Background: Occupational exposure to extremely low frequency magnetic fields (ELF) is a suspected risk factor for brain tumours, however the literature is inconsistent. Few studies have assessed whether ELF in different time windows of exposure may be associated with specific histologic types of brain tumours. This study examines the association between ELF and brain tumours in the large-scale INTEROCC study. Methods: Cases of adult primary glioma and meningioma were recruited in seven countries (Australia, Canada, France, Germany, Israel, New Zealand, United Kingdom) between 2000 and 2004. Estimates of mean workday ELF exposure based on a job exposure matrix assigned. Estimates of cumulative exposure, average exposure, maximum exposure, and exposure duration were calculated for the lifetime, and 1-4, 5-9, and 10+ years prior to the diagnosis/reference date. Results: There were 3,761 included brain tumour cases (1,939 glioma, 1,822 meningioma) and 5,404 population controls. There was no association between lifetime cumulative ELF exposure and glioma or meningioma risk. However, there were positive associations between cumulative ELF 1-4 years prior to the diagnosis/reference date and glioma (odds ratio (OR) >/= 90th percentile vs < 25th percentile = 1.67, 95% confidence interval (CI) 1.36-2.07, p < 0.0001 linear trend), and, somewhat weaker associations with meningioma (OR >/= 90th percentile vs < 25th percentile = 1.23, 95% CI 0.97-1.57, p = 0.02 linear trend). Conclusions: Results showed positive associations between ELF in the recent past and glioma. Impact: Occupational ELF exposure may play a role in the later stages (promotion and progression) of brain tumourigenesis.
Magnetic-fields; Magnetic-properties; Electromagnetic-fields; Brain-tumors; Ionizing-radiation; Epidemiology; Job-analysis; Occupational-exposure; Occupations; Chemical-deposition; Biological-effects; Exposure-assessment; Synergism; Tumorigenesis; Tumors;
Author Keywords: extremely low frequency magnetic fields; occupation; glioma; meningioma; case-control study
Michelle C. Turner, CREAL-Centre for Research in Environmental Epidemiology, Parc de Recerca Biomèdica de Barcelona, Doctor Aiguader, 88 | 08003 Barcelona Spain