Mortality from Neurodegenerative Disease and Exposure to Extremely Low-Frequency Magnetic Fields: 31 Years of Observations on Swiss Railway Employees

Aims: The objective of the present study was to investigate the relationship between extremely low-frequency magnetic field (ELF-MF) exposure and mortality from several neurodegenerative conditions in Swiss railway employees. Methods: We studied a cohort of 20,141 Swiss railway employees with 464,129 person-years of follow-up between 1972 and 2002. For each individual, cumulative exposure was calculated from on-site measurements and modelling of past exposure. We compared cause-specific mortality in highly exposed train drivers (mean exposure: 21 µT) with less exposed occupational groups (for example station masters: 1 µT). Results: The hazard ratio for train drivers compared to station masters was 1.96 [95% confidence interval (CI) = 0.98–3.92] for senile dementia and 3.15 (95% CI = 0.90–11.04) for Alzheimer’s disease. For every 10 µT years of cumulative exposure senile dementia mortality increased by 5.7% (95% CI = 1.3–10.4), Alzheimer’s disease by 9.4% (95% CI = 2.7–16.4) and amyotrophic lateral sclerosis by 2.1% (95% CI = –6.8 to 11.7). There was no evidence for an increase in mortality from Parkinson’s disease and multiple sclerosis. Conclusions: This study suggests a link between exposure to ELF-MF and Alzheimer’s disease and indicates that ELF-MF might act in later stages of the disease process.