Epidemiological study (observational study)

Work-related exposure to extremely low-frequency magnetic fields and dementia: results from the population-based study of dementia in Swedish twins epidem.

By: Andel R, Crowe M, Feychting M, Pedersen NL, Fratiglioni L, Johansson B, Gatz M

Published in: J Gerontol A Biol Sci Med Sci 2010; 65 (11): 1220-1227

Aim of study (acc. to author)

The association between the work-related exposure to extremely low-frequency magnetic fields and the risk of dementia and Alzheimer disease was studied in participants of the Study of Dementia in Swedish Twins (HARMONY).

Further details

Occupations with elevated exposure to extremely low-frequency EMF included, for example, railway workers (4.03 µT), welders (1.12 µT), forest workers (0.76 µT), cashiers (0.45 µT), retail traders (0.34 µT), post office workers (0.31 µT), cooks (0.31 µT), electrical workers (0.31 µT), dental nurses (0.30 µT), chemical engineers (0.28 µT), train dispatchers (0.25 µT), and dentists (0.24 µT).
Data analysis was conducted with the sample stratified by age of onset (≤ 75 vs. > 75 years), gender, and occupational status (manual vs. nonmanual work).

Endpoint/type of risk estimation

neurodegenerative diseases: dementia, Alzheimer disease

Exposure

- 16 2/3 Hz (train)
- 50/60 Hz
- magnetic field
- occupational

Assessment

interview: kind of occupation during the major part of the working life
job exposure matrix: Swedish job exposure matrix based on EMF measurements in a sample form the general male Swedish population between 1989 and 1991

Exposure groups

Group	Description
Reference group 1	level of work-related exposure to magnetic fields: < 0.12 µT
Group 2	level of work-related exposure to magnetic fields: ≥ 0.12 - < 0.20 µT
Group 3	level of work-related exposure to magnetic fields: ≥ 0.20 µT

Population

Group:
- men
- women
Age: ≥ 65 years
Characteristics: members of the Swedish Twin Registry
Observation period: 1998 - 2002
Study location: Sweden
Data source: Study of Dementia in Swedish Twins (HARMONY)

Study size

Type	Value
Total	20,206
Participants	13,693

Statistical analysis method:

conditional logistic regression

(adjustment:

age
sex
education
complexity of work with people and things, coronary artery disease and stroke

)

Results (acc. to author)

Allover, work-related exposure to extremely low-frequency magnetic fields was not significantly associated with dementia or Alzheimer disease. However, in stratified analyses, medium and high levels of exposure were associated with increased dementia risk in cases with onset by age 75 years and in participants with manual occupations.
The authors conclude that work-related exposure to extremely low-frequency magnetic fields may increase the risk of dementia with an earlier onset and among former manual workers.

Study funded by

Alzheimer's Association, USA
National Institute on Aging (NIA; U.S. National Institutes of Health), Maryland, USA

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