title: Epidemiologic study of residential proximity to transmission lines and childhood cancer in California: description of design, epidemiologic methods and study population.
abstract: We conducted a large epidemiologic case-control study in California to examine the association between childhood cancer risk and distance from the home address at birth to the nearest high-voltage overhead transmission line as a replication of the study of Draper et al. in the United Kingdom. We present a detailed description of the study design, methods of case ascertainment, control selection, exposure assessment and data analysis plan. A total of 5788 childhood leukemia cases and 3308 childhood central nervous system cancer cases (included for comparison) and matched controls were available for analysis. Birth and diagnosis addresses of cases and birth addresses of controls were geocoded. Distance from the home to nearby overhead transmission lines was ascertained on the basis of the electric power companies' geographic information system (GIS) databases, additional Google Earth aerial evaluation and site visits to selected residences. We evaluated distances to power lines up to 2000 m and included consideration of lower voltages (60-69 kV). Distance measures based on GIS and Google Earth evaluation showed close agreement (Pearson correlation >0.99). Our three-tiered approach to exposure assessment allowed us to achieve high specificity, which is crucial for studies of rare diseases with low exposure prevalence.
authors.affiliation: Department of Epidemiology, UCLA Fielding School of Public Health, Los Angeles, California, USA.
authors.forename: Leeka
authors.initials: L
authors.lastname: Kheifets
authors.affiliation: Department of Biostatistics, UCLA Fielding School of Public Health, Los Angeles, California, USA.
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Crespi
authors.affiliation: Enertech Consultants, Campbell, California, USA.
authors.forename: Chris
authors.initials: C
authors.lastname: Hooper
authors.affiliation: Department of Epidemiology, UCLA Fielding School of Public Health, Los Angeles, California, USA.
authors.forename: Sona
authors.initials: S
authors.lastname: Oksuzyan
authors.affiliation: Department of Preventive Medicine, University of Southern California, Los Angeles, California, USA.
authors.forename: Myles
authors.initials: M
authors.lastname: Cockburn
authors.affiliation: Department of Preventive Medicine, University of Southern California, Los Angeles, California, USA.
authors.forename: Thomas
authors.initials: T
authors.lastname: Ly
authors.affiliation: Environment Department, Electric Power Research Institute, Palo Alto, California, USA.
authors.forename: Gabor
authors.initials: G
authors.lastname: Mezei
mesh_terms: D000293:Adolescent; D002140:California / Q000453:epidemiology; D016543:Central Nervous System Neoplasms / Q000453:epidemiology / Q000209:etiology; D002648:Child; D002675:Child, Preschool; D004559:Electric Wiring / Q000009:adverse effects* / Q000706:statistics & numerical data; D004574:Electromagnetic Fields / Q000009:adverse effects*; D004781:Environmental Exposure / Q000009:adverse effects* / Q000706:statistics & numerical data; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans; D007223:Infant; D007938:Leukemia / Q000453:epidemiology / Q000209:etiology; D008297:Male; D009369:Neoplasms / Q000453:epidemiology* / Q000209:etiology; D012042:Registries; D018426:SEER Program
references.citation: J Clin Epidemiol. 1993 Jun;46(6):545-8
references.pmid: 8501481
references.citation: Blood Cancer J. 2012 Dec 21;2:e98
references.pmid: 23262804
references.citation: Cancer Causes Control. 2014 Feb;25(2):171-7
references.pmid: 24197706
references.citation: Br J Cancer. 2000 Sep;83(5):692-8
references.pmid: 10944614
references.citation: J Radiol Prot. 2013 Jun;33(2):349-65
references.pmid: 23481003
references.citation: Am J Epidemiol. 1979 Mar;109(3):273-84
references.pmid: 453167
references.citation: Epidemiology. 2000 Nov;11(6):624-34
references.pmid: 11055621
references.citation: Bioelectromagnetics. 2005;Suppl 7:S51-9
references.pmid: 16059924
references.citation: Int J Epidemiol. 2006 Apr;35(2):397-406
references.pmid: 16303812
references.citation: Bioelectromagnetics. 2001;Suppl 5:S19-31
references.pmid: 11170115
references.citation: Cancer Epidemiol. 2013 Aug;37(4):402-9
references.pmid: 23562044
references.citation: Br J Cancer. 2010 Sep 28;103(7):1122-7
references.pmid: 20877338
references.citation: Risk Anal. 2006 Apr;26(2):471-82
references.pmid: 16573634
references.citation: Cancer Causes Control. 1994 May;5(3):279-83
references.pmid: 7710486
references.citation: Stat Med. 1991 Apr;10(4):585-98
references.pmid: 2057657
references.citation: Br J Cancer. 2010 Sep 28;103(7):1128-35
references.pmid: 20877339
references.citation: Br J Haematol. 2000 Sep;110(3):512-24
references.pmid: 10997960
references.citation: BMJ. 2002 Feb 2;324(7332):283-7
references.pmid: 11823363
references.citation: BMJ. 2005 Jun 4;330(7503):1290
references.pmid: 15933351
references.citation: Cancer Epidemiol. 2012 Dec;36(6):e359-65
references.pmid: 22926338
references.citation: BMJ. 2005 Sep 17;331(7517):635; discussion 636; author reply 636-7
references.pmid: 16166141