Leukaemia, Brain Tumours and Exposure to Extremely Low Frequency Magnetic Fields: Cohort Study of Swiss Railway Employees

Abstract

Aims: We investigated the relationship between extremely low frequency magnetic field (ELF-MF) exposure and mortality from leukaemia and brain tumour in a cohort of Swiss railway workers Methods: We studied 20,141 Swiss railway employees with 464,129 person-years of follow-up between 1972 and 2002. Mortality rates for leukaemia and brain tumour of highly exposed train drivers (21 µT average annual exposure) were compared with medium and low exposed occupational groups (i.e. station masters with an average exposure of 1 µT). In addition, individual cumulative exposure was calculated from on-site measurements and modelling of past exposures. Results: The hazard ratio (HR) for leukaemia mortality of train drivers was 1.43 (95% CI 0.74 to 2.77) compared to station masters. For myeloid leukaemia the HR of train drivers was 4.74 (95% CI 1.04 to 21.60) and for Hodgkin's disease 3.29 (95% CI 0.69 to 15.63). Lymphoid leukaemia, non-Hodgkin's disease and brain tumour mortality were not associated with magnetic field exposure. Concordant results were obtained from analyses based on individual cumulative exposure. Conclusions: We found some evidence of an exposure-response association for myeloid leukaemia and Hodgkin's disease, but not for other haematopoietic and lymphatic malignancies and brain tumours.