title: Pooled analysis of recent studies on magnetic fields and childhood leukaemia.
abstract: BACKGROUND
  Previous pooled analyses have reported an association between magnetic fields and childhood leukaemia. We present a pooled analysis based on primary data from studies on residential magnetic fields and childhood leukaemia published after 2000.
  
  
  METHODS
  Seven studies with a total of 10,865 cases and 12,853 controls were included. The main analysis focused on 24-h magnetic field measurements or calculated fields in residences.
  
  
  RESULTS
  In the combined results, risk increased with increase in exposure, but the estimates were imprecise. The odds ratios for exposure categories of 0.1-0.2 μT, 0.2-0.3 μT and ≥0.3 μT, compared with <0.1 μT, were 1.07 (95% CI 0.81-1.41), 1.16 (0.69-1.93) and 1.44 (0.88-2.36), respectively. Without the most influential study from Brazil, the odds ratios increased somewhat. An increasing trend was also suggested by a nonparametric analysis conducted using a generalised additive model.
  
  
  CONCLUSIONS
  Our results are in line with previous pooled analyses showing an association between magnetic fields and childhood leukaemia. Overall, the association is weaker in the most recently conducted studies, but these studies are small and lack methodological improvements needed to resolve the apparent association. We conclude that recent studies on magnetic fields and childhood leukaemia do not alter the previous assessment that magnetic fields are possibly carcinogenic.
authors.affiliation: Department of Epidemiology, UCLA School of Public Health, 650 Charles Young Drive, Los Angeles, CA 90095, USA. kheifets@ucla.edu
authors.forename: L
authors.initials: L
authors.lastname: Kheifets
authors.forename: A
authors.initials: A
authors.lastname: Ahlbom
authors.forename: C M
authors.initials: CM
authors.lastname: Crespi
authors.forename: G
authors.initials: G
authors.lastname: Draper
authors.forename: J
authors.initials: J
authors.lastname: Hagihara
authors.forename: R M
authors.initials: RM
authors.lastname: Lowenthal
authors.forename: G
authors.initials: G
authors.lastname: Mezei
authors.forename: S
authors.initials: S
authors.lastname: Oksuzyan
authors.forename: J
authors.initials: J
authors.lastname: Schüz
authors.forename: J
authors.initials: J
authors.lastname: Swanson
authors.forename: A
authors.initials: A
authors.lastname: Tittarelli
authors.forename: M
authors.initials: M
authors.lastname: Vinceti
authors.forename: V
authors.initials: V
authors.lastname: Wunsch Filho
mesh_terms: D002648:Child; D002675:Child, Preschool; D004574:Electromagnetic Fields / Q000009:adverse effects*; D004781:Environmental Exposure / Q000009:adverse effects; D005260:Female; D006801:Humans; D007953:Leukemia, Radiation-Induced / Q000453:epidemiology*; D008297:Male; D012306:Risk