Occupational Exposure to Extremely Low Frequency Magnetic Fields and Mortality from Cardiovascular Disease

• Published in: American journal of epidemiology Vol. 158; no. 6; pp. 534 - 542
• Main Authors: Håkansson, Niclas, Gustavsson, Per, Sastre, Antonio, Floderus, Birgitta
• Format: Journal Article
• Language: English
• Published: Cary, NC Oxford University Press 15.09.2003; Oxford Publishing Limited (England)
• Subjects: acute myocardial infarction; Adult; Aged; Aged, 80 and over; AMI; Biological and medical sciences; Cardiology. Vascular system; Cardiovascular diseases; Cardiovascular Diseases - genetics; Cardiovascular Diseases - mortality; Coronary heart disease; electromagnetic fields; ELF; extremely low frequency; Female; Genetic Predisposition to Disease; Health risks; Heart; Humans; Magnetic fields; Magnetics - adverse effects; Male; Medical sciences; Middle Aged; Mortality; Myocardial infarction; Occupational Exposure; occupations; Prevalence; Proportional Hazards Models; Registries; Risk Factors; Sweden - epidemiology; Sweden; Human; Infarct; Mortality; myocardial infarction; Cardiovascular disease; cardiovascular diseases; Occupational exposure; occupations; Coronary heart disease; Myocardial disease; Low frequency; Epidemiology; Twin; Vascular disease; Ischemia; electromagnetic fields; Risk factor; Myocardium; Magnetic field; Occupational medicine; Public health
• ISSN: 0002-9262; 1476-6256; 0002-9262
• DOI: 10.1093/aje/kwg197

The authors evaluated the relation between occupational exposure to extremely low frequency (ELF) magnetic fields and mortality from cardiovascular diseases. The study was based on 27,790 subjects from the Swedish Twin Registry. Exposure to ELF magnetic fields was assessed by linking occupation reported in 1967 or 1973 to a job exposure matrix. Four levels of exposure were related to cause-specific mortality through 1996, and primary and contributing causes of death were considered. The authors estimated relative risks by Cox regression, with adjustment for several cardiovascular disease risk indicators. The authors calculated the synergy index to evaluate potential interaction between exposure to ELF magnetic fields (>0.2 µT) and genetic susceptibility to acute myocardial infarction (AMI). Arrhythmia-related death, ischemic heart disease other than AMI, and atherosclerosis showed no association with ELF magnetic fields. The authors found a low-level increase in AMI risk in the highest exposure group (relative risk = 1.3, 95% confidence interval: 0.9, 1.9) and suggestions of an exposure-response relation (p = 0.02). A synergy index of 2.7 (95% confidence interval: 1.1, 6.6) in monozygotic twins indicated that the risk of AMI was strengthened among ELF magnetic field-exposed subjects with genetic susceptibility to the disease. The results for AMI corroborate previous findings from the United States. The unusual opportunity to include genetic susceptibility in the present analyses showed that evaluations of effect modification in vulnerable subjects are warranted in ELF magnetic field research.