ALL)",
    "Childhood acute myeloid leukaemia (AML)"
  ],
  "main_findings": "In pooled analyses, paternal occupational ELF-MF exposure >0.2 µT at conception was not associated with ALL (OR 1.04, 95% CI 0.95 to 1.13) or AML (OR 1.06, 95% CI 0.87 to 1.29) versus ≤0.2 µT. Maternal occupational ELF-MF exposure during pregnancy was not associated with ALL (OR 1.00, 95% CI 0.89 to 1.12) or AML (OR 0.85, 95% CI 0.61 to 1.16), with no exposure–response trends and no associations in meta-analyses.",
  "effect_direction": "no_effect",
  "limitations": [
    "Potential exposure misclassification due to retrospective exposure assessment using a job-exposure matrix (JEM) that assigns mean exposure within occupations despite substantial within-occupation heterogeneity",
    "JEM does not specify jobs by industrial groups; exposure intensity may vary within the same occupation by industrial group",
    "Possible selection bias (not further detailed in abstract)",
    "Non-differential exposure misclassification could bias estimates toward the null, potentially underestimating associations for dichotomous/high exposure categories"
  ],
  "evidence_strength": "moderate",
  "confidence": 0.86,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "extremely low-frequency magnetic fields",
    "ELF-MF",
    "occupational exposure",
    "job-exposure matrix",
    "JEM",
    "parental exposure",
    "paternal exposure",
    "maternal exposure",
    "pregnancy",
    "conception",
    "childhood leukemia",
    "acute lymphoblastic leukaemia",
    "ALL",
    "acute myeloid leukaemia",
    "AML",
    "case-control",
    "pooled analysis",
    "meta-analysis",
    "CLIC"
  ],
  "suggested_hubs": [
    {
      "slug": "occupational-exposure",
      "weight": 0.95,
      "reason": "Study evaluates parental occupational exposure to ELF magnetic fields using a job-exposure matrix across multiple case-control studies."
    }
  ]
}

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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: 10.1136/oemed-2019-105706
PubMed: Not supplied

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