title: A systematic review and meta-analysis of childhood leukemia and parental occupational pesticide exposure.
abstract: OBJECTIVE
  We conducted a systematic review and meta-analysis of childhood leukemia and parental occupational pesticide exposure.
  
  
  METHODS
  Searches of MEDLINE (1950-2009) and other electronic databases yielded 31 included studies.
  
  
  METHODS
  Two authors independently abstracted data and assessed the quality of each study.
  
  
  RESULTS
  Random effects models were used to obtain summary odds ratios (ORs) and 95% confidence intervals (CIs). There was no overall association between childhood leukemia and any paternal occupational pesticide exposure (OR = 1.09; 95% CI, 0.88-1.34); there were slightly elevated risks in subgroups of studies with low total-quality scores (OR = 1.39; 95% CI, 0.99-1.95), ill-defined exposure time windows (OR = 1.36; 95% CI, 1.00-1.85), and exposure information collected after offspring leukemia diagnosis (OR = 1.34; 95% CI, 1.05-1.70). Childhood leukemia was associated with prenatal maternal occupational pesticide exposure (OR = 2.09; 95% CI, 1.51-2.88); this association was slightly stronger for studies with high exposure-measurement-quality scores (OR = 2.45; 95% CI, 1.68-3.58), higher confounder control scores (OR = 2.38; 95% CI, 1.56-3.62), and farm-related exposures (OR = 2.44; 95% CI, 1.53-3.89). Childhood leukemia risk was also elevated for prenatal maternal occupational exposure to insecticides (OR = 2.72; 95% CI, 1.47-5.04) and herbicides (OR = 3.62; 95% CI, 1.28-10.3).
  
  
  CONCLUSIONS
  Childhood leukemia was associated with prenatal maternal occupational pesticide exposure in analyses of all studies combined and in several subgroups. Associations with paternal occupational pesticide exposure were weaker and less consistent. Research needs include improved pesticide exposure indices, continued follow-up of existing cohorts, genetic susceptibility assessment, and basic research on childhood leukemia initiation and progression.
authors.affiliation: McLaughlin Centre for Population Health Risk Assessment, University of Ottawa, Ottawa, Ontario, Canada. don.wigle@sympatico.ca
authors.forename: Donald T
authors.initials: DT
authors.lastname: Wigle
authors.forename: Michelle C
authors.initials: MC
authors.lastname: Turner
authors.forename: Daniel
authors.initials: D
authors.lastname: Krewski
mesh_terms: D002648:Child; D002675:Child, Preschool; D004781:Environmental Exposure; D005260:Female; D006801:Humans; D007938:Leukemia / Q000453:epidemiology* / Q000209:etiology*; D008297:Male; D018811:Maternal Exposure; D016273:Occupational Exposure; D018812:Paternal Exposure; D010575:Pesticides / Q000633:toxicity*
chemical_list: D010575:Pesticides