Epidemiological study (observational study)

Occupational exposure to extremely low-frequency magnetic fields and neurodegenerative disease: a meta-analysis epidem.

By: Vergara X, Kheifets L, Greenland S, Oksuzyan S, Cho YS, Mezei G

Published in: J Occup Environ Med 2013; 55 (2): 135-146

Aim of study (acc. to author)

The association between occupational exposure to extremely low-frequency magnetic fields and neurodegenerative disease was evaluated in a meta-analysis based on 42 publications. The occupational exposure to magnetic fields was evaluated using several proxies including actual magnetic field measurements, assignment of exposure based on expert judgment, the use of job exposure matrix, or just occupational titles where magnetic field exposure may have occurred.

Further details

Following studies were included: Andel et al (2010), Davanipour et al (2007), Davanipour et al (1997), Deapen and Henderson (1986), Fang et al (2009), Feychting et al (1998), Feychting et al (2003), Graves et al (1999), Gunnarson et al (1992), Gunnarsson et al (1991), Hakansson et al (2003), Harmanci et al (2003), Johansen (2000), Johansen (1999), Noonan et al (2002), Park et al (2005), Parlett et al (2011), Qiu et al (2004), Röösli et al (2007), Savitz et al (1998), Savitz et al (1998), Schulte et al (1996), Seidler et al (2007), Sobel et al (1996), Sobel et al (1995), Sorahan and Kheifets (2007), Strickland et al (1996), and Weisskopf et al (2005). Additionally, 14 more studies were included in which the job title was given without explicit relation to electromagnetic fields, therefore these studies are not included in the EMF-Portal.

Endpoint/type of risk estimation

neurodegenerative diseases: Alzheimer disease, amyotrophic lateral sclerosis, Parkinson disease, dementia, multiple sclerosis, motor neuron disease

Type of risk estimation:

incidence
mortality
prevalence

Exposure

- 50/60 Hz
- magnetic field
- occupational

Assessment

list: expert judgment; occupational titles where magnetric field exposure may have occurred
job exposure matrix
measurement

Population

Group:
- men
- women
Study location: USA, Nordic countries, Germany, Switzerland, the Netherlands, South Korea, UK

Statistical analysis method:

fixed- and random-effects models, metaregression analysis, heterogeneity, funnel plot

Results (acc. to author)

Weak associations between indicators of occupational magnetic field exposure and both motor neuron disease and Alzheimer disease were observed, and no association between magnetic field exposure and other neurodegenerative outcomes, such as dementia, multiple sclerosis, and Parkinson disease. Motor neuron disease risk was associated with occupational titles, whereas Alzheimer disease risk was associated with estimated magnetic field levels. Results varied in study design (e.g., risk parameter incidence, prevalence or mortality; method of exposure assessment) with dissimilar variation across diseases.
The authors conclude that the results do not support magnetic field exposure as the explanation for observed associations between occupational titles and motor neuron disease. Disease misclassification, particularly for Alzheimer disease, and imprecise exposure assessment affected most studies.

Study funded by

Electric Power Research Institute (EPRI), USA

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