Copyright 2009 by the Society for Neuro-Oncology
Occupational exposure to magnetic fields and the risk of brain tumors
Division of Cancer Epidemiology and Genetics, Occupational and Environmental Epidemiology Branch (J.B.C., M.D., P.A.S., A.B.), Neuro-Oncology Branch (H.A.F.), and Radiation Epidemiology Branch (M.S.L., P.D.I.), National Cancer Institute, Bethesda, MD; Engineering and Physical Hazards Branch, Division of Applied Research and Technology, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Cincinnati, OH (J.B.); Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ (W.R.S.); Western Pennsylvania Hospital, Pittsburgh, PA (R.G.S.); Department of Radiation Oncology, Massachusetts General Hospital, Boston, MA (J.S.L.); Brigham and Women's Hospital, Boston, MA (P.M.B.); USA
Address correspondence to Joseph B. Coble, Occupational and Environmental Epidemiology Branch, National Cancer Institute, 6120 Executive Blvd., Rockville, MD 20892, USA (jcoble{at}mail.nih.gov).
 |
Abstract |
|---|
We investigated the association between occupational exposure to extremely low-frequency magnetic fields (MFs) and the risk of glioma and meningioma. Occupational exposure to MF was assessed for 489 glioma cases, 197 meningioma cases, and 799 controls enrolled in a hospital-based case–control study. Lifetime occupational history questionnaires were administered to all subjects; for 24% of jobs, these were supplemented with job-specific questionnaires, or "job modules," to obtain information on the use of electrically powered tools or equipment at work. Job-specific quantitative estimates for exposure to MF in milligauss were assigned using a previously published job exposure matrix (JEM) with modification based on the job modules. Jobs were categorized as 
1.5 mG, >1.5 to <3.0 mG, and 
3.0 mG. Four exposure metrics were evaluated: (1) maximum exposed job; (2) total years of exposure >1.5 mG; (3) cumulative lifetime exposure; and (4) average lifetime exposure. Odds ratios (ORs) were calculated using unconditional logistic regression with adjustment for the age, gender, and hospital site. The job modules increased the number of jobs with exposure 3.0 mG from 4% to 7% relative to the JEM. No statistically significant elevation in ORs or trends in ORs across exposure categories was observed using four different exposure metrics for the three tumor types analyzed. Occupational exposure to MFs assessed using job modules was not associated with an increase in the risk for glioma, glioblastoma, or meningioma among the subjects evaluated in this study.
Keywords: glioma, job modules, magnetic fields, meningioma, occupation
Received July 28, 2008; Accepted September 1, 2008