[Exposure to electromagnetic fields and risk of central nervous system diseases among employees at Danish electric companies].
BACKGROUND
Occupational exposure to electromagnetic fields has been associated with neurological diseases, such as amyotrophic lateral sclerosis, senile dementia, Parkinson's disease and Alzheimer's disease.


METHODS
I studied the incidence of disease in the central nervous system in 30,631 persons employed at Danish electric companies between 1900 and 1993. I linked the cohort to the nationwide, population-based Danish National Register of Patients and compared the number of cases of these diseases found between 1978 and 1993 with the corresponding rates in the general population. In addition, I fit the data on utility workers to a multiplicative Poisson regression model in relation to estimated levels of exposure to 50 Hz electromagnetic fields.


RESULTS
Overall, there was an increase in the risk of senile dementia and motor neuron diseases combined. The incidences of Parkinson's disease, Alzheimer's disease and other diseases of the central nervous system were essentially unrelated to exposure to electromagnetic fields. A decreased risk of epilepsy compared with the general population probably reflects a healthy worker effect; I observed an increased risk of epilepsy based on internal comparisons.


CONCLUSIONS
The increased risk of senile dementia and motor neuron diseases may be associated with above average levels of exposure to electromagnetic fields.
Johansen
C
C
Institut for Epidemiologisk Kraeftforskning, Kraeftens Bekaempelse, Strandboulevarden 49, DK-2100 København. christof@cancer.dk
D000544:Alzheimer Disease / Q000453:epidemiology / Q000209:etiology; D001927:Brain Diseases / Q000453:epidemiology / Q000209:etiology*; D015331:Cohort Studies; D004560:Electricity; D004574:Electromagnetic Fields / Q000009:adverse effects*; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D016472:Motor Neuron Disease / Q000453:epidemiology / Q000209:etiology*; D009784:Occupational Diseases / Q000453:epidemiology / Q000209:etiology*; D016273:Occupational Exposure / Q000009:adverse effects*; D011210:Power Plants; D012307:Risk Factors; D013118:Spinal Cord Diseases / Q000453:epidemiology / Q000209:etiology*