Occupational exposure to low frequency magnetic fields and dementia - a case-control study

Andreas Seidler ^1*, Petra Geller ¹, Albert Nienhaus ², Tanja Bernhardt ³, Ingeburg Ruppe ⁴, Siegfried Eggert ⁴, Maila Hietanen ⁵, Timo Kauppinen ⁵ and Lutz Froelich ³

¹ Institute of Occupational Medicine, Frankfurt University, Germany
² Institution for Statutory Accident Insurance and Prevention in the Health and Welfare Services, Germany
³ Central Institute of Mental Health, Germany
⁴ Federal Institute for Occupational Safety and Health (BAuA), Germany
⁵ Department of Epidemiology and Biostatistics, Finnish Institute of Occupational Health, Finland

^* To whom correspondence should be addressed. E-mail: a.seidler{at}em.uni-frankfurt.de.

Accepted 27 September 2006

Abstract

Background. Several studies point to a potential etiological relevance to dementia of exposure to low frequency magnetic fields, but the evidence is inconclusive. The aim of the present case-control study is to further examine the relationship between low frequency magnetic fields and dementia. Methods. In 23 general practices we recruited 195 patients with dementia. Of these, 108 were suffering from possible Alzheimers disease, 59 from possible vascular dementia and 28 from secondary or unclassified dementia. A total of 229 control subjects was recruited: 122 population controls and 107 dementia-free ambulatory patients. Data were gathered in a structured personal interview; in cases, the interview was administered to the next-of-kin. Exposure to low-frequency electromagnetic fields was assessment by expert rating. To identify occupations suspected to be associated with dementia, major occupations were a priori formed. Odds ratios were calculated using logistic regression, to control for age, region, sex, dementia in parents, and smoking. Results. Exposure to magnetic fields was not significantly associated with dementia; restriction of the analysis to cases with possible Alzheimers disease or to cases with possible vascular dementia did not lead to statistically significant results. We found an elevated risk of dementia in blue-collar occupations (electrical and electronics workers, metal workers, construction workers, food and beverage processors, and labourers). Conclusions. Our study does not support a strong association between occupational exposure to low frequency magnetic fields and dementia. Further studies should address the relationship between blue-collar work and the later development of dementia.

Keywords: case-control study, dementia, magnetic fields

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