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.
- acute lymphoblastic leukemia
- acute myeloid leukemia
- case-control study
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Contributors MT, JS, AO, FE and HB designed the study. MT conducted data analyses and wrote the manuscript. The results were interpreted and manuscript was revised by all authors.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Ethics approval Individual studies were approved by their respective ethical committees (COG-E15 study: Minnesota Human Subjects Research Protection Program, study approval number 1403E49261; ADELE study: CNIL (339392) – RBM (CCPPRB 1995/9443); ESCALE study: CNIL (902162) – RBM (DGS 2003/0259); CCLS study: Committee for Protection of Human Subjects (CPHS), University of California, Berkeley, CPHS Protocol Number 2010-10-2438; NZCCS study: Ethical Committees of Waikato Area Health Board RDL:JD, Auckland Area Health Board 90/20 Committee B, Otago Area Health Board 216 00001207, Southland Area Health Board 13-3-1-7, West Coast Area Health Board, Nelson Marlborough Area Health Board, Hawkes Bay Area Health Board 1991/5, Manawatu-Manganui Area Health Board 2/91, Taranaki Area Health Board, Tairawhiti Area Health Board, Bay of Plenty Area Health Board, Canterbury Area Health Board WJP/AQ, Wellington Area Health Board Te Waiora a Tara 90/82; GCCR study: ethical and data protection approval granted by University of Mainz, 1990 (IMSD-1990); SETIL study: Ethical Review Board for the Piedmont Region, authorisation n. 2886, on 15/2/1999, letter n. 1852/28.3 on 17/2/1999; UKCCS study: Yorkshire and the Humber – Leeds West Research Ethics Committee 18/YHO/0135; Integrated Research Application System 203822; Confidential Advisory Group (CAG) 18/CAG/0066; Greece NARECHEM 1993-1994 study: no ethics committee had been established at that time; the dataset was used in doctoral thesis supervised by the principal investigator E Petridou; Greece NARECHEM 1996-2011 study: Ethics Committee of the National and Kapodistrian University of Athens, letter on 20 March 2000, authorization n. 5097 on 17 February 2012 and authorisation n. 1516003877 on 9 October 2015 as the study expanded; written informed consents obtained from family members who provided data in the presence of the child). In interview-based studies, written informed consent was obtained from family members who provided data.
Provenance and peer review Not commissioned; externally peer reviewed.
Correction notice This article has been corrected since it published Online First.
Patient consent for publication Not required.
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